init

lib/R_detection/RMS_Dll_global.h

@@ -0,0 +1,12 @@
+#ifndef RMS_DLL_GLOBAL_H
+#define RMS_DLL_GLOBAL_H
+
+#include <QtCore/qglobal.h>
+
+#if defined(RMS_DLL_LIBRARY)
+#  define RMS_DLL_EXPORT Q_DECL_EXPORT
+#else
+#  define RMS_DLL_EXPORT Q_DECL_IMPORT
+#endif
+
+#endif // RMS_DLL_GLOBAL_H

lib/R_detection/rms_dll.h

@@ -0,0 +1,75 @@
+#ifndef RMS_DLL_H
+#define RMS_DLL_H
+#include"qtcpserver.h"
+#include"qtcpsocket.h"
+#include "RMS_Dll_global.h"
+#include <QImage>
+
+class RMS_DLL_EXPORT RMS_Dll
+{
+public:
+    RMS_Dll();
+    int add(int a,int b);
+
+    QVector<double> x;//存储电阻率值
+
+    int isshow = 0;
+    QTcpSocket* _Socket;
+
+    //连接探头
+    bool RMS_Connect(QString IP, quint16 Port);
+
+    //取消连接
+    void RMS_Disconnect();
+
+    //RMS_Read_Empty()调用即空采
+    bool RMS_Read_Empty();
+
+    //正常采集，传入x坐标，y坐标
+    bool RMS_Read(int cx,int cy);
+    double RMS_Read_Single();
+
+    //所有点采集完成后，获取四个值
+    void RMS_ACQ(double *max,double *min,double *med,double *mode);//返回最大值，最小值，中位数，众数
+
+    //传入mode、Pm和Po，获取Pt和Ps
+    void RMS_P(double mode,double *Pt,double *Ps,double Pm,double Po);
+
+    //传入晶锭尺寸size，40、60、80，分别为四英寸、六英寸和八英寸，返回QImage
+    QImage RMS_Image(int size);
+
+
+    //之前tcp传输的点，这回直接用就行
+    QString StrPlotSixInch = "(0,-60)(-30,-50)(-20,-50)(-10,-50)(0,-50)(10,-50)(20,-50)(30,-50)(-40,-40)(-30,-40)(-20,-40)(-10,-40)(0,-40)(10,-40)"
+                         "(20,-40)(30,-40)(40,-40)(-50,-30)(-40,-30)(-30,-30)(-20,-30)(-10,-30)(0,-30)(10,-30)(20,-30)(30,-30)(40,-30)(50,-30)"
+                         "(-50,-20)(-40,-20)(-30,-20)(-20,-20)(-10,-20)(0,-20)(10,-20)(20,-20)(30,-20)(40,-20)(50,-20)(-50,-10)(-40,-10)(-30,-10)"
+                         "(-20,-10)(-10,-10)(0,-10)(10,-10)(20,-10)(30,-10)(40,-10)(50,-10)(-60,0)(-50,0)(-40,0)(-30,0)(-20,0)(-10,0)(0,0)(10,0)"
+                         "(20,0)(30,0)(40,0)(50,0)(60,0)(-50,10)(-40,10)(-30,10)(-20,10)(-10,10)(0,10)(10,10)(20,10)(30,10)(40,10)(50,10)(-50,20)"
+                         "(-40,20)(-30,20)(-20,20)(-10,20)(0,20)(10,20)(20,20)(30,20)(40,20)(50,20)(-50,30)(-40,30)(-30,30)(-20,30)(-10,30)(0,30)"
+                         "(10,30)(20,30)(30,30)(40,30)(50,30)(-40,40)(-30,40)(-20,40)(-10,40)(0,40)(10,40)(20,40)(30,40)(40,40)(-30,50)(-20,50)"
+                         "(-10,50)(0,50)(10,50)(20,50)(30,50)(0,60)";
+    QString StrPlotEightInch = "(-44,-72)(-30,-72)(-16,-72)(-2,-72)(12,-72)(26,-72)(40,-72)(-58,-58)"
+                           "(-44,-58)(-30,-58)(-16,-58)(-2,-58)(12,-58)(26,-58)(40,-58)(54,-58)"
+                           "(-72,-44)(-58,-44)(-44,-44)(-30,-44)(-16,-44)(-2,-44)(12,-44)(26,-44)"
+                           "(40,-44)(54,-44)(68,-44)(-72,-30)(-58,-30)(-44,-30)(-30,-30)(-16,-30)"
+                           "(-2,-30)(12,-30)(26,-30)(40,-30)(54,-30)(68,-30)(-72,-16)(-58,-16)"
+                           "(-44,-16)(-30,-16)(-16,-16)(-2,-16)(12,-16)(26,-16)(40,-16)(54,-16)"
+                           "(68,-16)(82,-16)(-72,-2)(-58,-2)(-44,-2)(-30,-2)(-16,-2)(-2,-2)"
+                           "(12,-2)(26,-2)(40,-2)(54,-2)(68,-2)(82,-2)(-72,12)(-58,12)(-44,12)"
+                           "(-30,12)(-16,12)(-2,12)(12,12)(26,12)(40,12)(54,12)(68,12)(82,12)"
+                           "(-72,26)(-58,26)(-44,26)(-30,26)(-16,26)(-2,26)(12,26)(26,26)(40,26)"
+                           "(54,26)(68,26)(-72,40)(-58,40)(-44,40)(-30,40)(-16,40)(-2,40)(12,40)"
+                           "(26,40)(40,40)(54,40)(68,40)(-58,54)(-44,54)(-30,54)(-16,54)(-2,54)"
+                           "(12,54)(26,54)(40,54)(54,54)(-44,68)(-30,68)(-16,68)(-2,68)(12,68)"
+                           "(26,68)(40,68)(-16,82)(-2,82)(12,82)";
+    QString StrPlotFourInch = "(-2,-44)(-30,-30)(-16,-30)(-2,-30)(12,-30)(26,-30)(-30,-16)(-16,-16)"
+                        "(-2,-16)(12,-16)(26,-16)(40,-16)(-44,-2)(-30,-2)(-16,-2)(-2,-2)(12,-2)"
+                        "(26,-2)(40,-2)(-30,12)(-16,12)(-2,12)(12,12)(26,12)(40,12)(-30,26)(-16,26)"
+                        "(-2,26)(12,26)(26,26)(-16,40)(-2,40)(12,40)";
+
+
+
+
+};
+
+#endif // RMS_DLL_H

lib/actions/rs_actioninterface.cpp

@@ -0,0 +1,326 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include <QKeyEvent>
+#include "rs_actioninterface.h"
+#include "rs_graphicview.h"
+#include "rs_commands.h"
+#include "rs_dialogfactory.h"
+#include "rs_coordinateevent.h"
+#include "rs_debug.h"
+
+/**
+ * Constructor.
+ *
+ * Sets the entity container on which the action class inherited
+ * from this interface operates.
+ *
+ * @param name Action name. This can be used internally for
+ *             debugging mainly.
+ * @param container Entity container this action operates on.
+ * @param graphicView Graphic view instance this action operates on.
+ *                    Please note that an action belongs to this
+ *                    view.
+ * @param cursor Default mouse cursor for this action. If the action
+ *               is suspended and resumed again the cursor will always
+ *               be reset to the one given here.
+ */
+RS_ActionInterface::RS_ActionInterface(const char* name,
+                                       RS_EntityContainer& container,
+                                       RS_GraphicView& graphicView) :
+RS_Snapper(container, graphicView) {
+
+    RS_DEBUG->print("RS_ActionInterface::RS_ActionInterface: Setting up action: \"%s\"", name);
+
+    this->name = name;
+    status = 0;
+    finished = false;
+    //triggerOnResume = false;
+
+    // graphic provides a pointer to the graphic if the
+    // entity container is a graphic (i.e. can also hold
+    // layers).
+    graphic = container.getGraphic();
+
+    // document pointer will be used for undo / redo
+    document = container.getDocument();
+
+    //this->cursor = cursor;
+    //setSnapMode(graphicView.getDefaultSnapMode());
+    actionType=RS2::ActionNone;
+
+    RS_DEBUG->print("RS_ActionInterface::RS_ActionInterface: Setting up action: \"%s\": OK", name);
+
+}
+
+/**
+ * Must be implemented to return the ID of this action.
+*
+* @todo no default implementation
+ */
+RS2::ActionType RS_ActionInterface::rtti() const{
+	return actionType;
+}
+
+/**
+ * @return name of this action
+ */
+QString RS_ActionInterface::getName() {
+    return name;
+}
+
+void RS_ActionInterface::setName(const char* _name) {
+    this->name=_name;
+}
+
+/**
+ * Called to initiate an action. This funtcion is often
+ * overwritten by the implementing action.
+ *
+ * @param status The status on which to initiate this action.
+ * default is 0 to begin the action.
+ */
+void RS_ActionInterface::init(int status)
+{
+    setStatus(status);
+    if (status>=0) {
+        RS_Snapper::init();
+        updateMouseButtonHints();
+        updateMouseCursor();
+    }else{
+        //delete snapper when finished, bug#3416878
+        deleteSnapper();
+
+    }
+}
+
+
+
+/**
+ * Called when the mouse moves and this is the current action.
+ * This function can be overwritten by the implementing action.
+ * The default implementation keeps track of the mouse position.
+ */
+void RS_ActionInterface::mouseMoveEvent(QMouseEvent*) {}
+
+/**
+ * Called when the left mouse button is pressed and this is the
+ * current action.
+ * This function can be overwritten by the implementing action.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::mousePressEvent(QMouseEvent*) {}
+
+/**
+ * Called when the left mouse button is released and this is
+ * the current action.
+ * This function can be overwritten by the implementing action.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::mouseReleaseEvent(QMouseEvent*) {}
+
+/**
+ * Called when a key is pressed and this is the current action.
+ * This function can be overwritten by the implementing action.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::keyPressEvent(QKeyEvent* e) {
+    e->ignore();
+}
+
+/**
+ * Called when a key is released and this is the current action.
+ * This function can be overwritten by the implementing action.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::keyReleaseEvent(QKeyEvent* e) {
+    e->ignore();
+}
+
+/**
+ * Coordinate event. Triggered usually from a command line.
+ * This function can be overwritten by the implementing action.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::coordinateEvent(RS_CoordinateEvent*) {}
+
+/**
+ * Called when a command from the command line is launched.
+ * and this is the current action.
+ * This function can be overwritten by the implementing action.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::commandEvent(RS_CommandEvent*) {
+}
+
+/**
+ * Must be implemented to return the currently available commands
+ *  for the command line.
+ */
+QStringList RS_ActionInterface::getAvailableCommands() {
+	return QStringList{};
+}
+
+/**
+ * Sets the current status (progress) of this action.
+ * The default implementation sets the class variable 'status' to the
+ * given value and finishes the action if 'status' is negative.
+ *
+ * @param status Status number. It's up to the action implementor
+ *               what the action uses the status for. However, a
+ *               negative status number finishes the action. Usually
+ *               the status of an action increases for every step
+ *               of progress and decreases when the user goes one
+ *               step back (i.e. presses the right mouse button).
+ */
+void RS_ActionInterface::setStatus(int status) {
+    this->status = status;
+    updateMouseButtonHints();
+    updateMouseCursor();
+    if(status<0) finish();
+}
+
+/**
+ * @return Current status of this action.
+ */
+int RS_ActionInterface::getStatus() {
+    return status;
+}
+
+/**
+ * Triggers this action. This should be called after all
+ * data needed for this action was collected / set.
+ * The default implementation does nothing.
+ */
+void RS_ActionInterface::trigger() {}
+
+/**
+ * Should be overwritten to update the mouse button hints
+ * wherever they might needed.
+ */
+void RS_ActionInterface::updateMouseButtonHints() {}
+
+/**
+ * Should be overwritten to set the mouse cursor for this action.
+ */
+void RS_ActionInterface::updateMouseCursor() {}
+
+/**
+ * @return true, if the action is finished and can be deleted.
+ */
+bool RS_ActionInterface::isFinished() {
+    return finished;
+}
+
+
+/**
+ * Forces a termination of the action without any cleanup.
+ */
+void RS_ActionInterface::setFinished() {
+        status = -1;
+}
+
+
+/**
+ * Finishes this action.
+ */
+void RS_ActionInterface::finish(bool /*updateTB*/)
+{
+	RS_DEBUG->print("RS_ActionInterface::finish");
+	//refuse to quit the default action
+	if(rtti() != RS2::ActionDefault) {
+		status = -1;
+		finished = true;
+		hideOptions();
+		RS_Snapper::finish();
+	}
+	RS_DEBUG->print("RS_ActionInterface::finish: OK");
+}
+
+/**
+ * Called by the event handler to give this action a chance to
+ * communicate with its predecessor.
+ */
+void RS_ActionInterface::setPredecessor(RS_ActionInterface* pre) {
+    predecessor = pre;
+}
+
+/**
+ * Suspends this action while another action takes place.
+ */
+void RS_ActionInterface::suspend() {
+    RS_Snapper::suspend();
+}
+
+/**
+ * Resumes an action after it was suspended.
+ */
+void RS_ActionInterface::resume() {
+    updateMouseCursor();
+    updateMouseButtonHints();
+    RS_Snapper::resume();
+}
+
+/**
+ * Hides the tool options. Default implementation does nothing.
+ */
+void RS_ActionInterface::hideOptions() {
+    RS_Snapper::hideOptions();
+}
+
+/**
+ * Shows the tool options. Default implementation does nothing.
+ */
+void RS_ActionInterface::showOptions() {
+    RS_Snapper::showOptions();
+}
+
+void RS_ActionInterface::setActionType(RS2::ActionType actionType){
+	this->actionType=actionType;
+}
+
+/**
+ * Calls checkCommand() from the RS_COMMANDS module.
+ */
+bool RS_ActionInterface::checkCommand(const QString& cmd, const QString& str,
+                                      RS2::ActionType action) {
+    return RS_COMMANDS->checkCommand(cmd, str, action);
+}
+
+/**
+ * Calls command() from the RS_COMMANDS module.
+ */
+QString RS_ActionInterface::command(const QString& cmd) {
+    return RS_COMMANDS->command(cmd);
+}
+
+/**
+ * Calls msgAvailableCommands() from the RS_COMMANDS module.
+ */
+QString RS_ActionInterface::msgAvailableCommands() {
+    return RS_COMMANDS->msgAvailableCommands();
+}
+

lib/actions/rs_actioninterface.h

@@ -0,0 +1,161 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_ACTIONINTERFACE_H
+#define RS_ACTIONINTERFACE_H
+
+#include <QObject>
+
+#include "rs_snapper.h"
+
+class QKeyEvent;
+class RS_CommandEvent;
+class RS_CoordinateEvent;
+class RS_Graphic;
+class RS_Document;
+class QAction;
+
+/**
+ * This is the interface that must be implemented for all
+ * action classes. Action classes handle actions such
+ * as drawing lines, moving entities or zooming in.
+ *
+ * Inherited from QObject for Qt translation features.
+ *
+ * @author Andrew Mustun
+ */
+class RS_ActionInterface : public QObject, public RS_Snapper {
+    Q_OBJECT
+public:
+    RS_ActionInterface(const char* name,
+                       RS_EntityContainer& container,
+                       RS_GraphicView& graphicView);
+	virtual ~RS_ActionInterface() = default;
+
+    virtual RS2::ActionType rtti() const;
+
+    void setName(const char* _name);
+    QString getName();
+
+    virtual void init(int status=0);
+    virtual void mouseMoveEvent(QMouseEvent*);
+    virtual void mousePressEvent(QMouseEvent*);
+
+    virtual void mouseReleaseEvent(QMouseEvent*);
+    virtual void keyPressEvent(QKeyEvent* e);
+    virtual void keyReleaseEvent(QKeyEvent* e);
+    virtual void coordinateEvent(RS_CoordinateEvent*);
+    virtual void commandEvent(RS_CommandEvent*);
+    virtual QStringList getAvailableCommands();
+    virtual void setStatus(int status);
+    virtual int getStatus();
+    virtual void trigger();
+    virtual void updateMouseButtonHints();
+    virtual void updateMouseCursor();
+    virtual bool isFinished();
+    virtual void setFinished();
+    virtual void finish(bool updateTB = true );
+    virtual void setPredecessor(RS_ActionInterface* pre);
+    virtual void suspend();
+    virtual void resume();
+    virtual void hideOptions();
+    virtual void showOptions();
+	virtual void setActionType(RS2::ActionType actionType);
+    bool checkCommand(const QString& cmd, const QString& str,
+                             RS2::ActionType action=RS2::ActionNone);
+        QString command(const QString& cmd);
+        QString msgAvailableCommands();
+
+private:
+    /**
+     * Current status of the action. After an action has
+     * been created the action status is set to 0. Actions
+     * that are terminated have a stats of -1. Other status
+     * numbers can be used to describe the stage this action
+     * is in. E.g. a window zoom consists of selecting the
+     * first corner (status 0), and selecting the second
+     * corner (status 1).
+     */
+    int status;
+
+protected:
+    /** Action name. Used internally for debugging */
+    QString name;
+
+    /**
+     * This flag is set when the action has terminated and
+     * can be deleted.
+     */
+    bool finished;
+
+    /**
+     * Pointer to the graphic is this container is a graphic.
+     * NULL otherwise
+     */
+    RS_Graphic* graphic;
+
+        /**
+         * Pointer to the document (graphic or block) or NULL.
+         */
+        RS_Document* document;
+
+    /**
+     * Pointer to the default mouse cursor for this action or NULL.
+     */
+    //RS2::CursorType cursor;
+
+    /**
+     * Predecessor of this action or NULL.
+     */
+    RS_ActionInterface* predecessor;
+
+    /**
+     * String prepended to the help text for currently available commands.
+     */
+    //static QString msgAvailableCommands;
+
+    /**
+     * Command used for showing help for every action.
+     */
+    //static QString cmdHelp;
+
+    /**
+     * Command for answering yes to a question.
+     */
+    //static QString cmdYes;
+    //static QString cmdYes2;
+
+     /**
+     * Command for answering no to a question.
+     */
+    //static QString cmdNo;
+    //static QString cmdNo2;
+    RS2::ActionType actionType;
+};
+
+
+#endif

lib/actions/rs_preview.cpp

@@ -0,0 +1,190 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include "rs_preview.h"
+#include "rs_entitycontainer.h"
+#include "rs_line.h"
+#include "rs_graphicview.h"
+#include "rs_information.h"
+#include "rs_settings.h"
+
+/**
+ * Constructor.
+ */
+RS_Preview::RS_Preview(RS_EntityContainer* parent)
+		: RS_EntityContainer(parent, true) {
+
+    RS_SETTINGS->beginGroup("/Appearance");
+    maxEntities = RS_SETTINGS->readNumEntry("/MaxPreview", 100);
+    RS_SETTINGS->endGroup();
+}
+
+/**
+ * Adds an entity to this preview and removes any attributes / layer
+ * connections before that.
+ */
+void RS_Preview::addEntity(RS_Entity* entity) {
+	if (!entity || entity->isUndone()) {
+        return;
+    }
+
+    // only border preview for complex entities:
+    //if ((entity->count() > maxEntities-count()) &&
+
+    bool addBorder = false;
+
+    if (entity->rtti()==RS2::EntityImage || entity->rtti()==RS2::EntityHatch ||
+                entity->rtti()==RS2::EntityInsert) {
+
+        addBorder = true;
+    } else {
+        if (entity->isContainer() && entity->rtti()!=RS2::EntitySpline) {
+            if (entity->countDeep() > maxEntities-countDeep()) {
+                addBorder = true;
+            }
+        }
+    }
+
+    if (addBorder) {
+        RS_Vector min = entity->getMin();
+        RS_Vector max = entity->getMax();
+
+        RS_Line* l1 =
+			new RS_Line(this, {min.x, min.y}, {max.x, min.y});
+        RS_Line* l2 =
+			new RS_Line(this, {max.x, min.y}, {max.x, max.y});
+        RS_Line* l3 =
+			new RS_Line(this, {max.x, max.y}, {min.x, max.y});
+        RS_Line* l4 =
+			new RS_Line(this, {min.x, max.y}, {min.x, min.y});
+
+        RS_EntityContainer::addEntity(l1);
+        RS_EntityContainer::addEntity(l2);
+        RS_EntityContainer::addEntity(l3);
+        RS_EntityContainer::addEntity(l4);
+
+        delete entity;
+        entity = nullptr;
+    } else {
+        entity->setLayer(nullptr);
+        entity->setSelected(false);
+        entity->reparent(this);
+                // Don't set this pen, let drawing routines decide entity->setPenToActive();
+        RS_EntityContainer::addEntity(entity);
+    }
+}
+
+/**
+ * Clones the given entity and adds the clone to the preview.
+ */
+void RS_Preview::addCloneOf(RS_Entity* entity) {
+    if (!entity) {
+        return;
+    }
+
+    RS_Entity* clone = entity->clone();
+    clone->reparent(this);
+    addEntity(clone);
+}
+
+/**
+ * Adds all entities from 'container' to the preview (unselected).
+ */
+void RS_Preview::addAllFrom(RS_EntityContainer& container) {
+	int c=0;
+	for(auto e: container){
+
+        if (c<maxEntities) {
+            RS_Entity* clone = e->clone();
+            clone->setSelected(false);
+            clone->reparent(this);
+
+            c+=clone->countDeep();
+            addEntity(clone);
+            // clone might be nullptr after this point
+        }
+    }
+}
+
+/**
+ * Adds all selected entities from 'container' to the preview (unselected).
+ */
+void RS_Preview::addSelectionFrom(RS_EntityContainer& container) {
+	int c=0;
+	for(auto e: container){
+
+        if (e->isSelected() && c<maxEntities) {
+            RS_Entity* clone = e->clone();
+            clone->setSelected(false);
+            clone->reparent(this);
+
+            c+=clone->countDeep();
+            addEntity(clone);
+            // clone might be nullptr after this point
+        }
+    }
+}
+
+/**
+ * Adds all entities in the given range and those which have endpoints
+ * in the given range to the preview.
+ */
+void RS_Preview::addStretchablesFrom(RS_EntityContainer& container,
+                                     const RS_Vector& v1, const RS_Vector& v2) {
+    int c=0;
+
+	for(auto e: container){
+
+        if (e->isVisible() &&
+                e->rtti()!=RS2::EntityHatch &&
+                ((e->isInWindow(v1, v2)) ||
+                 e->hasEndpointsWithinWindow(v1, v2)) &&
+
+                c<maxEntities) {
+
+            RS_Entity* clone = e->clone();
+            //clone->setSelected(false);
+            clone->reparent(this);
+
+            c+=clone->countDeep();
+            addEntity(clone);
+            // clone might be nullptr after this point
+        }
+    }
+}
+
+void RS_Preview::draw(RS_Painter* painter, RS_GraphicView* view,
+                              double& patternOffset) {
+
+    if (!(painter && view)) {
+        return;
+    }
+
+    foreach (auto e, entities)
+    {
+        e->draw(painter, view, patternOffset);
+    }
+}

lib/actions/rs_preview.h

@@ -0,0 +1,60 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_PREVIEW_H
+#define RS_PREVIEW_H
+
+#include "rs_entitycontainer.h"
+
+/**
+ * This class supports previewing. The RS_Snapper class uses
+ * an instance of RS_Preview to preview entities, ranges, 
+ * lines, arcs, ... on the fly.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Preview : public RS_EntityContainer {
+public:
+    RS_Preview(RS_EntityContainer* parent=nullptr);
+	~RS_Preview() = default;
+    virtual RS2::EntityType rtti() const override{
+        return RS2::EntityPreview;
+    }
+    virtual void addEntity(RS_Entity* entity) override;
+    void addCloneOf(RS_Entity* entity);
+    virtual void addSelectionFrom(RS_EntityContainer& container);
+    virtual void addAllFrom(RS_EntityContainer& container);
+    virtual void addStretchablesFrom(RS_EntityContainer& container,
+           const RS_Vector& v1, const RS_Vector& v2);
+
+    void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+private:
+	int maxEntities;
+};
+
+#endif

lib/actions/rs_previewactioninterface.cpp

@@ -0,0 +1,130 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include "rs_previewactioninterface.h"
+
+#include "rs_graphicview.h"
+#include "rs_preview.h"
+#include "rs_debug.h"
+
+/**
+ * Constructor.
+ *
+ * Sets the entity container on which the action class inherited
+ * from this interface operates.
+ */
+RS_PreviewActionInterface::RS_PreviewActionInterface(const char* name,
+													 RS_EntityContainer& container,
+													 RS_GraphicView& graphicView) :
+	RS_ActionInterface(name, container, graphicView)
+  ,preview(new RS_Preview(&container))
+//  ,offset(new RS_Vector{})
+{
+
+    RS_DEBUG->print("RS_PreviewActionInterface::RS_PreviewActionInterface: Setting up action with preview: \"%s\"", name);
+
+    // preview is linked to the container for getting access to
+    //   document settings / dictionary variables
+
+    preview->setLayer(NULL);
+    hasPreview = true;
+
+    RS_DEBUG->print("RS_PreviewActionInterface::RS_PreviewActionInterface: Setting up action with preview: \"%s\": OK", name);
+}
+
+
+
+/** Destructor */
+RS_PreviewActionInterface::~RS_PreviewActionInterface() {
+    deletePreview();
+}
+
+
+
+void RS_PreviewActionInterface::init(int status) {
+    deletePreview();
+    RS_ActionInterface::init(status);
+}
+
+
+
+void RS_PreviewActionInterface::finish(bool updateTB) {
+    deletePreview();
+    RS_ActionInterface::finish(updateTB);
+}
+
+
+
+void RS_PreviewActionInterface::suspend() {
+    RS_ActionInterface::suspend();
+    deletePreview();
+}
+
+
+
+void RS_PreviewActionInterface::resume() {
+    RS_ActionInterface::resume();
+    drawPreview();
+}
+
+
+
+void RS_PreviewActionInterface::trigger() {
+    RS_ActionInterface::trigger();
+    deletePreview();
+}
+
+
+/**
+ * Deletes the preview from the screen.
+ */
+void RS_PreviewActionInterface::deletePreview() {
+		if (hasPreview){
+                //avoid deleting NULL or empty preview
+            preview->clear();
+            hasPreview=false;
+        }
+	if(!graphicView->isCleanUp()){
+		graphicView->getOverlayContainer(RS2::ActionPreviewEntity)->clear();
+	}
+}
+
+
+
+/**
+ * Draws / deletes the current preview.
+ */
+void RS_PreviewActionInterface::drawPreview() {
+	// RVT_PORT How does offset work??        painter->setOffset(offset);
+	RS_EntityContainer *container=graphicView->getOverlayContainer(RS2::ActionPreviewEntity);
+	container->clear();
+	container->setOwner(false); // Little hack for now so we don't delete the preview twice
+	container->addEntity(preview.get());
+	graphicView->redraw(RS2::RedrawOverlay);
+	hasPreview=true;
+}
+

lib/actions/rs_previewactioninterface.h

@@ -0,0 +1,69 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_PREVIEWACTIONINTERFACE_H
+#define RS_PREVIEWACTIONINTERFACE_H
+
+#include <memory>
+#include "rs_actioninterface.h"
+
+/**
+ * This is the interface that must be implemented for all
+ * action classes which need a preview.
+ *
+ * @author Andrew Mustun
+ */
+class RS_PreviewActionInterface : public RS_ActionInterface {
+public:
+    RS_PreviewActionInterface(const char* name,
+                              RS_EntityContainer& container,
+                              RS_GraphicView& graphicView);
+	~RS_PreviewActionInterface() override;
+
+	void init(int status=0) override;
+	void finish(bool updateTB=true) override;
+	void suspend() override;
+	void resume() override;
+	void trigger() override;
+    void drawPreview();
+    void deletePreview();
+
+private:
+
+protected:
+    /**
+     * Preview that holds the entities to be previewed.
+     */
+	std::unique_ptr<RS_Preview> preview;
+    bool hasPreview;//whether preview is in use
+//    /**
+//     * Current offset of the preview.
+//     */
+//	std::unique_ptr<RS_Vector> offset;
+};
+
+#endif

lib/actions/rs_snapper.h

@@ -0,0 +1,237 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#ifndef RS_SNAPPER_H
+#define RS_SNAPPER_H
+
+#include<memory>
+#include "rs.h"
+
+class RS_Entity;
+class RS_GraphicView;
+class RS_Vector;
+class RS_Preview;
+class QMouseEvent;
+class RS_EntityContainer;
+
+/**
+  * This class holds information on how to snap the mouse.
+  *
+  * @author Kevin Cox
+  */
+struct RS_SnapMode {
+    /* SnapModes for RS_SnapMode to Int conversion and vice versa
+     *
+     * The conversion is only used for save/restore of active snap modes in application settings.
+     * Don't change existing mode order, because this will mess up settings on upgrades
+     *
+     * When adding new values, take care for correct implementation in \p toInt() and \p fromInt()
+     */
+    enum SnapModes {
+        SnapIntersection    = 1 << 0,
+        SnapOnEntity        = 1 << 1,
+        SnapCenter          = 1 << 2,
+        SnapDistance        = 1 << 3,
+        SnapMiddle          = 1 << 4,
+        SnapEndpoint        = 1 << 5,
+        SnapGrid            = 1 << 6,
+        SnapFree            = 1 << 7,
+        RestrictHorizontal  = 1 << 8,
+        RestrictVertical    = 1 << 9,
+        RestrictOrthogonal  = RestrictHorizontal | RestrictVertical,
+        SnapAngle           = 1 << 10
+    };
+
+    bool snapIntersection   {false}; //< Whether to snap to intersections or not.
+    bool snapOnEntity       {false}; //< Whether to snap to entities or not.
+    bool snapCenter         {false}; //< Whether to snap to centers or not.
+    bool snapDistance       {false}; //< Whether to snap to distance from endpoints or not.
+    bool snapMiddle         {false}; //< Whether to snap to midpoints or not.
+    bool snapEndpoint       {false}; //< Whether to snap to endpoints or not.
+    bool snapGrid           {false}; //< Whether to snap to grid or not.
+    bool snapFree           {false}; //< Whether to snap freely
+    bool snapAngle          {false}; //< Whether to snap along line under certain angle
+
+    RS2::SnapRestriction restriction {RS2::RestrictNothing}; /// The restriction on the free snap.
+
+    double distance {5.0}; //< The distance to snap before defaulting to free snapping.
+
+    /**
+      * Disable all snapping.
+      *
+      * This effectively puts the object into free snap mode.
+      *
+      * @returns A reference to itself.
+      */
+    RS_SnapMode const & clear(void);
+    bool operator == (RS_SnapMode const& rhs) const;
+
+    static uint toInt(const RS_SnapMode& s);    //< convert to int, to save settings
+    static RS_SnapMode fromInt(unsigned int);   //< convert from int, to restore settings
+};
+
+typedef std::initializer_list<RS2::EntityType> EntityTypeList;
+
+/**
+ * This class is used for snapping functions in a graphic view.
+ * Actions are usually derived from this base class if they need
+ * to catch entities or snap to coordinates. Use the methods to
+ * retrieve a graphic coordinate from a mouse coordinate.
+ *
+ * Possible snapping functions are described in RS_SnapMode.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Snapper {
+public:
+	RS_Snapper() = delete;
+    RS_Snapper(RS_EntityContainer& container, RS_GraphicView& graphicView);
+	virtual ~RS_Snapper();
+
+    void init();
+	//!
+	//! \brief finish stop using snapper
+	//!
+        void finish();
+
+    /**
+     * @return Pointer to the entity which was the key entity for the
+     * last successful snapping action. If the snap mode is "end point"
+     * the key entity is the entity whose end point was caught.
+     * If the snap mode didn't require an entity (e.g. free, grid) this
+     * method will return NULL.
+     */
+	RS_Entity* getKeyEntity() const {
+        return keyEntity;
+    }
+
+    /** Sets a new snap mode. */
+    void setSnapMode(const RS_SnapMode& snapMode);
+
+	RS_SnapMode const* getSnapMode() const;
+	RS_SnapMode* getSnapMode();
+
+    /** Sets a new snap restriction. */
+    void setSnapRestriction(RS2::SnapRestriction /*snapRes*/) {
+        //this->snapRes = snapRes;
+    }
+
+        /**
+         * Sets the snap range in pixels for catchEntity().
+         *
+         * @see catchEntity()
+         */
+        void setSnapRange(int r) {
+                snapRange = r;
+        }
+
+        /**manually set snapPoint*/
+    RS_Vector snapPoint(const RS_Vector& coord, bool setSpot = false);
+    RS_Vector snapPoint(QMouseEvent* e);
+    RS_Vector snapFree(QMouseEvent* e);
+
+    RS_Vector snapFree(const RS_Vector& coord);
+    RS_Vector snapGrid(const RS_Vector& coord);
+    RS_Vector snapEndpoint(const RS_Vector& coord);
+    RS_Vector snapOnEntity(const RS_Vector& coord);
+    RS_Vector snapCenter(const RS_Vector& coord);
+    RS_Vector snapMiddle(const RS_Vector& coord);
+    RS_Vector snapDist(const RS_Vector& coord);
+    RS_Vector snapIntersection(const RS_Vector& coord);
+    //RS_Vector snapDirect(RS_Vector coord, bool abs);
+    RS_Vector snapToAngle(const RS_Vector &coord, const RS_Vector &ref_coord, const double ang_res);
+
+    RS_Vector restrictOrthogonal(const RS_Vector& coord);
+    RS_Vector restrictHorizontal(const RS_Vector& coord);
+    RS_Vector restrictVertical(const RS_Vector& coord);
+
+
+    //RS_Entity* catchLeafEntity(const RS_Vector& pos);
+    //RS_Entity* catchLeafEntity(QMouseEvent* e);
+    RS_Entity* catchEntity(const RS_Vector& pos,
+                           RS2::ResolveLevel level=RS2::ResolveNone);
+    RS_Entity* catchEntity(QMouseEvent* e,
+                           RS2::ResolveLevel level=RS2::ResolveNone);
+    // catch Entity closest to pos and of the given entity type of enType, only search for a particular entity type
+    RS_Entity* catchEntity(const RS_Vector& pos, RS2::EntityType enType,
+                           RS2::ResolveLevel level=RS2::ResolveNone);
+    RS_Entity* catchEntity(QMouseEvent* e, RS2::EntityType enType,
+                           RS2::ResolveLevel level=RS2::ResolveNone);
+	RS_Entity* catchEntity(QMouseEvent* e, const EntityTypeList& enTypeList,
+                           RS2::ResolveLevel level=RS2::ResolveNone);
+
+    /**
+     * Suspends this snapper while another action takes place.
+     */
+	virtual void suspend();
+
+    /**
+     * Resumes this snapper after it has been suspended.
+     */
+    virtual void resume() {
+        drawSnapper();
+    }
+
+    virtual void hideOptions();
+    virtual void showOptions();
+
+    void drawSnapper();
+
+protected:
+    void deleteSnapper();
+    double getSnapRange() const;
+    RS_EntityContainer* container;
+    RS_GraphicView* graphicView;
+	RS_Entity* keyEntity;
+    RS_SnapMode snapMode;
+    //RS2::SnapRestriction snapRes;
+    /**
+     * Snap distance for snapping to points with a
+     * given distance from endpoints.
+     */
+	double m_SnapDistance;
+    /**
+     * Snap to equidistant middle points
+     * default to 1, i.e., equidistant to start/end points
+     */
+    int middlePoints;
+    /**
+     * Snap range for catching entities.
+     */
+    int snapRange;
+    bool finished{false};
+
+private:
+	struct ImpData;
+	std::unique_ptr<ImpData> pImpData;
+
+    struct Indicator;
+    Indicator* snap_indicator{nullptr};
+};
+
+#endif
+//EOF

lib/coordinate/coordinate.h

@@ -0,0 +1,24 @@
+#ifndef COORDINATE_H
+#define COORDINATE_H
+
+#include <QtCore/qglobal.h>
+
+#if defined(COORDINATE_LIBRARY)
+#  define COORDINATESHARED_EXPORT Q_DECL_EXPORT
+#else
+#  define COORDINATESHARED_EXPORT Q_DECL_IMPORT
+#endif
+
+class COORDINATESHARED_EXPORT Coordinate
+{
+
+public:
+    Coordinate();
+
+    int add(int a,int b);
+    void getCoordinate(QVector<QVector<int>> **vec,int *row,int *col);
+
+
+};
+
+#endif // COORDINATE_H

lib/creation/rs_creation.h

@@ -0,0 +1,164 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_CREATION_H
+#define RS_CREATION_H
+
+#include "rs_vector.h"
+
+class RS_Document;
+class RS_EntityContainer;
+class RS_GraphicView;
+class RS_Graphic;
+class RS_Entity;
+class RS_Arc;
+class RS_Circle;
+class RS_Ellipse;
+class RS_Line;
+class LC_SplinePoints;
+struct RS_BlockData;
+struct RS_ImageData;
+class RS_Image;
+struct RS_InsertData;
+class RS_Insert;
+class RS_Block;
+class QString;
+
+/**
+ * Data needed to insert library items.
+ */
+struct RS_LibraryInsertData {
+    QString file;
+    RS_Vector insertionPoint;
+    double factor;
+    double angle;
+};
+
+
+/**
+ * Class for the creation of new entities.
+ * This class is bound to an entity container in which the
+ * entities are stored. 
+ *
+ * @author Andrew Mustun
+ */
+class RS_Creation {
+public:
+    RS_Creation(RS_EntityContainer* container,
+                RS_GraphicView* graphicView=nullptr,
+                bool handleUndo=true);
+    ~RS_Creation()=default;
+
+    RS_Entity* createParallelThrough(const RS_Vector& coord,
+                                     int number,
+                                     RS_Entity* e);
+
+    RS_Entity* createParallel(const RS_Vector& coord,
+                              double distance,
+                              int number,
+                              RS_Entity* e);
+
+    RS_Line* createParallelLine(const RS_Vector& coord,
+                                double distance, int number,
+                                RS_Line* e);
+
+    RS_Arc* createParallelArc(const RS_Vector& coord,
+                              double distance, int number,
+                              RS_Arc* e);
+
+    RS_Circle* createParallelCircle(const RS_Vector& coord,
+                                    double distance, int number,
+                                    RS_Circle* e);
+
+    LC_SplinePoints* createParallelSplinePoints(const RS_Vector& coord,
+                                                double distance, int number,
+                                                LC_SplinePoints* e);
+
+    RS_Line* createBisector(const RS_Vector& coord1,
+                            const RS_Vector& coord2,
+                            double length,
+                            int num,
+                            RS_Line* l1,
+                            RS_Line* l2);
+
+    RS_Line* createTangent1(const RS_Vector& coord,
+                            const RS_Vector& point,
+                            RS_Entity* circle);
+/**
+ * create a tangent line which is orthogonal to the given RS_Line(normal)
+ */
+    RS_Line* createLineOrthTan(const RS_Vector& coord,
+                               RS_Line* normal,
+                               RS_Entity* circle);
+    RS_Line* createTangent2(const RS_Vector& coord,
+                            RS_Entity* circle1,
+                            RS_Entity* circle2);
+    /**
+      * create the path of centers of common tangent circles of the two given circles
+      *@ return nullptr, if failed
+      *@ at success return either an ellipse or hyperbola
+      */
+    std::vector<RS_Entity*> createCircleTangent2( RS_Entity* circle1,RS_Entity* circle2);
+
+    RS_Line* createLineRelAngle(const RS_Vector& coord,
+                                RS_Entity* entity,
+                                double angle,
+                                double length);
+
+    RS_Line* createPolygon(const RS_Vector& center,
+                           const RS_Vector& corner,
+                           int number);
+
+    RS_Line* createPolygon2(const RS_Vector& corner1,
+                            const RS_Vector& corner2,
+                            int number);
+
+    RS_Line* createPolygon3(const RS_Vector& center,
+                            const RS_Vector& tangent,
+                            int number);
+
+    RS_Insert* createInsert(const RS_InsertData* pdata);
+
+    RS_Image* createImage(const RS_ImageData* pdata);
+
+    RS_Block* createBlock(const RS_BlockData* data,
+                          const RS_Vector& referencePoint,
+                          const bool remove);
+
+    RS_Insert* createLibraryInsert(RS_LibraryInsertData& data);
+
+protected:
+    RS_EntityContainer* container;
+    RS_Graphic* graphic;
+    RS_Document* document;
+    RS_GraphicView* graphicView;
+    bool handleUndo;
+private:
+    void setEntity(RS_Entity* en) const;
+};
+
+#endif

lib/debug/rs_debug.cpp

@@ -0,0 +1,180 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#include "rs_debug.h"
+
+#include <iostream>
+#include <cstdio>
+#include <cstdarg>
+#include <QString>
+
+#include <QDateTime>
+#include <QDebug>
+
+RS_Debug* RS_Debug::uniqueInstance = nullptr;
+void debugHeader(char const* file, char const* func, int line)
+{
+	std::cout<<file<<" : "<<func<<" : line "<<line<<std::endl;
+}
+
+/**
+ *  Gets the one and only RS_Debug instance
+ *  (creates a new one on first call only)
+ *
+ *  @return Pointer to the single instance of this
+ * singleton class
+ */
+RS_Debug* RS_Debug::instance() {
+	if(!uniqueInstance) {
+        QDateTime now = QDateTime::currentDateTime();
+        QString nowStr;
+		nowStr = now.toString("yyyyMMdd_hhmmss");
+
+        //QString fName = QString("%1/debug_%2.log")
+		//	.arg(RS_SYSTEM->getHomeDir())
+		//	.arg(nowStr);
+        // 定义打印日志名称
+        QString fName = QString("debug_%1.log").arg(nowStr);
+
+        uniqueInstance = new RS_Debug;
+        // 获取日志文件句柄
+        //uniqueInstance->stream = fopen(fName.latin1(), "wt");
+        uniqueInstance->stream = stderr;
+    }
+    return uniqueInstance;
+}
+
+
+/**
+ * Deletes the one and only RS_Debug instance.
+ */
+void
+RS_Debug::deleteInstance() {
+    if (uniqueInstance) {
+        fclose(uniqueInstance->stream);
+        delete uniqueInstance;
+    }
+}
+
+/**
+ * Constructor setting the default debug level.
+ */
+RS_Debug::RS_Debug()
+{
+    debugLevel = D_DEBUGGING;
+}
+
+/**
+ * Sets the debugging level.
+ */
+void RS_Debug::setLevel(RS_DebugLevel level) {
+    if(debugLevel==level) return;
+    debugLevel = level;
+    print( D_NOTHING, "RS_DEBUG::setLevel(%d)", level);
+    print( D_CRITICAL, "RS_DEBUG: Critical");
+    print( D_ERROR, "RS_DEBUG: Errors");
+    print( D_WARNING, "RS_DEBUG: Warnings");
+    print( D_NOTICE, "RS_DEBUG: Notice");
+    print( D_INFORMATIONAL, "RS_DEBUG: Informational");
+    print( D_DEBUGGING, "RS_DEBUG: Debugging");
+}
+
+
+/**
+ * Gets the current debugging level.
+ */
+RS_Debug::RS_DebugLevel RS_Debug::getLevel() {
+    return debugLevel;
+}
+
+
+/**
+ * Prints the given message to stdout.
+ * 实现把文本字符串写入文件，并且文本字符可以带多个格式参数
+ */
+void RS_Debug::print(const char* format ...) {
+    if(debugLevel==D_DEBUGGING) {
+        // 定义可变参数指针
+        va_list ap;
+        // 初始化可变参数指针，指向第一个可变参数
+        va_start(ap, format);
+        // 使用参数列表发送格式化输出到流 stream 中
+        // 参数1：这是指向 FILE 对象的指针，该 FILE 对象标识了流
+        // 参数2：这是 C 字符串，包含了要被写入到流 stream 中的文本。它可以包含嵌入的 format 标签，format 标签可被随后的附加参数中指定的值替换，并按需求进行格式化。
+        // 参数3：可变参数指针
+        vfprintf(stream, format, ap);
+        fprintf(stream, "\n");
+        va_end(ap);
+        fflush(stream);
+    }
+}
+
+/**
+ * Prints the given message to stdout if the current debug level
+ * is lower then the given level
+ *
+ * @param level Debug level.
+ */
+void RS_Debug::print(RS_DebugLevel level, const char* format ...) {
+
+    if(debugLevel>=level) {
+        va_list ap;
+        va_start(ap, format);
+        vfprintf(stream, format, ap);
+        fprintf(stream, "\n");
+        va_end(ap);
+        fflush(stream);
+    }
+
+}
+
+
+/**
+ * Prints a time stamp in the format yyyyMMdd_hhmmss.
+ */
+void RS_Debug::timestamp() {
+    QDateTime now = QDateTime::currentDateTime();
+    QString nowStr;
+
+	nowStr = now.toString("yyyyMMdd_hh:mm:ss:zzz ");
+    fprintf(stream, "%s", nowStr.toLatin1().data());
+    fprintf(stream, "\n");
+    fflush(stream);
+}
+
+
+/**
+ * Prints the unicode for every character in the given string.
+ */
+void RS_Debug::printUnicode(const QString& text) {
+	for(auto const& v: text){
+		print("[%X] %c", v.unicode(), v.toLatin1());
+    }
+}
+
+
+// EOF

lib/debug/rs_debug.h

@@ -0,0 +1,109 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_DEBUG_H
+#define RS_DEBUG_H
+
+#include <iosfwd>
+#ifdef __hpux
+#include <sys/_size_t.h>
+#endif
+#include<QObject>
+
+class QString;
+
+/** print out a debug header*/
+#define DEBUG_HEADER debugHeader(__FILE__, __func__, __LINE__);
+void debugHeader(char const* file, char const* func, int line);
+#define RS_DEBUG RS_Debug::instance()
+#define RS_DEBUG_VERBOSE DEBUG_HEADER \
+	RS_Debug::instance()
+
+/**
+ * Debugging facilities.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Debug:public QObject
+{
+    Q_OBJECT
+public:
+    /**
+     * Enum for debug levels. Only messages of the current
+     * or a higher level are printed.
+     * <ul>
+     *  <li>D_NOTHING:  nothing
+     *  <li>D_CRITICAL: critical messages
+     *  <li>D_ERROR:    errors
+     *  <li>D_WARNING:  warnings
+     *  <li>D_NOTICE:   notes
+     *  <li>D_INFORMATIONAL: infos
+     *  <li>D_DEBUGGING: very verbose
+     * </ul>
+     */
+    enum RS_DebugLevel { D_NOTHING,
+                         D_CRITICAL,
+                         D_ERROR,
+                         D_WARNING,
+                         D_NOTICE,
+                         D_INFORMATIONAL,
+                         D_DEBUGGING };
+
+private:
+    RS_Debug();
+	RS_Debug(const RS_Debug&)=delete;
+	RS_Debug& operator = (const RS_Debug&)=delete;
+	RS_Debug(RS_Debug&&)=delete;
+	RS_Debug& operator = (RS_Debug&&)=delete;
+
+
+
+public:
+    static RS_Debug* instance();
+
+    static void deleteInstance();
+    void setLevel(RS_DebugLevel level);
+    RS_DebugLevel getLevel();
+    void print(RS_DebugLevel level, const char* format ...);
+    void print(const char* format ...);
+
+
+    void printUnicode(const QString& text);
+    void timestamp();
+    void setStream(FILE* s) {
+        stream = s;
+    }
+
+private:
+    static RS_Debug* uniqueInstance;
+
+    RS_DebugLevel debugLevel;
+    FILE* stream;
+};
+
+#endif
+// EOF

lib/engine/lc_hyperbola.cpp

@@ -0,0 +1,202 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include "lc_hyperbola.h"
+
+#include "rs_graphic.h"
+#include "rs_graphicview.h"
+#include "rs_painter.h"
+#include "rs_information.h"
+#include "rs_linetypepattern.h"
+#include "lc_quadratic.h"
+
+LC_HyperbolaData::LC_HyperbolaData(const RS_Vector& _center,
+			   const RS_Vector& _majorP,
+			   double _ratio,
+			   double _angle1, double _angle2,
+			   bool _reversed):
+	center(_center)
+	,majorP(_majorP)
+	,ratio(_ratio)
+	,angle1(_angle1)
+	,angle2(_angle2)
+	,reversed(_reversed)
+{
+}
+
+std::ostream& operator << (std::ostream& os, const LC_HyperbolaData& ed) {
+	os << "(" << ed.center <<
+	   "/" << ed.majorP <<
+	   " " << ed.ratio <<
+	   " " << ed.angle1 <<
+	   "," << ed.angle2 <<
+	   ")";
+	return os;
+}
+
+#ifdef EMU_C99
+#include "emu_c99.h" /* C99 math */
+#endif
+
+/**
+ * Constructor.
+ */
+LC_Hyperbola::LC_Hyperbola(RS_EntityContainer* parent,
+                       const LC_HyperbolaData& d)
+    :RS_AtomicEntity(parent)
+    ,data(d)
+    ,m_bValid(true)
+{
+    if(data.majorP.squared()<RS_TOLERANCE2) {
+        m_bValid=false;
+        return;
+    }
+    //calculateEndpoints();
+    calculateBorders();
+}
+
+/** create data based on foci and a point on hyperbola */
+LC_HyperbolaData::LC_HyperbolaData(const RS_Vector& focus0,
+                 const RS_Vector& focus1,
+                 const RS_Vector& point):
+    center((focus0+focus1)*0.5)
+{
+    double ds0=focus0.distanceTo(point);
+    ds0 -= focus1.distanceTo(point);
+
+    majorP= (ds0>0.)?focus0-center:focus1-center;
+    double dc=focus0.distanceTo(focus1);
+    double dd=fabs(ds0);
+    //no hyperbola for middle equidistant
+    if(dc<RS_TOLERANCE||dd<RS_TOLERANCE) {
+        majorP.set(0.,0.);
+        return;
+    }
+    ratio= dc/dd;
+    majorP /= ratio;
+    ratio=sqrt(ratio*ratio - 1.);
+
+}
+
+///** create data based on foci and a point on hyperbola */
+//LC_Hyperbola::LC_Hyperbola(const RS_Vector& focus0,
+//                 const RS_Vector& focus1,
+//                 const RS_Vector& point):
+//    data(focus0,focus1,point)
+//{
+//    m_bValid = data.majorP.squared()> RS_TOLERANCE2;
+//}
+/**
+ * Recalculates the endpoints using the angles and the radius.
+ */
+/*
+void LC_Hyperbola::calculateEndpoints() {
+   double angle = data.majorP.angle();
+   double radius1 = getMajorRadius();
+   double radius2 = getMinorRadius();
+
+   startpoint.set(data.center.x + cos(data.angle1) * radius1,
+                  data.center.y + sin(data.angle1) * radius2);
+   startpoint.rotate(data.center, angle);
+   endpoint.set(data.center.x + cos(data.angle2) * radius1,
+                data.center.y + sin(data.angle2) * radius2);
+   endpoint.rotate(data.center, angle);
+}
+*/
+
+
+/**
+ * Calculates the boundary box of this ellipse.
+ */
+
+
+RS_Entity* LC_Hyperbola::clone() const {
+	LC_Hyperbola* e = new LC_Hyperbola(*this);
+	e->initId();
+	return e;
+}
+
+
+/**
+  * return the foci of ellipse
+  *
+  *@Author: Dongxu Li
+  */
+
+RS_VectorSolutions LC_Hyperbola::getFoci() const {
+    RS_Vector vp(getMajorP()*sqrt(1.-getRatio()*getRatio()));
+	return RS_VectorSolutions({getCenter()+vp, getCenter()-vp});
+}
+
+RS_VectorSolutions LC_Hyperbola::getRefPoints() const{
+	RS_VectorSolutions ret({data.center});
+    ret.push_back(getFoci());
+    return ret;
+}
+
+bool LC_Hyperbola::isPointOnEntity(const RS_Vector& coord,
+                             double tolerance) const
+{
+    double a=data.majorP.magnitude();
+    double b=a*data.ratio;
+    if(fabs(a)<tolerance || fabs(b)<tolerance) return false;
+    RS_Vector vp(coord - data.center);
+    vp=vp.rotate(-data.majorP.angle());
+    return fabs( vp.x*vp.x/(a*a)- vp.y*vp.y/(b*b) -1.)<tolerance;
+}
+
+
+LC_Quadratic LC_Hyperbola::getQuadratic() const
+{
+    std::vector<double> ce(6,0.);
+    ce[0]=data.majorP.squared();
+    ce[2]=-data.ratio*data.ratio*ce[0];
+    if(ce[0]>RS_TOLERANCE2) ce[0]=1./ce[0];
+    if(fabs(ce[2])>RS_TOLERANCE2) ce[2]=1./ce[2];
+    ce[5]=-1.;
+    LC_Quadratic ret(ce);
+    if(ce[0]<RS_TOLERANCE2 || fabs(ce[2])<RS_TOLERANCE2) {
+		ret.setValid(false);
+        return ret;
+    }
+    ret.rotate(data.majorP.angle());
+    ret.move(data.center);
+    return ret;
+}
+
+//RS_Vector LC_Hyperbola::getNearestEndpoint(const RS_Vector& /*coord*/,
+//                                         double* /*dist*/ = NULL) const
+//{
+//}
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const LC_Hyperbola& a) {
+    os << " Hyperbola: " << a.data << "\n";
+    return os;
+}
+

lib/engine/lc_hyperbola.h

@@ -0,0 +1,262 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2011-2012 Dongxu Li (dongxuli2011@gmail.com)
+
+Copyright (C) 2012 Dongxu Li (dongxuli2011@gmail.com)
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+**********************************************************************/
+
+
+#ifndef LC_HYPERBOLA_H
+#define LC_HYPERBOLA_H
+
+#include "rs_atomicentity.h"
+
+class RS_Circle;
+class LC_Quadratic;
+
+/**
+ * Holds the data that defines one branch of a hyperbola.
+ * majorP is the vector from center to the vertex
+ * ratio is the ratio between semi-major and semi-minor axis
+
+ */
+struct LC_HyperbolaData {
+	LC_HyperbolaData() = default;
+	LC_HyperbolaData(const RS_Vector& center,
+					 const RS_Vector& majorP,
+					 double ratio,
+					 double angle1, double angle2,
+					 bool reversed);
+	~LC_HyperbolaData() = default;
+	/** create data based on foci and a point on hyperbola */
+	LC_HyperbolaData(const RS_Vector& focus0,
+					 const RS_Vector& focus1,
+					 const RS_Vector& point);
+
+	//! Hyperbola center
+	RS_Vector center;
+	//! Endpoint of major axis relative to center.
+	RS_Vector majorP;
+	//! Ratio of minor axis to major axis.
+	double ratio;
+	//! Start angle
+	double angle1;
+	//! End angle
+	double angle2;
+	//! Reversed (cw) flag
+	bool reversed;
+};
+
+std::ostream& operator << (std::ostream& os, const LC_HyperbolaData& ed);
+
+
+/**
+ * Class for an hyperbola entity.
+ *
+ * @author Dongxu Li
+ */
+class LC_Hyperbola : public RS_AtomicEntity {
+public:
+	LC_Hyperbola() = default;
+    LC_Hyperbola(RS_EntityContainer* parent,
+               const LC_HyperbolaData& d);
+
+    /** create data based on foci and a point on hyperbola */
+    LC_Hyperbola(const RS_Vector& focus0,
+                     const RS_Vector& focus1,
+                     const RS_Vector& point);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityHyperbola */
+	RS2::EntityType rtti() const  override{
+        return RS2::EntityHyperbola;
+    }
+	bool isValid() const{
+        return m_bValid;
+    }
+
+
+
+//    double getLength() const;
+
+//    /**
+//    //Hyperbola must have ratio<1, and not reversed
+//    *@ x1, hyperbola angle
+//    *@ x2, hyperbola angle
+//    //@return the arc length between hyperbola angle x1, x2
+//    **/
+//    double getHyperbolaLength(double a1, double a2) const;
+//    double getHyperbolaLength(double a2) const;
+
+
+    /** @return Copy of data that defines the hyperbola. **/
+    LC_HyperbolaData getData() const {
+        return data;
+    }
+	RS_VectorSolutions getFoci() const;
+	RS_VectorSolutions getRefPoints() const override;
+
+    /**
+     * @retval true if the arc is reversed (clockwise),
+     * @retval false otherwise
+     */
+	bool isReversed() const{
+        return data.reversed;
+    }
+    /** sets the reversed status. */
+	void setReversed(bool r){
+        data.reversed = r;
+    }
+
+    /** @return The rotation angle of this hyperbola */
+	double getAngle() const {
+        return data.majorP.angle();
+    }
+
+    /** @return The start angle of this arc */
+    double getAngle1() const {
+        return data.angle1;
+    }
+    /** Sets new start angle. */
+    void setAngle1(double a1) {
+        data.angle1 = a1;
+    }
+    /** @return The end angle of this arc */
+    double getAngle2() const {
+        return data.angle2;
+    }
+    /** Sets new end angle. */
+    void setAngle2(double a2) {
+        data.angle2 = a2;
+    }
+
+
+    /** @return The center point (x) of this arc */
+	RS_Vector getCenter() const override{
+        return data.center;
+    }
+    /** Sets new center. */
+    void setCenter(const RS_Vector& c) {
+        data.center = c;
+    }
+
+    /** @return The endpoint of the major axis (relative to center). */
+    RS_Vector getMajorP() const {
+        return data.majorP;
+    }
+    /** Sets new major point (relative to center). */
+    void setMajorP(const RS_Vector& p) {
+        data.majorP = p;
+    }
+
+    /** @return The ratio of minor to major axis */
+    double getRatio() const {
+        return data.ratio;
+    }
+    /** Sets new ratio. */
+    void setRatio(double r) {
+        data.ratio = r;
+    }
+
+
+    /** @return The major radius of this hyperbola. Same as getRadius() */
+    double getMajorRadius() const {
+        return data.majorP.magnitude();
+    }
+
+    /** @return The minor radius of this hyperbola */
+    double getMinorRadius() const {
+        return data.majorP.magnitude()*data.ratio;
+    }
+
+	void calculateBorders() override{}
+
+	RS_Vector getMiddlePoint(void)const override{return RS_Vector(false);}
+	RS_Vector getNearestEndpoint(const RS_Vector& /*coord*/,
+										 double*/* dist = NULL*/) const override
+    {return RS_Vector(false);}
+	RS_Vector getNearestPointOnEntity(const RS_Vector& /*coord*/,
+			bool /*onEntity = true*/, double*/* dist = NULL*/, RS_Entity**/* entity=NULL*/) const override
+    {return RS_Vector(false);}
+	RS_Vector getNearestCenter(const RS_Vector& /*coord*/,
+									   double*/* dist = NULL*/) const override
+   {return RS_Vector(false);}
+	RS_Vector getNearestMiddle(const RS_Vector& /*coord*/,
+                                       double*/* dist = NULL*/,
+                                       int/* middlePoints = 1*/
+									   )const override
+   {return RS_Vector(false);}
+	RS_Vector getNearestDist(double /*distance*/,
+                                     const RS_Vector&/* coord*/,
+									 double*/* dist = NULL*/) const override
+    {return RS_Vector(false);}
+	RS_Vector getNearestOrthTan(const RS_Vector& /*coord*/,
+                                    const RS_Line& /*normal*/,
+									 bool /*onEntity = false*/) const override
+    {return RS_Vector(false);}
+	double getDistanceToPoint(const RS_Vector& /*coord*/,
+                                      RS_Entity** /*entity=NULL*/,
+                                      RS2::ResolveLevel/* level=RS2::ResolveNone*/,
+									  double /*solidDist = RS_MAXDOUBLE*/) const override
+    {return RS_MAXDOUBLE;}
+	bool isPointOnEntity(const RS_Vector& /*coord*/,
+								 double /*tolerance=RS_TOLERANCE*/) const override;
+
+	void move(const RS_Vector& /*offset*/) override{}
+	void rotate(const double& /*angle*/) {}
+	void rotate(const RS_Vector& /*angleVector*/){}
+	void rotate(const RS_Vector& /*center*/, const double& /*angle*/) override{}
+	void rotate(const RS_Vector& /*center*/, const RS_Vector& /*angle*/)override{}
+	void scale(const RS_Vector& /*center*/, const RS_Vector& /*factor*/)override{}
+	void mirror(const RS_Vector& /*axisPoint1*/, const RS_Vector& /*axisPoint2*/)override{}
+	void moveRef(const RS_Vector& /*ref*/, const RS_Vector& /*offset*/)override{}
+
+	void draw(RS_Painter* /*painter*/, RS_GraphicView* /*view*/, double& /*patternOffset*/)override{}
+
+    friend std::ostream& operator << (std::ostream& os, const LC_Hyperbola& a);
+
+	//void calculateEndpoints();
+//    void calculateBorders();
+
+    //direction of tangent at endpoints
+	double getDirection1() const override{return 0.;}
+	double getDirection2() const override{return 0.;}
+    /** return the equation of the entity
+    for quadratic,
+
+    return a vector contains:
+    m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+    for linear:
+    m0 x + m1 y + m2 =0
+    **/
+	LC_Quadratic getQuadratic() const override;
+
+protected:
+    LC_HyperbolaData data;
+    bool m_bValid;
+
+};
+
+
+
+#endif
+//EOF

lib/engine/lc_rect.cpp

@@ -0,0 +1,309 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2015 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2015 librecad.org (www.librecad.org)
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+**********************************************************************/
+#include<iostream>
+#include <QDebug>
+#include <cassert>
+#include "lc_rect.h"
+
+#define INTERT_TEST(s) qDebug()<<"\ntesting " #s; \
+	assert(s); \
+	qDebug()<<"Passed";
+
+using namespace lc::geo;
+
+Coordinate LC_Rect::Vector(Coordinate const& p, Coordinate const& q) {
+	return {q.x - p.x, q.y - p.y};
+}
+
+	/**
+	  * Create a new Area. The coordinates coordA and coordB will be ordered so that minP will always be < maxP
+	  * The coordinates are not allowed to describe a volume
+	  *
+	  * @param CoordA First coordinate of an area
+	  * @param CoordB Second coordinate of an area
+	  */
+LC_Rect::Area(const Coordinate& coordA, const Coordinate& coordB) :
+_minP{std::min(coordA.x, coordB.x), std::min(coordA.y, coordB.y)},
+_maxP{std::max(coordA.x, coordB.x), std::max(coordA.y, coordB.y)}
+{
+}
+
+LC_Rect::Area() : _minP{0., 0.}, _maxP{0., 0.} {}
+
+	/**
+	 * @brief Area
+	 * given at a coordinate with a given width and height
+	 * @param coordA
+	 * @param width
+	 * @param height
+	 */
+	LC_Rect::Area(const Coordinate& coord, double width, double height):
+Area(coord, {coord.x + width, coord.y + height})
+{}
+
+	/**
+	  * Return the smallest corner (closest to (0,0,0) )
+	  */
+	const Coordinate& LC_Rect::minP() const {
+		return _minP;
+	}
+
+	/**
+	  * Return the highest corner
+	  */
+	const Coordinate& LC_Rect::maxP() const {
+		return _maxP;
+	}
+	/**
+	 * @brief topLeftCorner return the upperLeftCorner coordinates
+	 * _minP is considered lowerLeft, _maxP is the upperRight
+	 * @return {_minP.x, _maxP.y}
+	 */
+	Coordinate LC_Rect::upperLeftCorner() const {
+	  return {_minP.x, _maxP.y};
+	}
+	Coordinate LC_Rect::upperRightCorner() const {
+	  return _maxP;
+	}
+
+	/**
+	 * @brief lowerRightCorner return the lowerRight coordinates
+	 * _minP is considered lowerLeft, _maxP is the upperRight
+	 * @return {_maxP.x, _minP.y}
+	 */
+	Coordinate LC_Rect::lowerRightCorner() const {
+	  return {_maxP.x, _minP.y};
+	}
+
+	Coordinate LC_Rect::lowerLeftCorner() const {
+	  return _minP;
+	}
+
+	/**
+	 * @brief width
+	 * Returns the wid th of this area
+	 * @return
+	 */
+	double LC_Rect::width() const {
+		return _maxP.x - _minP.x;
+	}
+
+	/**
+	 * @brief height
+	 * Returns the height f this area
+	 * @return
+	 */
+	double LC_Rect::height() const {
+		return _maxP.y - _minP.y;
+	}
+
+	/**
+	  * @brief Test of a specific point lies within an area
+	  * @param point Point to test against
+	  * @return boolean true of the point is within the area
+	  */
+	bool LC_Rect::inArea(const Coordinate& point, double tolerance) const {
+		return (point.x >= _minP.x - tolerance && point.x <= _maxP.x + tolerance && point.y >= _minP.y - tolerance && point.y <= _maxP.y + tolerance);
+	}
+
+	/**
+	 * @brief inArea
+	 * test if this object's fit's fully in area
+	 * @param area
+	 * @return
+	 */
+	bool LC_Rect::inArea(const Area& area) const {
+		return _minP.x >= area._minP.x && _minP.y >= area._minP.y && _maxP.x <= area._maxP.x && _maxP.y <= area._maxP.y;
+	}
+
+	/**
+	 * @brief overlaps
+	 * returns true if any overlap is happening between the two area's, even if otherArea fit's within this area
+	 * @param other
+	 * @return
+	 */
+	bool LC_Rect::overlaps(const Area& otherArea) const {
+		return intersects(otherArea);
+	}
+
+	/**
+	 * @brief numCornersInside
+	 * count the number of corners this object has in otherArea
+	 * @param other
+	 * @return
+	 */
+	short LC_Rect::numCornersInside(const Area& otherArea) const  {
+		short pointsInside = 0;
+
+		if (otherArea.inArea(_minP)) {
+			pointsInside++;
+		}
+
+		if (otherArea.inArea(_maxP)) {
+			pointsInside++;
+		}
+
+		if (otherArea.inArea(upperLeftCorner())) {
+			pointsInside++;
+		}
+
+		if (otherArea.inArea(lowerRightCorner())) {
+			pointsInside++;
+		}
+
+		return pointsInside;
+	}
+
+	/**
+	 * @brief merge
+	 * two area's and expand if required to largest containing area
+	 * @param other
+	 * @return
+	 */
+	Area LC_Rect::merge(const Area& other) const {
+		return {
+				   {std::min(other.minP().x, this->minP().x), std::min(other.minP().y, this->minP().y)},
+				   {std::max(other.maxP().x, this->maxP().x), std::max(other.maxP().y, this->maxP().y)}
+		  };
+	}
+
+	 /**
+	  * @brief merge
+	  * two area's and expand if required to largest containing area
+	  * @param other
+	  * @return
+	  */
+	Area LC_Rect::merge(const Coordinate& other) const {
+		return {
+				{std::min(other.x, this->minP().x), std::min(other.y, this->minP().y)},
+				{std::max(other.x, this->maxP().x), std::max(other.y, this->maxP().y)}
+		  };
+	}
+
+	/**
+	 * @brief merge
+	 * two area's and expand if required to largest containing area
+	 * @param other
+	 * @param tolerance, tolerance to detect zero size intersection
+	 * @return
+	 */
+	Area LC_Rect::intersection(const Area& other, double tolerance) const {
+
+	  Area const ret{
+		  {std::max(other.minP().x, this->minP().x), std::max(other.minP().y, this->minP().y)},
+		  {std::min(other.maxP().x, this->maxP().x), std::min(other.maxP().y, this->maxP().y)}
+		};
+		if (ret.width() < tolerance || ret.height() < tolerance) {
+			return {};
+		}
+		return ret;
+	}
+
+	bool LC_Rect::intersects(Area const& rhs, double tolerance) const {
+		return maxP().x + tolerance >= rhs.minP().x &&
+				maxP().y + tolerance >= rhs.minP().y &&
+				rhs.maxP().x + tolerance >= minP().x &&
+				rhs.maxP().y + tolerance >= minP().y;
+	}
+
+	/**
+	 * @brief top
+	 * vector of this area
+	 * @return
+	 */
+	Coordinate LC_Rect::top() const {
+		return Vector(upperLeftCorner(), _maxP);
+	}
+
+	/**
+	 * @brief bottom
+	 * vector of this area
+	 * @return
+	 */
+	Coordinate LC_Rect::bottom() const {
+		return Vector(_minP, lowerRightCorner());
+	}
+
+	/**
+	 * @brief left
+	 * vector for this area
+	 * @return
+	 */
+	Coordinate LC_Rect::left() const {
+		return Vector(_minP, upperLeftCorner());
+	}
+
+	/**
+	 * @brief right
+	 * vector of this area
+	 * @return
+	 */
+	Coordinate LC_Rect::right() const {
+		return Vector(lowerRightCorner(), _maxP);
+	}
+
+	/**
+	 * Increase the area on each side by increaseBy
+	 */
+	Area LC_Rect::increaseBy(double increaseBy) const {
+		return {_minP - increaseBy, _maxP + increaseBy};
+	}
+
+	std::array<Coordinate, 4> LC_Rect::vertices() const
+	{
+		return {{lowerLeftCorner(), lowerRightCorner(),
+					upperRightCorner(), upperLeftCorner()}};
+	}
+
+	std::ostream& operator<<(std::ostream& os, const Area& area) {
+		os << "Area(" << area.minP() << " " << area.maxP() << ")";
+		return os;
+	}
+
+void LC_Rect::unitTest() {
+	LC_Rect const rect0{{0., 0.}, {1., 1.}};
+	LC_Rect const rect1{{0.5, 0.5}, {1.5, 1.5}};
+	LC_Rect const rect2{{1.5, 1.5}, {2.5, 2.5}};
+	LC_Rect const rect3{{0.0, 1.}, {1.5, 1.5}};
+
+	//intersects() tests
+	INTERT_TEST(rect0.intersects(rect1))
+	INTERT_TEST(rect1.intersects(rect0))
+	INTERT_TEST(rect1.intersects(rect2))
+	INTERT_TEST(rect2.intersects(rect1))
+
+	INTERT_TEST(!rect0.intersects(rect2))
+	INTERT_TEST(!rect2.intersects(rect0))
+
+	INTERT_TEST(rect2.intersects(rect3))
+	INTERT_TEST(rect3.intersects(rect2))
+
+	// inArea() tests
+	INTERT_TEST(rect0.inArea({0.1, 0.1}))
+	INTERT_TEST(rect0.inArea({0.5, 0.5}))
+
+	INTERT_TEST(!rect0.inArea({1.1, 1.1}))
+	INTERT_TEST(!rect0.inArea({-1.1, -1.1}))
+
+}
+

lib/engine/lc_rect.h

@@ -0,0 +1,217 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2015 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2015 librecad.org (www.librecad.org)
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+**********************************************************************/
+
+#ifndef LC_RECT_H
+#define LC_RECT_H
+#include "rs_vector.h"
+#include <array>
+
+//ported from LibreCAD V3
+namespace lc {
+namespace geo {
+
+typedef RS_Vector Coordinate;
+
+/**
+		  * Class that describes an area or window.
+		  */
+class Area {
+
+public:
+	Area();
+	/**
+		  * Create a new Area. The coordinates coordA and coordB will be ordered so that minP will always be < maxP
+		  * The coordinates are not allowed to describe a volume
+		  *
+		  * @param CoordA First coordinate of an area
+		  * @param CoordB Second coordinate of an area
+		  */
+	Area(const Coordinate& coordA, const Coordinate& coordB);
+
+
+	/**
+		 * @brief Area
+		 * given at a coordinate with a given width and height
+		 * @param coordA
+		 * @param width
+		 * @param height
+		 */
+	explicit Area(const Coordinate& coord, double width, double height);
+
+	/**
+		  * Return the smallest corner (closest to (0,0,0) )
+		  */
+	const Coordinate& minP() const;
+
+	/**
+		  * Return the highest corner
+		  */
+	const Coordinate& maxP() const;
+	/**
+		 * @brief topLeftCorner return the upperLeftCorner coordinates
+		 * _minP is considered lowerLeft, _maxP is the upperRight
+		 * @return {_minP.x, _maxP.y}
+		 */
+	Coordinate upperLeftCorner() const;
+	Coordinate upperRightCorner() const;
+	/**
+		 * @brief lowerRightCorner return the lowerRight coordinates
+		 * _minP is considered lowerLeft, _maxP is the upperRight
+		 * @return {_maxP.x, _minP.y}
+		 */
+	Coordinate lowerLeftCorner() const;
+	Coordinate lowerRightCorner() const;
+
+	/**
+		 * @brief width
+		 * Returns the width of this area
+		 * @return
+		 */
+	double width() const;
+
+	/**
+		 * @brief height
+		 * Returns the height of this area
+		 * @return
+		 */
+	double height() const;
+
+	/**
+		  * @brief Test of a specific point lies within an area
+		  * @param point Point to test against
+		  * @return boolean true of the point is within the area
+		  */
+	bool inArea(const Coordinate& point, double tolerance = 0.) const;
+
+	/**
+		 * @brief inArea
+		 * test if this object's fit's fully in area
+		 * @param area
+		 * @return
+		 */
+	bool inArea(const Area& area) const;
+
+	/**
+		 * @brief overlaps
+		 * returns true if any overlap is happening between the two area's, even if otherArea fit's within this area
+		 * @param other
+		 * @return
+		 */
+	bool overlaps(const Area& otherArea) const;
+
+	/**
+		 * @brief numCornersInside
+		 * count the number of corners this object has in otherArea
+		 * @param other
+		 * @return
+		 */
+	short numCornersInside(const Area& otherArea) const;
+
+	/**
+		 * @brief merge
+		 * two area's and expand if required to largest containing area
+		 * @param other
+		 * @return
+		 */
+	Area merge(const Area& other) const;
+
+	/**
+		  * @brief merge
+		  * two area's and expand if required to largest containing area
+		  * @param other
+		  * @return
+		  */
+	Area merge(const Coordinate& other) const;
+
+	/**
+		 * @brief merge
+		 * two area's and expand if required to largest containing area
+		 * @param other
+		 * @param tolerance, tolerance to detect zero size intersection
+		 * @return
+		 */
+	Area intersection(const Area& other, double tolerance = 0.) const;
+
+	/**
+	 * @brief intersects whether two rectangular area
+	 * if the closest distance between two Areas is smaller than tolerance, they
+	 * are considered to have intersection
+	 * @param rhs the other rect
+	 * @return true if closest distance is smaller than or equal to tolerance
+	 */
+	bool intersects(Area const& rhs, double tolerance = 0.) const;
+
+	/**
+		 * @brief top
+		 * vector of this area
+		 * @return
+		 */
+	Coordinate top() const;
+
+	/**
+		 * @brief bottom
+		 * vector of this area
+		 * @return
+		 */
+	Coordinate bottom() const;
+
+	/**
+		 * @brief left
+		 * vector for this area
+		 * @return
+		 */
+	Coordinate left() const;
+
+	/**
+		 * @brief right
+		 * vector of this area
+		 * @return
+		 */
+	Coordinate right() const;
+
+	/**
+		 * Increase the area on each side by increaseBy
+		 */
+	Area increaseBy (double increaseBy) const;
+	/**
+	 * @brief vertices generate vertices of the rectangular area
+	 * @return array of vertices by the order {ll, lr, ur, rl} starting with
+	 * lower-left corner, i.e. _minP
+	 */
+	std::array<Coordinate, 4> vertices() const;
+
+	static void unitTest();
+
+private:
+	static Coordinate Vector(Coordinate const& p, Coordinate const& q);
+	friend std::ostream& operator<<(std::ostream& os, const Area& area);
+
+private:
+	Coordinate _minP;
+	Coordinate _maxP;
+};
+}
+}
+
+using LC_Rect = lc::geo::Area;
+#endif // LC_RECT_H

lib/engine/lc_splinepoints.h

@@ -0,0 +1,245 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2014 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2014 Pavel Krejcir (pavel@pamsoft.cz)
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+**********************************************************************/
+
+
+#ifndef LC_SPLINEPOINTS_H
+#define LC_SPLINEPOINTS_H
+
+#include <vector>
+#include "rs_atomicentity.h"
+
+class QPolygonF;
+struct RS_LineTypePattern;
+
+/**
+ * Holds the data that defines a line.
+ * Few notes about implementation:
+ * When drawing, the spline is defined via splinePoints collection.
+ * However, since we want to allow trimming/cutting the spline,
+ * we cannot guarantee that the shape would stay unchanged after
+ * a part of the spline would be cut off. This would espetially be
+ * obvious after cutting closed splines. So we introduce the "cut"
+ * state. After that, all splinePoints will be deleted except start
+ * and end points, and the controlPoints become the reference points
+ * of that shape. It will be further possible to modify the spline,
+ * but the control points will serve as handles then. 
+ */
+struct LC_SplinePointsData
+{
+	/**
+	* Default constructor. Leaves the data object uninitialized.
+	*/
+    LC_SplinePointsData() = default;
+	~LC_SplinePointsData() = default;
+
+	LC_SplinePointsData(bool closed, bool cut);
+
+	bool closed;
+	bool cut;
+	/** points on the spline. */
+	std::vector<RS_Vector> splinePoints;
+	std::vector<RS_Vector> controlPoints;
+};
+
+std::ostream& operator << (std::ostream& os, const LC_SplinePointsData& ld);
+
+/**
+ * Class for a spline entity.
+ *
+ * @author Pavel Krejcir
+ */
+class LC_SplinePoints : public RS_AtomicEntity // RS_EntityContainer
+{
+private:
+	void drawPattern(RS_Painter* painter, RS_GraphicView* view,
+        double& patternOffset, const RS_LineTypePattern* pat);
+	void drawSimple(RS_Painter* painter, RS_GraphicView* view);
+	void UpdateControlPoints();
+	void UpdateQuadExtent(const RS_Vector& x1, const RS_Vector& c1, const RS_Vector& x2);
+	int GetNearestQuad(const RS_Vector& coord, double* dist, double* dt) const;
+	RS_Vector GetSplinePointAtDist(double dDist, int iStartSeg, double dStartT,
+		int *piSeg, double *pdt) const;
+	int GetQuadPoints(int iSeg, RS_Vector *pvStart, RS_Vector *pvControl,
+		RS_Vector *pvEnd) const;
+
+    bool offsetCut(const RS_Vector& coord, const double& distance);
+    bool offsetSpline(const RS_Vector& coord, const double& distance);
+	std::vector<RS_Entity*> offsetTwoSidesSpline(const double& distance) const;
+	std::vector<RS_Entity*> offsetTwoSidesCut(const double& distance) const;
+    LC_SplinePointsData data;
+
+public:
+    LC_SplinePoints(RS_EntityContainer* parent, const LC_SplinePointsData& d);
+	RS_Entity* clone() const override;
+
+	/**	@return RS2::EntitySpline */
+	RS2::EntityType rtti() const override;
+
+	/** @return false */
+	bool isEdge() const override;
+
+	/** @return Copy of data that defines the spline. */
+	LC_SplinePointsData const& getData() const;
+	LC_SplinePointsData& getData();
+
+	/** @return Number of control points. */
+	size_t getNumberOfControlPoints() const;
+
+	/**
+	* @retval true if the spline is closed.
+	* @retval false otherwise.
+	*/
+	bool isClosed() const;
+
+	/**
+    * Sets the closed flag of this spline.
+	*/
+	void setClosed(bool c);
+	
+	void update() override;
+
+	RS_VectorSolutions getRefPoints() const override;
+
+	/** @return Start point of the entity */
+	RS_Vector getStartpoint() const override;
+
+	/** @return End point of the entity */
+	RS_Vector getEndpoint() const override;
+
+	/** Sets the startpoint */
+	//void setStartpoint(RS_Vector s) {
+	//    data.startpoint = s;
+	//    calculateBorders();
+	//}
+	/** Sets the endpoint */
+	//void setEndpoint(RS_Vector e) {
+	//    data.endpoint = e;
+	//    calculateBorders();
+	//}
+
+	double getDirection1() const override;
+	double getDirection2() const override;
+
+	//void moveStartpoint(const RS_Vector& pos) override;
+	//void moveEndpoint(const RS_Vector& pos) override;
+	//RS2::Ending getTrimPoint(const RS_Vector& coord,
+	//          const RS_Vector& trimPoint);
+	//void reverse() override;
+	/** @return the center point of the line. */
+	//RS_Vector getMiddlePoint() {
+	//    return (data.startpoint + data.endpoint)/2.0;
+	//}
+	//bool hasEndpointsWithinWindow(RS_Vector v1, RS_Vector v2) override;
+
+	/**
+	* @return The length of the line.
+	*/
+	double getLength() const override;
+
+	/**
+	* @return The angle of the line (from start to endpoint).
+	*/
+	//double getAngle1() {
+	//    return data.startpoint.angleTo(data.endpoint);
+	//}
+
+	/**
+	* @return The angle of the line (from end to startpoint).
+	*/
+	//double getAngle2() {
+	//    return data.endpoint.angleTo(data.startpoint);
+	//}
+
+	RS_VectorSolutions getTangentPoint(const RS_Vector& point) const override;
+	RS_Vector getTangentDirection(const RS_Vector& point) const override;
+
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+		double* dist = nullptr) const override;
+    /**
+     * @brief getNearestPointOnEntity
+     * @param coord
+     * @param onEntity, unused, because current implementation finds the nearest point on the spline
+     * @param dist
+     * @param entity
+     * @return
+     */
+	RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+		bool onEntity = true, double* dist = nullptr, RS_Entity** entity = nullptr) const override;
+//	RS_Vector getNearestCenter(const RS_Vector& coord,
+//		double* dist = nullptr) const;
+	RS_Vector getNearestMiddle(const RS_Vector& coord,
+		double* dist = nullptr, int middlePoints = 1) const override;
+	RS_Vector getNearestDist(double distance,
+		const RS_Vector& coord, double* dist = nullptr) const override;
+	//RS_Vector getNearestRef(const RS_Vector& coord,
+	//                                 double* dist = nullptr);
+	double getDistanceToPoint(const RS_Vector& coord,
+		RS_Entity** entity = nullptr, RS2::ResolveLevel level = RS2::ResolveNone,
+		double solidDist = RS_MAXDOUBLE) const override;
+
+	bool addPoint(const RS_Vector& v);
+	void removeLastPoint();
+	void addControlPoint(const RS_Vector& v);
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+	void revertDirection() override;
+
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+    std::vector<RS_Vector> const& getPoints() const;
+    std::vector<RS_Vector> const& getControlPoints() const;
+    std::vector<RS_Vector> getStrokePoints() const;
+
+    friend std::ostream& operator << (std::ostream& os, const LC_SplinePoints& l);
+
+	void calculateBorders() override;
+
+	bool offset(const RS_Vector& coord, const double& distance) override;
+	std::vector<RS_Entity*> offsetTwoSides(const double& distance) const override;
+
+	static RS_VectorSolutions getIntersection(RS_Entity const* e1, RS_Entity const* e2);
+	RS_VectorSolutions getLineIntersect(const RS_Vector& x1, const RS_Vector& x2);
+	void addQuadIntersect(RS_VectorSolutions *pVS, const RS_Vector& x1,
+		const RS_Vector& c1, const RS_Vector& x2);
+	RS_VectorSolutions getSplinePointsIntersect(LC_SplinePoints* l1);
+	RS_VectorSolutions getQuadraticIntersect(RS_Entity const* e1);
+
+	// we will not enable trimming, maybe in the future
+	//void trimStartpoint(const RS_Vector& pos) override;
+	//void trimEndpoint(const RS_Vector& pos) override;
+
+    LC_SplinePoints* cut(const RS_Vector& pos);
+    //! \{ getBoundingRect find bounding rectangle for the bezier segment
+    //! \param x1,c1,x2 first/center/last control points
+    //! \return rectangle as a polygon
+    static QPolygonF getBoundingRect(const RS_Vector& x1, const RS_Vector& c1, const RS_Vector& x2);
+    //! \}
+};
+
+#endif
+

lib/engine/lc_undosection.cpp

@@ -0,0 +1,50 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2018 A. Stebich (librecad@mail.lordofbikes.de)
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include "lc_undosection.h"
+#include "rs_document.h"
+
+LC_UndoSection::LC_UndoSection(RS_Document *doc, const bool handleUndo /*= true*/) :
+    document( doc),
+    valid( handleUndo && nullptr != doc)
+{
+    if (valid) {
+        document->startUndoCycle();
+    }
+}
+
+LC_UndoSection::~LC_UndoSection()
+{
+    if (valid) {
+        document->endUndoCycle();
+    }
+}
+
+void LC_UndoSection::addUndoable(RS_Undoable *undoable)
+{
+    if (valid) {
+        document->addUndoable( undoable);
+    }
+}

lib/engine/lc_undosection.h

@@ -0,0 +1,56 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2018 A. Stebich (librecad@mail.lordofbikes.de)
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#ifndef LC_UNDOSECTION_H
+#define LC_UNDOSECTION_H
+
+class RS_Document;
+class RS_Undoable;
+
+/** \brief This class is a wrapper for RS_Undo methods
+ *
+ * It's important that calls to RS_Undo::startUndoCycle() and
+ * RS_Undo::endUndoCycle() are balanced.
+ * On instantiation the constructor calls startUndoCycle().
+ * The class handles also validation of the RS_Document pointer.
+ * When the instance is leaving the scope, the destructor
+ * calls endUndoCycle().
+ * This way the balance is guaranteed.
+ * It simplifies undo handling specially in RS_Creation and RS_Modification classes
+*/
+class LC_UndoSection
+{
+public:
+    LC_UndoSection(RS_Document * doc, const bool handleUndo = true);
+    ~LC_UndoSection();
+
+    void addUndoable(RS_Undoable * undoable);
+
+private:
+    RS_Document *document {nullptr};
+    bool valid {true};
+};
+
+#endif // LC_UNDOSECTION_H

lib/engine/rs.cpp

@@ -0,0 +1,51 @@
+#include<iostream>
+#include<vector>
+#include<utility>
+#include<climits>
+#include "rs.h"
+
+RS2::LineWidth RS2::intToLineWidth(int w) {
+	std::vector<std::pair<int, LineWidth>> const table{
+		{-2, WidthDefault}, //for w = -3
+		{-1, WidthByBlock}, //for w = -2
+		{0, WidthByLayer}, //for w = -1
+		// for w < 3, return Width00
+		{3, Width00},
+		{8, Width01},
+		{12, Width02},
+		{14, Width03},
+		{17, Width04},
+		{19, Width05},
+		{23, Width06},
+		{28, Width07},
+		{33, Width08},
+		{38, Width09},
+		{46, Width10},
+		{52, Width11},
+		{57, Width12},
+		{66, Width13},
+		{76, Width14},
+		{86, Width15},
+		{96, Width16},
+		{104, Width17},
+		{114, Width18},
+		{131, Width19},
+		{150, Width20},
+		{180, Width21},
+		{206, Width22},
+		{INT_MAX, Width23}
+	};
+
+	//binary search
+	//assume table size is at least 2
+	size_t low = -1;
+	size_t high = table.size() - 1;
+	while (low + 1 < high) {
+		size_t const mid = low + (high - low)/2;
+		if (w >= table.at(mid).first)
+			low = mid;
+		else
+			high = mid;
+	}
+	return table.at(high).second;
+}

lib/engine/rs.h

@@ -0,0 +1,945 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#ifndef RS_H
+#define RS_H
+
+//#define RS_TEST
+
+// Windoze XP can't handle the original MAX/MINDOUBLE's
+#define RS_MAXDOUBLE 1.0E+10
+#define RS_MINDOUBLE -1.0E+10
+//tolerance
+#define RS_TOLERANCE 1.0e-10
+//squared tolerance
+#define RS_TOLERANCE15 1.5e-15
+#define RS_TOLERANCE2 1.0e-20
+#define RS_TOLERANCE_ANGLE 1.0e-8
+
+/**
+ * Class namespace for various enums along with some simple
+ * wrapper methods for converting the enums to the Qt
+ * counterparts.
+ *
+ * @author Andrew Mustun
+ */
+class RS2 {
+public:
+
+    /**
+     * Flags.
+     */
+    enum Flags {
+        /** Flag for Undoables. */
+        FlagUndone      = 1<<0,
+        /** Entity Visibility. */
+        FlagVisible     = 1<<1,
+        /** Entity attribute (e.g. color) is defined by layer. */
+        FlagByLayer     = 1<<2,
+        /** Entity attribute (e.g. color) defined by block. */
+        FlagByBlock     = 1<<3,
+        /** Layer frozen. */
+        FlagFrozen      = 1<<4,
+        /** Layer frozen by default. */
+        FlagDefFrozen   = 1<<5,
+        /** Layer locked. */
+        FlagLocked      = 1<<6,
+        /** Used for invalid pens. */
+        FlagInvalid     = 1<<7,
+        /** Entity in current selection. */
+        FlagSelected    = 1<<8,
+        /** Polyline closed? */
+        FlagClosed      = 1<<9,
+        /** Flag for temporary entities (e.g. hatch) */
+        FlagTemp        = 1<<10,
+        /** Flag for processed entities (optcontour) */
+        FlagProcessed   = 1<<11,
+        /** Startpoint selected */
+        FlagSelected1   = 1<<12,
+        /** Endpoint selected */
+        FlagSelected2   = 1<<13,
+                /** Entity is highlighted temporarily (as a user action feedback) */
+                FlagHighlighted = 1<<14
+    };
+
+    /**
+     * Variable types used by RS_VariableDict and RS_Variable.
+     */
+    enum VariableType {
+        VariableString,
+        VariableInt,
+        VariableDouble,
+        VariableVector,
+        VariableVoid
+    };
+
+    /**
+     * File types. Used by file dialogs. Note: the extension might not
+     * be enough to distinguish file types.
+     */
+    enum FormatType {
+        FormatUnknown,       /**< Unknown / unsupported format. */
+        FormatDXF1,          /**< QCad 1 compatibility DXF format. */
+        FormatDXFRW,           /**< DXF format. v2007. */
+        FormatDXFRW2004,           /**< DXF format. v2004. */
+        FormatDXFRW2000,           /**< DXF format. v2000. */
+        FormatDXFRW14,           /**< DXF format. v14. */
+        FormatDXFRW12,           /**< DXF format. v12. */
+#ifdef DWGSUPPORT
+        FormatDWG,           /**< DWG format. */
+#endif
+        FormatLFF,           /**< LibreCAD Font File format. */
+        FormatCXF,           /**< CAM Expert Font format. */
+        FormatJWW,           /**< JWW Format type */
+        FormatJWC            /**< JWC Format type */
+    };
+
+    /**
+     * Entity types returned by the rtti() method
+     */
+    enum EntityType {
+        EntityUnknown,      /**< Unknown */
+        EntityContainer,    /**< Container */
+        EntityBlock,        /**< Block (Group definition) */
+        EntityFontChar,     /**< Font character */
+        EntityInsert,       /**< Insert (Group instance) */
+        EntityGraphic,      /**< Graphic with layers */
+        EntityPoint,        /**< Point */
+        EntityLine,         /**< Line */
+        EntityPolyline,     /**< Polyline */
+        EntityVertex,       /**< Vertex (part of a polyline) */
+        EntityArc,          /**< Arc */
+        EntityCircle,       /**< Circle */
+        EntityEllipse,      /**< Ellipse */
+        EntityHyperbola,      /**< Hyperbola */
+        EntitySolid,        /**< Solid */
+        EntityConstructionLine, /**< Construction line */
+        EntityMText,         /**< Multi-line Text */
+        EntityText,         /**< Single-line Text */
+        EntityDimAligned,   /**< Aligned Dimension */
+        EntityDimLinear,    /**< Linear Dimension */
+        EntityDimRadial,    /**< Radial Dimension */
+        EntityDimDiametric, /**< Diametric Dimension */
+        EntityDimAngular,   /**< Angular Dimension */
+        EntityDimLeader,    /**< Leader Dimension */
+        EntityHatch,        /**< Hatch */
+        EntityImage,        /**< Image */
+        EntitySpline,       /**< Spline */
+        EntitySplinePoints,       /**< SplinePoints */
+        EntityOverlayBox,    /**< OverlayBox */
+        EntityPreview,    /**< Preview Container */
+        EntityPattern,
+        EntityOverlayLine
+    };
+
+
+    /**
+     * Action types used by action factories.
+     */
+    enum ActionType {
+        ActionNone,        /**< Invalid action id. */
+
+        ActionDefault,
+
+        ActionFileNew,
+        ActionFileNewTemplate,
+        ActionFileOpen,
+        ActionFileSave,
+        ActionFileSaveAs,
+        ActionFileExport,
+        ActionFileClose,
+        ActionFilePrint,
+        ActionFilePrintPDF,
+        ActionFilePrintPreview,
+        ActionFileExportMakerCam,
+        ActionFileQuit,
+
+        ActionEditKillAllActions,
+        ActionEditUndo,
+        ActionEditRedo,
+        ActionEditCut,
+        ActionEditCutNoSelect,
+        ActionEditCopy,
+        ActionEditCopyNoSelect,
+        ActionEditPaste,
+        ActionOrderNoSelect,
+        ActionOrderBottom,
+        ActionOrderLower,
+        ActionOrderRaise,
+        ActionOrderTop,
+
+        ActionViewStatusBar,
+        ActionViewLayerList,
+        ActionViewBlockList,
+        ActionViewCommandLine,
+        ActionViewLibrary,
+
+        ActionViewPenToolbar,
+        ActionViewOptionToolbar,
+        ActionViewCadToolbar,
+        ActionViewFileToolbar,
+        ActionViewEditToolbar,
+        ActionViewSnapToolbar,
+
+        ActionViewGrid,
+        ActionViewDraft,
+
+        ActionZoomIn,
+        ActionZoomOut,
+        ActionZoomAuto,
+        ActionZoomWindow,
+        ActionZoomPan,
+        ActionZoomRedraw,
+        ActionZoomPrevious,
+
+        ActionSelect,
+        ActionSelectSingle,
+        ActionSelectContour,
+        ActionSelectWindow,
+        ActionDeselectWindow,
+        ActionSelectAll,
+        ActionDeselectAll,
+        ActionSelectIntersected,
+        ActionDeselectIntersected,
+        ActionSelectInvert,
+        ActionSelectLayer,
+        ActionSelectDouble,
+        ActionGetSelect,
+
+        ActionDrawArc,
+        ActionDrawArc3P,
+        ActionDrawArcParallel,
+        ActionDrawArcTangential,
+        ActionDrawCircle,
+        ActionDrawCircle2P,
+        ActionDrawCircle2PR,
+        ActionDrawCircle3P,
+        ActionDrawCircleCR,
+        ActionDrawCircleParallel,
+        ActionDrawCircleInscribe,
+        ActionDrawCircleTan2_1P,
+        ActionDrawCircleTan1_2P,
+        ActionDrawCircleTan2,
+        ActionDrawCircleTan3,
+
+        ActionDrawEllipseArcAxis,
+        ActionDrawEllipseAxis,
+        ActionDrawEllipseFociPoint,
+        ActionDrawEllipse4Points,
+        ActionDrawEllipseCenter3Points,
+        ActionDrawEllipseInscribe,
+
+        ActionDrawHatch,
+        ActionDrawHatchNoSelect,
+        ActionDrawImage,
+        ActionDrawLine,
+        ActionDrawLineAngle,
+        ActionDrawLineBisector,
+        ActionDrawLineFree,
+        ActionDrawLineHorVert,
+        ActionDrawLineHorizontal,
+        ActionDrawLineOrthogonal,
+        ActionDrawLineOrthTan,
+        ActionDrawLineParallel,
+        ActionDrawLineParallelThrough,
+        ActionDrawLinePolygonCenCor,
+        ActionDrawLinePolygonCenTan,//add by txmy
+        ActionDrawLinePolygonCorCor,
+        ActionDrawLineRectangle,
+        ActionDrawLineRelAngle,
+        ActionDrawLineTangent1,
+        ActionDrawLineTangent2,
+        ActionDrawLineVertical,
+        ActionDrawMText,
+        ActionDrawPoint,
+        ActionDrawSpline,
+        ActionDrawSplinePoints, //interpolation spline
+        ActionDrawPolyline,
+        ActionDrawText,
+
+        ActionPolylineAdd,
+        ActionPolylineAppend,
+        ActionPolylineDel,
+        ActionPolylineDelBetween,
+        ActionPolylineTrim,
+        ActionPolylineEquidistant,
+        ActionPolylineSegment,
+
+        ActionDimAligned,
+        ActionDimLinear,
+        ActionDimLinearVer,
+        ActionDimLinearHor,
+        ActionDimRadial,
+        ActionDimDiametric,
+        ActionDimAngular,
+        ActionDimLeader,
+
+        ActionModifyAttributes,
+        ActionModifyAttributesNoSelect,
+        ActionModifyDelete,
+        ActionModifyDeleteNoSelect,
+        ActionModifyDeleteQuick,
+        ActionModifyDeleteFree,
+        ActionModifyMove,
+        ActionModifyMoveNoSelect,
+        ActionModifyRotate,
+        ActionModifyRotateNoSelect,
+        ActionModifyScale,
+        ActionModifyScaleNoSelect,
+        ActionModifyMirror,
+        ActionModifyMirrorNoSelect,
+        ActionModifyMoveRotate,
+        ActionModifyMoveRotateNoSelect,
+		ActionModifyRevertDirection,
+		ActionModifyRevertDirectionNoSelect,
+        ActionModifyRotate2,
+        ActionModifyRotate2NoSelect,
+        ActionModifyEntity,
+        ActionModifyTrim,
+        ActionModifyTrim2,
+        ActionModifyTrimAmount,
+        ActionModifyCut,
+        ActionModifyStretch,
+        ActionModifyBevel,
+        ActionModifyRound,
+        ActionModifyOffset,
+        ActionModifyOffsetNoSelect,
+
+        ActionSnapFree,
+        ActionSnapGrid,
+        ActionSnapEndpoint,
+        ActionSnapOnEntity,
+        ActionSnapCenter,
+        ActionSnapMiddle,
+        ActionSnapDist,
+        ActionSnapIntersection,
+        ActionSnapIntersectionManual,
+
+        ActionRestrictNothing,
+        ActionRestrictOrthogonal,
+        ActionRestrictHorizontal,
+        ActionRestrictVertical,
+
+        ActionSetRelativeZero,
+        ActionLockRelativeZero,
+        ActionUnlockRelativeZero,
+
+        ActionInfoInside,
+        ActionInfoDist,
+        ActionInfoDist2,
+        ActionInfoAngle,
+        ActionInfoTotalLength,
+        ActionInfoTotalLengthNoSelect,
+        ActionInfoArea,
+
+        ActionLayersDefreezeAll,
+        ActionLayersFreezeAll,
+        ActionLayersUnlockAll,
+        ActionLayersLockAll,
+        ActionLayersAdd,
+        ActionLayersRemove,
+        ActionLayersEdit,
+        ActionLayersToggleView,
+        ActionLayersToggleLock,
+        ActionLayersTogglePrint,
+        ActionLayersToggleConstruction,
+
+        ActionBlocksDefreezeAll,
+        ActionBlocksFreezeAll,
+        ActionBlocksAdd,
+        ActionBlocksRemove,
+        ActionBlocksAttributes,
+        ActionBlocksEdit,
+        ActionBlocksSave,
+        ActionBlocksInsert,
+        ActionBlocksToggleView,
+        ActionBlocksCreate,
+        ActionBlocksCreateNoSelect,
+        ActionBlocksExplode,
+        ActionBlocksExplodeNoSelect,
+        ActionBlocksImport,
+
+        ActionModifyExplodeText,
+        ActionModifyExplodeTextNoSelect,
+
+        ActionLibraryInsert,
+
+        ActionOptionsGeneral,
+        ActionOptionsDrawing,
+
+        ActionToolRegenerateDimensions,
+
+        ActionScriptOpenIDE,
+        ActionScriptRun,
+
+        /** Needed to loop through all actions */
+        ActionLast
+    };
+
+    /**
+    * Entity ending. Used for returning which end of an entity is meant.
+     */
+    enum Ending {
+        EndingStart,    /**< Start point. */
+        EndingEnd,      /**< End point. */
+        EndingNone      /**< Neither. */
+    };
+
+    /**
+     * Update mode for non-atomic entities that need to be updated when
+     * they change. e.g. texts, inserts, ...
+     */
+    enum UpdateMode {
+        NoUpdate,       /**< No automatic updates. */
+        Update,         /**< Always update automatically when modified. */
+                PreviewUpdate   /**< Update automatically but only for previews (quick update) */
+    };
+
+    /**
+     * Drawing mode.
+     */
+    enum DrawingMode {
+        ModeFull,       /**< Draw everything always detailed (default) */
+        ModeAuto,       /**< Draw details when reasonable */
+        ModePreview,    /**< Draw only in black/white without styles */
+        ModeBW,         /**< Black/white. Can be used for printing. */
+        ModeWB,         /**< White/black, used for export */
+    };
+
+    /**
+     * Undoable rtti.
+     */
+    enum UndoableType {
+        UndoableUnknown,    /**< Unknown undoable */
+        UndoableEntity,     /**< Entity */
+        UndoableLayer       /**< Layer */
+    };
+
+    /**
+     * Units.
+     */
+    enum Unit {
+        None = 0,               /**< No unit (unit from parent) */
+        Inch = 1,               /**< Inch */
+        Foot = 2,               /**< Foot: 12 Inches */
+        Mile = 3,               /**< Mile: 1760 Yards = 1609 m */
+        Millimeter = 4,         /**< Millimeter: 0.001m */
+        Centimeter = 5,         /**< Centimeter: 0.01m */
+        Meter = 6,              /**< Meter */
+        Kilometer = 7,          /**< Kilometer: 1000m */
+        Microinch = 8,          /**< Microinch: 0.000001 */
+        Mil = 9,                /**< Mil = 0.001 Inch*/
+        Yard = 10,              /**< Yard: 3 Feet */
+        Angstrom = 11,          /**< Angstrom: 10^-10m  */
+        Nanometer = 12,         /**< Nanometer: 10^-9m  */
+        Micron = 13,            /**< Micron: 10^-6m  */
+        Decimeter = 14,         /**< Decimeter: 0.1m */
+        Decameter = 15,         /**< Decameter: 10m */
+        Hectometer = 16,        /**< Hectometer: 100m */
+        Gigameter = 17,         /**< Gigameter: 1000000m */
+        Astro = 18,             /**< Astro: 149.6 x 10^9m */
+        Lightyear = 19,         /**< Lightyear: 9460731798 x 10^6m */
+        Parsec = 20,            /**< Parsec: 30857 x 10^12 */
+
+        LastUnit = 21           /**< Used to iterate through units */
+    };
+
+
+    /**
+     * Format for length values.
+     */
+    enum LinearFormat {
+        /** Scientific (e.g. 2.5E+05) */
+        Scientific,
+        /** Decimal (e.g. 9.5)*/
+        Decimal,
+        /** Engineering (e.g. 7' 11.5")*/
+        Engineering,
+        /** Architectural (e.g. 7'-9 1/8")*/
+        Architectural,
+        /** Fractional (e.g. 7 9 1/8) */
+        Fractional,
+        /** Metric Architectural using DIN 406 (e.g. 1.12⁵)*/
+        ArchitecturalMetric
+    };
+
+    /**
+     * Angle Units.
+     */
+    enum AngleUnit {
+        Deg,               /**< Degrees */
+        Rad,               /**< Radians */
+        Gra                /**< Gradians */
+    };
+
+    /**
+     * Display formats for angles.
+     */
+    enum AngleFormat {
+        /** Degrees with decimal point (e.g. 24.5<EFBFBD>) */
+        DegreesDecimal,
+        /** Degrees, Minutes and Seconds (e.g. 24<32>30'5'') */
+        DegreesMinutesSeconds,
+        /** Gradians with decimal point (e.g. 390.5)*/
+        Gradians,
+        /** Radians with decimal point (e.g. 1.57)*/
+        Radians,
+        /** Surveyor's units */
+        Surveyors
+    };
+
+    /**
+     * Enum of levels of resolving when iterating through an entity tree.
+     */
+    enum ResolveLevel {
+        /** Groups are not resolved */
+        ResolveNone,
+        /**
+        * Resolve all but not Inserts.
+        */
+        ResolveAllButInserts,
+        /**
+         * Resolve all but not Text or MText.
+         */
+        ResolveAllButTexts,
+        /**
+         * Resolve no text or images, added as a quick fix for bug#422
+         */
+        ResolveAllButTextImage,
+        /**
+         * all Entity Containers are resolved
+         * (including Texts, Polylines, ...)
+         */
+        ResolveAll
+    };
+
+    /**
+     * Direction used for scrolling actions.
+     */
+    enum Direction {
+        Up, Left, Right, Down
+    };
+
+	enum SubWindowMode {
+		CurrentMode = -1, Maximized, Cascade, Tile, TileVertical, TileHorizontal
+	};
+
+	enum TabShape {
+		AnyShape = -1, Rounded, Triangular
+	};
+
+	enum TabPosition {
+		AnyPosition = -1, North, South, West, East
+	};
+
+    /**
+     * Vertical alignments.
+     */
+//    enum VAlign {
+//        VAlignTop,      /**< Top. */
+//        VAlignMiddle,   /**< Middle */
+//        VAlignBottom    /**< Bottom */
+//    };
+
+    /**
+     * Horizontal alignments.
+     */
+//    enum HAlign {
+//        HAlignLeft,     /**< Left */
+//        HAlignCenter,   /**< Centered */
+//        HAlignRight     /**< Right */
+//    };
+
+    /**
+     * Text drawing direction.
+     */
+//    enum TextDrawingDirection {
+//        LeftToRight,     /**< Left to right */
+//        TopToBottom,     /**< Top to bottom */
+//        ByStyle          /**< Inherited from associated text style */
+//    };
+
+    /**
+     * Line spacing style for texts.
+     */
+//    enum TextLineSpacingStyle {
+//        AtLeast,        /**< Taller characters will override */
+//        Exact           /**< Taller characters will not override */
+//    };
+
+    /**
+     * Leader path type.
+     */
+    enum LeaderPathType {
+        Straight,      /**< Straight line segments */
+        Spline         /**< Splines */
+    };
+
+    /**
+     * Direction for zooming actions.
+     */
+    enum ZoomDirection {
+        In, Out
+    };
+
+    /**
+     * Axis specification for zooming actions.
+     */
+    enum Axis {
+        OnlyX, OnlyY, Both
+    };
+
+    /**
+     * Crosshair type
+     */
+    enum CrosshairType {
+        LeftCrosshair,         /**< Left type isometric Crosshair */
+        TopCrosshair,         /**< Top type isometric Crosshair */
+        RightCrosshair,         /**< Right type isometric Crosshair */
+        OrthogonalCrosshair         /**< Orthogonal Crosshair */
+    };
+
+    /**
+     * Snapping modes
+     */
+    enum SnapMode {
+        SnapFree,         /**< Free positioning */
+        SnapGrid,         /**< Snap to grid points */
+        SnapEndpoint,     /**< Snap to endpoints */
+        SnapMiddle,       /**< Snap to middle points */
+        SnapCenter,       /**< Snap to centers */
+        SnapOnEntity,     /**< Snap to the next point on an entity */
+        SnapDist,         /**< Snap to points with a distance to an endpoint */
+        SnapIntersection, /**< Snap to intersection */
+        SnapIntersectionManual  /**< Snap to intersection manually */
+    };
+
+    /**
+     * Snap restrictions
+     */
+    enum SnapRestriction {
+        RestrictNothing,        /**< No restriction to snap mode */
+        RestrictHorizontal,     /**< Restrict to 0,180 degrees */
+        RestrictVertical,       /**< Restrict to 90,270 degrees */
+        RestrictOrthogonal      /**< Restrict to 90,180,270,0 degrees */
+    };
+
+    /**
+     * Enum of line styles:
+     */
+    enum LineType {
+        LineByBlock = -2,      /**< Line type defined by block not entity */
+        LineByLayer = -1,     /**< Line type defined by layer not entity */
+        NoPen = 0,            /**< No line at all. */
+        SolidLine = 1,        /**< Normal line. */
+
+        DotLine = 2,          /**< Dotted line. */
+        DotLineTiny = 3,          /**< Dotted line tiny */
+        DotLine2 = 4,         /**< Dotted line small. */
+        DotLineX2 = 5,        /**< Dotted line large. */
+
+        DashLine = 6,         /**< Dashed line. */
+        DashLineTiny=7,       /**< Dashed line tiny */
+        DashLine2 = 8,        /**< Dashed line small. */
+        DashLineX2 = 9,       /**< Dashed line large. */
+
+        DashDotLine = 10,      /**< Alternate dots and dashes. */
+        DashDotLineTiny = 11,      /**< Alternate dots and dashes tiny. */
+        DashDotLine2 = 12,     /**< Alternate dots and dashes small. */
+        DashDotLineX2 = 13,   /**< Alternate dots and dashes large. */
+
+        DivideLine = 14,      /**< dash, dot, dot. */
+        DivideLineTiny = 15,      /**< dash, dot, dot, tiny */
+        DivideLine2 = 16,     /**< dash, dot, dot small. */
+        DivideLineX2 = 17,    /**< dash, dot, dot large. */
+
+        CenterLine = 18,      /**< dash, small dash. */
+        CenterLineTiny = 19,      /**< dash, small dash tiny */
+        CenterLine2 = 20,     /**< dash, small dash small. */
+        CenterLineX2 = 21,    /**< dash, small dash large. */
+
+        BorderLine = 22,      /**< dash, dash, dot. */
+        BorderLineTiny = 23,      /**< dash, dash, dot tiny */
+        BorderLine2 = 24,     /**< dash, dash, dot small. */
+        BorderLineX2 = 25,    /**< dash, dash, dot large. */
+
+        LineTypeUnchanged=26      /**< Line type defined by block not entity */
+    };
+
+    /**
+     * Enum of line widths:
+     */
+    enum LineWidth {
+        Width00 = 0,       /**< Width 1.  (0.00mm) */
+        Width01 = 5,       /**< Width 2.  (0.05mm) */
+        Width02 = 9,       /**< Width 3.  (0.09mm) */
+        Width03 = 13,      /**< Width 4.  (0.13mm) */
+        Width04 = 15,      /**< Width 5.  (0.15mm) */
+        Width05 = 18,      /**< Width 6.  (0.18mm) */
+        Width06 = 20,      /**< Width 7.  (0.20mm) */
+        Width07 = 25,      /**< Width 8.  (0.25mm) */
+        Width08 = 30,      /**< Width 9.  (0.30mm) */
+        Width09 = 35,      /**< Width 10. (0.35mm) */
+        Width10 = 40,      /**< Width 11. (0.40mm) */
+        Width11 = 50,      /**< Width 12. (0.50mm) */
+        Width12 = 53,      /**< Width 13. (0.53mm) */
+        Width13 = 60,      /**< Width 14. (0.60mm) */
+        Width14 = 70,      /**< Width 15. (0.70mm) */
+        Width15 = 80,      /**< Width 16. (0.80mm) */
+        Width16 = 90,      /**< Width 17. (0.90mm) */
+        Width17 = 100,     /**< Width 18. (1.00mm) */
+        Width18 = 106,     /**< Width 19. (1.06mm) */
+        Width19 = 120,     /**< Width 20. (1.20mm) */
+        Width20 = 140,     /**< Width 21. (1.40mm) */
+        Width21 = 158,     /**< Width 22. (1.58mm) */
+        Width22 = 200,     /**< Width 23. (2.00mm) */
+        Width23 = 211,     /**< Width 24. (2.11mm) */
+        WidthByLayer = -1, /**< Line width defined by layer not entity. */
+        WidthByBlock = -2, /**< Line width defined by block not entity. */
+        WidthDefault = -3  /**< Line width defaults to the predefined line width. */
+    };
+
+    /**
+     * Wrapper for Qt
+     */
+    /*
+       static int qw(RS2::LineWidth w) {
+           switch (w) {
+           case Width00:
+               return 1;  // 0 is more accurate but quite slow
+               break;
+           case WidthByLayer:
+           case WidthByBlock:
+           case WidthDefault:
+               return 1;
+               break;
+           case Width01:
+           case Width02:
+           case Width03:
+           case Width04:
+           case Width05:
+           case Width06:
+           case Width07:
+           case Width08:
+               return 1;
+               break;
+           case Width09:
+           case Width10:
+               return 3;
+               break;
+           case Width11:
+               return 4;
+               break;
+           case Width12:
+           case Width13:
+               return 5;
+               break;
+           case Width14:
+               return 6;
+               break;
+           case Width15:
+               return 7;
+               break;
+           case Width16:
+               return 8;
+               break;
+           case Width17:
+               return 9;
+               break;
+           case Width18:
+           case Width19:
+               return 10;
+               break;
+           case Width20:
+               return 12;
+               break;
+           case Width21:
+           case Width22:
+           case Width23:
+           //case Width24:
+               return 14;
+               break;
+           default:
+               return (int)w;
+               break;
+           }
+           return (int)w;
+       }
+    */
+
+    /**
+     * Wrapper for Qt
+     */
+	static LineWidth intToLineWidth(int w);
+
+    /**
+     * Enum of cursor types.
+     */
+    enum CursorType {
+        ArrowCursor,          /**< ArrowCursor - standard arrow cursor. */
+        UpArrowCursor,        /**< UpArrowCursor - upwards arrow. */
+        CrossCursor,          /**< CrossCursor - crosshair. */
+        WaitCursor,           /**< WaitCursor - hourglass/watch. */
+        IbeamCursor,          /**< IbeamCursor - ibeam/text entry. */
+        SizeVerCursor,        /**< SizeVerCursor - vertical resize. */
+        SizeHorCursor,        /**< SizeHorCursor - horizontal resize. */
+        SizeBDiagCursor,      /**< SizeBDiagCursor - diagonal resize (/). */
+        SizeFDiagCursor,      /**< SizeFDiagCursor - diagonal resize (\). */
+        SizeAllCursor,        /**< SizeAllCursor - all directions resize. */
+        BlankCursor,          /**< BlankCursor - blank/invisible cursor. */
+        SplitVCursor,         /**< SplitVCursor - vertical splitting. */
+        SplitHCursor,         /**< SplitHCursor - horizontal splitting. */
+        PointingHandCursor,   /**< PointingHandCursor - a pointing hand. */
+        ForbiddenCursor,      /**< ForbiddenCursor - a slashed circle. */
+        WhatsThisCursor,      /**< WhatsThisCursor - an arrow with a ?. */
+        OpenHandCursor,       /**< Qt OpenHandCursor */
+        ClosedHandCursor,     /**< Qt ClosedHandCursor */
+        CadCursor,            /**< CadCursor - a bigger cross. */
+        DelCursor,            /**< DelCursor - cursor for choosing entities */
+        SelectCursor,         /**< SelectCursor - for selecting single entities */
+        MagnifierCursor,      /**< MagnifierCursor - a magnifying glass. */
+        MovingHandCursor      /**< Moving hand - a little flat hand. */
+    };
+
+    /**
+     * Wrapper for Qt.
+     */
+	/*
+    static Qt::CursorShape rsToQtCursorType(RS2::CursorType t) {
+        switch (t) {
+        case ArrowCursor:
+            return Qt::ArrowCursor;
+        case UpArrowCursor:
+            return Qt::UpArrowCursor;
+        case CrossCursor:
+            return Qt::CrossCursor;
+        case WaitCursor:
+            return Qt::WaitCursor;
+        case IbeamCursor:
+            return Qt::IBeamCursor;
+        case SizeVerCursor:
+            return Qt::SizeVerCursor;
+        case SizeHorCursor:
+            return Qt::SizeHorCursor;
+        case SizeBDiagCursor:
+            return Qt::SizeBDiagCursor;
+        case SizeFDiagCursor:
+            return Qt::SizeFDiagCursor;
+        case SizeAllCursor:
+            return Qt::SizeAllCursor;
+        case BlankCursor:
+            return Qt::BlankCursor;
+        case SplitVCursor:
+            return Qt::SplitVCursor;
+        case SplitHCursor:
+            return Qt::SplitHCursor;
+        case PointingHandCursor:
+            return Qt::PointingHandCursor;
+        case OpenHandCursor:
+            return Qt::OpenHandCursor;
+        case ClosedHandCursor:
+            return Qt::ClosedHandCursor;
+        case ForbiddenCursor:
+            return Qt::ForbiddenCursor;
+        case WhatsThisCursor:
+            return Qt::WhatsThisCursor;
+        default:
+            return Qt::ArrowCursor;
+        }
+    }
+*/
+    /**
+     * Paper formats.
+     */
+    enum PaperFormat {
+        FirstPaperFormat,
+        Custom = FirstPaperFormat,
+
+        /* ISO "A" Series */
+        A0,   /* 841 x 1189 mm	33.1 x 46.8 in */
+        A1,   /* 594 x 841 mm	23.4 x 33.1 in */
+        A2,   /* 420 x 594 mm	16.5 x 23.4 in */
+        A3,   /* 297 x 420 mm	11.7 x 16.5 in */
+        A4,   /* 210 x 297 mm	8.3 x 11.7 in  */
+
+        /* Removed ISO "B" and "C" series, C5E, Comm10E, DLE, (envelope sizes) */
+
+        /* US "Office" */
+        Letter,   /* 216 x 279 mm   8.5 x 11.0 in */
+        Legal,    /* 216 x 356 mm   8.5 x 14.0 in */
+        Tabloid,  /* 279 x 432 mm   11.0 x 17.0 in */
+        /* Tabloid = Ledger = ANSI B.  Although, technically, both ANSI B and  
+           Ledger are defined in the qt library as 431.8 mm x 279.4 mm / 17 
+           x 11", while Tabloid is 279 x 432 mm / 11.0 x 17.0 in .  Using either 
+           "Ledger" or "AnsiB" will result in the wrong page orientation when 
+           printing or exporting to PDF.) */
+
+        /* ANSI */
+        //Ansi_A,   /* 216 x 279 mm	8.5 x 11.0 in */
+        //Ansi_B,   /* 279 x 432 mm	11.0 x 17.0 in */
+        Ansi_C,   /* 432 x 559 mm	17.0 x 22.0 in */
+        Ansi_D,   /* 559 x 864 mm	22.0 x 34.0 in */
+        Ansi_E,   /* 864 x 1118 mm	34.0 x 44.0 in */
+
+        /* Architectural */
+        Arch_A,    /* 229 x 305 mm	9.0 x 12.0 in */
+        Arch_B,    /* 305 x 457 mm	12.0 x 18.0 in */
+        Arch_C,    /* 457 x 610 mm	18.0 x 24.0 in */
+        Arch_D,    /* 610 x 914 mm	24.0 x 36.0 in */
+        Arch_E,    /* 914 x 1219 mm	36.0 x 48.0 in */
+
+        NPageFormat
+    };
+
+        /**
+         * Items that can be put on a overlay, the items are rendered in this order. Best is to leave snapper as last so
+         * it always shows up
+         */
+        enum OverlayGraphics {
+                ActionPreviewEntity, // Action Entities
+                Snapper // Snapper
+        };
+
+        //Different re-draw methods to speed up rendering of the screen
+        enum RedrawMethod {
+                RedrawNone = 0,
+                RedrawGrid = 1,
+                RedrawOverlay = 2,
+                RedrawDrawing = 4,
+                RedrawAll = 0xffff
+        };
+
+        /**
+         * Text drawing direction.
+         */
+        enum TextLocaleDirection {
+            locLeftToRight,     /** Left to right **/
+            locRightToLeft      /** Right to Left **/
+        };
+
+};
+
+#endif

lib/engine/rs_arc.h

@@ -0,0 +1,257 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#ifndef RS_ARC_H
+#define RS_ARC_H
+
+#include "rs_atomicentity.h"
+class LC_Quadratic;
+
+
+/**
+ * Holds the data that defines an arc.
+ */
+struct RS_ArcData {
+	RS_ArcData() = default;
+	~RS_ArcData() = default;
+
+	RS_ArcData(const RS_Vector& center,
+			   double radius,
+			   double angle1, double angle2,
+			   bool reversed);
+
+	void reset();
+
+	bool isValid() const;
+
+	RS_Vector center;
+	double radius;
+	double angle1;
+	double angle2;
+	bool reversed;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_ArcData& ad);
+
+
+/**
+ * Class for an arc entity. All angles are in Rad.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Arc : public RS_AtomicEntity {
+public:
+	RS_Arc()=default;
+    RS_Arc(RS_EntityContainer* parent,
+           const RS_ArcData& d);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityArc */
+	RS2::EntityType rtti() const override
+	{
+        return RS2::EntityArc;
+    }
+    /** @return true */
+	bool isEdge() const override {
+        return true;
+    }
+
+    /** @return Copy of data that defines the arc. **/
+	RS_ArcData getData() const {
+        return data;
+    }
+
+	RS_VectorSolutions getRefPoints() const override;
+
+    /** Sets new arc parameters. **/
+    void setData(RS_ArcData d) {
+        data = d;
+    }
+
+    /** @return The center point (x) of this arc */
+	RS_Vector getCenter() const override {
+        return data.center;
+    }
+    /** Sets new center. */
+    void setCenter(const RS_Vector& c) {
+        data.center = c;
+    }
+
+    /** @return The radius of this arc */
+	double getRadius() const override {
+        return data.radius;
+    }
+    /** Sets new radius. */
+    void setRadius(double r) {
+        data.radius = r;
+    }
+
+    /** @return The start angle of this arc */
+	double getAngle1() const {
+        return data.angle1;
+    }
+    /** Sets new start angle. */
+    void setAngle1(double a1) {
+        data.angle1 = a1;
+    }
+    /** @return The end angle of this arc */
+    double getAngle2() const {
+        return data.angle2;
+    }
+    /** Sets new end angle. */
+    void setAngle2(double a2) {
+        data.angle2 = a2;
+    }
+    /** get angle relative arc center*/
+    double getArcAngle(const RS_Vector& vp) {
+        return (vp - data.center).angle();
+    }
+    /**
+     * @return Direction 1. The angle at which the arc starts at
+     * the startpoint.
+     */
+	double getDirection1() const override;
+    /**
+     * @return Direction 2. The angle at which the arc starts at
+     * the endpoint.
+     */
+	double getDirection2() const override;
+
+    /**
+     * @retval true if the arc is reversed (clockwise),
+     * @retval false otherwise
+     */
+	bool isReversed() const {
+        return data.reversed;
+    }
+    /** sets the reversed status. */
+    void setReversed(bool r) {
+        data.reversed = r;
+    }
+
+    /** @return Start point of the entity. */
+	RS_Vector getStartpoint() const override;
+    /** @return End point of the entity. */
+	RS_Vector getEndpoint() const override;
+	std::vector<RS_Entity* > offsetTwoSides(const double& distance) const override;
+    /**
+          * implementations must revert the direction of an atomic entity
+          */
+	void revertDirection() override;
+	void correctAngles();//make sure angleLength() is not more than 2*M_PI
+	void moveStartpoint(const RS_Vector& pos) override;
+	void moveEndpoint(const RS_Vector& pos) override;
+	bool offset(const RS_Vector& position, const double& distance) override;
+
+	void trimStartpoint(const RS_Vector& pos) override;
+	void trimEndpoint(const RS_Vector& pos) override;
+
+	RS2::Ending getTrimPoint(const RS_Vector& coord,
+									 const RS_Vector& trimPoint) override;
+    /** choose an intersection to trim to based on mouse point */
+	RS_Vector prepareTrim(const RS_Vector& mousePoint,
+								  const RS_VectorSolutions& trimSol)override;
+
+	void reverse() override;
+
+	RS_Vector getMiddlePoint() const override;
+    double getAngleLength() const;
+	double getLength() const override;
+    double getBulge() const;
+
+    bool createFrom3P(const RS_Vector& p1, const RS_Vector& p2,
+                      const RS_Vector& p3);
+    bool createFrom2PDirectionRadius(const RS_Vector& startPoint, const RS_Vector& endPoint,
+                                     double direction1, double radius);
+    bool createFrom2PDirectionAngle(const RS_Vector& startPoint, const RS_Vector& endPoint,
+                                     double direction1, double angleLength);
+    bool createFrom2PBulge(const RS_Vector& startPoint, const RS_Vector& endPoint,
+                           double bulge);
+
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist = nullptr) const override;
+	RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+											  bool onEntity = true,
+											  double* dist = nullptr,
+											  RS_Entity** entity=nullptr) const override;
+	RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = nullptr) const override;
+	RS_Vector getNearestMiddle(const RS_Vector& coord,
+									   double* dist = nullptr,
+                                       int middlePoints = 1
+									   ) const override;
+	RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = nullptr) const override;
+	RS_Vector getNearestDist(double distance,
+									 bool startp) const override;
+	RS_Vector getNearestOrthTan(const RS_Vector& coord,
+                    const RS_Line& normal,
+					bool onEntity = false) const override;
+	RS_VectorSolutions getTangentPoint(const RS_Vector& point) const override;//find the tangential points seeing from given point
+	RS_Vector getTangentDirection(const RS_Vector& point) const override;
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+	void stretch(const RS_Vector& firstCorner,
+                         const RS_Vector& secondCorner,
+						 const RS_Vector& offset) override;
+
+    /** find the visible part of the arc, and call drawVisible() to draw */
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+    /** directly draw the arc, assuming the whole arc is within visible window */
+	void drawVisible(RS_Painter* painter, RS_GraphicView* view, double& patternOffset);
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Arc& a);
+
+	virtual void calculateBorders() override;
+    /** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+	virtual LC_Quadratic getQuadratic() const override;
+    /**
+     * @brief areaLineIntegral, line integral for contour area calculation by Green's Theorem
+     * Contour Area =\oint x dy
+     * @return line integral \oint x dy along the entity
+     * \oint x dy = c_x r \sin t + \frac{1}{4}r^2\sin 2t +  \frac{1}{2}r^2 t
+     */
+	virtual double areaLineIntegral() const override;
+
+protected:
+	RS_ArcData data;
+};
+
+#endif

lib/engine/rs_atomicentity.cpp

@@ -0,0 +1,206 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+
+Copyright (C) 2012-2015 Dongxu Li (dongxuli2011@gmail.com)
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+**********************************************************************/
+
+#include "rs_atomicentity.h"
+RS_AtomicEntity::RS_AtomicEntity(RS_EntityContainer* parent) : RS_Entity(parent) {}
+
+bool RS_AtomicEntity::isContainer() const {
+	return false;
+}
+
+/**
+ * @return true because entities made from subclasses are
+ *  atomic entities.
+ */
+bool RS_AtomicEntity::isAtomic() const {
+	return true;
+}
+
+/**
+ * @return Always 1 for atomic entities.
+ */
+unsigned int RS_AtomicEntity::count() const{
+	return 1;
+}
+
+/**
+ * @return Always 1 for atomic entities.
+ */
+unsigned int RS_AtomicEntity::countDeep() const{
+	return 1;
+}
+
+/**
+ * Implementation must return the endpoint of the entity or
+ * an invalid vector if the entity has no endpoint.
+ */
+RS_Vector RS_AtomicEntity::getEndpoint() const {
+	return RS_Vector(false);
+}
+
+/**
+ * Implementation must return the startpoint of the entity or
+ * an invalid vector if the entity has no startpoint.
+ */
+RS_Vector RS_AtomicEntity::getStartpoint() const {
+	return RS_Vector(false);
+}
+
+/**
+ * Implementation must return the angle in which direction the entity starts.
+ */
+double RS_AtomicEntity::getDirection1() const {
+	return 0.0;
+}
+
+/**
+ * Implementation must return the angle in which direction the entity starts the opposite way.
+ */
+double RS_AtomicEntity::getDirection2() const {
+	return 0.0;
+}
+RS_Vector RS_AtomicEntity::getCenter() const {
+	return RS_Vector(false);
+}
+double RS_AtomicEntity::getRadius() const {
+	   return 0.;
+   }
+/**
+* return the nearest center for snapping
+* @param coord Coordinate (typically a mouse coordinate)
+* @param dist Pointer to a value which will contain the measured
+* distance between 'coord' and the closest center point. The passed
+* pointer can also be NULL in which case the distance will be
+* lost.
+*
+* @return The closest center point.
+*/
+RS_Vector RS_AtomicEntity::getNearestCenter(const RS_Vector& /*coord*/,
+								  double* /*dist*/) const{
+	return RS_Vector(false);
+}
+
+/**
+ * (De-)selects startpoint.
+ */
+void RS_AtomicEntity::setStartpointSelected(bool select) {
+	if (select) {
+		setFlag(RS2::FlagSelected1);
+	} else {
+		delFlag(RS2::FlagSelected1);
+	}
+}
+
+/**
+ * (De-)selects endpoint.
+ */
+void RS_AtomicEntity::setEndpointSelected(bool select) {
+	if (select) {
+		setFlag(RS2::FlagSelected2);
+	} else {
+		delFlag(RS2::FlagSelected2);
+	}
+}
+bool RS_AtomicEntity::isTangent(const RS_CircleData& /* circleData */) const{
+	return false;
+}
+
+/**
+ * @return True if the entities startpoint is selected.
+ */
+bool RS_AtomicEntity::isStartpointSelected() const {
+	return getFlag(RS2::FlagSelected1);
+}
+
+/**
+ * @return True if the entities endpoint is selected.
+ */
+bool RS_AtomicEntity::isEndpointSelected() const {
+	return getFlag(RS2::FlagSelected2);
+}
+
+void RS_AtomicEntity::revertDirection(){}
+
+/**
+ * Implementation must create offset of the entity to
+ * the given direction and distance
+ */
+bool RS_AtomicEntity::offset(const RS_Vector& /*position*/, const double& /*distance*/) {return false;}
+
+/**
+ * Implementation must move the startpoint of the entity to
+ * the given position.
+ */
+void RS_AtomicEntity::moveStartpoint(const RS_Vector& /*pos*/) {}
+
+/**
+ * Implementation must move the endpoint of the entity to
+ * the given position.
+ */
+void RS_AtomicEntity::moveEndpoint(const RS_Vector& /*pos*/) {}
+
+/**
+ * Implementation must trim the startpoint of the entity to
+ * the given position.
+ */
+void RS_AtomicEntity::trimStartpoint(const RS_Vector& pos) {
+	moveStartpoint(pos);
+}
+
+/**
+ * Implementation must trim the endpoint of the entity to
+ * the given position.
+ */
+void RS_AtomicEntity::trimEndpoint(const RS_Vector& pos) {
+	moveEndpoint(pos);
+}
+
+/**
+ * Implementation must return which ending of the entity will
+ * be trimmed if 'coord' is the coordinate chosen to indicate the
+ * trim entity and 'trimPoint' is the point to which the entity will
+ * be trimmed.
+ */
+RS2::Ending RS_AtomicEntity::getTrimPoint(const RS_Vector& /*coord*/,
+								 const RS_Vector& /*trimPoint*/) {
+	return RS2::EndingNone;
+}
+
+/**
+ * Implementation must trim the entity in the case of multiple
+ * intersections and return the trimPoint
+ * trimCoord indicts the trigger trim position
+ * trimSol contains intersections
+ * */
+RS_Vector RS_AtomicEntity::prepareTrim(const RS_Vector& /*trimCoord*/,
+							  const RS_VectorSolutions& /*trimSol*/) {
+	return RS_Vector(false);
+}
+
+void RS_AtomicEntity::reverse() {}
+
+void RS_AtomicEntity::moveSelectedRef(const RS_Vector& ref, const RS_Vector& offset) {
+	if (isSelected()) {
+		moveRef(ref, offset);
+	}
+}

lib/engine/rs_atomicentity.h

@@ -0,0 +1,185 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_ATOMICENTITY_H
+#define RS_ATOMICENTITY_H
+
+#include "rs_entity.h"
+
+struct RS_CircleData;
+
+/**
+ * Class representing an atomic entity
+ * Typical atomic entities: RS_Line, RS_Arc, RS_Circle, RS_Ellipse
+ *
+ * @author Andrew Mustun
+ */
+class RS_AtomicEntity : public RS_Entity {
+
+public:
+    /**
+     * Constructor.
+     */
+	RS_AtomicEntity(RS_EntityContainer* parent=nullptr);
+
+    /**
+     * @return false because entities made from subclasses are
+     *  atomic entities.
+     */
+	bool isContainer() const override;
+
+    /**
+     * @return true because entities made from subclasses are
+     *  atomic entities.
+     */
+	bool isAtomic() const override;
+
+    /**
+     * @return Always 1 for atomic entities.
+     */
+	unsigned count() const override;
+
+    /**
+     * @return Always 1 for atomic entities.
+     */
+	unsigned countDeep() const override;
+
+    /**
+     * Implementation must return the endpoint of the entity or
+     * an invalid vector if the entity has no endpoint.
+     */
+	RS_Vector getEndpoint() const override;
+
+    /**
+     * Implementation must return the startpoint of the entity or
+     * an invalid vector if the entity has no startpoint.
+     */
+	RS_Vector getStartpoint() const override;
+
+    /**
+     * Implementation must return the angle in which direction the entity starts.
+     */
+	double getDirection1() const override;
+
+    /**
+     * Implementation must return the angle in which direction the entity starts the opposite way.
+     */
+	double getDirection2() const override;
+
+	RS_Vector getCenter() const override;
+	double getRadius() const override;
+	/**
+    * return the nearest center for snapping
+    * @param coord Coordinate (typically a mouse coordinate)
+    * @param dist Pointer to a value which will contain the measured
+    * distance between 'coord' and the closest center point. The passed
+    * pointer can also be NULL in which case the distance will be
+    * lost.
+    *
+    * @return The closest center point.
+    */
+   RS_Vector getNearestCenter(const RS_Vector& /*coord*/,
+									  double* /*dist*/) const override;
+
+    /**
+     * (De-)selects startpoint.
+     */
+	virtual void setStartpointSelected(bool select);
+
+    /**
+     * (De-)selects endpoint.
+     */
+	virtual void setEndpointSelected(bool select);
+	virtual bool isTangent(const RS_CircleData& /* circleData */) const;
+
+    /**
+     * @return True if the entities startpoint is selected.
+     */
+	bool isStartpointSelected() const;
+
+    /**
+     * @return True if the entities endpoint is selected.
+     */
+	bool isEndpointSelected() const;
+
+	void revertDirection() override;
+
+    /**
+     * Implementation must create offset of the entity to
+     * the given direction and distance
+     */
+	bool offset(const RS_Vector& /*position*/, const double& /*distance*/) override;
+
+    /**
+     * Implementation must move the startpoint of the entity to
+     * the given position.
+     */
+	virtual void moveStartpoint(const RS_Vector& /*pos*/);
+
+    /**
+     * Implementation must move the endpoint of the entity to
+     * the given position.
+     */
+	virtual void moveEndpoint(const RS_Vector& /*pos*/);
+
+    /**
+     * Implementation must trim the startpoint of the entity to
+     * the given position.
+     */
+	virtual void trimStartpoint(const RS_Vector& pos);
+
+    /**
+     * Implementation must trim the endpoint of the entity to
+     * the given position.
+     */
+	virtual void trimEndpoint(const RS_Vector& pos);
+
+    /**
+     * Implementation must return which ending of the entity will
+     * be trimmed if 'coord' is the coordinate chosen to indicate the
+     * trim entity and 'trimPoint' is the point to which the entity will
+     * be trimmed.
+     */
+	virtual RS2::Ending getTrimPoint(const RS_Vector& /*coord*/,
+									 const RS_Vector& /*trimPoint*/);
+
+    /**
+     * Implementation must trim the entity in the case of multiple
+     * intersections and return the trimPoint
+     * trimCoord indicts the trigger trim position
+     * trimSol contains intersections
+     * */
+	virtual RS_Vector prepareTrim(const RS_Vector& /*trimCoord*/,
+								  const RS_VectorSolutions& /*trimSol*/);
+
+	virtual void reverse();
+
+	void moveSelectedRef(const RS_Vector& ref, const RS_Vector& offset) override;
+};
+
+
+#endif

lib/engine/rs_block.cpp

@@ -0,0 +1,202 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include<iostream>
+#include "rs_block.h"
+
+#include "rs_graphic.h"
+#include "rs_insert.h"
+
+RS_BlockData::RS_BlockData(const QString& _name,
+						   const RS_Vector& _basePoint,
+						   bool _frozen):
+	name(_name)
+  ,basePoint(_basePoint)
+  ,frozen(_frozen)
+{
+}
+
+bool RS_BlockData::isValid() const{
+	return (!name.isEmpty() && basePoint.valid);
+}
+
+/**
+ * @param parent The graphic this block belongs to.
+ * @param name The name of the block used as an identifier.
+ * @param basePoint Base point (offset) of the block.
+ */
+RS_Block::RS_Block(RS_EntityContainer* parent,
+                   const RS_BlockData& d)
+        : RS_Document(parent), data(d) {
+
+    pen = RS_Pen(RS_Color(128,128,128), RS2::Width01, RS2::SolidLine);
+}
+
+
+RS_Entity* RS_Block::clone() const {
+    RS_Block* blk = new RS_Block(*this);
+    blk->setOwner(isOwner());
+    blk->detach();
+    blk->initId();
+    return blk;
+}
+
+
+
+RS_LayerList* RS_Block::getLayerList() {
+    RS_Graphic* g = getGraphic();
+    if (g) {
+        return g->getLayerList();
+    } else {
+        return NULL;
+    }
+}
+
+
+
+RS_BlockList* RS_Block::getBlockList() {
+    RS_Graphic* g = getGraphic();
+    if (g) {
+        return g->getBlockList();
+    } else {
+        return NULL;
+    }
+}
+
+
+bool RS_Block::save(bool isAutoSave) {
+    RS_Graphic* g = getGraphic();
+    if (g) {
+        return g->save(isAutoSave);
+    } else {
+        return false;
+    }
+}
+
+
+bool RS_Block::saveAs(const QString& filename, RS2::FormatType type, bool force) {
+    RS_Graphic* g = getGraphic();
+    if (g) {
+        return g->saveAs(filename, type, force);
+    } else {
+        return false;
+    }
+}
+
+
+
+/**
+ * Sets the parent documents modified status to 'm'.
+ */
+void RS_Block::setModified(bool m) {
+    RS_Graphic* p = getGraphic();
+    if (p) {
+        p->setModified(m);
+    }
+    modified = m;
+}
+
+
+/**
+ * Sets the visibility of the Block in block list
+ *
+ * @param v true: visible, false: invisible
+ */
+void RS_Block::visibleInBlockList(bool v) {
+    data.visibleInBlockList = v;
+}
+
+
+/**
+ * Returns the visibility of the Block in block list
+ */
+bool RS_Block::isVisibleInBlockList() const {
+    return data.visibleInBlockList;
+}
+
+
+/**
+ * Sets selection state of the block in block list
+ *
+ * @param v true: selected, false: deselected
+ */
+void RS_Block::selectedInBlockList(bool v) {
+    data.selectedInBlockList = v;
+}
+
+/**
+ * Returns selection state of the block in block list
+ */
+bool RS_Block::isSelectedInBlockList() const {
+    return data.selectedInBlockList;
+}
+
+/**
+ * Block may contain inserts of other blocks.
+ * Find name of the nested block that contain the insert
+ * of specified block.
+ *
+ * @param bName name of the block the nested insert references to
+ *
+ * @return block name chain to the block that contain searched insert
+ */
+QStringList RS_Block::findNestedInsert(const QString& bName) {
+
+    QStringList bnChain;
+
+    for (RS_Entity* e: entities) {
+        if (e->rtti()==RS2::EntityInsert) {
+            RS_Insert* i = ((RS_Insert*)e);
+            QString iName = i->getName();
+            if (iName == bName) {
+                bnChain << data.name;
+                break;
+            } else {
+                RS_BlockList* bList = getBlockList();
+                if (bList) {
+                    RS_Block* nestedBlock = bList->find(iName);
+                    if (nestedBlock) {
+                        QStringList nestedChain;
+                        nestedChain = nestedBlock->findNestedInsert(bName);
+                        if (!nestedChain.empty()) {
+                            bnChain << data.name;
+                            bnChain << nestedChain;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    return bnChain;
+}
+
+std::ostream& operator << (std::ostream& os, const RS_Block& b) {
+    os << " name: " << b.getName().toLatin1().data() << "\n";
+    os << " entities: " << (RS_EntityContainer&)b << "\n";
+    return os;
+}

lib/engine/rs_block.h

@@ -0,0 +1,228 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_BLOCK_H
+#define RS_BLOCK_H
+
+#include "rs_document.h"
+
+/**
+ * Holds the data that defines a block.
+ */
+struct RS_BlockData {
+	RS_BlockData() = default;
+
+	RS_BlockData(const QString& name,
+	           const RS_Vector& basePoint,
+			   bool frozen);
+
+	bool isValid() const;
+
+	/**
+	 * Block name. Acts as an id.
+	 */
+	QString name;
+	/**
+	 * Base point of the Block. Usually 0/0 since blocks can be moved around
+	 * using the insertion point of Insert entities.
+	 */
+	RS_Vector basePoint;
+
+	bool frozen {false};              //!< Frozen flag
+	bool visibleInBlockList {true};   //!< Visible in block list
+	bool selectedInBlockList {false}; //!< selected in block list
+};
+
+
+
+/**
+ * A block is a group of entities. A block unlike an other entity
+ * container has a base point which defines the offset of the
+ * block. Note that although technically possible, a block should
+ * never be part of the entity tree of a graphic. Blocks are 
+ * stored in a separate list inside the graphic document (a block list).
+ * The graphic can contain RS_Insert entities that refer to such 
+ * blocks.
+ *
+ * blocks are documents and can therefore be handled by graphic views.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Block : public RS_Document {
+
+	friend class RS_BlockList;
+
+public:
+    /**
+     * @param parent The graphic this block belongs to.
+     * @param blockData defining data of the block.
+     */
+    RS_Block(RS_EntityContainer* parent, const RS_BlockData& d);
+
+	virtual ~RS_Block() = default;
+	
+	virtual RS_Entity* clone() const;
+
+    /** @return RS2::EntityBlock */
+    virtual RS2::EntityType rtti() const {
+        return RS2::EntityBlock;
+    }
+
+    /**
+     * @return Name of this block (the name is an Id for this block).
+     */
+    QString getName() const {
+		return data.name;
+    }
+
+    /**
+     * @return base point of this block.
+     */
+    RS_Vector getBasePoint() const {
+        return data.basePoint;
+    }
+
+    virtual RS_LayerList* getLayerList();
+    virtual RS_BlockList* getBlockList();
+
+    /**
+     * Reimplementation from RS_Document. Does nothing.
+     */
+    virtual void newDoc() {
+        // do nothing
+    }
+
+    /**
+     * Reimplementation from RS_Document. Saves the parent graphic document.
+     */
+    virtual bool save(bool isAutoSave = false);
+
+    /**
+     * Reimplementation from RS_Document. Does nothing.
+     */
+    virtual bool saveAs(const QString& filename, RS2::FormatType type, bool force = false);
+
+    /**
+     * Reimplementation from RS_Document. Does nothing.
+     */
+    virtual bool open(const QString& , RS2::FormatType) {
+        // do nothing
+        return false;
+    }
+    virtual bool loadTemplate(const QString& , RS2::FormatType) {
+        // do nothing
+        return false;
+    }
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Block& b);
+
+    /** 
+	 * sets a new name for the block. Only called by blocklist to
+	 * assure that block names stay unique.
+	 */
+    void setName(const QString& n) {
+		data.name = n;
+    }
+    
+	/**
+     * @retval true if this block is frozen (invisible)
+     * @retval false if this block isn't frozen (visible)
+     */
+    bool isFrozen() const {
+        return data.frozen;
+    }
+
+    /**
+     * Toggles the visibility of this block.
+     * Freezes the block if it's not frozen, thaws the block otherwise
+     */
+    void toggle() {
+		data.frozen = !data.frozen;
+    }
+
+    /**
+     * (De-)freezes this block.
+     *
+     * @param freeze true: freeze, false: defreeze
+     */
+    void freeze(bool freeze) {
+		data.frozen = freeze;
+    }
+	
+    /**
+     * Sets the parent documents modified status to 'm'.
+     */
+	virtual void setModified(bool m);
+
+    /**
+     * Sets only this block modified status to 'm'
+     * without touching parent document.
+     */
+    void setModifiedFlag(bool m) { modified = m; }
+
+    /**
+     * Sets the visibility of the Block in block list
+     *
+     * @param v true: visible, false: invisible
+     */
+    void visibleInBlockList(bool v);
+
+    /**
+     * Returns the visibility of the Block in block list
+     */
+    bool isVisibleInBlockList() const;
+
+    /**
+     * Sets selection state of the block in block list
+     *
+     * @param v true: selected, false: deselected
+     */
+    void selectedInBlockList(bool v);
+
+    /**
+     * Returns selection state of the block in block list
+     */
+    bool isSelectedInBlockList() const;
+
+    /**
+     * Block may contain inserts of other blocks.
+     * Find name of the nested block that contain the insert
+     * of specified block.
+     *
+     * @param bName name of the block the nested insert references to
+     *
+     * @return block name chain to the block that contain searched insert
+     */
+    QStringList findNestedInsert(const QString& bName);
+
+protected:
+	//! Block data
+	RS_BlockData data;
+};
+
+
+#endif

lib/engine/rs_blocklist.cpp

@@ -0,0 +1,426 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include <set>
+#include <iostream>
+#include <QString>
+#include <QRegExp>
+#include "rs_debug.h"
+#include "rs_blocklist.h"
+#include "rs_block.h"
+#include "rs_blocklistlistener.h"
+
+/**
+ * Constructor.
+ * 
+ * @param owner true if this is the owner of the blocks added.
+ *              If so, the blocks will be deleted when the block
+ *              list is deleted.
+ */
+RS_BlockList::RS_BlockList(bool owner) {
+    this->owner = owner;
+    //blocks.setAutoDelete(owner);
+	activeBlock = nullptr;
+	setModified(false);
+}
+
+
+/**
+ * Removes all blocks in the blocklist.
+ */
+void RS_BlockList::clear() {
+    blocks.clear();
+	activeBlock = nullptr;
+	setModified(true);
+}
+
+
+/**
+ * Activates the given block.
+ * Listeners are notified.
+ */
+void RS_BlockList::activate(const QString& name) {
+    RS_DEBUG->print("RS_BlockList::activateBlock");
+
+    activate(find(name));
+}
+
+/**
+ * Activates the given block.
+ * Listeners are notified.
+ */
+void RS_BlockList::activate(RS_Block* block) {
+    RS_DEBUG->print("RS_BlockList::activateBlock");
+	activeBlock = block;
+}
+
+
+/**
+ * Adds a block to the block list. If a block with the same name
+ * exists already, the given block will be deleted if the blocklist
+ * owns the blocks.
+ *
+ * @param notify true if you want listeners to be notified.
+ *
+ * @return false: block already existed and was deleted.
+ */
+bool RS_BlockList::add(RS_Block* block, bool notify) {
+    RS_DEBUG->print("RS_BlockList::add()");
+
+	if (!block) {
+        return false;
+    }
+
+    // check if block already exists:
+    RS_Block* b = find(block->getName());
+	if (!b) {
+        blocks.append(block);
+
+        if (notify) {
+            addNotification();
+        }
+		setModified(true);
+
+		return true;
+    } else {
+        if (owner) {
+            delete block;
+			block = nullptr;
+        }
+		return false;
+    }
+
+}
+
+
+
+/**
+ * Notifies the listeners about blocks that were added. This can be
+ * used after adding a lot of blocks without auto-update or simply
+ * to force an update of GUI blocklists.
+ */
+void RS_BlockList::addNotification() {
+	for(auto l: blockListListeners){
+		l->blockAdded(nullptr);
+	}
+}
+
+
+
+/**
+ * Removes a block from the list.
+ * Listeners are notified after the block was removed from 
+ * the list but before it gets deleted.
+ */
+void RS_BlockList::remove(RS_Block* block) {
+    RS_DEBUG->print("RS_BlockList::removeBlock()");
+
+    // here the block is removed from the list but not deleted
+    blocks.removeOne(block);
+
+	for(auto l: blockListListeners){
+		l->blockRemoved(block);
+	}
+		
+	setModified(true);
+
+    // / *
+    // activate an other block if necessary:
+    if (activeBlock==block) {
+    	//activate(blocks.first());
+		activeBlock = nullptr;
+	}
+    // * /
+
+    // now it's save to delete the block
+    if (owner) {
+        delete block;
+    }
+}
+
+
+
+/**
+ * Tries to rename the given block to 'name'. Block names are unique in the
+ * block list.
+ *
+ * @retval true block was successfully renamed.
+ * @retval false block couldn't be renamed.
+ */
+bool RS_BlockList::rename(RS_Block* block, const QString& name) {
+	if (block) {
+		if (!find(name)) {
+			QString oldName = block->getName();
+			block->setName(name);
+			setModified(true);
+
+			// when the renamed block is nested within other block, we need to rename its inserts as well
+			for(RS_Block* b: blocks) {
+				b->renameInserts(oldName, name);
+			}
+
+			return true;
+		}
+	}
+
+	return false;
+}
+
+
+/**
+ * Changes a block's attributes. The attributes of block 'block'
+ * are copied from block 'source'.
+ * Listeners are notified.
+ */
+/*
+void RS_BlockList::editBlock(RS_Block* block, const RS_Block& source) {
+	*block = source;
+	
+    for (unsigned i=0; i<blockListListeners.count(); ++i) {
+		RS_BlockListListener* l = blockListListeners.at(i);
+ 
+		l->blockEdited(block);
+	}
+}
+*/
+
+/**
+ * @return Pointer to the block with the given name or
+ * \p nullptr if no such block was found.
+ */
+RS_Block* RS_BlockList::find(const QString& name) {
+    try {
+        RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_BlockList::find(): %s", name.toLatin1().constData());
+    }
+    catch(...) {
+        RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_BlockList::find(): wrong name to find");
+        return nullptr;
+    }
+	// Todo : reduce this from O(N) to O(log(N)) complexity based on sorted list or hash
+	//DFS
+	for(RS_Block* b: blocks) {
+		if (b->getName()==name) {
+			return b;
+		}
+	}
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_BlockList::find(): bad");
+	return nullptr;
+}
+
+/**
+ * Finds a new unique block name.
+ *
+ * @param suggestion Suggested name the new name will be based on.
+ */
+QString RS_BlockList::newName(const QString& suggestion) {
+//	qDebug()<<"begin: suggestion: "<<suggestion;
+	if(!find(suggestion))
+		return suggestion;
+
+	QString name=suggestion;
+	QRegExp const rx(R"(-\d+$)");
+	int index=name.lastIndexOf(rx);
+	int i=-1;
+	if(index>0){
+		i=name.mid(index+1).toInt();
+		name=name.mid(0, index);
+	}
+	for(RS_Block* b: blocks){
+		index=b->getName().lastIndexOf(rx);
+		if(index<0) continue;
+		QString const part1= b->getName().mid(0, index);
+		if(part1 != name) continue;
+		i=std::max(b->getName().mid(index+1).toInt(),i);
+	}
+//	qDebug()<<QString("%1-%2").arg(name).arg(i+1);
+	return QString("%1-%2").arg(name).arg(i+1);
+}
+
+/**
+ * Switches on / off the given block. 
+ * Listeners are notified.
+ */
+void RS_BlockList::toggle(const QString& name) {
+    toggle(find(name));
+}
+
+/**
+ * Switches on / off the given block. 
+ * Listeners are notified.
+ */
+void RS_BlockList::toggle(RS_Block* block) {
+	if (!block) {
+        return;
+    }
+
+    block->toggle();
+    // TODO LordOfBikes: when block attributes are saved, activate this
+    //setModified(true);
+
+    // Notify listeners:
+	for(auto l: blockListListeners){
+		l->blockToggled(block);
+	}
+}
+
+/**
+ * Freezes or defreezes all blocks.
+ *
+ * @param freeze true: freeze, false: defreeze
+ */
+void RS_BlockList::freezeAll(bool freeze) {
+
+    for (int l=0; l<count(); l++) {
+        if (at(l)->isVisibleInBlockList()) {
+            at(l)->freeze(freeze);
+        }
+    }
+    // TODO LordOfBikes: when block attributes are saved, activate this
+    //setModified(true);
+
+	for(auto l: blockListListeners){
+		l->blockToggled(nullptr);
+	}
+}
+
+
+/**
+ * Switches on / off the given block. 
+ * Listeners are notified.
+ */
+/*
+void RS_BlockList::toggleBlock(const QString& name) {
+	RS_Block* block = findBlock(name);
+	block->toggle();
+	
+    // Notify listeners:
+    for (unsigned i=0; i<blockListListeners.count(); ++i) {
+		RS_BlockListListener* l = blockListListeners.at(i);
+ 
+		l->blockToggled(block);
+	}
+}
+*/
+
+
+/**
+ * adds a BlockListListener to the list of listeners. Listeners
+ * are notified when the block list changes.
+ */
+void RS_BlockList::addListener(RS_BlockListListener* listener) {
+    blockListListeners.append(listener);
+}
+
+
+
+/**
+ * removes a BlockListListener from the list of listeners. 
+ */
+void RS_BlockList::removeListener(RS_BlockListListener* listener) {
+    blockListListeners.removeOne(listener);
+}
+
+int RS_BlockList::count() const{
+	return blocks.count();
+}
+
+/**
+ * @return Block at given position or nullptr if i is out of range.
+ */
+RS_Block* RS_BlockList::at(int i) {
+	return blocks.at(i);
+}
+RS_Block* RS_BlockList::at(int i) const{
+	return blocks.at(i);
+}
+QList<RS_Block*>::iterator RS_BlockList::begin()
+{
+	return blocks.begin();
+}
+
+QList<RS_Block*>::iterator RS_BlockList::end()
+{
+	return blocks.end();
+}
+
+QList<RS_Block*>::const_iterator RS_BlockList::begin()const
+{
+	return blocks.begin();
+}
+
+QList<RS_Block*>::const_iterator RS_BlockList::end()const
+{
+	return blocks.end();
+}
+
+//! @return The active block of nullptr if no block is activated.
+RS_Block* RS_BlockList::getActive() {
+	return activeBlock;
+}
+
+/**
+ * Sets the block list modified status to 'm'.
+ */
+void RS_BlockList::setModified(bool m) {
+	modified = m;
+
+	// Update each block modified status,
+	// but only when the status is set to false.
+	if (m == false) {
+		for (auto b: blocks) {
+			b->setModifiedFlag(false);
+		}
+	}
+
+	// Notify listeners
+	for (auto l: blockListListeners) {
+		l->blockListModified(m);
+	}
+}
+
+/**
+ * @retval true The block list has been modified.
+ * @retval false The block list has not been modified.
+ */
+bool RS_BlockList::isModified() const {
+	return modified;
+}
+
+/**
+ * Dumps the blocks to stdout.
+ */
+std::ostream& operator << (std::ostream& os, RS_BlockList& b) {
+
+    os << "Blocklist: \n";
+    for (int i=0; i<b.count(); ++i) {
+        RS_Block* blk = b.at(i);
+
+        os << *blk << "\n";
+    }
+
+    return os;
+}
+

lib/engine/rs_blocklist.h

@@ -0,0 +1,116 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_BLOCKLIST_H
+#define RS_BLOCKLIST_H
+
+
+#include <QList>
+
+class QString;
+class RS_Block;
+class RS_BlockListListener;
+
+/**
+ * List of blocks.
+ *
+ * @see RS_Block
+ *
+ * @author Andrew Mustun
+ */
+class RS_BlockList {
+public:
+    RS_BlockList(bool owner=false);
+	virtual ~RS_BlockList() = default;
+
+    void clear();
+    /**
+     * @return Number of blocks available.
+     */
+	int count() const;
+
+    /**
+     * @return Block at given position or NULL if i is out of range.
+     */
+	RS_Block* at(int i);
+	RS_Block* at(int i) const;
+	//! \{ \brief range based loop
+	QList<RS_Block*>::iterator begin();
+	QList<RS_Block*>::iterator end();
+	QList<RS_Block*>::const_iterator begin()const;
+	QList<RS_Block*>::const_iterator end()const;
+	//! \}
+
+    void activate(const QString& name);
+    void activate(RS_Block* block);
+    //! @return The active block of NULL if no block is activated.
+	RS_Block* getActive();
+
+    virtual bool add(RS_Block* block, bool notify=true);
+    virtual void addNotification();
+    virtual void remove(RS_Block* block);
+    virtual bool rename(RS_Block* block, const QString& name);
+    //virtual void editBlock(RS_Block* block, const RS_Block& source);
+    RS_Block* find(const QString& name);
+    QString newName(const QString& suggestion = "");
+    void toggle(const QString& name);
+    void toggle(RS_Block* block);
+    void freezeAll(bool freeze);
+
+    void addListener(RS_BlockListListener* listener);
+    void removeListener(RS_BlockListListener* listener);
+
+    bool isOwner() const {return owner;}
+    void setOwner(bool ow) {owner = ow;}
+
+    /**
+     * Sets the block list modified status to 'm'.
+     */
+	void setModified(bool m);
+
+    /**
+     * @retval true The block list has been modified.
+     * @retval false The block list has not been modified.
+     */
+	bool isModified() const;
+
+    friend std::ostream& operator << (std::ostream& os, RS_BlockList& b);
+
+private:
+    //! Is the list owning the blocks?
+    bool owner;
+    //! Blocks in the graphic
+    QList<RS_Block*> blocks;
+    //! List of registered BlockListListeners
+    QList<RS_BlockListListener*> blockListListeners;
+    //! Currently active block
+    RS_Block* activeBlock;
+    /** Flag set if the block list was modified and not yet saved. */
+    bool modified;
+};
+
+#endif

lib/engine/rs_blocklistlistener.h

@@ -0,0 +1,74 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_BLOCKLISTLISTENER_H
+#define RS_BLOCKLISTLISTENER_H
+
+#include "rs_block.h"
+
+/**
+ * This class is an interface for classes that are interested in
+ * knowing about changes in the block list. 
+ */
+class RS_BlockListListener {
+public:
+    RS_BlockListListener() {}
+    virtual ~RS_BlockListListener() {}
+
+    /**
+     * Called when the active block changes.
+     */
+    virtual void blockActivated(RS_Block*) {}
+
+    /**
+     * Called when a new block is added to the list.
+     */
+    virtual void blockAdded(RS_Block*) {}
+
+    /**
+     * Called when a block is removed from the list.
+     */
+    virtual void blockRemoved(RS_Block*) {}
+
+    /**
+     * Called when a block's attributes are modified.
+     */
+    virtual void blockEdited(RS_Block*) {}
+
+    /**
+     * Called when a block's visibility is toggled. 
+     */
+    virtual void blockToggled(RS_Block*) {}
+
+    /**
+     * Called when block list is modified.
+     */
+    virtual void blockListModified(bool) {}
+}
+;
+
+#endif

lib/engine/rs_circle.cpp

@@ -0,0 +1,841 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2011-2012 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include <cfloat>
+#include <QPolygonF>
+#include "rs_circle.h"
+
+#include "rs_arc.h"
+#include "rs_line.h"
+#include "rs_constructionline.h"
+#include "rs_information.h"
+#include "rs_graphicview.h"
+#include "rs_painter.h"
+#include "rs_linetypepattern.h"
+#include "rs_math.h"
+#include "lc_hyperbola.h"
+#include "lc_quadratic.h"
+#include "rs_debug.h"
+
+RS_CircleData::RS_CircleData(RS_Vector const& center, double radius):
+	center(center)
+	, radius(radius)
+{
+}
+
+bool RS_CircleData::isValid() const {
+	return (center.valid && radius>RS_TOLERANCE);
+}
+
+bool RS_CircleData::operator == (RS_CircleData const& rhs) const
+{
+	if(! (center.valid && rhs.center.valid)) return false;
+	if( center.squaredTo(rhs.center) > RS_TOLERANCE2) return false;
+	return fabs(radius - rhs.radius)< RS_TOLERANCE;
+}
+
+std::ostream& operator << (std::ostream& os, const RS_CircleData& ad)
+{
+	os << "(" << ad.center <<
+		  "/" << ad.radius <<
+		  ")";
+	return os;
+}
+
+
+/**
+ * constructor.
+ */
+RS_Circle::RS_Circle(RS_EntityContainer* parent,
+                     const RS_CircleData& d)
+    :RS_AtomicEntity(parent), data(d) {
+    calculateBorders();
+}
+
+RS_Entity* RS_Circle::clone() const {
+	RS_Circle* c = new RS_Circle(*this);
+	c->initId();
+	return c;
+}
+
+
+void RS_Circle::calculateBorders() {
+	RS_Vector r(data.radius,data.radius);
+	minV = data.center - r;
+	maxV = data.center + r;
+}
+
+
+/** @return The center point (x) of this arc */
+RS_Vector RS_Circle::getCenter() const {
+	return data.center;
+}
+/** Sets new center. */
+void RS_Circle::setCenter(const RS_Vector& c) {
+	data.center = c;
+}
+/** @return The radius of this arc */
+double RS_Circle::getRadius() const {
+	return data.radius;
+}
+/** Sets new radius. */
+void RS_Circle::setRadius(double r) {
+	data.radius = r;
+}
+
+/**
+ * @return Angle length in rad.
+ */
+double RS_Circle::getAngleLength() const {
+    return 2*M_PI;
+}
+
+
+
+/**
+ * @return Length of the circle which is the circumference.
+ */
+double RS_Circle::getLength() const {
+	return 2*M_PI*data.radius;
+}
+
+bool RS_Circle::isTangent(const RS_CircleData&  circleData) const{
+	const double d=circleData.center.distanceTo(data.center);
+//    DEBUG_HEADER
+	const double r0=fabs(circleData.radius);
+	const double r1=fabs(data.radius);
+//    std::cout<<fabs(d-fabs(r0-r1))<<" : "<<fabs(d-fabs(r0+r1))<<std::endl;
+    if( fabs(d-fabs(r0-r1))<20.*RS_TOLERANCE ||
+            fabs(d-fabs(r0+r1))<20.*RS_TOLERANCE ) return true;
+    return false;
+}
+
+
+/**
+ * Creates this circle from a center point and a radius.
+ *
+ * @param c Center.
+ * @param r Radius
+ */
+bool RS_Circle::createFromCR(const RS_Vector& c, double r) {
+    if (fabs(r)>RS_TOLERANCE && c.valid ) {
+		data.radius = fabs(r);
+		data.center = c;
+        return true;
+    } else {
+        RS_DEBUG->print(RS_Debug::D_WARNING, "RS_Circle::createFromCR(): "
+                        "Cannot create a circle with radius 0.0.");
+        return false;
+    }
+}
+
+
+
+/**
+ * Creates this circle from two opposite points.
+ *
+ * @param p1 1st point.
+ * @param p2 2nd point.
+ */
+bool RS_Circle::createFrom2P(const RS_Vector& p1, const RS_Vector& p2) {
+        double r=0.5*p1.distanceTo(p2);
+    if (r>RS_TOLERANCE) {
+		data.radius = r;
+		data.center = (p1+p2)*0.5;
+        return true;
+    } else {
+//        RS_DEBUG->print(RS_Debug::D_WARNING, "RS_Circle::createFrom2P(): "
+//                        "Cannot create a circle with radius 0.0.");
+        return false;
+    }
+}
+
+
+
+/**
+ * Creates this circle from 3 given points which define the circle line.
+ *
+ * @param p1 1st point.
+ * @param p2 2nd point.
+ * @param p3 3rd point.
+ */
+bool RS_Circle::createFrom3P(const RS_Vector& p1, const RS_Vector& p2,
+                             const RS_Vector& p3) {
+        RS_Vector vra=p2 - p1;
+        RS_Vector vrb=p3 - p1;
+        double ra2=vra.squared()*0.5;
+        double rb2=vrb.squared()*0.5;
+        double crossp=vra.x * vrb.y - vra.y * vrb.x;
+        if (fabs(crossp)< RS_TOLERANCE2) {
+                RS_DEBUG->print(RS_Debug::D_WARNING, "RS_Circle::createFrom3P(): "
+                        "Cannot create a circle with radius 0.0.");
+                return false;
+        }
+        crossp=1./crossp;
+		data.center.set((ra2*vrb.y - rb2*vra.y)*crossp,(rb2*vra.x - ra2*vrb.x)*crossp);
+		data.radius=data.center.magnitude();
+		data.center += p1;
+        return true;
+}
+//*create Circle from 3 points
+//Author: Dongxu Li
+bool RS_Circle::createFrom3P(const RS_VectorSolutions& sol) {
+    if(sol.getNumber() < 2) return false;
+    if(sol.getNumber() == 2) return createFrom2P(sol.get(0),sol.get(1));
+    if((sol.get(1)-sol.get(2)).squared() < RS_TOLERANCE2)
+        return createFrom2P(sol.get(0),sol.get(1));
+    RS_Vector vra(sol.get(1) - sol.get(0));
+    RS_Vector vrb(sol.get(2) - sol.get(0));
+    double ra2=vra.squared()*0.5;
+    double rb2=vrb.squared()*0.5;
+    double crossp=vra.x * vrb.y - vra.y * vrb.x;
+    if (fabs(crossp)< RS_TOLERANCE2) {
+        RS_DEBUG->print(RS_Debug::D_WARNING, "RS_Circle::createFrom3P(): "
+                        "Cannot create a circle with radius 0.0.");
+        return false;
+    }
+    crossp=1./crossp;
+	data.center.set((ra2*vrb.y - rb2*vra.y)*crossp,(rb2*vra.x - ra2*vrb.x)*crossp);
+	data.radius=data.center.magnitude();
+	data.center += sol.get(0);
+    return true;
+}
+
+/**
+  *create circle inscribled in a triangle
+  *
+  *Author: Dongxu Li
+  */
+bool RS_Circle::createInscribe(const RS_Vector& coord, const std::vector<RS_Line*>& lines){
+    if(lines.size()<3) return false;
+	std::vector<RS_Line*> tri(lines);
+    RS_VectorSolutions sol=RS_Information::getIntersectionLineLine(tri[0],tri[1]);
+    if(sol.getNumber() == 0 ) {//move parallel to opposite
+        std::swap(tri[1],tri[2]);
+        sol=RS_Information::getIntersectionLineLine(tri[0],tri[1]);
+    }
+    if(sol.getNumber() == 0 ) return false;
+    RS_Vector vp0(sol.get(0));
+    sol=RS_Information::getIntersectionLineLine(tri[2],tri[1]);
+    if(sol.getNumber() == 0 ) return false;
+    RS_Vector vp1(sol.get(0));
+    RS_Vector dvp(vp1-vp0);
+    double a(dvp.squared());
+    if( a< RS_TOLERANCE2) return false; //three lines share a common intersecting point
+    RS_Vector vp(coord - vp0);
+    vp -= dvp*(RS_Vector::dotP(dvp,vp)/a); //normal component
+    RS_Vector vl0(tri[0]->getEndpoint() - tri[0]->getStartpoint());
+    a=dvp.angle();
+    double angle0(0.5*(vl0.angle() + a));
+    if( RS_Vector::dotP(vp,vl0) <0.) {
+        angle0 += 0.5*M_PI;
+    }
+
+    RS_Line line0(vp0, vp0+RS_Vector(angle0));//first bisecting line
+    vl0=(tri[2]->getEndpoint() - tri[2]->getStartpoint());
+    angle0=0.5*(vl0.angle() + a+M_PI);
+    if( RS_Vector::dotP(vp,vl0) <0.) {
+        angle0 += 0.5*M_PI;
+    }
+    RS_Line line1(vp1, vp1+RS_Vector(angle0));//second bisection line
+    sol=RS_Information::getIntersectionLineLine(&line0,&line1);
+    if(sol.getNumber() == 0 ) return false;
+
+	bool ret=createFromCR(sol.get(0),tri[1]->getDistanceToPoint(sol.get(0)));
+	if(!ret) return false;
+	for(auto p: lines){
+		if(! p->isTangent(data)) return false;
+	}
+	return true;
+}
+
+std::vector<RS_Entity* > RS_Circle::offsetTwoSides(const double& distance) const
+{
+	std::vector<RS_Entity*> ret(0,nullptr);
+	ret.push_back(new RS_Circle(nullptr, {getCenter(),getRadius()+distance}));
+	if(fabs(getRadius()-distance)>RS_TOLERANCE)
+	ret.push_back(new RS_Circle(nullptr, {getCenter(),fabs(getRadius()-distance)}));
+    return ret;
+}
+
+RS_VectorSolutions RS_Circle::createTan1_2P(const RS_AtomicEntity* circle, const std::vector<RS_Vector>& points)
+{
+    RS_VectorSolutions ret;
+	if (!circle||points.size()<2) return ret;
+    return LC_Quadratic::getIntersection(
+                LC_Quadratic(circle,points[0]),
+                LC_Quadratic(circle,points[1])
+                );
+}
+
+/**
+  * create a circle of radius r and tangential to two given entities
+  */
+RS_VectorSolutions RS_Circle::createTan2(const std::vector<RS_AtomicEntity*>& circles, const double& r)
+{
+    if(circles.size()<2) return false;
+	auto e0=circles[0]->offsetTwoSides(r);
+	auto e1=circles[1]->offsetTwoSides(r);
+    RS_VectorSolutions centers;
+	if(e0.size() && e1.size()) {
+        for(auto it0=e0.begin();it0!=e0.end();it0++){
+            for(auto it1=e1.begin();it1!=e1.end();it1++){
+                centers.push_back(RS_Information::getIntersection(*it0,*it1));
+            }
+        }
+    }
+    for(auto it0=e0.begin();it0!=e0.end();it0++){
+        delete *it0;
+    }
+    for(auto it0=e1.begin();it0!=e1.end();it0++){
+        delete *it0;
+	}
+    return centers;
+
+}
+
+std::vector<RS_Circle> RS_Circle::createTan3(const std::vector<RS_AtomicEntity*>& circles)
+{
+	std::vector<RS_Circle> ret;
+    if(circles.size()!=3) return ret;
+	 std::vector<RS_Circle> cs;
+	 for(auto c: circles){
+		 cs.emplace_back(RS_Circle(nullptr, {c->getCenter(),c->getRadius()}));
+	 }
+    unsigned short flags=0;
+    do{
+        for(unsigned short j=0u;j<3u;++j){
+            if(flags & (1u<<j)) {
+                cs[j].setRadius( - fabs(cs[j].getRadius()));
+            }else{
+                cs[j].setRadius( fabs(cs[j].getRadius()));
+            }
+        }
+//        RS_DEBUG->print(RS_Debug::D_ERROR, "flags=%d\n",flags);
+		auto list=solveAppolloniusSingle(cs);
+        if(list.size()>=1){
+            for(RS_Circle& c0: list){
+                bool addNew=true;
+                for(RS_Circle& c: ret){
+                    if((c0.getCenter()-c.getCenter()).squared()<RS_TOLERANCE15 && fabs(c0.getRadius() - c.getRadius())<RS_TOLERANCE){
+                        addNew=false;
+                        break;
+                    }
+                }
+				if(addNew) ret.push_back(c0);
+            }
+        }
+
+
+    }while(++flags<8u);
+//    std::cout<<__FILE__<<" : "<<__func__<<" : line "<<__LINE__<<std::endl;
+//    std::cout<<"before testing, ret.size()="<<ret.size()<<std::endl;
+	for(size_t i=0;i<ret.size();){
+        if(ret[i].testTan3(circles) == false) {
+            ret.erase(ret.begin()+i);
+        }else{
+            ++i;
+        }
+    }
+//        DEBUG_HEADER
+//    std::cout<<"after testing, ret.size()="<<ret.size()<<std::endl;
+    return ret;
+}
+
+bool RS_Circle::testTan3(const std::vector<RS_AtomicEntity*>& circles)
+{
+
+    if(circles.size()!=3) return false;
+
+//        std::cout<<__FILE__<<" : "<<__func__<<" : line "<<__LINE__<<std::endl;
+//        std::cout<<"to verify Center = ( "<<data.center.x<<" , "<<data.center.y<<" ), r= "<<data.radius<<std::endl;
+    for(auto const& c: circles){
+		const double r0 = fabs(data.radius);
+        const double r1 = fabs(c->getRadius());
+
+        const double dist=fabs((data.center - c->getCenter()).magnitude());
+//        DEBUG_HEADER
+//        std::cout<<"testing: "<<getCenter()<<" r="<<getRadius()<<". \twith Center = ( "<<(*it)->getCenter().x<<" , "<<(*it)->getCenter().y<<" ), r= "<<(*it)->getRadius()<<std::endl;
+//        std::cout<<"r0="<<r0<<"\tr1="<<r1<<"\tdist="<<dist<<"\tdelta0="<<fabs(dist - fabs(r0 - r1)) <<"\tdelta1="<<fabs(dist - fabs(r0 + r1))
+//                <<"\t"<<sqrt(DBL_EPSILON)*qMax(r0,r1)<<std::endl;
+
+        double const rmax=std::max(r0,r1);
+        if( dist < rmax )
+                return fabs(dist - fabs(r0 - r1)) <= sqrt(DBL_EPSILON)*rmax;
+        else
+                return fabs(dist - fabs(r0 + r1)) <= sqrt(DBL_EPSILON)*rmax;
+    }
+    return true;
+}
+
+/** solve one of the eight Appollonius Equations
+| Cx - Ci|^2=(Rx+Ri)^2
+with Cx the center of the common tangent circle, Rx the radius. Ci and Ri are the Center and radius of the i-th existing circle
+**/
+std::vector<RS_Circle> RS_Circle::solveAppolloniusSingle(const std::vector<RS_Circle>& circles)
+{
+//          std::cout<<__FILE__<<" : "<<__func__<<" : line "<<__LINE__<<std::endl;
+//          for(int i=0;i<circles.size();i++){
+//std::cout<<"i="<<i<<"\t center="<<circles[i].getCenter()<<"\tr="<<circles[i].getRadius()<<std::endl;
+//          }
+	std::vector<RS_Circle> ret;
+
+	std::vector<RS_Vector> centers;
+	std::vector<double> radii;
+
+	for(auto c: circles){
+		if(c.getCenter().valid==false) return ret;
+		centers.push_back(c.getCenter());
+		radii.push_back(c.getRadius());
+	}
+//              for(int i=0;i<circles.size();i++){
+//    std::cout<<"i="<<i<<"\t center="<<circles[i].getCenter()<<"\tr="<<radii.at(i)<<std::endl;
+//              }
+/** form the linear equation to solve center in radius **/
+	std::vector<std::vector<double> > mat(2,std::vector<double>(3,0.));
+    mat[0][0]=centers[2].x - centers[0].x;
+    mat[0][1]=centers[2].y - centers[0].y;
+    mat[1][0]=centers[2].x - centers[1].x;
+    mat[1][1]=centers[2].y - centers[1].y;
+    if(fabs(mat[0][0]*mat[1][1] - mat[0][1]*mat[1][0])<RS_TOLERANCE2){
+//        DEBUG_HEADER
+//        std::cout<<"The provided circles are in a line, not common tangent circle"<<std::endl;
+        size_t i0=0;
+        if( centers[0].distanceTo(centers[1]) <= RS_TOLERANCE ||  centers[0].distanceTo(centers[2]) <= RS_TOLERANCE) i0 = 1;
+        LC_Quadratic lc0(& (circles[i0]), & (circles[(i0+1)%3]));
+        LC_Quadratic lc1(& (circles[i0]), & (circles[(i0+2)%3]));
+		auto c0 = LC_Quadratic::getIntersection(lc0, lc1);
+//        qDebug()<<"c0.size()="<<c0.size();
+        for(size_t i=0; i<c0.size(); i++){
+            const double dc =  c0[i].distanceTo(centers[i0]);
+			ret.push_back(RS_Circle(nullptr, {c0[i], fabs(dc - radii[i0])}));
+            if( dc > radii[i0]) {
+				ret.push_back(RS_Circle(nullptr, {c0[i], dc + radii[i0]}));
+            }
+        }
+        return ret;
+    }
+    // r^0 term
+    mat[0][2]=0.5*(centers[2].squared()-centers[0].squared()+radii[0]*radii[0]-radii[2]*radii[2]);
+    mat[1][2]=0.5*(centers[2].squared()-centers[1].squared()+radii[1]*radii[1]-radii[2]*radii[2]);
+//    std::cout<<__FILE__<<" : "<<__func__<<" : line "<<__LINE__<<std::endl;
+//    for(unsigned short i=0;i<=1;i++){
+//        std::cout<<"eqs P:"<<i<<" : "<<mat[i][0]<<"*x + "<<mat[i][1]<<"*y = "<<mat[i][2]<<std::endl;
+//    }
+//    std::vector<std::vector<double> > sm(2,std::vector<double>(2,0.));
+	std::vector<double> sm(2,0.);
+    if(RS_Math::linearSolver(mat,sm)==false){
+        return ret;
+    }
+
+    RS_Vector vp(sm[0],sm[1]);
+//      std::cout<<__FILE__<<" : "<<__func__<<" : line "<<__LINE__<<std::endl;
+//      std::cout<<"vp="<<vp<<std::endl;
+
+    // r term
+    mat[0][2]= radii[0]-radii[2];
+    mat[1][2]= radii[1]-radii[2];
+//    for(unsigned short i=0;i<=1;i++){
+//        std::cout<<"eqs Q:"<<i<<" : "<<mat[i][0]<<"*x + "<<mat[i][1]<<"*y = "<<mat[i][2]<<std::endl;
+//    }
+    if(RS_Math::linearSolver(mat,sm)==false){
+        return ret;
+    }
+    RS_Vector vq(sm[0],sm[1]);
+//      std::cout<<"vq="<<vq<<std::endl;
+    //form quadratic equation for r
+    RS_Vector dcp=vp-centers[0];
+    double a=vq.squared()-1.;
+    if(fabs(a)<RS_TOLERANCE*1e-4) {
+        return ret;
+    }
+    std::vector<double> ce(0,0.);
+    ce.push_back(2.*(dcp.dotP(vq)-radii[0])/a);
+    ce.push_back((dcp.squared()-radii[0]*radii[0])/a);
+    std::vector<double>&& vr=RS_Math::quadraticSolver(ce);
+    for(size_t i=0; i < vr.size();i++){
+        if(vr.at(i)<RS_TOLERANCE) continue;
+		ret.emplace_back(RS_Circle(nullptr, {vp+vq*vr.at(i),fabs(vr.at(i))}));
+    }
+//    std::cout<<__FILE__<<" : "<<__func__<<" : line "<<__LINE__<<std::endl;
+//    std::cout<<"Found "<<ret.size()<<" solutions"<<std::endl;
+
+    return ret;
+}
+
+RS_VectorSolutions RS_Circle::getRefPoints() const
+{
+	RS_Vector v1(data.radius, 0.0);
+	RS_Vector v2(0.0, data.radius);
+
+	return RS_VectorSolutions ({data.center,
+						   data.center+v1, data.center+v2,
+						   data.center-v1, data.center-v2});
+}
+
+
+/**
+ * @brief compute nearest endpoint, intersection with X/Y axis at 0, 90, 180 and 270 degree
+ *
+ * Use getNearestMiddle() method to compute the nearest circle quadrant endpoints
+ *
+ * @param coord coordinates to compute, e.g. mouse cursor position
+ * @param dist double pointer to return distance between mouse pointer and nearest entity point
+ * @return the nearest intersection of the circle with X/Y axis.
+ */
+RS_Vector RS_Circle::getNearestEndpoint(const RS_Vector& coord, double* dist /*= nullptr*/) const
+{
+    return getNearestMiddle( coord, dist, 0);
+}
+
+
+RS_Vector RS_Circle::getNearestPointOnEntity(const RS_Vector& coord,
+        bool /*onEntity*/, double* dist, RS_Entity** entity)const {
+
+	if (entity) {
+        *entity = const_cast<RS_Circle*>(this);
+    }
+	RS_Vector vp(coord - data.center);
+    double d(vp.magnitude());
+    if( d < RS_TOLERANCE ) return RS_Vector(false);
+	vp =data.center+vp*(data.radius/d);
+//    RS_DEBUG->print(RS_Debug::D_ERROR, "circle(%g, %g), r=%g: distance to point (%g, %g)\n",data.center.x,data.center.y,coord.x,coord.y);
+
+	if(dist){
+        *dist=coord.distanceTo(vp);
+//        RS_DEBUG->print(RS_Debug::D_ERROR, "circle(%g, %g), r=%g: distance to point (%g, %g)=%g\n",data.center.x,data.center.y,coord.x,coord.y,*dist);
+    }
+    return vp;
+}
+
+
+/**
+  *find the tangential points from a given point, i.e., the tangent lines should pass
+  * the given point and tangential points
+  *
+  *Author: Dongxu Li
+  */
+RS_VectorSolutions RS_Circle::getTangentPoint(const RS_Vector& point) const {
+    RS_VectorSolutions ret;
+    double r2(getRadius()*getRadius());
+    if(r2<RS_TOLERANCE2) return ret; //circle too small
+    RS_Vector vp(point-getCenter());
+    double c2(vp.squared());
+    if(c2<r2-getRadius()*2.*RS_TOLERANCE) {
+        //inside point, no tangential point
+        return ret;
+    }
+    if(c2>r2+getRadius()*2.*RS_TOLERANCE) {
+        //external point
+        RS_Vector vp1(-vp.y,vp.x);
+        vp1*=getRadius()*sqrt(c2-r2)/c2;
+        vp *= r2/c2;
+        vp += getCenter();
+        if(vp1.squared()>RS_TOLERANCE2) {
+            ret.push_back(vp+vp1);
+            ret.push_back(vp-vp1);
+            return ret;
+        }
+    }
+    ret.push_back(point);
+    return ret;
+}
+RS_Vector RS_Circle::getTangentDirection(const RS_Vector& point) const {
+    RS_Vector vp(point-getCenter());
+//    double c2(vp.squared());
+//    if(c2<r2-getRadius()*2.*RS_TOLERANCE) {
+//        //inside point, no tangential point
+//        return RS_Vector(false);
+//    }
+    return RS_Vector(-vp.y,vp.x);
+
+}
+
+RS_Vector RS_Circle::getNearestCenter(const RS_Vector& coord,
+									  double* dist) const{
+	if (dist) {
+		*dist = coord.distanceTo(data.center);
+    }
+	return data.center;
+}
+
+
+
+RS_Vector RS_Circle::getMiddlePoint(void)const
+{
+    return RS_Vector(false);
+}
+
+/**
+ * @brief compute middlePoints for each quadrant of a circle
+ *
+ * 0 middlePoints snaps to axis intersection at 0, 90, 180 and 270 degree (getNearestEndpoint) \n
+ * 1 middlePoints snaps to 45, 135, 225 and 315 degree \n
+ * 2 middlePoints snaps to 30, 60, 120, 150, 210, 240, 300 and 330 degree \n
+ * and so on
+ *
+ * @param coord coordinates to compute, e.g. mouse cursor position
+ * @param dist double pointer to return distance between mouse pointer and nearest entity point
+ * @param middlePoints number of middle points to compute per quadrant (0 for endpoints)
+ * @return the nearest of equidistant middle points of the circles quadrants.
+ */
+RS_Vector RS_Circle::getNearestMiddle(const RS_Vector& coord,
+                                      double* dist /*= nullptr*/,
+                                      const int middlePoints /*= 1*/) const
+{
+	if( data.radius <= RS_TOLERANCE) {
+        //circle too short
+        if ( nullptr != dist) {
+            *dist = RS_MAXDOUBLE;
+        }
+        return RS_Vector(false);
+    }
+
+    RS_Vector vPoint( getNearestPointOnEntity( coord, true, dist));
+    int iCounts = middlePoints + 1;
+	double dAngleSteps = M_PI_2 / iCounts;
+	double dAngleToPoint = data.center.angleTo(vPoint);
+    int iStepCount = static_cast<int>((dAngleToPoint + 0.5 * dAngleSteps) / dAngleSteps);
+    if( 0 < middlePoints) {
+        // for nearest middle eliminate start/endpoints
+        int iQuadrant = static_cast<int>(dAngleToPoint / 0.5 / M_PI);
+        int iQuadrantStep = iStepCount - iQuadrant * iCounts;
+        if( 0 == iQuadrantStep) {
+            ++iStepCount;
+        }
+        else if( iCounts == iQuadrantStep) {
+            --iStepCount;
+        }
+    }
+
+	vPoint.setPolar( data.radius, dAngleSteps * iStepCount);
+	vPoint.move( data.center);
+
+	if(dist) {
+        *dist = vPoint.distanceTo( coord);
+    }
+
+    return vPoint;
+}
+
+
+RS_Vector RS_Circle::getNearestDist(double /*distance*/,
+                                    const RS_Vector& /*coord*/,
+									double* dist) const{
+
+	if (dist) {
+        *dist = RS_MAXDOUBLE;
+    }
+    return RS_Vector(false);
+}
+
+RS_Vector RS_Circle::getNearestDist(double /*distance*/,
+									bool /*startp*/) const{
+
+    return RS_Vector(false);
+}
+
+
+RS_Vector RS_Circle::getNearestOrthTan(const RS_Vector& coord,
+                    const RS_Line& normal,
+					bool /*onEntity = false*/) const
+{
+        if ( !coord.valid) {
+                return RS_Vector(false);
+        }
+        RS_Vector vp0(coord-getCenter());
+        RS_Vector vp1(normal.getAngle1());
+        double d=RS_Vector::dotP(vp0,vp1);
+        if(d >= 0. ) {
+                return getCenter() + vp1*getRadius();
+        }else{
+                return getCenter() - vp1*getRadius();
+        }
+}
+
+void RS_Circle::move(const RS_Vector& offset) {
+	data.center.move(offset);
+    moveBorders(offset);
+//    calculateBorders();
+}
+
+/**
+  * this function creates offset
+  *@coord, position indicates the direction of offset
+  *@distance, distance of offset
+  * return true, if success, otherwise, false
+  *
+  *Author: Dongxu Li
+  */
+bool RS_Circle::offset(const RS_Vector& coord, const double& distance) {
+    double r0(coord.distanceTo(getCenter()));
+    if(r0 > getRadius()){
+        //external
+        r0 = getRadius()+ fabs(distance);
+    }else{
+        r0 = getRadius()- fabs(distance);
+        if(r0<RS_TOLERANCE) {
+            return false;
+        }
+    }
+    setRadius(r0);
+    calculateBorders();
+    return true;
+}
+
+void RS_Circle::rotate(const RS_Vector& center, const double& angle) {
+	data.center.rotate(center, angle);
+    calculateBorders();
+}
+
+void RS_Circle::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+	data.center.rotate(center, angleVector);
+    calculateBorders();
+}
+
+void RS_Circle::scale(const RS_Vector& center, const RS_Vector& factor) {
+	data.center.scale(center, factor);
+    //radius always is positive
+	data.radius *= fabs(factor.x);
+    scaleBorders(center,factor);
+//    calculateBorders();
+}
+
+double RS_Circle::getDirection1() const{
+		return M_PI_2;
+}
+
+double RS_Circle::getDirection2() const{
+		return M_PI_2*3.0;
+}
+
+
+
+void RS_Circle::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+	data.center.mirror(axisPoint1, axisPoint2);
+    calculateBorders();
+}
+
+
+/** whether the entity's bounding box intersects with visible portion of graphic view
+//fix me, need to handle overlay container separately
+*/
+bool RS_Circle::isVisibleInWindow(RS_GraphicView* view) const
+{
+
+    RS_Vector vpMin(view->toGraph(0,view->getHeight()));
+    RS_Vector vpMax(view->toGraph(view->getWidth(),0));
+    QPolygonF visualBox(QRectF(vpMin.x,vpMin.y,vpMax.x-vpMin.x, vpMax.y-vpMin.y));
+	std::vector<RS_Vector> vps;
+    for(unsigned short i=0;i<4;i++){
+        const QPointF& vp(visualBox.at(i));
+		vps.emplace_back(vp.x(),vp.y());
+    }
+    for(unsigned short i=0;i<4;i++){
+		RS_Line line{nullptr, {vps.at(i),vps.at((i+1)%4)}};
+		RS_Circle c0{nullptr, getData()};
+        if( RS_Information::getIntersection(&c0, &line, true).size()>0) return true;
+    }
+    if( getCenter().isInWindowOrdered(vpMin,vpMax)==false) return false;
+    return (vpMin-getCenter()).squared() > getRadius()*getRadius();
+}
+
+
+void RS_Circle::draw(RS_Painter* painter, RS_GraphicView* view, double& /*patternOffset*/) {
+//    // draw circle as a 2 pi arc
+//    RS_Arc arc(getParent(), RS_ArcData(getCenter(),getRadius(),0.,2.*M_PI, false));
+//    arc.setSelected(isSelected());
+//    arc.setPen(getPen());
+//    arc.draw(painter,view,patternOffset);
+
+    painter->drawCircle(view->toGui(getCenter()), view->toGuiDX(getRadius()));
+}
+
+
+void RS_Circle::moveRef(const RS_Vector& ref, const RS_Vector& offset) {
+	if(ref.distanceTo(data.center)<1.0e-4){
+		data.center += offset;
+        return;
+    }
+	RS_Vector v1(data.radius, 0.0);
+    RS_VectorSolutions sol;
+	sol.push_back(data.center + v1);
+	sol.push_back(data.center - v1);
+	v1.set(0., data.radius);
+	sol.push_back(data.center + v1);
+	sol.push_back(data.center - v1);
+    double dist;
+    v1=sol.getClosest(ref,&dist);
+    if(dist>1.0e-4) return;
+	data.radius = data.center.distanceTo(v1 + offset);
+}
+
+
+/** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+LC_Quadratic RS_Circle::getQuadratic() const
+{
+    std::vector<double> ce(6,0.);
+    ce[0]=1.;
+    ce[2]=1.;
+	ce[5]=-data.radius*data.radius;
+    LC_Quadratic ret(ce);
+	ret.move(data.center);
+    return ret;
+}
+
+
+/**
+* @brief Returns area of full circle
+* Note: Circular arcs are handled separately by RS_Arc (areaLIneIntegral) 
+* However, full ellipses and ellipse arcs are handled by RS_Ellipse
+* @return \pi r^2
+*/
+double RS_Circle::areaLineIntegral() const
+{
+	const double r = getRadius();
+	
+	return M_PI*r*r;
+}
+
+
+/**
+ * Dumps the circle's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Circle& a) {
+    os << " Circle: " << a.data << "\n";
+    return os;
+}
+

lib/engine/rs_circle.h

@@ -0,0 +1,186 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_CIRCLE_H
+#define RS_CIRCLE_H
+
+#include <vector>
+#include "rs_atomicentity.h"
+
+class LC_Quadratic;
+
+/**
+ * Holds the data that defines a circle.
+ */
+struct RS_CircleData {
+	RS_CircleData() = default;
+	RS_CircleData(RS_Vector const& center, double radius);
+	bool isValid() const;
+	bool operator == (RS_CircleData const&) const;
+	RS_Vector center;
+	double radius;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_CircleData& ad);
+
+/**
+ * Class for a circle entity.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Circle : public RS_AtomicEntity {
+public:
+	RS_Circle()=default;
+    RS_Circle (RS_EntityContainer* parent,
+               const RS_CircleData& d);
+	~RS_Circle() = default;
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityCircle */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityCircle;
+    }
+    /** @return true */
+	bool isEdge() const  override{
+        return true;
+    }
+
+    /** @return Copy of data that defines the circle. **/
+	const RS_CircleData& getData() const {
+        return data;
+    }
+
+	RS_VectorSolutions getRefPoints() const override;
+
+    //no start/end point for whole circle
+	//        RS_Vector getStartpoint() const {
+    //                return data.center + RS_Vector(data.radius, 0.0);
+    //        }
+	//        RS_Vector getEndpoint() const {
+    //                return data.center + RS_Vector(data.radius, 0.0);
+    //        }
+    /**
+         * @return Direction 1. The angle at which the arc starts at
+         * the startpoint.
+         */
+	double getDirection1() const override;
+    /**
+         * @return Direction 2. The angle at which the arc starts at
+         * the endpoint.
+         */
+	double getDirection2() const override;
+
+    /** @return The center point (x) of this arc */
+	RS_Vector getCenter() const override;
+    /** Sets new center. */
+	void setCenter(const RS_Vector& c);
+    /** @return The radius of this arc */
+	double getRadius() const override;
+    /** Sets new radius. */
+	void setRadius(double r);
+    double getAngleLength() const;
+	double getLength() const override;
+	bool isTangent(const RS_CircleData&  circleData) const override;
+
+    bool createFromCR(const RS_Vector& c, double r);
+    bool createFrom2P(const RS_Vector& p1, const RS_Vector& p2);
+    bool createFrom3P(const RS_Vector& p1, const RS_Vector& p2,
+                      const RS_Vector& p3);
+    bool createFrom3P(const RS_VectorSolutions& sol);
+	bool createInscribe(const RS_Vector& coord, const std::vector<RS_Line*>& lines);
+	std::vector<RS_Entity* > offsetTwoSides(const double& distance) const override;
+	RS_VectorSolutions createTan1_2P(const RS_AtomicEntity* circle, const std::vector<RS_Vector>& points);
+	static RS_VectorSolutions createTan2(const std::vector<RS_AtomicEntity*>& circles, const double& r);
+    /** solve one of the eight Appollonius Equations
+| Cx - Ci|^2=(Rx+Ri)^2
+with Cx the center of the common tangent circle, Rx the radius. Ci and Ri are the Center and radius of the i-th existing circle
+**/
+	static std::vector<RS_Circle> solveAppolloniusSingle(const std::vector<RS_Circle>& circles);
+
+	std::vector<RS_Circle> createTan3(const std::vector<RS_AtomicEntity*>& circles);
+	bool testTan3(const std::vector<RS_AtomicEntity*>& circles);
+	RS_Vector getMiddlePoint(void)const override;
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist = nullptr) const override;
+	RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+											  bool onEntity = true, double* dist = NULL, RS_Entity** entity=NULL)const override;
+	RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = NULL)const override;
+	RS_Vector getNearestMiddle(const RS_Vector& coord,
+                                       double* dist = nullptr,
+									   int middlePoints = 1 ) const override;
+	RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = NULL)const override;
+	RS_Vector getNearestDist(double distance,
+									 bool startp)const override;
+	RS_Vector getNearestOrthTan(const RS_Vector& coord,
+                                        const RS_Line& normal,
+										bool onEntity = false) const override;
+
+	bool offset(const RS_Vector& coord, const double& distance) override;
+	RS_VectorSolutions getTangentPoint(const RS_Vector& point) const override;//find the tangential points seeing from given point
+	RS_Vector getTangentDirection(const RS_Vector& point)const override;
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+    /** whether the entity's bounding box intersects with visible portion of graphic view */
+	bool isVisibleInWindow(RS_GraphicView* view) const override;
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+    /** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+	LC_Quadratic getQuadratic() const override;
+    
+/**
+* @brief Returns area of full circle
+* Note: Circular arcs are handled separately by RS_Arc (areaLIneIntegral) 
+* However, full ellipses and ellipse arcs are handled by RS_Ellipse
+* @return \pi r^2
+*/
+	double areaLineIntegral() const override;
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Circle& a);
+
+	void calculateBorders() override;
+
+protected:
+    RS_CircleData data;
+};
+
+#endif

lib/engine/rs_clipboard.cpp

@@ -0,0 +1,91 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include <iostream>
+#include "rs_clipboard.h"
+#include "rs_block.h"
+#include "rs_layer.h"
+#include "rs_entity.h"
+
+RS_Clipboard* RS_Clipboard::uniqueInstance = NULL;
+
+
+
+void RS_Clipboard::clear() {
+	graphic.clear();
+	graphic.clearBlocks();
+	graphic.clearLayers();
+	graphic.clearVariables();
+}
+
+
+
+
+
+void RS_Clipboard::addBlock(RS_Block* b) {
+	if (b) {
+		graphic.addBlock(b, false);
+	}
+}
+
+
+bool RS_Clipboard::hasBlock(const QString& name) {
+	return (graphic.findBlock(name));
+}
+
+
+void RS_Clipboard::addLayer(RS_Layer* l) {
+	if (l) {
+		//graphic.addLayer(l->clone());
+		graphic.addLayer(l);
+	}
+}
+
+
+
+bool RS_Clipboard::hasLayer(const QString& name) {
+	return (graphic.findLayer(name));
+}
+
+
+
+void RS_Clipboard::addEntity(RS_Entity* e) {
+	if (e) {
+		//graphic.addEntity(e->clone());
+		graphic.addEntity(e);
+		e->reparent(&graphic);
+	}
+}
+
+/**
+ * Dumps the clipboard contents to stdout.
+ */
+std::ostream& operator << (std::ostream& os, RS_Clipboard& cb) {
+	os << "Clipboard: " << cb.graphic << "\n";
+
+	return os;
+}
+

lib/engine/rs_clipboard.h

@@ -0,0 +1,112 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_CLIPBOARD_H
+#define RS_CLIPBOARD_H
+
+#include <iosfwd>
+#include "rs_graphic.h"
+
+#define RS_CLIPBOARD RS_Clipboard::instance()
+
+class RS_Block;
+class RS_Layer;
+class RS_Entity;
+
+/**
+ * LibreCAD internal clipboard. We don't use the system clipboard for
+ * better portaility.
+ * Implemented as singleton.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Clipboard {
+protected:
+    RS_Clipboard() {
+    }
+
+public:
+    /**
+     * @return Instance to the unique clipboard object.
+     */
+    static RS_Clipboard* instance() {
+        if (uniqueInstance==NULL) {
+            uniqueInstance = new RS_Clipboard();
+        }
+        return uniqueInstance;
+    }
+
+	void clear();
+
+	void addBlock(RS_Block* b);
+        bool hasBlock(const QString& name);
+	int  countBlocks() {
+		return graphic.countBlocks();
+	}
+	RS_Block* blockAt(int i) {
+		return graphic.blockAt(i);
+	}
+	
+	void addLayer(RS_Layer* l);
+        bool hasLayer(const QString& name);
+	int  countLayers() {
+		return graphic.countLayers();
+	}
+	RS_Layer* layerAt(int i) {
+		return graphic.layerAt(i);
+	}
+
+	void addEntity(RS_Entity* e);
+
+    unsigned count() {
+		return graphic.count();
+	}
+    RS_Entity* entityAt(unsigned i) {
+		return graphic.entityAt(i);
+	}
+	RS_Entity* firstEntity() {
+		return graphic.firstEntity();
+	}
+	
+	RS_Entity* nextEntity() {
+		return graphic.nextEntity();
+	}
+
+	RS_Graphic* getGraphic() {
+		return &graphic;
+	}
+
+    friend std::ostream& operator << (std::ostream& os, RS_Clipboard& cb);
+
+protected:
+    static RS_Clipboard* uniqueInstance;
+
+	RS_Graphic graphic;
+};
+
+#endif
+

lib/engine/rs_color.cpp

@@ -0,0 +1,94 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2020 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include <iostream>
+#include <cmath>
+#include "rs_color.h"
+
+//This method is used for plugins
+int RS_Color::toIntColor(void) const {
+    if (isByLayer())
+        return -1;
+    if (isByBlock())
+        return -2;
+//    int tmp1 = red() << 16;
+//    int tmp2 = green() << 8;
+//    int tmp3 = tmp1+tmp2+blue();
+    int cd = (red() << 16) + (green() << 8) + blue();
+        return cd;
+
+}
+
+//This method is used for plugins
+void RS_Color::fromIntColor(int co) {
+    if (co == -1)
+        setFlags(RS2::FlagByLayer);
+    else if (co == -2)
+        setFlags(RS2::FlagByBlock);
+    else {
+        setRed((co >> 16) & 0xFF);
+        setGreen((co >> 8) & 0xFF);
+        setBlue(co & 0xFF);
+    }
+
+}
+
+/**
+ * Color distance
+ *
+ * Calculate distance between two RGB colors using low-cost approximation of
+ * human eye response by Thiadmer Riemersma. Formula explanation found here:
+ * https://www.compuphase.com/cmetric.htm
+ *
+ * @author Thiadmer Riemersma
+ * @author Jeremy Ruhland
+ *
+ * @param c Color to perform comparison against
+ *
+ * @return Distance between colors in percent, value ranging from 0 (identical)
+ *         to 100 (maximum difference)
+ */
+int RS_Color::colorDistance(const RS_Color& c) const {
+
+    int myRed {red()};
+    int otherRed {c.red()};
+    int redMean {(myRed + otherRed) / 2};
+
+    // Convert difference value to percentage using maximum color difference (764.834 / 100)
+    return std::lround( std::sqrt( std::pow(otherRed - myRed, 2) * (512 + redMean) / 256
+                                   + std::pow(c.green() - green(), 2) * 4
+                                   + std::pow(c.blue() - blue(), 2) * (767 - redMean) / 256)
+                        / 7.64834);
+}
+
+std::ostream& operator << (std::ostream& os, const RS_Color& c) {
+       os << " color: " << c.name().toLatin1().data()
+       << " flags: " << (c.getFlag(RS2::FlagByLayer) ? "RS2::FlagByLayer " : "")
+       << (c.getFlag(RS2::FlagByBlock) ? "RS2::FlagByBlock " : "");
+       return os;
+}

lib/engine/rs_color.h

@@ -0,0 +1,114 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2020 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_COLOR_H
+#define RS_COLOR_H
+
+#include <QColor>
+
+#include "rs.h"
+#include "rs_flags.h"
+
+//! Color defined by layer not entity
+//#define C_BY_LAYER     0x00000001
+//! Color defined by block not entity
+//#define C_BY_BLOCK     0x00000002
+
+/**
+ * Color class.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Color: public QColor, public RS_Flags {
+public:
+    RS_Color() : QColor(), RS_Flags() {}
+    RS_Color(int r, int g, int b) : QColor(r, g, b), RS_Flags() {}
+    RS_Color(int r, int g, int b, int a) : QColor(r, g, b, a), RS_Flags() {}
+    RS_Color(const QColor& c) : QColor(c), RS_Flags() {}
+    RS_Color(const Qt::GlobalColor color) : QColor(color), RS_Flags() {}
+    RS_Color(const RS_Color& c) : QColor(c), RS_Flags() {
+        setFlags(c.getFlags());
+    }
+    RS_Color(unsigned int f) : QColor(), RS_Flags(f) {}
+    RS_Color(QString name) : QColor(name), RS_Flags() {}
+
+
+    /** @return A copy of this color without flags. */
+    RS_Color stripFlags() const {
+        return RS_Color(red(), green(), blue());
+    }
+
+    /** @return true if the color is defined by layer. */
+    bool isByLayer() const {
+        return getFlag(RS2::FlagByLayer);
+    }
+
+    /** @return true if the color is defined by block. */
+    bool isByBlock() const {
+        return getFlag(RS2::FlagByBlock);
+    }
+
+    QColor toQColor(void) const {
+            QColor c0;
+            c0.setRgb(red(),green(),blue());
+            return c0;
+    }
+
+    //These 3 methods are used for plugins
+    int toIntColor(void) const;
+    void fromIntColor(int co);
+    int colorDistance(const RS_Color& c) const;
+
+    enum {
+        Black = 0,
+        /**
+         * Minimum acceptable distance between two colors before visibility
+         * enhancement is required. Determined empirically.
+         */
+        MinColorDistance = 20,  //< in %
+    };
+
+    RS_Color& operator = (const RS_Color& c) {
+        setRgb(c.red(), c.green(), c.blue());
+        setFlags(c.getFlags());
+
+        return *this;
+    }
+
+    bool operator == (const RS_Color& c) const {
+        return (red()==c.red() &&
+                green()==c.green() &&
+                blue()==c.blue() &&
+                getFlags()==c.getFlags());
+    }
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Color& c);
+};
+
+#endif
+

lib/engine/rs_constructionline.cpp

@@ -0,0 +1,286 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include "rs_constructionline.h"
+
+#include "rs_debug.h"
+#include "lc_quadratic.h"
+#include "rs_math.h"
+
+RS_ConstructionLineData::RS_ConstructionLineData():
+	point1(false),
+	point2(false)
+{}
+
+RS_ConstructionLineData::RS_ConstructionLineData(const RS_Vector& point1,
+						const RS_Vector& point2):
+	point1(point1)
+	,point2(point2)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+								  const RS_ConstructionLineData& ld)
+{
+	os << "(" << ld.point1 <<
+	"/" << ld.point2 <<
+	")";
+	return os;
+}
+
+/**
+ * Constructor.
+ */
+RS_ConstructionLine::RS_ConstructionLine(RS_EntityContainer* parent,
+        const RS_ConstructionLineData& d)
+        :RS_AtomicEntity(parent), data(d) {
+
+    calculateBorders();
+}
+
+RS_Entity* RS_ConstructionLine::clone() const {
+    RS_ConstructionLine* c = new RS_ConstructionLine(*this);
+    c->initId();
+    return c;
+}
+
+void RS_ConstructionLine::calculateBorders() {
+    minV = RS_Vector::minimum(data.point1, data.point2);
+    maxV = RS_Vector::maximum(data.point1, data.point2);
+}
+
+RS_Vector RS_ConstructionLine::getNearestEndpoint(const RS_Vector& coord,
+        double* dist) const{
+    double dist1, dist2;
+
+    dist1 = (data.point1-coord).squared();
+    dist2 = (data.point2-coord).squared();
+
+    if (dist2<dist1) {
+		if (dist) {
+            *dist = sqrt(dist2);
+        }
+        return data.point2;
+    } else {
+		if (dist) {
+            *dist = sqrt(dist1);
+        }
+        return data.point1;
+    }
+}
+
+RS_Vector RS_ConstructionLine::getNearestPointOnEntity(const RS_Vector& coord,
+        bool /*onEntity*/, double* /*dist*/, RS_Entity** entity) const{
+
+	if (entity) {
+        *entity = const_cast<RS_ConstructionLine*>(this);
+    }
+
+    RS_Vector ae = data.point2-data.point1;
+    RS_Vector ea = data.point1-data.point2;
+    RS_Vector ap = coord-data.point1;
+//    RS_Vector ep = coord-data.point2;
+
+        if (ae.magnitude()<1.0e-6 || ea.magnitude()<1.0e-6) {
+                return RS_Vector(false);
+        }
+
+    // Orthogonal projection from both sides:
+    RS_Vector ba = ae * RS_Vector::dotP(ae, ap)
+                   / (ae.magnitude()*ae.magnitude());
+//    RS_Vector be = ea * RS_Vector::dotP(ea, ep)
+//                   / (ea.magnitude()*ea.magnitude());
+
+    return data.point1+ba;
+}
+
+RS_Vector RS_ConstructionLine::getNearestCenter(const RS_Vector& /*coord*/,
+		double* dist) const{
+
+	if (dist) {
+        *dist = RS_MAXDOUBLE;
+    }
+
+    return RS_Vector(false);
+}
+
+/** @return Copy of data that defines the line. */
+RS_ConstructionLineData const& RS_ConstructionLine::getData() const {
+	return data;
+}
+
+/** @return First definition point. */
+RS_Vector const& RS_ConstructionLine::getPoint1() const {
+	return data.point1;
+}
+/** @return Second definition point. */
+RS_Vector const& RS_ConstructionLine::getPoint2() const {
+	return data.point2;
+}
+
+/** @return Start point of the entity */
+RS_Vector RS_ConstructionLine::getStartpoint() const
+{
+    return data.point1;
+}
+
+/** @return End point of the entity */
+RS_Vector RS_ConstructionLine::getEndpoint() const
+{
+    return data.point2;
+}
+
+/**
+ * @return Direction 1. The angle at which the arc starts at
+ * the startpoint.
+ */
+double RS_ConstructionLine::getDirection1(void) const
+{
+    return RS_Math::correctAngle( data.point1.angleTo( data.point2));
+}
+
+/**
+ * @return Direction 2. The angle at which the arc starts at
+ * the endpoint.
+ */
+double RS_ConstructionLine::getDirection2(void) const
+{
+    return RS_Math::correctAngle( data.point2.angleTo( data.point1));
+}
+
+/** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+LC_Quadratic RS_ConstructionLine::getQuadratic() const
+{
+    std::vector<double> ce(3,0.);
+	auto dvp=data.point2 - data.point1;
+    RS_Vector normal(-dvp.y,dvp.x);
+    ce[0]=normal.x;
+    ce[1]=normal.y;
+    ce[2]= -normal.dotP(data.point2);
+    return LC_Quadratic(ce);
+}
+
+RS_Vector RS_ConstructionLine::getMiddlePoint() const{
+    return RS_Vector(false);
+}
+RS_Vector RS_ConstructionLine::getNearestMiddle(const RS_Vector& /*coord*/,
+        double* dist, const int /*middlePoints*/)const {
+	if (dist) {
+        *dist = RS_MAXDOUBLE;
+    }
+    return RS_Vector(false);
+}
+
+
+
+RS_Vector RS_ConstructionLine::getNearestDist(double /*distance*/,
+        const RS_Vector& /*coord*/,
+		double* dist) const{
+	if (dist) {
+        *dist = RS_MAXDOUBLE;
+    }
+    return RS_Vector(false);
+}
+
+
+double RS_ConstructionLine::getDistanceToPoint(const RS_Vector& coord,
+        RS_Entity** entity,
+        RS2::ResolveLevel /*level*/, double /*solidDist*/) const {
+
+    RS_DEBUG->print("RS_ConstructionLine::getDistanceToPoint");
+
+	if (entity) {
+        *entity = const_cast<RS_ConstructionLine*>(this);
+    }
+    //double dist = RS_MAXDOUBLE;
+    RS_Vector se = data.point2-data.point1;
+    double d(se.magnitude());
+    if(d<RS_TOLERANCE) {
+        //line too short
+        return RS_MAXDOUBLE;
+    }
+    se.set( se.x/d,-se.y/d); //normalized
+    RS_Vector vpc= coord - data.point1;
+    vpc.rotate(se); // rotate to use the line as x-axis, and the distance is fabs(y)
+    return ( fabs(vpc.y) );
+}
+
+
+
+void RS_ConstructionLine::move(const RS_Vector& offset) {
+    data.point1.move(offset);
+    data.point2.move(offset);
+    //calculateBorders();
+}
+
+
+
+void RS_ConstructionLine::rotate(const RS_Vector& center, const double& angle) {
+    RS_Vector angleVector(angle);
+    data.point1.rotate(center, angleVector);
+    data.point2.rotate(center, angleVector);
+    //calculateBorders();
+}
+
+void RS_ConstructionLine::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    data.point1.rotate(center, angleVector);
+    data.point2.rotate(center, angleVector);
+    //calculateBorders();
+}
+
+void RS_ConstructionLine::scale(const RS_Vector& center, const RS_Vector& factor) {
+    data.point1.scale(center, factor);
+    data.point2.scale(center, factor);
+    //calculateBorders();
+}
+
+
+
+void RS_ConstructionLine::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+        data.point1.mirror(axisPoint1, axisPoint2);
+        data.point2.mirror(axisPoint1, axisPoint2);
+}
+
+
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_ConstructionLine& l) {
+    os << " ConstructionLine: " << l.getData() << "\n";
+    return os;
+}
+
+

lib/engine/rs_constructionline.h

@@ -0,0 +1,140 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_CONSTRUCTIONLINE_H
+#define RS_CONSTRUCTIONLINE_H
+
+#include "rs_atomicentity.h"
+#include "rs_vector.h"
+
+/**
+ * Holds the data that defines a construction line (a line
+ * which is not limited to both directions).
+ */
+class RS_ConstructionLineData {
+public:
+    /**
+	 * Default constructor
+     */
+	RS_ConstructionLineData();
+
+    RS_ConstructionLineData(const RS_Vector& point1,
+							const RS_Vector& point2);
+
+    friend class RS_ConstructionLine;
+
+    friend std::ostream& operator << (std::ostream& os,
+									  const RS_ConstructionLineData& ld);
+
+private:
+    RS_Vector point1;
+    RS_Vector point2;
+};
+
+
+/**
+ * Class for a construction line entity.
+ *
+ * @author Andrew Mustun
+ */
+class RS_ConstructionLine : public RS_AtomicEntity {
+public:
+	RS_ConstructionLine()=default;
+    RS_ConstructionLine(RS_EntityContainer* parent,
+                        const RS_ConstructionLineData& d);
+
+	virtual RS_Entity* clone() const;
+
+	virtual ~RS_ConstructionLine()=default;
+
+    /**	@return RS2::EntityConstructionLine */
+    virtual RS2::EntityType rtti() const {
+        return RS2::EntityConstructionLine;
+    }
+
+    /** @return Copy of data that defines the line. */
+	RS_ConstructionLineData const& getData() const;
+
+    /** @return First definition point. */
+	RS_Vector const& getPoint1() const;
+    /** @return Second definition point. */
+	RS_Vector const& getPoint2() const;
+
+    /** @return Start point of the entity */
+    RS_Vector getStartpoint() const override;
+    /** @return End point of the entity */
+    RS_Vector getEndpoint() const override;
+    double getDirection1(void) const override;
+    double getDirection2(void) const override;
+
+    /** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+    virtual LC_Quadratic getQuadratic() const;
+    virtual RS_Vector getMiddlePoint(void) const;
+    virtual RS_Vector getNearestEndpoint(const RS_Vector& coord,
+                                         double* dist = NULL)const;
+    virtual RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+            bool onEntity = true, double* dist = NULL, RS_Entity** entity=NULL)const;
+    virtual RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = NULL)const;
+    virtual RS_Vector getNearestMiddle(const RS_Vector& coord,
+                                       double* dist = NULL,
+                                       int middlePoints = 1)const;
+    virtual RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = NULL)const;
+    virtual double getDistanceToPoint(const RS_Vector& coord,
+                                      RS_Entity** entity=NULL,
+                                      RS2::ResolveLevel level=RS2::ResolveNone,
+                                                                          double solidDist = RS_MAXDOUBLE) const;
+
+    virtual void move(const RS_Vector& offset);
+    virtual void rotate(const RS_Vector& center, const double& angle);
+    virtual void rotate(const RS_Vector& center, const RS_Vector& angleVector);
+    virtual void scale(const RS_Vector& center, const RS_Vector& factor);
+    virtual void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2);
+
+    virtual void draw(RS_Painter* /*painter*/, RS_GraphicView* /*view*/,
+                double& /*patternOffset*/) {}
+
+    friend std::ostream& operator << (std::ostream& os,
+                                      const RS_ConstructionLine& l);
+
+    virtual void calculateBorders();
+
+protected:
+    RS_ConstructionLineData data;
+};
+
+#endif

lib/engine/rs_dimaligned.cpp

@@ -0,0 +1,380 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include <iostream>
+#include <cmath>
+#include "rs_dimaligned.h"
+#include "rs_line.h"
+
+#include "rs_graphic.h"
+#include "rs_units.h"
+#include "rs_constructionline.h"
+#include "rs_math.h"
+#include "rs_debug.h"
+
+RS_DimAlignedData::RS_DimAlignedData():
+	extensionPoint1(false),
+	extensionPoint2(false)
+{}
+
+/**
+ * Constructor with initialisation.
+ *
+	* @para extensionPoint1 Definition point. Startpoint of the
+ *         first extension line.
+	* @para extensionPoint2 Definition point. Startpoint of the
+ *         second extension line.
+ */
+RS_DimAlignedData::RS_DimAlignedData(const RS_Vector& _extensionPoint1,
+				  const RS_Vector& _extensionPoint2):
+	extensionPoint1(_extensionPoint1)
+	,extensionPoint2(_extensionPoint2)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+								  const RS_DimAlignedData& dd) {
+	os << "(" << dd.extensionPoint1 << "/" << dd.extensionPoint1 << ")";
+	return os;
+}
+
+/**
+ * Constructor.
+ *
+ * @para parent Parent Entity Container.
+ * @para d Common dimension geometrical data.
+ * @para ed Extended geometrical data for aligned dimension.
+ */
+RS_DimAligned::RS_DimAligned(RS_EntityContainer* parent,
+                             const RS_DimensionData& d,
+                             const RS_DimAlignedData& ed)
+        : RS_Dimension(parent, d), edata(ed) {
+
+    calculateBorders();
+}
+
+
+
+/**
+ * Sets a new text. The entities representing the
+ * text are updated.
+ */
+//void RS_DimAligned::setText(const QString& t) {
+//    data.text = t;
+//    update();
+//}
+
+RS_Entity* RS_DimAligned::clone() const{
+	RS_DimAligned* d = new RS_DimAligned(*this);
+	d->setOwner(isOwner());
+	d->initId();
+	d->detach();
+	return d;
+}
+
+RS_VectorSolutions RS_DimAligned::getRefPoints() const
+{
+		return RS_VectorSolutions({edata.extensionPoint1, edata.extensionPoint2,
+												data.definitionPoint, data.middleOfText});
+}
+
+/**
+ * @return Automatically created label for the default
+ * measurement of this dimension.
+ */
+QString RS_DimAligned::getMeasuredLabel() {
+	double dist = edata.extensionPoint1.distanceTo(edata.extensionPoint2) * getGeneralFactor();
+
+    RS_Graphic* graphic = getGraphic();
+    QString ret;
+    if (graphic) {
+        int dimlunit = getGraphicVariableInt("$DIMLUNIT", 2);
+        int dimdec = getGraphicVariableInt("$DIMDEC", 4);
+        int dimzin = getGraphicVariableInt("$DIMZIN", 1);
+        RS2::LinearFormat format = graphic->getLinearFormat(dimlunit);
+
+        ret = RS_Units::formatLinear(dist, RS2::None, format, dimdec);
+        if (format == RS2::Decimal)
+            ret = stripZerosLinear(ret, dimzin);
+        //verify if units are decimal and comma separator
+        if (format == RS2::Decimal || format == RS2::ArchitecturalMetric){
+            if (getGraphicVariableInt("$DIMDSEP", 0) == 44)
+                ret.replace(QChar('.'), QChar(','));
+        }
+    }
+    else {
+        ret = QString("%1").arg(dist);
+    }
+    return ret;
+}
+
+
+RS_DimAlignedData const& RS_DimAligned::getEData() const {
+	return edata;
+}
+
+RS_Vector const& RS_DimAligned::getExtensionPoint1() const {
+	return edata.extensionPoint1;
+}
+
+RS_Vector const& RS_DimAligned::getExtensionPoint2() const {
+	return edata.extensionPoint2;
+}
+
+/**
+ * Updates the sub entities of this dimension. Called when the
+ * text or the position, alignment, .. changes.
+ *
+ * @param autoText Automatically reposition the text label
+ */
+void RS_DimAligned::updateDim(bool autoText) {
+
+    RS_DEBUG->print("RS_DimAligned::update");
+
+    clear();
+
+    if (isUndone()) {
+        return;
+    }
+
+    // general scale (DIMSCALE)
+    double dimscale = getGeneralScale();
+    // distance from entities (DIMEXO)
+    double dimexo = getExtensionLineOffset()*dimscale;
+    // definition line definition (DIMEXE)
+    double dimexe = getExtensionLineExtension()*dimscale;
+    // text height (DIMTXT)
+    //double dimtxt = getTextHeight();
+    // text distance to line (DIMGAP)
+    //double dimgap = getDimensionLineGap();
+
+    // Angle from extension endpoints towards dimension line
+	double extAngle = edata.extensionPoint2.angleTo(data.definitionPoint);
+    // extension lines length
+	double extLength = edata.extensionPoint2.distanceTo(data.definitionPoint);
+
+    if (getFixedLengthOn()){
+        double dimfxl = getFixedLength()*dimscale;
+        if (extLength-dimexo > dimfxl)
+            dimexo =  extLength - dimfxl;
+    }
+
+	RS_Vector v1 = RS_Vector::polar(dimexo, extAngle);
+	RS_Vector v2 = RS_Vector::polar(dimexe, extAngle);
+	RS_Vector e1 = RS_Vector::polar(1.0, extAngle);
+
+    RS_Pen pen(getExtensionLineColor(),
+           getExtensionLineWidth(),
+           RS2::LineByBlock);
+
+    // Extension line 1:
+	RS_Line* line = new RS_Line{this,
+			edata.extensionPoint1 + v1,
+			edata.extensionPoint1 + e1*extLength + v2};
+    //line->setLayerToActive();
+    //line->setPenToActive();
+//    line->setPen(RS_Pen(RS2::FlagInvalid));
+    line->setPen(pen);
+	line->setLayer(nullptr);
+    addEntity(line);
+
+    // Extension line 2:
+	line = new RS_Line{this,
+			edata.extensionPoint2 + v1,
+			edata.extensionPoint2 + e1*extLength + v2};
+    //line->setLayerToActive();
+    //line->setPenToActive();
+//    line->setPen(RS_Pen(RS2::FlagInvalid));
+    line->setPen(pen);
+	line->setLayer(nullptr);
+    addEntity(line);
+
+    // Dimension line:
+    updateCreateDimensionLine(edata.extensionPoint1 + e1*extLength,
+                              edata.extensionPoint2 + e1*extLength,
+                                                          true, true, autoText);
+
+    calculateBorders();
+}
+
+
+void RS_DimAligned::updateDimPoint(){
+    // temporary construction line
+	RS_ConstructionLine tmpLine( nullptr,
+        RS_ConstructionLineData(edata.extensionPoint1, edata.extensionPoint2));
+
+	RS_Vector tmpP1 = tmpLine.getNearestPointOnEntity(data.definitionPoint);
+	data.definitionPoint += edata.extensionPoint2 - tmpP1;
+}
+
+
+bool RS_DimAligned::hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2) {
+        return (edata.extensionPoint1.isInWindow(v1, v2) ||
+                edata.extensionPoint2.isInWindow(v1, v2));
+}
+
+
+void RS_DimAligned::move(const RS_Vector& offset) {
+    RS_Dimension::move(offset);
+
+    edata.extensionPoint1.move(offset);
+    edata.extensionPoint2.move(offset);
+    update();
+}
+
+
+
+void RS_DimAligned::rotate(const RS_Vector& center, const double& angle) {
+   rotate(center,RS_Vector(angle));
+}
+
+
+void RS_DimAligned::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_Dimension::rotate(center, angleVector);
+    edata.extensionPoint1.rotate(center, angleVector);
+    edata.extensionPoint2.rotate(center, angleVector);
+    update();
+}
+
+void RS_DimAligned::scale(const RS_Vector& center, const RS_Vector& factor) {
+    RS_Dimension::scale(center, factor);
+
+    edata.extensionPoint1.scale(center, factor);
+    edata.extensionPoint2.scale(center, factor);
+    update();
+}
+
+
+void RS_DimAligned::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    RS_Dimension::mirror(axisPoint1, axisPoint2);
+
+    edata.extensionPoint1.mirror(axisPoint1, axisPoint2);
+    edata.extensionPoint2.mirror(axisPoint1, axisPoint2);
+    update();
+}
+
+
+void RS_DimAligned::stretch(const RS_Vector& firstCorner,
+                            const RS_Vector& secondCorner,
+                            const RS_Vector& offset) {
+
+    //e->calculateBorders();
+    if (getMin().isInWindow(firstCorner, secondCorner) &&
+            getMax().isInWindow(firstCorner, secondCorner)) {
+
+        move(offset);
+    }
+        else {
+                //RS_Vector v = data.definitionPoint - edata.extensionPoint2;
+				double len = edata.extensionPoint2.distanceTo(data.definitionPoint);
+                double ang1 = edata.extensionPoint1.angleTo(edata.extensionPoint2)
+							 + M_PI_2;
+
+        if (edata.extensionPoint1.isInWindow(firstCorner,
+                                      secondCorner)) {
+                edata.extensionPoint1.move(offset);
+        }
+        if (edata.extensionPoint2.isInWindow(firstCorner,
+                                      secondCorner)) {
+                edata.extensionPoint2.move(offset);
+        }
+
+                double ang2 = edata.extensionPoint1.angleTo(edata.extensionPoint2)
+							 + M_PI_2;
+
+                double diff = RS_Math::getAngleDifference(ang1, ang2);
+                if (diff>M_PI) {
+                        diff-=2*M_PI;
+                }
+
+				if (fabs(diff)>M_PI_2) {
+                        ang2 = RS_Math::correctAngle(ang2+M_PI);
+                }
+
+				RS_Vector v = RS_Vector::polar(len, ang2);
+				data.definitionPoint = edata.extensionPoint2 + v;
+        }
+        updateDim(true);
+}
+
+
+
+void RS_DimAligned::moveRef(const RS_Vector& ref, const RS_Vector& offset) {
+
+	if (ref.distanceTo(data.definitionPoint)<1.0e-4) {
+				RS_ConstructionLine l(nullptr,
+                        RS_ConstructionLineData(edata.extensionPoint1,
+                                edata.extensionPoint2));
+				double d = l.getDistanceToPoint(data.definitionPoint+offset);
+				double a = edata.extensionPoint2.angleTo(data.definitionPoint);
+                double ad = RS_Math::getAngleDifference(a,
+						edata.extensionPoint2.angleTo(data.definitionPoint+offset));
+
+				if (fabs(ad)>M_PI_2 && fabs(ad)<3.0/2.0*M_PI) {
+                        a = RS_Math::correctAngle(a+M_PI);
+                }
+
+				RS_Vector v = RS_Vector::polar(d, a);
+		data.definitionPoint = edata.extensionPoint2 + v;
+                updateDim(true);
+    }
+        else if (ref.distanceTo(data.middleOfText)<1.0e-4) {
+        data.middleOfText.move(offset);
+                updateDim(false);
+    }
+        else if (ref.distanceTo(edata.extensionPoint1)<1.0e-4) {
+                double a1 = edata.extensionPoint2.angleTo(edata.extensionPoint1);
+                double a2 = edata.extensionPoint2.angleTo(edata.extensionPoint1+offset);
+                double d1 = edata.extensionPoint2.distanceTo(edata.extensionPoint1);
+                double d2 = edata.extensionPoint2.distanceTo(edata.extensionPoint1+offset);
+                rotate(edata.extensionPoint2, a2-a1);
+                if (fabs(d1)>1.0e-4) {
+                        scale(edata.extensionPoint2, RS_Vector(d2/d1, d2/d1));
+                }
+                updateDim(true);
+    }
+        else if (ref.distanceTo(edata.extensionPoint2)<1.0e-4) {
+                double a1 = edata.extensionPoint1.angleTo(edata.extensionPoint2);
+                double a2 = edata.extensionPoint1.angleTo(edata.extensionPoint2+offset);
+                double d1 = edata.extensionPoint1.distanceTo(edata.extensionPoint2);
+                double d2 = edata.extensionPoint1.distanceTo(edata.extensionPoint2+offset);
+                rotate(edata.extensionPoint1, a2-a1);
+                if (fabs(d1)>1.0e-4) {
+                        scale(edata.extensionPoint1, RS_Vector(d2/d1, d2/d1));
+                }
+                updateDim(true);
+    }
+}
+
+
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_DimAligned& d) {
+    os << " DimAligned: " << d.getData() << "\n" << d.getEData() << "\n";
+    return os;
+}

lib/engine/rs_dimaligned.h

@@ -0,0 +1,119 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_DIMALIGNED_H
+#define RS_DIMALIGNED_H
+
+#include "rs_dimension.h"
+
+/**
+ * Holds the data that defines an aligned dimension entity.
+ */
+struct RS_DimAlignedData {
+	/**
+	 * Default constructor
+	 */
+	RS_DimAlignedData();
+	/**
+	 * Constructor with initialisation.
+	 *
+		* @para extensionPoint1 Definition point. Startpoint of the
+	 *         first extension line.
+		* @para extensionPoint2 Definition point. Startpoint of the
+	 *         second extension line.
+	 */
+	RS_DimAlignedData(const RS_Vector& extensionPoint1,
+					  const RS_Vector& extensionPoint2);
+
+	/** Definition point. Startpoint of the first extension line. */
+	RS_Vector extensionPoint1;
+	/** Definition point. Startpoint of the second extension line. */
+	RS_Vector extensionPoint2;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_DimAlignedData& dd);
+
+/**
+ * Class for aligned dimension entities.
+ *
+ * @author Andrew Mustun
+ */
+class RS_DimAligned : public RS_Dimension {
+public:
+    RS_DimAligned(RS_EntityContainer* parent,
+                  const RS_DimensionData& d,
+                  const RS_DimAlignedData& ed);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityDimAligned */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityDimAligned;
+    }
+
+    /**
+     * @return Copy of data that defines the aligned dimension.
+     * @see getData()
+     */
+	RS_DimAlignedData const& getEData() const;
+
+	RS_VectorSolutions getRefPoints() const override;
+
+	QString getMeasuredLabel() override;
+
+	void updateDim(bool autoText=false) override;
+
+	RS_Vector const& getExtensionPoint1() const;
+
+	RS_Vector const& getExtensionPoint2() const;
+
+    /**
+     * Recalculate the original Dimension Point to remove Dim oblique angle.
+     * @author Rallaz
+     */
+	void updateDimPoint();
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	bool hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2) override;
+	void stretch(const RS_Vector& firstCorner,
+                         const RS_Vector& secondCorner,
+						 const RS_Vector& offset) override;
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+
+    friend std::ostream& operator << (std::ostream& os,
+                                      const RS_DimAligned& d);
+
+protected:
+    /** Extended data. */
+    RS_DimAlignedData edata;
+};
+
+#endif

lib/engine/rs_dimangular.cpp

@@ -0,0 +1,580 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2018 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include<cmath>
+#include "rs_dimangular.h"
+#include "rs_math.h"
+
+#include "rs_constructionline.h"
+#include "rs_arc.h"
+#include "rs_line.h"
+#include "rs_graphic.h"
+#include "rs_information.h"
+#include "rs_solid.h"
+#include "rs_mtext.h"
+#include "rs_debug.h"
+
+RS_DimAngularData::RS_DimAngularData():
+    definitionPoint1( false),
+    definitionPoint2( false),
+    definitionPoint3( false),
+    definitionPoint4( false)
+{
+}
+
+RS_DimAngularData::RS_DimAngularData(const RS_DimAngularData &ed):
+    definitionPoint1( ed.definitionPoint1),
+    definitionPoint2( ed.definitionPoint2),
+    definitionPoint3( ed.definitionPoint3),
+    definitionPoint4( ed.definitionPoint4)
+{
+}
+
+/**
+ * Constructor with initialisation.
+ *
+ * @param definitionPoint Definition point of the angular dimension.
+ * @param leader Leader length.
+ */
+RS_DimAngularData::RS_DimAngularData(const RS_Vector& _definitionPoint1,
+                                     const RS_Vector& _definitionPoint2,
+                                     const RS_Vector& _definitionPoint3,
+                                     const RS_Vector& _definitionPoint4):
+    definitionPoint1( _definitionPoint1),
+    definitionPoint2( _definitionPoint2),
+    definitionPoint3( _definitionPoint3),
+    definitionPoint4( _definitionPoint4)
+{
+}
+
+/**
+ * Constructor with initialisation.
+ *
+ * @param dimscale  general scale (DIMSCALE)
+ * @param dimexo  distance from entities (DIMEXO)
+ * @param dimexe  extension line extension (DIMEXE)
+ * @param dimtxt  text height (DIMTXT)
+ * @param dimgap  text distance to line (DIMGAP)
+ * @param arrowSize  arrow length
+ */
+LC_DimAngularVars::LC_DimAngularVars(const double _dimscale,
+                                     const double _dimexo,
+                                     const double _dimexe,
+                                     const double _dimtxt,
+                                     const double _dimgap,
+                                     const double _arrowSize) :
+    dimscale( _dimscale),
+    dimexo( _dimexo * _dimscale),
+    dimexe( _dimexe * _dimscale),
+    dimtxt( _dimtxt * _dimscale),
+    dimgap( _dimgap * _dimscale),
+    arrowSize( _arrowSize * _dimscale)
+{
+}
+
+LC_DimAngularVars::LC_DimAngularVars(const LC_DimAngularVars& av) :
+    dimscale( av.dimscale),
+    dimexo( av.dimexo),
+    dimexe( av.dimexe),
+    dimtxt( av.dimtxt),
+    dimgap( av.dimgap),
+    arrowSize( av.arrowSize)
+{
+}
+
+/**
+ * Constructor.
+ *
+ * @para parent Parent Entity Container.
+ * @para d Common dimension geometrical data.
+ * @para ed Extended geometrical data for angular dimension.
+ */
+RS_DimAngular::RS_DimAngular(RS_EntityContainer* parent,
+                             const RS_DimensionData& d,
+                             const RS_DimAngularData& ed) :
+    RS_Dimension( parent, d),
+    edata( ed)
+{
+    calcDimension();
+    calculateBorders();
+}
+
+RS_Entity* RS_DimAngular::clone() const
+{
+    RS_DimAngular *d {new RS_DimAngular(*this)};
+
+    d->setOwner( isOwner());
+    d->initId();
+    d->detach();
+
+    return d;
+}
+
+/**
+ * @return Automatically created label for the default
+ * measurement of this dimension.
+ */
+QString RS_DimAngular::getMeasuredLabel()
+{
+    int dimaunit {getGraphicVariableInt( QStringLiteral( "$DIMAUNIT"), 0)};
+    int dimadec {getGraphicVariableInt( QStringLiteral( "$DIMADEC"), 0)};
+    int dimazin {getGraphicVariableInt( QStringLiteral( "$DIMAZIN"), 0)};
+    RS2::AngleFormat format {RS_Units::numberToAngleFormat( dimaunit)};
+    QString strLabel( RS_Units::formatAngle( dimAngle, format, dimadec));
+
+    if (RS2::DegreesMinutesSeconds != format
+        && RS2::Surveyors != format) {
+        strLabel = stripZerosAngle( strLabel, dimazin);
+    }
+
+    //verify if units are decimal and comma separator
+    if (RS2::DegreesMinutesSeconds != dimaunit) {
+        if (',' == getGraphicVariableInt( QStringLiteral( "$DIMDSEP"), 0)) {
+            strLabel.replace( QChar('.'), QChar(','));
+        }
+    }
+
+    return strLabel;
+}
+
+/**
+ * @return Center of the measured dimension.
+ */
+RS_Vector RS_DimAngular::getCenter() const
+{
+    return dimCenter;
+}
+
+/**
+ * @brief Add an extension line if necessary
+ *
+ * @param dimLine  dimension definition line including extension offset
+ * @param dimPoint  point where the arc meets the definition line
+ * @param dirStart  unit vector defining the lines starting point direction
+ * @param dirEnd  unit vector defining the lines ending point direction
+ * @param av  DXF variables with offset and extension line length
+ * @param pen  pen to draw the extension line
+ */
+void RS_DimAngular::extensionLine(const RS_ConstructionLine& dimLine,
+                                  const RS_Vector& dimPoint,
+                                  const RS_Vector& dirStart,
+                                  const RS_Vector& dirEnd,
+                                  const LC_DimAngularVars& av,
+                                  const RS_Pen& pen)
+{
+    double diffLine {RS_Vector::posInLine( dimLine.getStartpoint(), dimLine.getEndpoint(), dimPoint)};
+    double diffCenter {RS_Vector::posInLine( dimLine.getStartpoint(), dimCenter, dimPoint)};
+
+    if( 0.0 <= diffLine && 1.0 >= diffLine) {
+        // dimension ends on entity, nothing to extend
+        return;
+    }
+
+    if( 0.0 > diffLine && 0.0 > diffCenter) {
+        RS_Line* line {new RS_Line( this,
+                                    dimLine.getStartpoint(),
+                                    dimPoint - dirStart * av.exe())};
+
+        line->setPen( pen);
+        line->setLayer( nullptr);
+        addEntity( line);
+    }
+    else if( 1.0 < diffLine && 0.0 < diffCenter) {
+        RS_Line* line {new RS_Line( this,
+                                    dimLine.getEndpoint(),
+                                    dimPoint - dirEnd * av.exe())};
+
+        line->setPen( pen);
+        line->setLayer( nullptr);
+        addEntity( line);
+    }
+    else if( 0.0 > diffLine && 1.0 < diffCenter) {
+        RS_Line* line {new RS_Line( this,
+                                    dimCenter - dirStart * av.exo(),
+                                    dimPoint + dirEnd * av.exe())};
+
+        line->setPen( pen);
+        line->setLayer( nullptr);
+        addEntity( line);
+    }
+}
+
+/**
+ * @brief Add an arrow to the dimension arc
+ *
+ * @param point  arc endpoint, the arrow tip
+ * @param angle  the angle from center to the arc endpoint
+ * @param direction  this holds the sign for the arrow endpoint direction
+ * @param outsideArrow  when the arc becomes too small, arrows are placed outside
+ * @param av  DXF variables with offset and extension line length
+ * @param pen  pen to draw the extension line
+ */
+void RS_DimAngular::arrow(const RS_Vector& point,
+                          const double angle,
+                          const double direction,
+                          const bool outsideArrows,
+                          const LC_DimAngularVars& av,
+                          const RS_Pen& pen)
+{
+    if (RS_TOLERANCE_ANGLE >= av.arrow()) {
+        // arrow size is 0, no need to add an arrow
+        return;
+    }
+
+    double arrowAngle {0.0};
+
+    if (outsideArrows) {
+        // for outside arrows use tangent angle on endpoints
+        // because for small radius the arrows looked inclined
+        arrowAngle = angle + std::copysign( M_PI_2, direction);
+    }
+    else {
+        // compute the angle from center to the endpoint of the arrow on the arc
+        double endAngle {0.0};
+        if (RS_TOLERANCE_ANGLE < dimRadius) {
+            endAngle = av.arrow() / dimRadius;
+        }
+
+        // compute the endpoint of the arrow on the arc
+        RS_Vector arrowEnd;
+        arrowEnd.setPolar( dimRadius, angle + std::copysign( endAngle, direction));
+        arrowEnd += dimCenter;
+        arrowAngle = arrowEnd.angleTo( point);
+    }
+
+    RS_SolidData sd;
+    RS_Solid* arrow;
+
+    arrow = new RS_Solid( this, sd);
+    arrow->shapeArrow( point, arrowAngle, av.arrow());
+    arrow->setPen( pen);
+    arrow->setLayer( nullptr);
+    addEntity( arrow);
+
+}
+
+/**
+ * Updates the sub entities of this dimension. Called when the
+ * dimension or the position, alignment, .. changes.
+ *
+ * @param autoText Automatically reposition the text label
+ */
+void RS_DimAngular::updateDim(bool autoText /*= false*/)
+{
+    Q_UNUSED( autoText)
+    RS_DEBUG->print("RS_DimAngular::update");
+
+    clear();
+
+    if (isUndone()) {
+        return;
+    }
+
+    if ( ! dimCenter.valid) {
+        return;
+    }
+
+    LC_DimAngularVars   av( getGeneralScale(),
+                            getExtensionLineOffset(),
+                            getExtensionLineExtension(),
+                            getTextHeight(),
+                            getDimensionLineGap(),
+                            getArrowSize());
+
+    // create new lines with offsets for extension lines
+    RS_ConstructionLine line1( nullptr,
+                               RS_ConstructionLineData( dimLine1.getStartpoint() - dimDir1s * av.exo(),
+                                                        dimLine1.getEndpoint() - dimDir1e * av.exo()));
+    RS_ConstructionLine line2( nullptr,
+                               RS_ConstructionLineData( dimLine2.getStartpoint() - dimDir2s * av.exo(),
+                                                        dimLine2.getEndpoint() - dimDir2e * av.exo()));
+
+    RS_Vector p1 {dimCenter + dimDir1e * dimRadius};
+    RS_Vector p2 {dimCenter + dimDir2e * dimRadius};
+    RS_Pen pen( getExtensionLineColor(), getExtensionLineWidth(), RS2::LineByBlock);
+
+    extensionLine( line1, p1, dimDir1s, dimDir1e, av, pen);
+    extensionLine( line2, p2, dimDir2s, dimDir2e, av, pen);
+
+    // Create dimension line (arc)
+    RS_Arc* arc {new RS_Arc( this, RS_ArcData( dimCenter, dimRadius, dimAngleL1, dimAngleL2, false))};
+    pen.setWidth( getDimensionLineWidth());
+    pen.setColor( getDimensionLineColor());
+    arc->setPen( pen);
+    arc->setLayer( nullptr);
+    addEntity( arc);
+
+    // do we have to put the arrows outside of the arc?
+    bool outsideArrows {arc->getLength() < 3.0 * av.arrow()};
+
+    arrow( p1, dimAngleL1, +1.0, outsideArrows, av, pen);
+    arrow( p2, dimAngleL2, -1.0, outsideArrows, av, pen);
+
+    // text label
+    RS_MTextData textData;
+    RS_Vector textPos {arc->getMiddlePoint()};
+
+    RS_Vector distV;
+    double textAngle {0.0};
+    double angle1 {textPos.angleTo( dimCenter) - M_PI_2};
+
+    // rotate text so it's readable from the bottom or right (ISO)
+    // quadrant 1 & 4
+    if (angle1 > M_PI_2 * 3.0 + 0.001
+        || angle1 < M_PI_2 + 0.001) {
+        distV.setPolar( av.gap(), angle1 + M_PI_2);
+        textAngle = angle1;
+    }
+    // quadrant 2 & 3
+    else {
+        distV.setPolar( av.gap(), angle1 - M_PI_2);
+        textAngle = angle1 + M_PI;
+    }
+
+    // move text away from dimension line:
+    textPos += distV;
+
+    textData = RS_MTextData( textPos,
+                             av.txt(), 30.0,
+                             RS_MTextData::VABottom,
+                             RS_MTextData::HACenter,
+                             RS_MTextData::LeftToRight,
+                             RS_MTextData::Exact,
+                             1.0,
+                             getLabel(),
+                             getTextStyle(),
+                             textAngle);
+
+    RS_MText* text {new RS_MText( this, textData)};
+
+    // move text to the side:
+    text->setPen( RS_Pen( getTextColor(), RS2::WidthByBlock, RS2::SolidLine));
+    text->setLayer( nullptr);
+    addEntity( text);
+
+    calculateBorders();
+}
+
+void RS_DimAngular::update()
+{
+    calcDimension();
+    RS_Dimension::update();
+}
+
+void RS_DimAngular::move(const RS_Vector& offset)
+{
+    RS_Dimension::move( offset);
+
+    edata.definitionPoint1.move( offset);
+    edata.definitionPoint2.move( offset);
+    edata.definitionPoint3.move( offset);
+    edata.definitionPoint4.move( offset);
+    update();
+}
+
+void RS_DimAngular::rotate(const RS_Vector& center, const double& angle)
+{
+    rotate( center, RS_Vector( angle));
+}
+
+void RS_DimAngular::rotate(const RS_Vector& center, const RS_Vector& angleVector)
+{
+    RS_Dimension::rotate( center, angleVector);
+
+    edata.definitionPoint1.rotate( center, angleVector);
+    edata.definitionPoint2.rotate( center, angleVector);
+    edata.definitionPoint3.rotate( center, angleVector);
+    edata.definitionPoint4.rotate( center, angleVector);
+    update();
+}
+
+void RS_DimAngular::scale(const RS_Vector& center, const RS_Vector& factor)
+{
+    RS_Dimension::scale( center, factor);
+
+    edata.definitionPoint1.scale( center, factor);
+    edata.definitionPoint2.scale( center, factor);
+    edata.definitionPoint3.scale( center, factor);
+    edata.definitionPoint4.scale( center, factor);
+    update();
+}
+
+void RS_DimAngular::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2)
+{
+    RS_Dimension::mirror( axisPoint1, axisPoint2);
+
+    edata.definitionPoint1.mirror( axisPoint1, axisPoint2);
+    edata.definitionPoint2.mirror( axisPoint1, axisPoint2);
+    edata.definitionPoint3.mirror( axisPoint1, axisPoint2);
+    edata.definitionPoint4.mirror( axisPoint1, axisPoint2);
+    update();
+}
+
+/**
+ * @brief Compute all static values for dimension.
+ *
+ * From DXF reference the lines are P2-P1 and P-P3.
+ * The dimension is drawn from line1 (P2-P1) to line2 (P-P3) in CCW direction.
+ */
+void RS_DimAngular::calcDimension(void)
+{
+    // get unit vectors for definition points
+    dimDir1s = RS_Vector::polar( 1.0, RS_Math::correctAngle( edata.definitionPoint2.angleTo( edata.definitionPoint1)));
+    dimDir1e = RS_Vector::polar( 1.0, RS_Math::correctAngle( edata.definitionPoint1.angleTo( edata.definitionPoint2)));
+    dimDir2s = RS_Vector::polar( 1.0, RS_Math::correctAngle( data.definitionPoint.angleTo( edata.definitionPoint3)));
+    dimDir2e = RS_Vector::polar( 1.0, RS_Math::correctAngle( edata.definitionPoint3.angleTo( data.definitionPoint)));
+
+    // create the two dimension definition lines
+    dimLine1 = RS_ConstructionLine( nullptr,
+                                    RS_ConstructionLineData( edata.definitionPoint2,
+                                                             edata.definitionPoint1));
+    dimLine2 = RS_ConstructionLine( nullptr,
+                                    RS_ConstructionLineData( data.definitionPoint,
+                                                             edata.definitionPoint3));
+
+    RS_VectorSolutions vs {RS_Information::getIntersection( &dimLine1, &dimLine2, false)};
+    dimCenter = vs.get(0);
+    dimRadius = dimCenter.distanceTo( edata.definitionPoint4);
+    dimDirRad = RS_Vector::polar( 1.0, RS_Math::correctAngle( dimCenter.angleTo( edata.definitionPoint4)));
+
+    fixDimension();
+
+    dimAngleL1 = dimLine1.getDirection2();
+    dimAngleL2 = dimLine2.getDirection2();
+
+    dimAngle = RS_Math::correctAngle( dimLine2.getDirection1() - dimLine1.getDirection1());
+}
+
+/**
+ * @brief check the dimension and fix non conform values from foreign CAD systems
+ *
+ * check if the radius definition point is on the arc,
+ * from line1 to line2 in counter clockwise direction
+ * LibreCAD takes care on correct orientation and line order in RS_ActionDimAngular
+ * but angular dimensions, created in other CAD software, may fail and must be fixed here
+ */
+void RS_DimAngular::fixDimension(void)
+{
+    if( ! RS_Math::isAngleBetween( dimDirRad.angle(), dimDir2s.angle(), dimDir1s.angle(), false)) {
+        double distance0 {data.definitionPoint.distanceTo( dimCenter)};
+        double distance1 {edata.definitionPoint1.distanceTo( dimCenter)};
+        double distance2 {edata.definitionPoint2.distanceTo( dimCenter)};
+        double distance3 {edata.definitionPoint3.distanceTo( dimCenter)};
+        double  angle0 {0.0};
+        double  angle1 {0.0};
+        double  angle2 {0.0};
+        double  angle3 {0.0};
+        if( RS_TOLERANCE >= distance0) {
+            angle3 = (edata.definitionPoint3 - dimCenter).angle();
+            angle0 = angle3;
+        }
+        else if( RS_TOLERANCE >= distance3) {
+            angle0 = (data.definitionPoint - dimCenter).angle();
+            angle3 = angle0;
+        }
+        else {
+            angle0 = (data.definitionPoint - dimCenter).angle();
+            angle3 = (edata.definitionPoint3 - dimCenter).angle();
+        }
+
+        if( RS_TOLERANCE >= distance1) {
+            angle2 = (edata.definitionPoint2- dimCenter).angle();
+            angle1 = angle2;
+        }
+        else if( RS_TOLERANCE >= distance2) {
+            angle1 = (edata.definitionPoint1 - dimCenter).angle();
+            angle2 = angle1;
+        }
+        else {
+            angle1 = (edata.definitionPoint1 - dimCenter).angle();
+            angle2 = (edata.definitionPoint2 - dimCenter).angle();
+        }
+
+        if( angle2 == angle1
+            && distance2 < distance1
+            && angle0 == angle3
+            && distance0 < distance3) {
+            // revert both lines
+            dimLine1 = RS_ConstructionLine( nullptr,
+                                            RS_ConstructionLineData( dimLine1.getEndpoint(),
+                                                                     dimLine1.getStartpoint()));
+            dimLine2 = RS_ConstructionLine( nullptr,
+                                            RS_ConstructionLineData( dimLine2.getEndpoint(),
+                                                                     dimLine2.getStartpoint()));
+
+            // and their unit vectors
+            RS_Vector swapDir {dimDir1s};
+            dimDir1s = dimDir1e;
+            dimDir1e = swapDir;
+
+            swapDir = dimDir2s;
+            dimDir2s = dimDir2e;
+            dimDir2e = swapDir;
+        }
+
+        // check again, as the previous revert may have made this condition false
+        if( ! RS_Math::isAngleBetween( dimDirRad.angle(), dimDir2s.angle(), dimDir1s.angle(), false)) {
+            // swap the lines
+            RS_ConstructionLine swapLine {dimLine1};
+            dimLine1 = dimLine2;
+            dimLine2 = swapLine;
+
+            // and their unit vectors
+            RS_Vector swapDir {dimDir1s};
+            dimDir1s = dimDir2s;
+            dimDir2s = swapDir;
+
+            swapDir = dimDir1e;
+            dimDir1e = dimDir2e;
+            dimDir2e = swapDir;
+        }
+    }
+}
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_DimAngular& d)
+{
+    os << " DimAngular: "
+       << d.getData() << std::endl
+       << d.getEData() << std::endl;
+
+    return os;
+}
+
+std::ostream& operator << (std::ostream& os, const RS_DimAngularData& dd)
+{
+    os << "(" << dd.definitionPoint1
+       << "," << dd.definitionPoint2
+       << "," << dd.definitionPoint3
+       << "," << dd.definitionPoint3
+       << ")";
+
+    return os;
+}

lib/engine/rs_dimangular.h

@@ -0,0 +1,193 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2018 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#ifndef RS_DIMANGULAR_H
+#define RS_DIMANGULAR_H
+
+#include "rs_dimension.h"
+#include "rs_constructionline.h"
+
+/**
+ * Holds the data that defines a angular dimension entity.
+ */
+struct RS_DimAngularData
+{
+    RS_DimAngularData();
+    RS_DimAngularData(const RS_DimAngularData& ed);
+
+    /**
+     * Constructor with initialisation.
+     *
+     * @param definitionPoint Definition point of the angular dimension.
+     * @param leader Leader length.
+     */
+    RS_DimAngularData(const RS_Vector& definitionPoint1,
+                      const RS_Vector& definitionPoint2,
+                      const RS_Vector& definitionPoint3,
+                      const RS_Vector& definitionPoint4);
+
+    RS_Vector definitionPoint1; ///< 1st line start point, DXF codes 13,23,33
+    RS_Vector definitionPoint2; ///< 1st line end point, DXF codes 14,24,34
+    RS_Vector definitionPoint3; ///< 2nd line start point, DXF codes 15,25,35
+                                ///< 2nd line end point is in common dim data, DXF codes 10,20,30
+    RS_Vector definitionPoint4; ///< dim arc radius point, DXF codes 16,26,36
+};
+
+std::ostream& operator << (std::ostream& os, const RS_DimAngularData& dd);
+
+/**
+ * Holds the DXF variables that defines a angular dimension entity.
+ */
+struct LC_DimAngularVars
+{
+    explicit LC_DimAngularVars(const double _dimscale,
+                               const double _dimexo,
+                               const double _dimexe,
+                               const double _dimtxt,
+                               const double _dimgap,
+                               const double _arrowSize);
+    explicit LC_DimAngularVars(const LC_DimAngularVars& av);
+
+    double scale(void) const {
+        return dimscale;
+    }
+    double exo(void) const {
+        return dimexo;
+    }
+    double exe(void) const {
+        return dimexe;
+    }
+    double txt(void) const {
+        return dimtxt;
+    }
+    double gap(void) const {
+        return dimgap;
+    }
+    double arrow(void) const {
+        return arrowSize;
+    }
+
+private:
+    double dimscale     {1.0};  ///< general scale (DIMSCALE)
+    double dimexo       {0.0};  ///< distance from entities (DIMEXO)
+    double dimexe       {0.0};  ///< extension line extension (DIMEXE)
+    double dimtxt       {0.0};  ///< text height (DIMTXT)
+    double dimgap       {0.0};  ///< text distance to line (DIMGAP)
+    double arrowSize    {0.0};  ///< arrow length
+};
+
+std::ostream& operator << (std::ostream& os, const LC_DimAngularVars& dd);
+
+/**
+ * Class for angular dimension entities.
+ *
+ * @author Andrew Mustun
+ */
+class RS_DimAngular : public RS_Dimension
+{
+    friend std::ostream& operator << (std::ostream& os, const RS_DimAngular& d);
+
+public:
+    RS_DimAngular(RS_EntityContainer* parent,
+                  const RS_DimensionData& d,
+                  const RS_DimAngularData& ed);
+
+    RS_Entity* clone() const override;
+
+    /** @return RS2::EntityDimAngular */
+    RS2::EntityType rtti() const override {
+        return RS2::EntityDimAngular;
+    }
+
+    /**
+     * @return Copy of data that defines the angular dimension.
+     * @see getData()
+     */
+    RS_DimAngularData getEData() const {
+        return edata;
+    }
+
+    QString getMeasuredLabel() override;
+    RS_Vector getCenter() const override;
+
+    void updateDim(bool autoText = false) override;
+
+    RS_Vector getDefinitionPoint1() {
+        return edata.definitionPoint1;
+    }
+    RS_Vector getDefinitionPoint2() {
+        return edata.definitionPoint2;
+    }
+    RS_Vector getDefinitionPoint3() {
+        return edata.definitionPoint3;
+    }
+    RS_Vector getDefinitionPoint4() {
+        return edata.definitionPoint4;
+    }
+
+    void update() override;
+    void move(const RS_Vector& offset) override;
+    void rotate(const RS_Vector& center, const double& angle) override;
+    void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+    void scale(const RS_Vector& center, const RS_Vector& factor) override;
+    void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+
+protected:
+    /** Extended data. */
+    RS_DimAngularData   edata;
+
+private:
+    void calcDimension(void);
+    void fixDimension(void);
+    void extensionLine(const RS_ConstructionLine& dimLine,
+                       const RS_Vector& dimPoint,
+                       const RS_Vector& dirStart,
+                       const RS_Vector& dirEnd,
+                       const LC_DimAngularVars& av,
+                       const RS_Pen& pen);
+    void arrow(const RS_Vector& point,
+               const double angle,
+               const double direction,
+               const bool outsideArrows,
+               const LC_DimAngularVars& av,
+               const RS_Pen& pen);
+
+    RS_Vector   dimDir1s;
+    RS_Vector   dimDir1e;
+    RS_Vector   dimDir2s;
+    RS_Vector   dimDir2e;
+    RS_Vector   dimDirRad;
+    RS_ConstructionLine dimLine1;
+    RS_ConstructionLine dimLine2;
+    double      dimRadius {0.0};
+    double      dimAngleL1 {0.0};
+    double      dimAngleL2 {0.0};
+    double      dimAngle {0.0};     ///< angle to dimension in rad
+    RS_Vector   dimCenter;          ///< intersection point of the dimension lines
+};
+
+#endif

lib/engine/rs_dimdiametric.cpp

@@ -0,0 +1,225 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include "rs_dimdiametric.h"
+#include "rs_mtext.h"
+#include "rs_solid.h"
+#include "rs_graphic.h"
+#include "rs_units.h"
+#include "rs_debug.h"
+
+RS_DimDiametricData::RS_DimDiametricData():
+	definitionPoint(false),
+	leader(0.0)
+{}
+
+/**
+ * Constructor with initialisation.
+ *
+ * @param definitionPoint Definition point of the diametric dimension.
+ * @param leader Leader length.
+ */
+RS_DimDiametricData::RS_DimDiametricData(const RS_Vector& _definitionPoint,
+				 double _leader):
+	definitionPoint(_definitionPoint)
+	,leader(_leader)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+								  const RS_DimDiametricData& dd) {
+	os << "(" << dd.definitionPoint << "," << dd.leader << ")";
+	return os;
+}
+
+/**
+ * Constructor.
+ *
+ * @para parent Parent Entity Container.
+ * @para d Common dimension geometrical data.
+ * @para ed Extended geometrical data for diametric dimension.
+ */
+RS_DimDiametric::RS_DimDiametric(RS_EntityContainer* parent,
+                           const RS_DimensionData& d,
+                           const RS_DimDiametricData& ed)
+        : RS_Dimension(parent, d), edata(ed) {
+
+    calculateBorders();
+}
+
+RS_Entity* RS_DimDiametric::clone() const {
+	RS_DimDiametric* d = new RS_DimDiametric(*this);
+	d->setOwner(isOwner());
+	d->initId();
+	d->detach();
+	return d;
+}
+
+/**
+ * @return Automatically created label for the default
+ * measurement of this dimension.
+ */
+QString RS_DimDiametric::getMeasuredLabel() {
+
+    // Definitive dimension line:
+	double dist = data.definitionPoint.distanceTo(edata.definitionPoint) * getGeneralFactor();
+
+    RS_Graphic* graphic = getGraphic();
+
+    QString ret;
+    if (graphic) {
+        int dimlunit = getGraphicVariableInt("$DIMLUNIT", 2);
+        int dimdec = getGraphicVariableInt("$DIMDEC", 4);
+        int dimzin = getGraphicVariableInt("$DIMZIN", 1);
+        RS2::LinearFormat format = graphic->getLinearFormat(dimlunit);
+        ret = RS_Units::formatLinear(dist, RS2::None, format, dimdec);
+        if (format == RS2::Decimal)
+            ret = stripZerosLinear(ret, dimzin);
+        //verify if units are decimal and comma separator
+        if (format == RS2::Decimal || format == RS2::ArchitecturalMetric){
+            if (getGraphicVariableInt("$DIMDSEP", 0) == 44)
+                ret.replace(QChar('.'), QChar(','));
+        }
+    }
+    else {
+        ret = QString("%1").arg(dist);
+    }
+
+    return ret;
+}
+
+
+
+RS_VectorSolutions RS_DimDiametric::getRefPoints() const
+{
+		return RS_VectorSolutions({edata.definitionPoint,
+												data.definitionPoint, data.middleOfText});
+}
+
+
+/**
+ * Updates the sub entities of this dimension. Called when the
+ * dimension or the position, alignment, .. changes.
+ *
+ * @param autoText Automatically reposition the text label
+ */
+void RS_DimDiametric::updateDim(bool autoText) {
+
+    RS_DEBUG->print("RS_DimDiametric::update");
+
+    clear();
+
+        if (isUndone()) {
+                return;
+        }
+
+    // dimension line:
+	updateCreateDimensionLine(data.definitionPoint, edata.definitionPoint,
+        true, true, autoText);
+
+    calculateBorders();
+}
+
+
+
+void RS_DimDiametric::move(const RS_Vector& offset) {
+    RS_Dimension::move(offset);
+
+    edata.definitionPoint.move(offset);
+    update();
+}
+
+
+
+void RS_DimDiametric::rotate(const RS_Vector& center, const double& angle) {
+    rotate(center,RS_Vector(angle));
+}
+
+void RS_DimDiametric::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_Dimension::rotate(center, angleVector);
+
+    edata.definitionPoint.rotate(center, angleVector);
+    update();
+}
+
+
+void RS_DimDiametric::scale(const RS_Vector& center, const RS_Vector& factor) {
+    RS_Dimension::scale(center, factor);
+
+    edata.definitionPoint.scale(center, factor);
+        edata.leader*=factor.x;
+    update();
+}
+
+
+
+void RS_DimDiametric::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    RS_Dimension::mirror(axisPoint1, axisPoint2);
+
+    edata.definitionPoint.mirror(axisPoint1, axisPoint2);
+    update();
+}
+
+
+
+void RS_DimDiametric::moveRef(const RS_Vector& ref, const RS_Vector& offset) {
+
+    if (ref.distanceTo(edata.definitionPoint)<1.0e-4) {
+				RS_Vector c = (edata.definitionPoint + data.definitionPoint)/2.0;
+                double d = c.distanceTo(edata.definitionPoint);
+                double a = c.angleTo(edata.definitionPoint + offset);
+
+				RS_Vector v = RS_Vector::polar(d, a);
+        edata.definitionPoint = c + v;
+				data.definitionPoint = c - v;
+                updateDim(true);
+    }
+	else if (ref.distanceTo(data.definitionPoint)<1.0e-4) {
+				RS_Vector c = (edata.definitionPoint + data.definitionPoint)/2.0;
+				double d = c.distanceTo(data.definitionPoint);
+				double a = c.angleTo(data.definitionPoint + offset);
+
+				RS_Vector v = RS_Vector::polar(d, a);
+		data.definitionPoint = c + v;
+                edata.definitionPoint = c - v;
+                updateDim(true);
+    }
+        else if (ref.distanceTo(data.middleOfText)<1.0e-4) {
+        data.middleOfText.move(offset);
+                updateDim(false);
+    }
+}
+
+
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_DimDiametric& d) {
+    os << " DimDiametric: " << d.getData() << "\n" << d.getEData() << "\n";
+    return os;
+}

lib/engine/rs_dimdiametric.h

@@ -0,0 +1,114 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_DIMDIAMETER_H
+#define RS_DIMDIAMETER_H
+
+#include "rs_dimension.h"
+
+/**
+ * Holds the data that defines a diametric dimension entity.
+ */
+struct RS_DimDiametricData {
+    /**
+	 * Default constructor
+     */
+	RS_DimDiametricData();
+
+    /**
+     * Constructor with initialisation.
+     *
+     * @param definitionPoint Definition point of the diametric dimension.
+     * @param leader Leader length.
+     */
+    RS_DimDiametricData(const RS_Vector& definitionPoint,
+					 double leader);
+
+
+    /** Definition point. */
+    RS_Vector definitionPoint;
+    /** Leader length. */
+    double leader;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_DimDiametricData& dd);
+
+/**
+ * Class for diametric dimension entities.
+ *
+ * @author Andrew Mustun
+ */
+class RS_DimDiametric : public RS_Dimension {
+public:
+    RS_DimDiametric(RS_EntityContainer* parent,
+                 const RS_DimensionData& d,
+                 const RS_DimDiametricData& ed);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityDimDiametric */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityDimDiametric;
+    }
+
+    /**
+     * @return Copy of data that defines the diametric dimension.
+     * @see getData()
+     */
+    RS_DimDiametricData getEData() const {
+        return edata;
+    }
+
+	RS_VectorSolutions getRefPoints() const override;
+
+	QString getMeasuredLabel() override;
+
+	void updateDim(bool autoText=false) override;
+
+    RS_Vector getDefinitionPoint() {
+        return edata.definitionPoint;
+    }
+    double getLeader() {
+        return edata.leader;
+    }
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+
+    friend std::ostream& operator << (std::ostream& os,
+                                      const RS_DimDiametric& d);
+
+protected:
+    /** Extended data. */
+    RS_DimDiametricData edata;
+};
+
+#endif

lib/engine/rs_dimension.cpp

@@ -0,0 +1,892 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+#include<iostream>
+#include<cmath>
+#include<string>
+#include "rs_information.h"
+#include "rs_line.h"
+#include "rs_dimension.h"
+#include "rs_solid.h"
+#include "rs_units.h"
+#include "rs_math.h"
+#include "rs_filterdxfrw.h" //for int <-> rs_color conversion
+#include "rs_debug.h"
+
+RS_DimensionData::RS_DimensionData():
+	definitionPoint(false),
+	middleOfText(false),
+	valign(RS_MTextData::VABottom),
+	halign(RS_MTextData::HALeft),
+	lineSpacingStyle(RS_MTextData::Exact),
+	lineSpacingFactor(0.0),
+	text(""),
+	style(""),
+	angle(0.0)
+{}
+
+/**
+ * Constructor with initialisation.
+ *
+ * @param definitionPoint Definition point.
+ * @param middleOfText Middle point of dimension text.
+ * @param valign Vertical alignment.
+ * @param halign Horizontal alignment.
+ * @param lineSpacingStyle Line spacing style.
+ * @param lineSpacingFactor Line spacing factor.
+ * @param text Text string entered explicitly by user or null
+ *         or "<>" for the actual measurement or " " (one blank space).
+ *         for suppressing the text.
+ * @param style Dimension style name.
+ * @param angle Rotation angle of dimension text away from
+ *         default orientation.
+ */
+RS_DimensionData::RS_DimensionData(const RS_Vector& _definitionPoint,
+				 const RS_Vector& _middleOfText,
+				 RS_MTextData::VAlign _valign,
+				 RS_MTextData::HAlign _halign,
+				 RS_MTextData::MTextLineSpacingStyle _lineSpacingStyle,
+				 double _lineSpacingFactor,
+				 QString _text,
+				 QString _style,
+				 double _angle):
+	definitionPoint(_definitionPoint)
+	,middleOfText(_middleOfText)
+	,valign(_valign)
+	,halign(_halign)
+	,lineSpacingStyle(_lineSpacingStyle)
+	,lineSpacingFactor(_lineSpacingFactor)
+	,text(_text)
+	,style(_style)
+	,angle(_angle)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+						   const RS_DimensionData& dd) {
+	os << "("
+	   << dd.definitionPoint<<','
+	   <<dd.middleOfText<<','
+	  <<dd.valign<<','
+	 <<dd.halign<<','
+	<<dd.lineSpacingStyle<<','
+	<<dd.lineSpacingFactor<<','
+	<<dd.text.toLatin1().data() <<','
+	<<dd.style.toLatin1().data()<<','
+	<<dd.angle
+	<< ")";
+	return os;
+}
+
+/**
+ * Constructor.
+ */
+RS_Dimension::RS_Dimension(RS_EntityContainer* parent,
+                           const RS_DimensionData& d)
+        : RS_EntityContainer(parent), data(d) {
+}
+
+RS_Vector RS_Dimension::getNearestRef( const RS_Vector& coord,
+                                       double* dist /*= nullptr*/) const
+{
+    // override the RS_EntityContainer method
+    // use RS_Entity instead for refpoint dragging
+    return RS_Entity::getNearestRef( coord, dist);
+}
+
+RS_Vector RS_Dimension::getNearestSelectedRef( const RS_Vector& coord,
+                                               double* dist /*= nullptr*/) const
+{
+    // override the RS_EntityContainer method
+    // use RS_Entity instead for refpoint dragging
+    return RS_Entity::getNearestSelectedRef( coord, dist);
+}
+
+
+/**
+ * @return Dimension text. Either a text the user defined or
+ *         the measured text.
+ *
+ * @param resolve false: return plain value. true: return measured
+ *      label if appropriate.
+ * @see getMeasuredLabel
+ */
+QString RS_Dimension::getLabel(bool resolve) {
+        if (!resolve) {
+                return data.text;
+        }
+
+    QString ret="";
+
+    // One space suppresses the text:
+    if (data.text==" ") {
+        ret = "";
+    }
+
+    // No text prints actual measurement:
+    else if (data.text=="") {
+        ret = getMeasuredLabel();
+    }
+
+    // Others print the text (<> is replaced by the measurement)
+    else {
+        ret = data.text;
+        ret = ret.replace(QString("<>"), getMeasuredLabel());
+    }
+
+    return ret;
+}
+
+
+/**
+ * Sets a new text for the label.
+ */
+void RS_Dimension::setLabel(const QString& l) {
+        data.text = l;
+}
+
+
+/**
+ * Find intersections between a line and an EntityContainer.  Solutions are
+ * sorted along the line before returning.
+ *
+ * @param infiniteLine Treat the line as infinitely long in both directions.
+ */
+RS_VectorSolutions RS_Dimension::getIntersectionsLineContainer(
+        const RS_Line* l, const RS_EntityContainer* c, bool infiniteLine)
+{
+    RS_VectorSolutions solutions_initial;
+    RS_VectorSolutions solutions_filtered;
+    const double tol = 1.0e-4;
+
+    // Find all intersections, including those beyond limits of container
+    // entities.
+    for(RS_Entity* e: *c) {
+        solutions_initial.push_back(
+            RS_Information::getIntersection(l, e, false)
+        );
+    }
+
+    // Filter solutions based on whether they are actually on any entities.
+    for(const RS_Vector& vp: solutions_initial){
+        for(RS_Entity* e: *c) {
+            if (e->isConstruction(true) || e->isPointOnEntity(vp, tol)) {
+                // the intersection is at least on the container, now check the line:
+                if (infiniteLine) {
+                    // The line is treated as infinitely long so we don't need to
+                    // check if the intersection is on the line.
+                    solutions_filtered.push_back(vp);
+                    break;
+                } else if (l->isConstruction(true) || l->isPointOnEntity(vp, tol)) {
+                    solutions_filtered.push_back(vp);
+                    break;
+                }
+            }
+        }
+    }
+
+    /**
+     * We cannot sort the solutions in place because getVector() returns a
+     * const vector, so first construct a copy:
+     */
+    std::vector<RS_Vector> solutions_sorted(solutions_filtered.getVector());
+    std::sort(solutions_sorted.begin(), solutions_sorted.end(),
+              [l](const RS_Vector& lhs, const RS_Vector& rhs)
+        {
+            return l->getProjectionValueAlongLine(lhs)
+                   < l->getProjectionValueAlongLine(rhs);
+        });
+
+    return RS_VectorSolutions(solutions_sorted);
+}
+
+
+/**
+ * Creates a horizontal-text dimensioning line (line with one, two or no arrows
+ * and "inside horizontal" text).
+ *
+ * @param forceAutoText Automatically reposition the text label.
+ */
+void RS_Dimension::updateCreateHorizontalTextDimensionLine(const RS_Vector& p1,
+        const RS_Vector& p2, bool arrow1, bool arrow2, bool forceAutoText) {
+    // general scale (DIMSCALE)
+    double dimscale = getGeneralScale();
+    // text height (DIMTXT)
+    double dimtxt = getTextHeight()*dimscale;
+    // text distance to line (DIMGAP)
+    double dimgap = getDimensionLineGap()*dimscale;
+
+    // length of dimension line:
+    double distance = p1.distanceTo(p2);
+    // arrow size:
+    double arrowSize = getArrowSize()*dimscale;
+
+    // arrow angles:
+    double arrowAngle1, arrowAngle2;
+
+    RS_Pen pen(getDimensionLineColor(),
+           getDimensionLineWidth(),
+           RS2::LineByBlock);
+
+    // Create dimension line:
+    RS_Line* dimensionLine {new RS_Line{this, p1, p2}};
+    RS_Line* dimensionLineInside1 {nullptr};
+    RS_Line* dimensionLineInside2 {nullptr};
+    RS_Line* dimensionLineOutside1 {nullptr};
+    RS_Line* dimensionLineOutside2 {nullptr};
+    dimensionLine->setPen(pen);
+    dimensionLine->setLayer(nullptr);
+
+    // Text label:
+    RS_MTextData textData;
+    RS_Vector textPos;
+    double textAngle = 0.0;
+    bool autoText = !data.middleOfText.valid || forceAutoText;
+
+    if (autoText) {
+        textPos = dimensionLine->getMiddlePoint();
+
+        //// the next update should still be able to adjust this
+        ////   auto text position. leave it invalid
+        data.middleOfText = textPos;
+    } else {
+        textPos = data.middleOfText;
+    }
+
+    textData = RS_MTextData(textPos,
+                            dimtxt, 30.0,
+                            RS_MTextData::VAMiddle,
+                            RS_MTextData::HACenter,
+                            RS_MTextData::LeftToRight,
+                            RS_MTextData::Exact,
+                            1.0,
+                            getLabel(),
+                            getTextStyle(),
+                            textAngle);
+
+    RS_MText* text = new RS_MText(this, textData);
+    text->setPen(RS_Pen(getTextColor(), RS2::WidthByBlock, RS2::SolidLine));
+    text->setLayer(nullptr);
+
+    // evaluate intersection between dim line and text
+    double textIntersectionLength = 0.0;
+    double w = text->getUsedTextWidth()/2+dimgap;
+    double h = text->getUsedTextHeight()/2+dimgap;
+    // textCorner variables correspond to the corners of the text bounding box
+    // if the text were to be positioned in the center of the dimensionLine.
+    RS_Vector textCorner1 = dimensionLine->getMiddlePoint() - RS_Vector{w, h};
+    RS_Vector textCorner2 = dimensionLine->getMiddlePoint() + RS_Vector{w, h};
+    RS_EntityContainer c;
+    c.addRectangle(textCorner1, textCorner2);
+    RS_VectorSolutions sol1 = getIntersectionsLineContainer(
+        dimensionLine, &c,
+        true  // treat line as infinitely long in both directions
+        );
+    textIntersectionLength = sol1.get(0).distanceTo(sol1.get(1));
+
+    // determine if we should use outside arrows
+    bool outsideArrows = (textIntersectionLength+3*arrowSize) > distance;
+
+    // add arrows
+    if (outsideArrows==false) {
+        arrowAngle1 = dimensionLine->getAngle2();
+        arrowAngle2 = dimensionLine->getAngle1();
+    } else {
+        arrowAngle1 = dimensionLine->getAngle1();
+        arrowAngle2 = dimensionLine->getAngle2();
+
+        // extend dimension line outside arrows
+        RS_Vector dir = RS_Vector::polar(arrowSize*2, dimensionLine->getAngle1());
+        dimensionLineOutside1 = new RS_Line{this, p1 - dir, p1};
+        dimensionLineOutside2 = new RS_Line{this, p2 + dir, p2};
+
+        // move text to the side if it won't fit either
+        RS_Vector distH;
+        if (textIntersectionLength>distance && autoText) {
+            distH.setPolar(textIntersectionLength/2.0+arrowSize*2+distance/2.0,
+                           arrowAngle1);
+            text->move(distH);
+            textPos = text->getInsertionPoint();
+            data.middleOfText = textPos;
+        }
+    }
+    double dimtsz=getTickSize()*dimscale;
+    bool displayArrows = dimtsz < 0.01;
+    if(displayArrows) {
+        //display arrow
+        // Arrows:
+        RS_SolidData sd;
+        RS_Solid* arrow;
+
+        if (arrow1) {
+            // arrow 1
+            arrow = new RS_Solid(this, sd);
+            arrow->shapeArrow(p1,
+                              arrowAngle1,
+                              arrowSize);
+            arrow->setPen(pen);
+            arrow->setLayer(nullptr);
+            addEntity(arrow);
+        }
+
+        if (arrow2) {
+            // arrow 2:
+            arrow = new RS_Solid(this, sd);
+            arrow->shapeArrow(p2,
+                              arrowAngle2,
+                              arrowSize);
+            arrow->setPen(pen);
+            arrow->setLayer(nullptr);
+            addEntity(arrow);
+        }
+    } else {
+        //display ticks
+        // Arrows:
+
+        RS_Line* tick;
+        RS_Vector tickVector = RS_Vector::polar(dimtsz,arrowAngle1 + M_PI*0.25); //tick is 45 degree away
+
+        if (arrow1) {
+            // tick 1
+            tick = new RS_Line(this, p1-tickVector, p1+tickVector);
+            tick->setPen(pen);
+            tick->setLayer(nullptr);
+            addEntity(tick);
+        }
+
+        if (arrow2) {
+            // tick 2:
+            tick = new RS_Line(this, p2-tickVector, p2+tickVector);
+            tick->setPen(pen);
+            tick->setLayer(nullptr);
+            addEntity(tick);
+        }
+    }
+
+    // calculate split dimension lines
+    bool splitDimensionLine = false;
+    if (!outsideArrows) {
+        w = text->getUsedTextWidth()/2+dimgap;
+        h = text->getUsedTextHeight()/2+dimgap;
+        RS_Vector s1 = text->getInsertionPoint() - RS_Vector{w, h};
+        RS_Vector s2 = text->getInsertionPoint() + RS_Vector{w, h};
+        c = RS_EntityContainer();
+        c.addRectangle(s1, s2);
+        sol1 = getIntersectionsLineContainer(dimensionLine, &c);
+        if (sol1.size()>1) {
+            // the text bounding box intersects dimensionLine on two sides
+            splitDimensionLine = true;
+            s1 = sol1.get(0);
+            s2 = sol1.get(1);
+        } else if (sol1.size()==1) {
+            // the text bounding box intersects dimensionLine on one side
+            splitDimensionLine = true;
+            if (RS_Information::isPointInsideContour(p1, &c)) {
+                // the dimension line begins inside the text bounds
+                s1 = p1;
+                s2 = sol1.get(0);
+            } else {
+                // the dimension line ends inside the text bounds
+                s1 = sol1.get(0);
+                s2 = p2;
+            }
+        } else {
+            // the text bounding box does not intersect with dimensionLine, but we
+            // should still check if dimensionLine endpoints are completely inside
+            // the bounding box.
+            if (RS_Information::isPointInsideContour(p1, &c)) {
+                splitDimensionLine = true;
+                s1 = p1;
+                s2 = p2;
+            }
+        }
+
+        if (splitDimensionLine) {
+            dimensionLineInside1 = new RS_Line{this, p1, s1};
+            dimensionLineInside2 = new RS_Line{this, s2, p2};
+        }
+    }
+
+    // finally, add the dimension line(s) and text to the drawing
+    if (outsideArrows && dimensionLineOutside1) {
+        addEntity(dimensionLineOutside1);
+        addEntity(dimensionLineOutside2);
+    } else if (splitDimensionLine && dimensionLineInside1) {
+        addEntity(dimensionLineInside1);
+        addEntity(dimensionLineInside2);
+    } else {
+        addEntity(dimensionLine);
+    }
+
+    addEntity(text);
+}
+
+
+/**
+ * Creates an aligned-text dimensioning line (line with one, two or no arrows
+ * and aligned text).
+ *
+ * @param forceAutoText Automatically reposition the text label.
+ */
+void RS_Dimension::updateCreateAlignedTextDimensionLine(const RS_Vector& p1,
+        const RS_Vector& p2, bool arrow1, bool arrow2, bool forceAutoText) {
+    // general scale (DIMSCALE)
+    double dimscale = getGeneralScale();
+    // text height (DIMTXT)
+    double dimtxt = getTextHeight()*dimscale;
+    // text distance to line (DIMGAP)
+    double dimgap = getDimensionLineGap()*dimscale;
+
+    // length of dimension line:
+    double distance = p1.distanceTo(p2);
+    // arrow size:
+    double arrowSize = getArrowSize()*dimscale;
+
+    // do we have to put the arrows outside of the line?
+    bool outsideArrows = (distance<arrowSize*2.5);
+
+    // arrow angles:
+    double arrowAngle1, arrowAngle2;
+
+    RS_Pen pen(getDimensionLineColor(),
+           getDimensionLineWidth(),
+           RS2::LineByBlock);
+
+    // Create dimension line:
+    RS_Line* dimensionLine = new RS_Line{this, p1, p2};
+    dimensionLine->setPen(pen);
+    dimensionLine->setLayer(nullptr);
+    addEntity(dimensionLine);
+
+    // Text label:
+    RS_MTextData textData;
+    RS_Vector textPos;
+    double dimAngle1 = dimensionLine->getAngle1();
+    bool corrected = false;
+    double textAngle = RS_Math::makeAngleReadable(dimAngle1, true, &corrected);
+
+    if (data.middleOfText.valid && !forceAutoText) {
+        textPos = data.middleOfText;
+    } else {
+        textPos = dimensionLine->getMiddlePoint();
+
+        // rotate text so it's readable from the bottom or right (ISO)
+        // quadrant 1 & 4
+        double const a = corrected?-M_PI_2:M_PI_2;
+        RS_Vector distV = RS_Vector::polar(dimgap + dimtxt/2.0, dimAngle1+a);
+
+        // move text away from dimension line:
+        textPos+=distV;
+
+        //// the next update should still be able to adjust this
+        ////   auto text position. leave it invalid
+        data.middleOfText = textPos;
+    }
+
+    textData = RS_MTextData(textPos,
+                            dimtxt, 30.0,
+                            RS_MTextData::VAMiddle,
+                            RS_MTextData::HACenter,
+                            RS_MTextData::LeftToRight,
+                            RS_MTextData::Exact,
+                            1.0,
+                            getLabel(),
+                            getTextStyle(),
+                            textAngle);
+
+    RS_MText* text = new RS_MText(this, textData);
+    text->setPen(RS_Pen(getTextColor(), RS2::WidthByBlock, RS2::SolidLine));
+    text->setLayer(nullptr);
+
+    // move text to the side:
+    RS_Vector distH;
+    if (text->getUsedTextWidth()>distance) {
+        distH.setPolar(text->getUsedTextWidth()/2.0
+                       +distance/2.0+dimgap, textAngle);
+        text->move(distH);
+    }
+
+    addEntity(text);
+
+    // add arrows
+    if (outsideArrows==false) {
+        arrowAngle1 = dimensionLine->getAngle2();
+        arrowAngle2 = dimensionLine->getAngle1();
+    } else {
+        arrowAngle1 = dimensionLine->getAngle1();
+        arrowAngle2 = dimensionLine->getAngle2();
+
+        // extend dimension line outside arrows
+        RS_Vector dir = RS_Vector::polar(arrowSize*2, arrowAngle2);
+        dimensionLine->setStartpoint(p1 + dir);
+        dimensionLine->setEndpoint(p2 - dir);
+    }
+    double dimtsz=getTickSize()*dimscale;
+    if(dimtsz < 0.01) {
+        //display arrow
+        // Arrows:
+        RS_SolidData sd;
+        RS_Solid* arrow;
+
+        if (arrow1) {
+            // arrow 1
+            arrow = new RS_Solid(this, sd);
+            arrow->shapeArrow(p1,
+                              arrowAngle1,
+                              arrowSize);
+            arrow->setPen(pen);
+            arrow->setLayer(nullptr);
+            addEntity(arrow);
+        }
+
+        if (arrow2) {
+            // arrow 2:
+            arrow = new RS_Solid(this, sd);
+            arrow->shapeArrow(p2,
+                              arrowAngle2,
+                              arrowSize);
+            arrow->setPen(pen);
+            arrow->setLayer(nullptr);
+            addEntity(arrow);
+        }
+    }else{
+        //display ticks
+        // Arrows:
+
+        RS_Line* tick;
+        RS_Vector tickVector = RS_Vector::polar(dimtsz,arrowAngle1 + M_PI*0.25); //tick is 45 degree away
+
+        if (arrow1) {
+            // tick 1
+            tick = new RS_Line(this, p1-tickVector, p1+tickVector);
+            tick->setPen(pen);
+            tick->setLayer(nullptr);
+            addEntity(tick);
+        }
+
+        if (arrow2) {
+            // tick 2:
+            tick = new RS_Line(this, p2-tickVector, p2+tickVector);
+            tick->setPen(pen);
+            tick->setLayer(nullptr);
+            addEntity(tick);
+        }
+    }
+}
+
+
+/**
+ * Creates a dimensioning line (line with one, two or no arrows and a text).
+ *
+ * @param forceAutoText Automatically reposition the text label.
+ */
+void RS_Dimension::updateCreateDimensionLine(const RS_Vector& p1,
+        const RS_Vector& p2, bool arrow1, bool arrow2, bool forceAutoText) {
+    if (getInsideHorizontalText())
+        updateCreateHorizontalTextDimensionLine(p1, p2, arrow1, arrow2, forceAutoText);
+    else
+        updateCreateAlignedTextDimensionLine(p1, p2, arrow1, arrow2, forceAutoText);
+}
+
+
+/**
+ * @return general factor for linear dimensions.
+ */
+double RS_Dimension::getGeneralFactor() {
+    return getGraphicVariable("$DIMLFAC", 1.0, 40);
+}
+
+/**
+ * @return general scale for dimensions.
+ */
+double RS_Dimension::getGeneralScale() {
+    return getGraphicVariable("$DIMSCALE", 1.0, 40);
+}
+
+/**
+ * @return arrow size in drawing units.
+ */
+double RS_Dimension::getArrowSize() {
+    return getGraphicVariable("$DIMASZ", 2.5, 40);
+}
+
+/**
+ * @return tick size in drawing units.
+ */
+double RS_Dimension::getTickSize() {
+    return getGraphicVariable("$DIMTSZ", 0., 40);
+}
+
+
+/**
+ * @return extension line overlength in drawing units.
+ */
+double RS_Dimension::getExtensionLineExtension() {
+    return getGraphicVariable("$DIMEXE", 1.25, 40);
+}
+
+
+
+/**
+ * @return extension line offset from entities in drawing units.
+ */
+double RS_Dimension::getExtensionLineOffset() {
+    return getGraphicVariable("$DIMEXO", 0.625, 40);
+}
+
+
+
+/**
+ * @return extension line gap to text in drawing units.
+ */
+double RS_Dimension::getDimensionLineGap() {
+    return getGraphicVariable("$DIMGAP", 0.625, 40);
+}
+
+
+
+/**
+ * @return Dimension labels text height.
+ */
+double RS_Dimension::getTextHeight() {
+    return getGraphicVariable("$DIMTXT", 2.5, 40);
+}
+
+
+/**
+ * @return Dimension labels alignment text true= horizontal, false= aligned.
+ */
+bool RS_Dimension::getInsideHorizontalText() {
+    int v = getGraphicVariableInt("$DIMTIH", 1);
+    if (v>0) {
+        addGraphicVariable("$DIMTIH", 1, 70);
+        getGraphicVariableInt("$DIMTIH", 1);
+		return true;
+    }
+	return false;
+}
+
+
+/**
+ * @return Dimension fixed length for extension lines true= fixed, false= not fixed.
+ */
+bool RS_Dimension::getFixedLengthOn() {
+    int v = getGraphicVariableInt("$DIMFXLON", 0);
+    if (v == 1) {
+        addGraphicVariable("$DIMFXLON", 1, 70);
+        getGraphicVariableInt("$DIMFXLON", 0);
+		return true;
+    }
+	return false;
+}
+
+/**
+ * @return Dimension fixed length for extension lines.
+ */
+double RS_Dimension::getFixedLength() {
+    return getGraphicVariable("$DIMFXL", 1.0, 40);
+}
+
+
+/**
+ * @return extension line Width.
+ */
+RS2::LineWidth RS_Dimension::getExtensionLineWidth() {
+    return RS2::intToLineWidth( getGraphicVariableInt("$DIMLWE", -2) ); //default -2 (RS2::WidthByBlock)
+}
+
+
+/**
+ * @return dimension line Width.
+ */
+RS2::LineWidth RS_Dimension::getDimensionLineWidth() {
+    return RS2::intToLineWidth( getGraphicVariableInt("$DIMLWD", -2) ); //default -2 (RS2::WidthByBlock)
+}
+
+/**
+ * @return dimension line Color.
+ */
+RS_Color RS_Dimension::getDimensionLineColor() {
+    return RS_FilterDXFRW::numberToColor(getGraphicVariableInt("$DIMCLRD", 0));
+}
+
+
+/**
+ * @return extension line Color.
+ */
+RS_Color RS_Dimension::getExtensionLineColor() {
+    return RS_FilterDXFRW::numberToColor(getGraphicVariableInt("$DIMCLRE", 0));
+}
+
+
+/**
+ * @return dimension text Color.
+ */
+RS_Color RS_Dimension::getTextColor() {
+    return RS_FilterDXFRW::numberToColor(getGraphicVariableInt("$DIMCLRT", 0));
+}
+
+
+/**
+ * @return text style for dimensions.
+ */
+QString RS_Dimension::getTextStyle() {
+    return getGraphicVariableString("$DIMTXSTY", "standard");
+}
+
+
+/**
+ * @return the given graphic variable or the default value given in mm
+ * converted to the graphic unit.
+ * If the variable is not found it is added with the given default
+ * value converted to the local unit.
+ */
+double RS_Dimension::getGraphicVariable(const QString& key, double defMM,
+                                        int code) {
+
+    double v = getGraphicVariableDouble(key, RS_MINDOUBLE);
+    if (v<=RS_MINDOUBLE) {
+        addGraphicVariable(
+            key,
+            RS_Units::convert(defMM, RS2::Millimeter, getGraphicUnit()),
+            code);
+        v = getGraphicVariableDouble(key, 1.0);
+    }
+
+    return v;
+}
+
+/**
+ * Removes zeros from angle string.
+ *
+ * @param angle The string representing angle.
+ * @param zeros Zeros suppression (0 none, 1 suppress leading, 2 suppress trailing, 3 both)
+ * Decimal separator are '.'
+ *
+ * @ret String with the formatted angle.
+ */
+
+QString RS_Dimension::stripZerosAngle(QString angle, int zeros){
+    if (zeros == 0) //do nothing
+        return angle;
+    if (zeros & 2 && (angle.contains(QString('.')) || angle.contains(QString(',')))) {
+        int end = angle.size() - 1;
+        QChar format = angle[end--];  //stores & skip format char
+        while (end > 0 && angle[end] == QChar('0')) // locate first 0 from end
+            end--;
+        if (angle[end] == QChar('.'))
+            end--;
+        angle.truncate(end+1);
+        angle.append(format);
+    }
+    if (zeros & 1){
+		if (angle[0] == QChar('0') && angle[1] == QChar('.'))
+        angle = angle.remove(0, 1);
+    }
+    return angle;
+}
+
+/**
+ * Removes zeros from linear string.
+ *
+ * @param linear The string representing linear measure.
+ * @param zeros Zeros suppression (see dimzin)
+ *
+ * @ret String with the formatted linear measure.
+ */
+
+QString RS_Dimension::stripZerosLinear(QString linear, int zeros){
+
+    //do nothing
+    if (zeros == 1)
+        return linear;
+
+    // return at least 1 character in string
+    int ls = linear.size();
+    if (ls <= 1) {
+        return linear;
+    }
+
+    // if removing of trailing zeroes is needed
+    if (zeros & 8 && (linear.contains(QString('.')) || linear.contains(QString(',')))) {
+        // search index
+        int i = ls - 1;
+        // locate first 0 in row from right
+        while (i > 0 && linear[i] == QChar('0')) {
+            i--;
+        }
+        // strip decimal point
+        if ((linear[i] == QChar('.') || linear[i] == QChar(',')) && i > 0)
+            i--;
+        // strip zeros. Leave at least one character at the beginning
+        linear = linear.remove(i+1, ls-i);
+    }
+    // if removing of initial zeroes is needed
+    if (zeros & 4) {
+        int i = 0;
+        // locate last 0 in row from left
+        while (i < ls-1 && linear[i] == QChar('0')) {
+            i++;
+        }
+        linear = linear.remove(0, i);
+    }
+    return linear;
+}
+
+
+void RS_Dimension::move(const RS_Vector& offset) {
+	data.definitionPoint.move(offset);
+    data.middleOfText.move(offset);
+}
+
+
+
+void RS_Dimension::rotate(const RS_Vector& center, const double& angle) {
+    RS_Vector angleVector(angle);
+	data.definitionPoint.rotate(center, angleVector);
+    data.middleOfText.rotate(center, angleVector);
+    data.angle = RS_Math::correctAngle(data.angle+angle);
+}
+
+void RS_Dimension::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+	data.definitionPoint.rotate(center, angleVector);
+    data.middleOfText.rotate(center, angleVector);
+    data.angle = RS_Math::correctAngle(data.angle+angleVector.angle());
+}
+
+
+void RS_Dimension::scale(const RS_Vector& center, const RS_Vector& factor) {
+	data.definitionPoint.scale(center, factor);
+    data.middleOfText.scale(center, factor);
+}
+
+
+
+void RS_Dimension::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+	data.definitionPoint.mirror(axisPoint1, axisPoint2);
+    data.middleOfText.mirror(axisPoint1, axisPoint2);
+}
+
+// EOF

lib/engine/rs_dimension.h

@@ -0,0 +1,219 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_DIMENSION_H
+#define RS_DIMENSION_H
+
+#include "rs_entitycontainer.h"
+#include "rs_mtext.h"
+
+/**
+ * Holds the data that is common to all dimension entities.
+ */
+struct RS_DimensionData : public RS_Flags {
+    /**
+	 * Default constructor
+     */
+	RS_DimensionData();
+
+    /**
+     * Constructor with initialisation.
+     *
+     * @param definitionPoint Definition point.
+     * @param middleOfText Middle point of dimension text.
+     * @param valign Vertical alignment.
+     * @param halign Horizontal alignment.
+     * @param lineSpacingStyle Line spacing style.
+     * @param lineSpacingFactor Line spacing factor.
+     * @param text Text string entered explicitly by user or null
+     *         or "<>" for the actual measurement or " " (one blank space).
+     *         for suppressing the text.
+     * @param style Dimension style name.
+     * @param angle Rotation angle of dimension text away from
+     *         default orientation.
+     */
+	RS_DimensionData(const RS_Vector& definitionPoint,
+                     const RS_Vector& middleOfText,
+                     RS_MTextData::VAlign valign,
+                     RS_MTextData::HAlign halign,
+                     RS_MTextData::MTextLineSpacingStyle lineSpacingStyle,
+                     double lineSpacingFactor,
+                     QString text,
+                     QString style,
+					 double angle);
+
+    /** Definition point */
+	RS_Vector definitionPoint;
+    /** Middle point of dimension text */
+    RS_Vector middleOfText;
+    /** Vertical alignment */
+    RS_MTextData::VAlign valign;
+    /** Horizontal alignment */
+    RS_MTextData::HAlign halign;
+    /** Line spacing style */
+    RS_MTextData::MTextLineSpacingStyle lineSpacingStyle;
+    /** Line spacing factor */
+    double lineSpacingFactor;
+    /**
+    * Text string entered explicitly by user or null
+    * or "<>" for the actual measurement or " " (one blank space)
+    * for suppressing the text.
+    */
+    QString text;
+    /** Dimension style name */
+    QString style;
+    /** Rotation angle of dimension text away from default orientation */
+    double angle;
+};
+
+std::ostream& operator << (std::ostream& os,
+								  const RS_DimensionData& dd);
+
+/**
+ * Abstract base class for dimension entity classes.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Dimension : public RS_EntityContainer {
+public:
+    RS_Dimension(RS_EntityContainer* parent,
+                 const RS_DimensionData& d);
+
+	RS_Vector getNearestRef( const RS_Vector& coord, double* dist = nullptr) const override;
+	RS_Vector getNearestSelectedRef( const RS_Vector& coord, double* dist = nullptr) const override;
+
+    /** @return Copy of data that defines the dimension. */
+    RS_DimensionData getData() const {
+        return data;
+    }
+
+    QString getLabel(bool resolve=true);
+        void setLabel(const QString& l);
+
+    /**
+     * Needs to be implemented by the dimension class to return the
+     * measurement of the dimension (e.g. 10.5 or 15'14").
+     */
+    virtual QString getMeasuredLabel() = 0;
+
+    /**
+     * Must be overwritten by implementing dimension entity class
+     * to update the subentities which make up the dimension entity.
+     */
+	void update() override{
+            updateDim();
+        }
+
+    virtual void updateDim(bool autoText=false) = 0;
+
+    void updateCreateDimensionLine(const RS_Vector& p1, const RS_Vector& p2,
+                  bool arrow1=true, bool arrow2=true, bool autoText=false);
+
+    RS_Vector getDefinitionPoint() {
+		return data.definitionPoint;
+    }
+
+    RS_Vector getMiddleOfText() {
+        return data.middleOfText;
+    }
+
+    RS_MTextData::VAlign getVAlign() {
+        return data.valign;
+    }
+
+    RS_MTextData::HAlign getHAlign() {
+        return data.halign;
+    }
+
+    RS_MTextData::MTextLineSpacingStyle getLineSpacingStyle() {
+        return data.lineSpacingStyle;
+    }
+
+    double getLineSpacingFactor() {
+        return data.lineSpacingFactor;
+    }
+
+    QString getText() {
+        return data.text;
+    }
+
+    QString getStyle() {
+        return data.style;
+    }
+
+    double getAngle() {
+        return data.angle;
+    }
+
+    double getGeneralFactor();
+    double getGeneralScale();
+    double getArrowSize();
+    double getTickSize();
+    double getExtensionLineExtension();
+    double getExtensionLineOffset();
+    double getDimensionLineGap();
+    double getTextHeight();
+    bool getInsideHorizontalText();
+    bool getFixedLengthOn();
+    double getFixedLength();
+    RS2::LineWidth getExtensionLineWidth();
+    RS2::LineWidth getDimensionLineWidth();
+    RS_Color getDimensionLineColor();
+    RS_Color getExtensionLineColor();
+    RS_Color getTextColor();
+    QString getTextStyle();
+
+        double getGraphicVariable(const QString& key, double defMM, int code);
+        static QString stripZerosAngle(QString angle, int zeros=0);
+        static QString stripZerosLinear(QString linear, int zeros=1);
+
+        //	virtual double getLength() {
+        //		return -1.0;
+        //	}
+
+		void move(const RS_Vector& offset) override;
+		void rotate(const RS_Vector& center, const double& angle) override;
+		void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+		void scale(const RS_Vector& center, const RS_Vector& factor) override;
+		void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+
+private:
+    static RS_VectorSolutions  getIntersectionsLineContainer(
+        const RS_Line* l, const RS_EntityContainer* c, bool infiniteLine=false);
+    void updateCreateHorizontalTextDimensionLine(
+        const RS_Vector& p1, const RS_Vector& p2,
+        bool arrow1=true, bool arrow2=true, bool autoText=false);
+    void updateCreateAlignedTextDimensionLine(
+        const RS_Vector& p1, const RS_Vector& p2,
+        bool arrow1=true, bool arrow2=true, bool autoText=false);
+
+protected:
+    /** Data common to all dimension entities. */
+    RS_DimensionData data;
+};
+
+#endif

lib/engine/rs_dimlinear.cpp

@@ -0,0 +1,384 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include<cmath>
+#include "rs_dimlinear.h"
+#include "rs_line.h"
+#include "rs_constructionline.h"
+#include "rs_mtext.h"
+#include "rs_solid.h"
+#include "rs_graphic.h"
+#include "rs_math.h"
+#include "rs_debug.h"
+
+
+RS_DimLinearData::RS_DimLinearData():
+	extensionPoint1(false),
+	extensionPoint2(false),
+	angle(0.0),
+	oblique(0.0)
+{}
+
+RS_DimLinearData::RS_DimLinearData(const RS_Vector& _extensionPoint1,
+				 const RS_Vector& _extensionPoint2,
+				 double _angle, double _oblique):
+	extensionPoint1(_extensionPoint1)
+	,extensionPoint2(_extensionPoint2)
+	,angle(_angle)
+	,oblique(_oblique)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+								  const RS_DimLinearData& dd) {
+	os << "(" << dd.extensionPoint1 << ","
+	   << dd.extensionPoint1 <<','
+	   << dd.angle <<','
+	   << dd.oblique <<','
+		  <<")";
+	return os;
+}
+
+/**
+ * Constructor.
+ *
+ * @para parent Parent Entity Container.
+ * @para d Common dimension geometrical data.
+ * @para ed Extended geometrical data for linear dimension.
+ */
+RS_DimLinear::RS_DimLinear(RS_EntityContainer* parent,
+                           const RS_DimensionData& d,
+                           const RS_DimLinearData& ed)
+        : RS_Dimension(parent, d), edata(ed) {
+
+    calculateBorders();
+}
+
+RS_Entity* RS_DimLinear::clone() const {
+	RS_DimLinear* d = new RS_DimLinear(*this);
+	d->setOwner(isOwner());
+	d->initId();
+	d->detach();
+	return d;
+}
+
+RS_VectorSolutions RS_DimLinear::getRefPoints() const
+{
+		return RS_VectorSolutions({edata.extensionPoint1, edata.extensionPoint2,
+												data.definitionPoint, data.middleOfText});
+}
+void RS_DimLinear::setAngle(double a) {
+	edata.angle = RS_Math::correctAngle(a);
+}
+
+
+/**
+ * @return Automatically created label for the default
+ * measurement of this dimension.
+ */
+QString RS_DimLinear::getMeasuredLabel() {
+    // direction of dimension line
+	RS_Vector dirDim = RS_Vector::polar(100.0, edata.angle);
+
+    // construction line for dimension line
+	RS_ConstructionLine dimLine(nullptr,
+								RS_ConstructionLineData(data.definitionPoint,
+														data.definitionPoint + dirDim));
+
+    RS_Vector dimP1 = dimLine.getNearestPointOnEntity(edata.extensionPoint1);
+    RS_Vector dimP2 = dimLine.getNearestPointOnEntity(edata.extensionPoint2);
+
+    // Definitive dimension line:
+    double dist = dimP1.distanceTo(dimP2) * getGeneralFactor();
+
+        RS_Graphic* graphic = getGraphic();
+
+    QString ret;
+        if (graphic) {
+            int dimlunit = getGraphicVariableInt("$DIMLUNIT", 2);
+            int dimdec = getGraphicVariableInt("$DIMDEC", 4);
+            int dimzin = getGraphicVariableInt("$DIMZIN", 1);
+            RS2::LinearFormat format = graphic->getLinearFormat(dimlunit);
+            ret = RS_Units::formatLinear(dist, RS2::None, format, dimdec);
+            if (format == RS2::Decimal)
+                ret = stripZerosLinear(ret, dimzin);
+            //verify if units are decimal and comma separator
+            if (format == RS2::Decimal || format == RS2::ArchitecturalMetric){
+                if (getGraphicVariableInt("$DIMDSEP", 0) == 44)
+                    ret.replace(QChar('.'), QChar(','));
+            }
+        }
+        else {
+        ret = QString("%1").arg(dist);
+        }
+
+    return ret;
+}
+
+
+
+bool RS_DimLinear::hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2) {
+        return (edata.extensionPoint1.isInWindow(v1, v2) ||
+                edata.extensionPoint2.isInWindow(v1, v2));
+}
+
+
+
+/**
+ * Updates the sub entities of this dimension. Called when the
+ * text or the position, alignment, .. changes.
+ *
+ * @param autoText Automatically reposition the text label
+ */
+void RS_DimLinear::updateDim(bool autoText) {
+
+    RS_DEBUG->print("RS_DimLinear::update");
+
+    clear();
+
+    if (isUndone()) {
+        return;
+    }
+
+    // general scale (DIMSCALE)
+    double dimscale = getGeneralScale();
+    // distance from entities (DIMEXO)
+    double dimexo = getExtensionLineOffset()*dimscale;
+    // extension line extension (DIMEXE)
+    double dimexe = getExtensionLineExtension()*dimscale;
+
+    // direction of dimension line
+	RS_Vector dirDim = RS_Vector::polar(100.0, edata.angle);
+
+    // construction line for dimension line
+    RS_ConstructionLine dimLine(
+		nullptr,
+		RS_ConstructionLineData(data.definitionPoint,
+								data.definitionPoint + dirDim));
+
+    RS_Vector dimP1 = dimLine.getNearestPointOnEntity(edata.extensionPoint1);
+    RS_Vector dimP2 = dimLine.getNearestPointOnEntity(edata.extensionPoint2);
+
+    // Definitive dimension line:
+    updateCreateDimensionLine(dimP1, dimP2, true, true, autoText);
+    /*
+    ld = RS_LineData(data.definitionPoint, dimP1);
+    RS_Line* dimensionLine = new RS_Line(this, ld);
+       addEntity(dimensionLine);
+    */
+
+    double extAngle1, extAngle2;
+
+    if ((edata.extensionPoint1-dimP1).magnitude()<1e-6) {
+        if ((edata.extensionPoint2-dimP2).magnitude()<1e-6) {
+            //boot extension points are in dimension line only rotate 90
+			extAngle2 = edata.angle + (M_PI_2);
+        } else {
+            //first extension point are in dimension line use second
+            extAngle2 = edata.extensionPoint2.angleTo(dimP2);
+        }
+            extAngle1 = extAngle2;
+    } else {
+        //first extension point not are in dimension line use it
+        extAngle1 = edata.extensionPoint1.angleTo(dimP1);
+        if ((edata.extensionPoint2-dimP2).magnitude()<1e-6)
+            extAngle2 = extAngle1;
+        else
+            extAngle2 = edata.extensionPoint2.angleTo(dimP2);
+    }
+
+    RS_Vector vDimexe1 = RS_Vector::polar(dimexe, extAngle1);
+    RS_Vector vDimexe2 = RS_Vector::polar(dimexe, extAngle2);
+
+    RS_Vector vDimexo1, vDimexo2;
+    if (getFixedLengthOn()){
+        double dimfxl = getFixedLength()*dimscale;
+        double extLength = (edata.extensionPoint1-dimP1).magnitude();
+        if (extLength-dimexo > dimfxl)
+            vDimexo1.setPolar(extLength - dimfxl, extAngle1);
+        extLength = (edata.extensionPoint2-dimP2).magnitude();
+        if (extLength-dimexo > dimfxl)
+            vDimexo2.setPolar(extLength - dimfxl, extAngle2);
+    } else {
+        vDimexo1.setPolar(dimexo, extAngle1);
+        vDimexo2.setPolar(dimexo, extAngle2);
+    }
+
+    RS_Pen pen(getExtensionLineColor(),
+           getExtensionLineWidth(),
+           RS2::LineByBlock);
+
+    // extension lines:
+	RS_Line* line = new RS_Line{this,
+			edata.extensionPoint1+vDimexo1, dimP1+vDimexe1};
+    line->setPen(pen);
+//    line->setPen(RS_Pen(RS2::FlagInvalid));
+	line->setLayer(nullptr);
+    addEntity(line);
+    //data.definitionPoint+vDimexe2);
+	line = new RS_Line{this,
+			edata.extensionPoint2+vDimexo2, dimP2+vDimexe2};
+    line->setPen(pen);
+//    line->setPen(RS_Pen(RS2::FlagInvalid));
+	line->setLayer(nullptr);
+    addEntity(line);
+
+    calculateBorders();
+}
+
+void RS_DimLinear::move(const RS_Vector& offset) {
+    RS_Dimension::move(offset);
+
+    edata.extensionPoint1.move(offset);
+    edata.extensionPoint2.move(offset);
+    update();
+}
+
+
+
+void RS_DimLinear::rotate(const RS_Vector& center, const double& angle) {
+    RS_Vector angleVector(angle);
+    RS_Dimension::rotate(center, angleVector);
+
+    edata.extensionPoint1.rotate(center, angleVector);
+    edata.extensionPoint2.rotate(center, angleVector);
+    edata.angle = RS_Math::correctAngle(edata.angle+angle);
+    update();
+}
+
+
+void RS_DimLinear::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_Dimension::rotate(center, angleVector);
+
+    edata.extensionPoint1.rotate(center, angleVector);
+    edata.extensionPoint2.rotate(center, angleVector);
+    edata.angle = RS_Math::correctAngle(edata.angle+angleVector.angle());
+    update();
+}
+
+
+
+void RS_DimLinear::scale(const RS_Vector& center, const RS_Vector& factor) {
+    RS_Dimension::scale(center, factor);
+
+    edata.extensionPoint1.scale(center, factor);
+    edata.extensionPoint2.scale(center, factor);
+    update();
+}
+
+
+
+void RS_DimLinear::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    RS_Dimension::mirror(axisPoint1, axisPoint2);
+
+    edata.extensionPoint1.mirror(axisPoint1, axisPoint2);
+    edata.extensionPoint2.mirror(axisPoint1, axisPoint2);
+
+    RS_Vector vec;
+    vec.setPolar(1.0, edata.angle);
+    vec.mirror(RS_Vector(0.0,0.0), axisPoint2-axisPoint1);
+    edata.angle = vec.angle();
+
+    update();
+}
+
+
+
+void RS_DimLinear::stretch(const RS_Vector& firstCorner,
+                           const RS_Vector& secondCorner,
+                           const RS_Vector& offset) {
+
+    //e->calculateBorders();
+    if (getMin().isInWindow(firstCorner, secondCorner) &&
+            getMax().isInWindow(firstCorner, secondCorner)) {
+
+        move(offset);
+    } else {
+        //RS_Vector v = data.definitionPoint - edata.extensionPoint2;
+        //double len = edata.extensionPoint2.distanceTo(data.definitionPoint);
+        //double ang1 = edata.extensionPoint1.angleTo(edata.extensionPoint2)
+		//              + M_PI_2;
+
+        if (edata.extensionPoint1.isInWindow(firstCorner,
+                                            secondCorner)) {
+            edata.extensionPoint1.move(offset);
+        }
+        if (edata.extensionPoint2.isInWindow(firstCorner,
+                                            secondCorner)) {
+            edata.extensionPoint2.move(offset);
+        }
+
+                /*
+        double ang2 = edata.extensionPoint1.angleTo(edata.extensionPoint2)
+					  + M_PI_2;
+
+        double diff = RS_Math::getAngleDifference(ang1, ang2);
+        if (diff>M_PI) {
+            diff-=2*M_PI;
+        }
+
+		if (fabs(diff)>M_PI_2) {
+            ang2 = RS_Math::correctAngle(ang2+M_PI);
+        }
+
+        RS_Vector v;
+        v.setPolar(len, ang2);
+        data.definitionPoint = edata.extensionPoint2 + v;
+                */
+    }
+    updateDim(true);
+}
+
+
+
+void RS_DimLinear::moveRef(const RS_Vector& ref, const RS_Vector& offset) {
+
+	if (ref.distanceTo(data.definitionPoint)<1.0e-4) {
+		data.definitionPoint += offset;
+                updateDim(true);
+    }
+        else if (ref.distanceTo(data.middleOfText)<1.0e-4) {
+        data.middleOfText += offset;
+                updateDim(false);
+    }
+        else if (ref.distanceTo(edata.extensionPoint1)<1.0e-4) {
+        edata.extensionPoint1 += offset;
+                updateDim(true);
+    }
+        else if (ref.distanceTo(edata.extensionPoint2)<1.0e-4) {
+        edata.extensionPoint2 += offset;
+                updateDim(true);
+    }
+}
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_DimLinear& d) {
+    os << " DimLinear: " << d.getData() << "\n" << d.getEData() << "\n";
+    return os;
+}

lib/engine/rs_dimlinear.h

@@ -0,0 +1,137 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_DIMLINEAR_H
+#define RS_DIMLINEAR_H
+
+#include "rs_dimension.h"
+
+/**
+ * Holds the data that defines a linear dimension entity.
+ */
+struct RS_DimLinearData {
+    /**
+	 * Default constructor
+     */
+	RS_DimLinearData();
+
+    /**
+     * Constructor with initialisation.
+     *
+     * @para extensionPoint1 Startpoint of the first extension line.
+     * @para extensionPoint2 Startpoint of the second extension line.
+     * @param angle Rotation angle in rad.
+     * @param oblique Oblique angle in rad.
+     */
+    RS_DimLinearData(const RS_Vector& extensionPoint1,
+                     const RS_Vector& extensionPoint2,
+					 double angle, double oblique);
+
+    /** Definition point. Startpoint of the first definition line. */
+    RS_Vector extensionPoint1;
+    /** Definition point. Startpoint of the second definition line. */
+    RS_Vector extensionPoint2;
+    /** Rotation angle in rad. */
+    double angle;
+    /** Oblique angle in rad. */
+    double oblique;
+};
+
+std::ostream& operator << (std::ostream& os,
+									  const RS_DimLinearData& dd);
+
+/**
+ * Class for aligned dimension entities.
+ *
+ * @author Andrew Mustun
+ */
+class RS_DimLinear : public RS_Dimension {
+public:
+    RS_DimLinear(RS_EntityContainer* parent,
+                 const RS_DimensionData& d,
+                 const RS_DimLinearData& ed);
+	virtual ~RS_DimLinear() = default;
+
+	virtual RS_Entity* clone() const;
+
+    /**	@return RS2::EntityDimLinear */
+    virtual RS2::EntityType rtti() const {
+        return RS2::EntityDimLinear;
+    }
+
+    /**
+     * @return Copy of data that defines the linear dimension.
+     * @see getData()
+     */
+    RS_DimLinearData getEData() const {
+        return edata;
+    }
+
+	virtual RS_VectorSolutions getRefPoints() const;
+
+    virtual QString getMeasuredLabel();
+
+    virtual void updateDim(bool autoText=false);
+
+	RS_Vector getExtensionPoint1() const{
+        return edata.extensionPoint1;
+    }
+
+	RS_Vector getExtensionPoint2() const{
+        return edata.extensionPoint2;
+    }
+
+	double getAngle() const{
+        return edata.angle;
+    }
+
+	void setAngle(double a);
+
+	double getOblique() const{
+        return edata.oblique;
+    }
+
+    virtual void move(const RS_Vector& offset);
+    virtual void rotate(const RS_Vector& center, const double& angle);
+    virtual void rotate(const RS_Vector& center, const RS_Vector& angleVector);
+    virtual void scale(const RS_Vector& center, const RS_Vector& factor);
+    virtual void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2);
+    virtual bool hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2);
+    virtual void stretch(const RS_Vector& firstCorner,
+                         const RS_Vector& secondCorner,
+                         const RS_Vector& offset);
+    virtual void moveRef(const RS_Vector& ref, const RS_Vector& offset);
+
+    friend std::ostream& operator << (std::ostream& os,
+                                      const RS_DimLinear& d);
+
+protected:
+    /** Extended data. */
+    RS_DimLinearData edata;
+};
+
+#endif

lib/engine/rs_dimradial.cpp

@@ -0,0 +1,318 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include <iostream>
+#include <cmath>
+#include "rs_dimradial.h"
+#include "rs_line.h"
+#include "rs_mtext.h"
+#include "rs_solid.h"
+#include "rs_graphic.h"
+#include "rs_debug.h"
+
+RS_DimRadialData::RS_DimRadialData():
+	definitionPoint(false),
+	leader(0.0)
+{}
+
+/**
+ * Constructor with initialisation.
+ *
+ * @param definitionPoint Definition point of the radial dimension.
+ * @param leader Leader length.
+ */
+RS_DimRadialData::RS_DimRadialData(const RS_Vector& _definitionPoint,
+				 double _leader):
+	definitionPoint(_definitionPoint)
+	,leader(_leader)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+								  const RS_DimRadialData& dd) {
+	os << "(" << dd.definitionPoint << "/" << dd.leader << ")";
+	return os;
+}
+
+/**
+ * Constructor.
+ *
+ * @para parent Parent Entity Container.
+ * @para d Common dimension geometrical data.
+ * @para ed Extended geometrical data for radial dimension.
+ */
+RS_DimRadial::RS_DimRadial(RS_EntityContainer* parent,
+                           const RS_DimensionData& d,
+                           const RS_DimRadialData& ed)
+        : RS_Dimension(parent, d), edata(ed) {}
+
+RS_Entity* RS_DimRadial::clone() const {
+	RS_DimRadial* d = new RS_DimRadial(*this);
+	d->setOwner(isOwner());
+	d->initId();
+	d->detach();
+	return d;
+}
+
+
+/**
+ * @return Automatically created label for the default
+ * measurement of this dimension.
+ */
+QString RS_DimRadial::getMeasuredLabel() {
+
+    // Definitive dimension line:
+	double dist = data.definitionPoint.distanceTo(edata.definitionPoint) * getGeneralFactor();
+
+    RS_Graphic* graphic = getGraphic();
+
+    QString ret;
+    if (graphic) {
+        int dimlunit = getGraphicVariableInt("$DIMLUNIT", 2);
+        int dimdec = getGraphicVariableInt("$DIMDEC", 4);
+        int dimzin = getGraphicVariableInt("$DIMZIN", 1);
+        RS2::LinearFormat format = graphic->getLinearFormat(dimlunit);
+        ret = RS_Units::formatLinear(dist, RS2::None, format, dimdec);
+        if (format == RS2::Decimal)
+            ret = stripZerosLinear(ret, dimzin);
+        //verify if units are decimal and comma separator
+        if (format == RS2::Decimal || format == RS2::ArchitecturalMetric){
+            if (getGraphicVariableInt("$DIMDSEP", 0) == 44)
+                ret.replace(QChar('.'), QChar(','));
+        }
+    } else {
+        ret = QString("%1").arg(dist);
+    }
+
+    return ret;
+}
+
+
+RS_VectorSolutions RS_DimRadial::getRefPoints() const
+{
+		return RS_VectorSolutions({edata.definitionPoint,
+												data.definitionPoint, data.middleOfText});
+}
+
+
+/**
+ * Updates the sub entities of this dimension. Called when the
+ * dimension or the position, alignment, .. changes.
+ *
+ * @param autoText Automatically reposition the text label
+ */
+void RS_DimRadial::updateDim(bool autoText) {
+
+    RS_DEBUG->print("RS_DimRadial::update");
+
+    clear();
+
+    if (isUndone()) {
+        return;
+    }
+
+    // general scale (DIMSCALE)
+    double dimscale = getGeneralScale();
+
+	RS_Vector p1 = data.definitionPoint;
+    RS_Vector p2 = edata.definitionPoint;
+    double angle = p1.angleTo(p2);
+
+    // text height (DIMTXT)
+    double dimtxt = getTextHeight()*dimscale;
+
+    RS_Pen pen(getDimensionLineColor(),
+           getDimensionLineWidth(),
+           RS2::LineByBlock);
+
+    RS_MTextData textData;
+
+    textData = RS_MTextData(RS_Vector(0.0,0.0),
+                           dimtxt, 30.0,
+                           RS_MTextData::VAMiddle,
+                           RS_MTextData::HACenter,
+                           RS_MTextData::LeftToRight,
+                           RS_MTextData::Exact,
+                           1.0,
+                           getLabel(),
+                           getTextStyle(),
+                           0.0);
+
+    RS_MText* text = new RS_MText(this, textData);
+    double textWidth = text->getSize().x;
+
+    double tick_size = getTickSize()*dimscale;
+    double arrow_size = getArrowSize()*dimscale;
+    double length = p1.distanceTo(p2); // line length
+
+    bool outsideArrow = false;
+
+    if (tick_size == 0 && arrow_size != 0)
+    {
+        // do we have to put the arrow / text outside of the arc?
+        outsideArrow = (length < arrow_size*2+textWidth);
+        double arrowAngle;
+
+        if (outsideArrow) {
+            length += arrow_size*2 + textWidth;
+            arrowAngle = angle+M_PI;
+        } else {
+            arrowAngle = angle;
+        }
+
+        // create arrow:
+        RS_SolidData sd;
+        RS_Solid* arrow;
+
+        arrow = new RS_Solid(this, sd);
+        arrow->shapeArrow(p2, arrowAngle, arrow_size);
+        arrow->setPen(pen);
+        arrow->setLayer(nullptr);
+        addEntity(arrow);
+    }
+
+	RS_Vector p3 = RS_Vector::polar(length, angle);
+    p3 += p1;
+
+    // Create dimension line:
+	RS_Line* dimensionLine = new RS_Line{this, p1, p3};
+    dimensionLine->setPen(pen);
+	dimensionLine->setLayer(nullptr);
+    addEntity(dimensionLine);
+
+    RS_Vector distV;
+    double textAngle;
+
+    // text distance to line (DIMGAP)
+    double dimgap = getDimensionLineGap()*dimscale;
+
+    // rotate text so it's readable from the bottom or right (ISO)
+    // quadrant 1 & 4
+    if (angle > M_PI_2*3.0+0.001 || angle < M_PI_2+0.001)
+    {
+		distV.setPolar(dimgap + dimtxt/2.0, angle+M_PI_2);
+        textAngle = angle;
+    }
+    // quadrant 2 & 3
+    else
+    {
+		distV.setPolar(dimgap + dimtxt/2.0, angle-M_PI_2);
+        textAngle = angle+M_PI;
+    }
+
+    // move text label:
+    RS_Vector textPos;
+
+    if (data.middleOfText.valid && !autoText) {
+        textPos = data.middleOfText;
+    } else {
+        if (outsideArrow) {
+            textPos.setPolar(length-textWidth/2.0-arrow_size, angle);
+        } else {
+            textPos.setPolar(length/2.0, angle);
+        }
+        textPos += p1;
+        // move text away from dimension line:
+        textPos += distV;
+        data.middleOfText = textPos;
+    }
+
+	text->rotate({0., 0.}, textAngle);
+    text->move(textPos);
+
+    text->setPen(RS_Pen(getTextColor(), RS2::WidthByBlock, RS2::SolidLine));
+	text->setLayer(nullptr);
+    addEntity(text);
+
+    calculateBorders();
+}
+
+
+
+void RS_DimRadial::move(const RS_Vector& offset) {
+    RS_Dimension::move(offset);
+
+    edata.definitionPoint.move(offset);
+    update();
+}
+
+
+
+void RS_DimRadial::rotate(const RS_Vector& center, const double& angle) {
+    rotate(center,RS_Vector(angle));
+}
+
+
+void RS_DimRadial::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_Dimension::rotate(center, angleVector);
+
+    edata.definitionPoint.rotate(center, angleVector);
+    update();
+}
+
+
+
+void RS_DimRadial::scale(const RS_Vector& center, const RS_Vector& factor) {
+    RS_Dimension::scale(center, factor);
+
+    edata.definitionPoint.scale(center, factor);
+    edata.leader*=factor.x;
+    update();
+}
+
+
+
+void RS_DimRadial::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    RS_Dimension::mirror(axisPoint1, axisPoint2);
+
+    edata.definitionPoint.mirror(axisPoint1, axisPoint2);
+    update();
+}
+
+
+void RS_DimRadial::moveRef(const RS_Vector& ref, const RS_Vector& offset) {
+
+    if (ref.distanceTo(edata.definitionPoint)<1.0e-4) {
+				double d = data.definitionPoint.distanceTo(edata.definitionPoint);
+				double a = data.definitionPoint.angleTo(edata.definitionPoint + offset);
+
+				RS_Vector v = RS_Vector::polar(d, a);
+		edata.definitionPoint = data.definitionPoint + v;
+                updateDim(true);
+    }
+        else if (ref.distanceTo(data.middleOfText)<1.0e-4) {
+        data.middleOfText.move(offset);
+                updateDim(false);
+    }
+}
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_DimRadial& d) {
+    os << " DimRadial: " << d.getData() << "\n" << d.getEData() << "\n";
+    return os;
+}

lib/engine/rs_dimradial.h

@@ -0,0 +1,114 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_DIMRADIAL_H
+#define RS_DIMRADIAL_H
+
+#include "rs_dimension.h"
+
+/**
+ * Holds the data that defines a radial dimension entity.
+ */
+struct RS_DimRadialData {
+    /**
+     * Default constructor. Leaves the data object uninitialized.
+     */
+	RS_DimRadialData();
+
+    /**
+     * Constructor with initialisation.
+     *
+     * @param definitionPoint Definition point of the radial dimension.
+     * @param leader Leader length.
+     */
+    RS_DimRadialData(const RS_Vector& definitionPoint,
+					 double leader);
+
+    /** Definition point. */
+    RS_Vector definitionPoint;
+    /** Leader length. */
+    double leader;
+};
+
+std::ostream& operator << (std::ostream& os,
+									  const RS_DimRadialData& dd);
+
+/**
+ * Class for radial dimension entities.
+ *
+ * @author Andrew Mustun
+ */
+class RS_DimRadial : public RS_Dimension {
+public:
+    RS_DimRadial(RS_EntityContainer* parent,
+                 const RS_DimensionData& d,
+                 const RS_DimRadialData& ed);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityDimRadial */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityDimRadial;
+    }
+
+    /**
+     * @return Copy of data that defines the radial dimension.
+     * @see getData()
+     */
+    RS_DimRadialData getEData() const {
+        return edata;
+    }
+
+	RS_VectorSolutions getRefPoints() const override;
+
+	QString getMeasuredLabel() override;
+
+	void updateDim(bool autoText=false) override;
+
+    RS_Vector getDefinitionPoint() {
+        return edata.definitionPoint;
+    }
+    double getLeader() {
+        return edata.leader;
+    }
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+
+    friend std::ostream& operator << (std::ostream& os,
+                                      const RS_DimRadial& d);
+
+protected:
+    /** Extended data. */
+    RS_DimRadialData edata;
+};
+
+#endif

lib/engine/rs_document.cpp

@@ -0,0 +1,65 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2018 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include "rs_document.h"
+#include "rs_debug.h"
+
+
+/**
+ * Constructor.
+ *
+ * @param parent Parent of the document. Often that's NULL but
+ *        for blocks it's the blocklist.
+ */
+RS_Document::RS_Document(RS_EntityContainer* parent)
+        : RS_EntityContainer(parent), RS_Undo() {
+
+    RS_DEBUG->print("RS_Document::RS_Document() ");
+
+    filename = "";
+    autosaveFilename = "Unnamed";
+	formatType = RS2::FormatUnknown;
+    setModified(false);
+    RS_Color col(RS2::FlagByLayer);
+    activePen = RS_Pen(col, RS2::WidthByLayer, RS2::LineByLayer);
+
+    gv = NULL;//used to read/save current view
+}
+
+/**
+ * Overwritten to set modified flag when undo cycle finished with undoable(s).
+ */
+void RS_Document::endUndoCycle()
+{
+    if (hasUndoable()) {
+        setModified(true);
+    }
+
+    RS_Undo::endUndoCycle();
+}
+

lib/engine/rs_document.h

@@ -0,0 +1,155 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2018 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_DOCUMENT_H
+#define RS_DOCUMENT_H
+
+#include "rs_layerlist.h"
+#include "rs_entitycontainer.h"
+#include "rs_undo.h"
+
+class RS_BlockList;
+
+/**
+ * Base class for documents. Documents can be either graphics or
+ * blocks and are typically shown in graphic views. Documents hold
+ * an active pen for drawing in the Document, a file name and they
+ * know whether they have been modified or not.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Document : public RS_EntityContainer,
+    public RS_Undo {
+public:
+	RS_Document(RS_EntityContainer* parent=nullptr);
+	virtual ~RS_Document() = default;
+
+    virtual RS_LayerList* getLayerList() = 0;
+    virtual RS_BlockList* getBlockList() = 0;
+
+    virtual void newDoc() = 0;
+    virtual bool save(bool isAutoSave = false) = 0;
+    virtual bool saveAs(const QString &filename, RS2::FormatType type, bool force) = 0;
+    virtual bool open(const QString &filename, RS2::FormatType type) = 0;
+    virtual bool loadTemplate(const QString &filename, RS2::FormatType type) = 0;
+
+
+    /**
+     * @return true for all document entities (e.g. Graphics or Blocks).
+     */
+    virtual bool isDocument() const {
+        return true;
+    }
+
+    /**
+     * Removes an entity from the entity container. Implementation
+     * from RS_Undo.
+     */
+    virtual void removeUndoable(RS_Undoable* u) {
+        if (u && u->undoRtti()==RS2::UndoableEntity && u->isUndone()) {
+			removeEntity(static_cast<RS_Entity*>(u));
+        }
+    }
+
+    /**
+     * @return Currently active drawing pen.
+     */
+    RS_Pen getActivePen() const {
+        return activePen;
+    }
+
+    /**
+     * Sets the currently active drawing pen to p.
+     */
+    void setActivePen(RS_Pen p) {
+        activePen = p;
+    }
+
+    /**
+     * @return File name of the document currently loaded.
+     * Note, that the default file name is empty.
+     */
+    QString getFilename() const {
+        return filename;
+    }
+
+    /**
+     * @return Auto-save file name of the document currently loaded.
+     */
+    QString getAutoSaveFilename() const {
+        return autosaveFilename;
+    }
+
+    /**
+     * Sets file name for the document currently loaded.
+     */
+    void setFilename(const QString& fn) {
+        filename = fn;
+    }
+
+	/**
+	 * Sets the documents modified status to 'm'.
+	 */
+	virtual void setModified(bool m) {
+		//std::cout << "RS_Document::setModified: %d" << (int)m << std::endl;
+		modified = m;
+	}
+
+	/**
+	 * @retval true The document has been modified since it was last saved.
+	 * @retval false The document has not been modified since it was last saved.
+	 */
+    virtual bool isModified() const {
+        return modified;
+    }
+
+    /**
+     * Overwritten to set modified flag when undo cycle finished with undoable(s).
+     */
+    virtual void endUndoCycle() override;
+
+    void setGraphicView(RS_GraphicView * g) {gv = g;}
+    RS_GraphicView* getGraphicView() {return gv;}
+
+protected:
+    /** Flag set if the document was modified and not yet saved. */
+    bool modified;
+    /** Active pen. */
+    RS_Pen activePen;
+    /** File name of the document or empty for a new document. */
+    QString filename;
+	/** Auto-save file name of document. */
+        QString autosaveFilename;
+	/** Format type */
+	RS2::FormatType formatType;
+    RS_GraphicView * gv;//used to read/save current view
+
+};
+
+
+#endif

lib/engine/rs_ellipse.h

@@ -0,0 +1,247 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2011-2015 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_ELLIPSE_H
+#define RS_ELLIPSE_H
+
+#include "rs_atomicentity.h"
+
+class LC_Quadratic;
+
+/**
+ * Holds the data that defines an ellipse.
+ * angle1=angle2=0.0 is reserved for whole ellipses
+ * add 2*M_PI to angle1 or angle2 to make whole range ellipse arcs
+ */
+struct RS_EllipseData {
+    //! Ellipse center
+    RS_Vector center;
+    //! Endpoint of major axis relative to center.
+    RS_Vector majorP;
+    //! Ratio of minor axis to major axis.
+	double ratio;
+    //! Start angle
+	double angle1;
+    //! End angle
+	double angle2;
+    //! Reversed (cw) flag
+	bool reversed;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_EllipseData& ed);
+
+/**
+ * Class for an ellipse entity. All angles are in Rad.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Ellipse : public RS_AtomicEntity {
+public:
+	RS_Ellipse()=default;
+	RS_Ellipse(RS_EntityContainer* parent, const RS_EllipseData& d);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityEllipse */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityEllipse;
+    }
+
+    /**
+     * @return Start point of the entity.
+     */
+	RS_Vector getStartpoint() const override;
+	RS_VectorSolutions getFoci() const;
+
+    /**
+     * @return End point of the entity.
+     */
+	RS_Vector getEndpoint() const override;
+	RS_Vector getEllipsePoint(const double& a) const; //find the point according to ellipse angle
+
+	void moveStartpoint(const RS_Vector& pos) override;
+	void moveEndpoint(const RS_Vector& pos) override;
+	double getLength() const override;
+
+    /**
+    //Ellipse must have ratio<1, and not reversed
+    *@ x1, ellipse angle
+    *@ x2, ellipse angle
+    //@return the arc length between ellipse angle x1, x2
+    **/
+    double getEllipseLength(double a1, double a2) const;
+	double getEllipseLength(double a2) const;
+	RS_VectorSolutions getTangentPoint(const RS_Vector& point) const override;//find the tangential points seeing from given point
+	RS_Vector getTangentDirection(const RS_Vector& point)const override;
+	RS2::Ending getTrimPoint(const RS_Vector& trimCoord,
+									 const RS_Vector& trimPoint) override;
+
+	RS_Vector prepareTrim(const RS_Vector& trimCoord,
+								  const RS_VectorSolutions& trimSol) override;
+
+    double getEllipseAngle (const RS_Vector& pos) const;
+
+    /** @return Copy of data that defines the ellipse. **/
+	const RS_EllipseData& getData() const;
+
+	RS_VectorSolutions getRefPoints() const override;
+
+    /**
+     * @retval true if the arc is reversed (clockwise),
+     * @retval false otherwise
+     */
+	bool isReversed() const;
+    /** sets the reversed status. */
+	void setReversed(bool r);
+
+    /** @return The rotation angle of this ellipse */
+	double getAngle() const;
+
+    /** @return The start angle of this arc */
+	double getAngle1() const;
+    /** Sets new start angle. */
+	void setAngle1(double a1);
+    /** @return The end angle of this arc */
+	double getAngle2() const;
+    /** Sets new end angle. */
+	void setAngle2(double a2);
+
+
+    /** @return The center point (x) of this arc */
+	RS_Vector getCenter() const override;
+    /** Sets new center. */
+	void setCenter(const RS_Vector& c);
+
+    /** @return The endpoint of the major axis (relative to center). */
+	const RS_Vector& getMajorP() const;
+    /** Sets new major point (relative to center). */
+	void setMajorP(const RS_Vector& p);
+
+    /** @return The ratio of minor to major axis */
+	double getRatio() const;
+    /** Sets new ratio. */
+	void setRatio(double r);
+
+    /**
+     * @return Angle length in rad.
+     */
+	double getAngleLength() const;
+
+    /** @return The major radius of this ellipse. Same as getRadius() */
+	double getMajorRadius() const;
+
+    /** @return the point by major minor radius directions */
+	RS_Vector getMajorPoint() const;
+	RS_Vector getMinorPoint() const;
+
+    /** @return The minor radius of this ellipse */
+	double getMinorRadius() const;
+	//! \brief isEllipticArc the ellipse an Arc, if angle1/angle2 are not both 0
+	bool isEllipticArc() const;
+	bool isEdge() const override{
+        return true;
+    }
+    bool createFrom4P(const RS_VectorSolutions& sol);
+    bool createFromCenter3Points(const RS_VectorSolutions& sol);
+	//! \{ \brief from quadratic form
+	/** : dn[0] x^2 + dn[1] xy + dn[2] y^2 =1 */
+	bool createFromQuadratic(const std::vector<double>& dn);
+	/** : generic quadratic: A x^2 + C xy + B y^2 + D x + E y + F =0 */
+	bool createFromQuadratic(const LC_Quadratic& q);
+	//! \}
+	bool createInscribeQuadrilateral(const std::vector<RS_Line*>& lines);
+	RS_Vector getMiddlePoint(void)const override;
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist = nullptr) const override;
+	RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+			bool onEntity = true, double* dist = nullptr, RS_Entity** entity=nullptr) const override;
+	RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = nullptr)const override;
+	RS_Vector getNearestMiddle(const RS_Vector& coord,
+									   double* dist = nullptr,
+                                       int middlePoints = 1
+									   )const override;
+	RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = nullptr)const override;
+	RS_Vector getNearestOrthTan(const RS_Vector& coord,
+                                    const RS_Line& normal,
+									 bool onEntity = false) const override;
+    bool switchMajorMinor(void); //switch major minor axes to keep major the longer ellipse radius
+	void correctAngles();//make sure angleLength() is not more than 2*M_PI
+	bool isPointOnEntity(const RS_Vector& coord,
+								 double tolerance=RS_TOLERANCE) const override;
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const double& angle);
+	void rotate(const RS_Vector& angleVector);
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angle) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+
+    /** whether the entity's bounding box intersects with visible portion of graphic view
+    */
+	bool isVisibleInWindow(RS_GraphicView* view) const override;
+	//! \{ \brief find visible segments of entity and draw only those visible portion
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+	void drawVisible(RS_Painter* painter, RS_GraphicView* view, double& patternOffset);
+	//! \}
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Ellipse& a);
+
+	//void calculateEndpoints() override;
+	void calculateBorders() override;
+
+    //direction of tangent at endpoints
+	double getDirection1() const override;
+	double getDirection2() const override;
+
+	/** \brief return the equation of the entity
+	a quadratic contains coefficients for quadratic:
+    m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+    for linear:
+    m0 x + m1 y + m2 =0
+    **/
+	LC_Quadratic getQuadratic() const override;
+	/**
+ * @brief areaLineIntegral, line integral for contour area calculation by Green's Theorem
+ * Contour Area =\oint x dy
+ * @return line integral \oint x dy along the entity
+ * \oint x dy = Cx y + \frac{1}{4}((a^{2}+b^{2})sin(2a)cos^{2}(t)-ab(2sin^{2}(a)sin(2t)-2t-sin(2t)))
+ */
+	double areaLineIntegral() const override;
+
+protected:
+    RS_EllipseData data;
+};
+
+#endif
+//EOF

lib/engine/rs_entity.h

@@ -0,0 +1,585 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_ENTITY_H
+#define RS_ENTITY_H
+
+#include <map>
+#include "rs_vector.h"
+#include "rs_pen.h"
+#include "rs_undoable.h"
+
+class RS_Arc;
+class RS_Block;
+class RS_Circle;
+class RS_Document;
+class RS_EntityContainer;
+class RS_Graphic;
+class RS_GraphicView;
+class RS_Insert;
+class RS_Line;
+class RS_Painter;
+class RS_Point;
+class RS_Polyline;
+class RS_Text;
+class RS_Layer;
+class LC_Quadratic;
+class RS_Vector;
+class RS_VectorSolutions;
+class QString;
+
+/**
+ * Base class for an entity (line, arc, circle, ...)
+ *
+ * @author Andrew Mustun
+ */
+class RS_Entity : public RS_Undoable {
+public:
+	RS_Entity(RS_EntityContainer* parent=nullptr);
+	virtual ~RS_Entity() = default;
+
+    void init();
+    virtual void initId();
+
+	virtual RS_Entity* clone() const = 0;
+
+	virtual void reparent(RS_EntityContainer* parent) {
+		this->parent = parent;
+	}
+
+    void resetBorders();
+	void moveBorders(const RS_Vector& offset);
+	void scaleBorders(const RS_Vector& center, const RS_Vector& factor);
+    /**
+     * Must be overwritten to return the rtti of this entity
+     * (e.g. RS2::EntityArc).
+     */
+	virtual RS2::EntityType rtti() const{
+		return RS2::EntityUnknown;
+	}
+
+    /**
+     * Identify all entities as undoable entities.
+     * @return RS2::UndoableEntity
+     */
+	virtual RS2::UndoableType undoRtti() const override {
+        return RS2::UndoableEntity;
+    }
+
+    /**
+     * @return Unique Id of this entity.
+     */
+    unsigned long int getId() const {
+        return id;
+    }
+
+    /**
+     * This method must be overwritten in subclasses and return the
+     * number of <b>atomic</b> entities in this entity.
+     */
+	virtual unsigned int count() const= 0;
+
+    /**
+     * This method must be overwritten in subclasses and return the
+     * number of <b>atomic</b> entities in this entity including sub containers.
+     */
+	virtual unsigned int countDeep() const= 0;
+
+
+    /**
+         * Implementations must return the total length of the entity
+         * or a negative number if the entity has no length (e.g. a text or hatch).
+         */
+    virtual double getLength() const {
+        return -1.0;
+    }
+
+    /**
+	 * @return Parent of this entity or nullptr if this is a root entity.
+     */
+    RS_EntityContainer* getParent() const {
+        return parent;
+    }
+
+    /**
+     * Reparents this entity.
+     */
+    void setParent(RS_EntityContainer* p) {
+        parent = p;
+    }
+    /** @return The center point (x) of this arc */
+    //get center for entities: arc, circle and ellipse
+	virtual RS_Vector getCenter() const;
+	virtual double getRadius() const;
+	RS_Graphic* getGraphic() const;
+	RS_Block* getBlock() const;
+	RS_Insert* getInsert() const;
+	RS_Entity* getBlockOrInsert() const;
+	RS_Document* getDocument() const;
+
+    void setLayer(const QString& name);
+    void setLayer(RS_Layer* l);
+    void setLayerToActive();
+    RS_Layer* getLayer(bool resolve = true) const;
+
+    /**
+     * Sets the explicit pen for this entity or a pen with special
+     * attributes such as BY_LAYER, ..
+     */
+    void setPen(const RS_Pen& pen) {
+        this->pen = pen;
+    }
+
+
+    void setPenToActive();
+    RS_Pen getPen(bool resolve = true) const;
+
+    /**
+     * Must be overwritten to return true if an entity type
+     * is a container for other entities (e.g. polyline, group, ...).
+     */
+    virtual bool isContainer() const = 0;
+
+    /**
+     * Must be overwritten to return true if an entity type
+     * is an atomic entity.
+     */
+    virtual bool isAtomic() const = 0;
+
+    /**
+     * Must be overwritten to return true if an entity type
+     * is a potential edge entity of a contour. By default
+    * this returns false.
+     */
+    virtual bool isEdge() const {
+        return false;
+    }
+
+    /**
+     * @return true for all document entities (e.g. Graphics or Blocks).
+     * false otherwise.
+     */
+    virtual bool isDocument() const {
+        return false;
+    }
+
+    virtual bool setSelected(bool select);
+    virtual bool toggleSelected();
+    virtual bool isSelected() const;
+	bool isParentSelected() const;
+    virtual bool isProcessed() const;
+    virtual void setProcessed(bool on);
+	bool isInWindow(RS_Vector v1, RS_Vector v2) const;
+    virtual bool hasEndpointsWithinWindow(const RS_Vector& /*v1*/, const RS_Vector& /*v2*/) {
+        return false;
+    }
+	virtual bool isVisible() const;
+	virtual void setVisible(bool v);
+    virtual void setHighlighted(bool on);
+	virtual bool isHighlighted() const;
+
+	bool isLocked() const;
+
+	void undoStateChanged(bool undone) override;
+    virtual bool isUndone() const;
+
+    /**
+     * Can be implemented by child classes to update the entities
+     * temporary subentities. update() is called if the entity's
+     * parameters or undo state changed.
+     */
+    virtual void update() {}
+
+    virtual void setUpdateEnabled(bool on) {
+        updateEnabled = on;
+    }
+
+    /**
+     * This method doesn't do any calculations.
+     * @return minimum coordinate of the entity.
+     * @see calculateBorders()
+     */
+    RS_Vector getMin() const {
+        return minV;
+    }
+
+    /**
+     * This method doesn't do any calculations.
+     * @return minimum coordinate of the entity.
+     * @see calculateBorders()
+     */
+    RS_Vector getMax() const {
+        return maxV;
+    }
+
+    /**
+     * This method returns the difference of max and min returned
+     * by the above functions.
+     * @return size of the entity.
+     * @see calculateBorders()
+     * @see getMin()
+     * @see getMax()
+     */
+	RS_Vector getSize() const;
+
+    void addGraphicVariable(const QString& key, double val, int code);
+    void addGraphicVariable(const QString& key, int val, int code);
+    void addGraphicVariable(const QString& key, const QString& val, int code);
+
+    double getGraphicVariableDouble(const QString& key, double def);
+	int getGraphicVariableInt(const QString& key, int def) const;
+    QString getGraphicVariableString(const QString& key,
+									 const QString& def) const;
+	virtual RS_Vector getStartpoint() const;
+	virtual RS_Vector getEndpoint() const;
+    //find the local direction at end points, derived entities
+    // must implement this if direction is supported by the entity type
+    virtual double getDirection1() const {
+        return 0.;
+    }
+    virtual double getDirection2() const {
+        return 0.;
+    }
+
+    //find the tangential points seeing from given point
+	virtual RS_VectorSolutions getTangentPoint(const RS_Vector& /*point*/) const;
+	virtual RS_Vector getTangentDirection(const RS_Vector& /*point*/)const;
+	RS2::Unit getGraphicUnit() const;
+
+    /**
+     * Must be overwritten to get all reference points of the entity.
+     */
+	virtual RS_VectorSolutions getRefPoints() const;
+
+    /**
+     * Must be overwritten to get the closest endpoint to the
+     * given coordinate for this entity.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between 'coord' and the closest endpoint. The passed
+	 * pointer can also be nullptr in which case the distance will be
+     * lost.
+     *
+     * @return The closest endpoint.
+     */
+    virtual RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist = nullptr)const = 0;
+
+    /**
+     * Must be overwritten to get the closest coordinate to the
+    * given coordinate which is on this entity.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between \p coord and the point. The passed pointer can
+	 * also be \p nullptr in which case the distance will be lost.
+     *
+     * @return The closest coordinate.
+     */
+    virtual RS_Vector getNearestPointOnEntity(const RS_Vector& /*coord*/,
+											  bool onEntity = true, double* dist = nullptr,
+											  RS_Entity** entity = nullptr) const = 0;
+
+    /**
+     * Must be overwritten to get the (nearest) center point to the
+     * given coordinate for this entity.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between 'coord' and the closest center point. The passed
+	 * pointer can also be nullptr in which case the distance will be
+     * lost.
+     *
+     * @return The closest center point.
+     */
+    virtual RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = nullptr) const= 0;
+
+    /**
+     * Must be overwritten to get the (nearest) middle point to the
+     * given coordinate for this entity.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between 'coord' and the closest middle point. The passed
+	 * pointer can also be nullptr in which case the distance will be
+     * lost.
+     *
+     * @return The closest middle point.
+     */
+    virtual RS_Vector getMiddlePoint(void)const{
+        return RS_Vector(false);
+    }
+    virtual RS_Vector getNearestMiddle(const RS_Vector& coord,
+									   double* dist = nullptr,
+                                       int middlePoints = 1
+            ) const= 0;
+
+    /**
+     * Must be overwritten to get the nearest point with a given
+     * distance to the endpoint to the given coordinate for this entity.
+     *
+     * @param distance Distance to endpoint.
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between 'coord' and the closest point. The passed
+	 * pointer can also be nullptr in which case the distance will be
+     * lost.
+     *
+     * @return The closest point with the given distance to the endpoint.
+     */
+    virtual RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = nullptr) const= 0;
+
+    /**
+     * Must be overwritten to get the point with a given
+     * distance to the start- or endpoint to the given coordinate for this entity.
+     *
+     * @param distance Distance to endpoint.
+     * @param startp true = measured from Startpoint, false = measured from Endpoint
+     *
+     * @return The point with the given distance to the start- or endpoint.
+     */
+    virtual RS_Vector getNearestDist(double /*distance*/,
+									 bool /*startp*/) const{
+        return RS_Vector(false);
+    }
+
+    /**
+     * Must be overwritten to get the nearest reference point for this entity.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between 'coord' and the closest point. The passed
+	 * pointer can also be nullptr in which case the distance will be
+     * lost.
+     *
+     * @return The closest point with the given distance to the endpoint.
+     */
+    virtual RS_Vector getNearestRef(const RS_Vector& coord,
+									double* dist = nullptr) const;
+
+    /**
+     * Gets the nearest reference point of this entity if it is selected.
+         * Containers re-implement this method to return the nearest reference
+         * point of a selected sub entity.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param dist Pointer to a value which will contain the measured
+     * distance between 'coord' and the closest point. The passed
+	 * pointer can also be nullptr in which case the distance will be
+     * lost.
+     *
+     * @return The closest point with the given distance to the endpoint.
+     */
+    virtual RS_Vector getNearestSelectedRef(const RS_Vector& coord,
+											double* dist = nullptr) const;
+
+    /**
+     * Must be overwritten to get the shortest distance between this
+     * entity and a coordinate.
+     *
+     * @param coord Coordinate (typically a mouse coordinate)
+     * @param entity Pointer which will contain the (sub-)entity which is
+	 *               closest to the given point or nullptr if the caller is not
+     *               interested in this information.
+     * @param level The resolve level.
+     *
+     * @sa RS2::ResolveLevel
+     *
+     * @return The measured distance between \p coord and the entity.
+     */
+    virtual RS_Vector getNearestOrthTan(const RS_Vector& /*coord*/,
+                                        const RS_Line& /*normal*/,
+										bool onEntity = false) const;
+    virtual double getDistanceToPoint(const RS_Vector& coord,
+									  RS_Entity** entity = nullptr,
+                                      RS2::ResolveLevel level = RS2::ResolveNone,
+                                      double solidDist = RS_MAXDOUBLE) const;
+
+    virtual bool isPointOnEntity(const RS_Vector& coord,
+                                 double tolerance=20.*RS_TOLERANCE) const;
+
+    /**
+     * Implementations must offset the entity by the given direction and distance.
+     */
+    virtual bool offset(const RS_Vector& /*coord*/, const double& /*distance*/) {return false;}
+
+    /**
+     * Implementations must offset the entity by the distance at both directions
+     * used to generate tangential circles
+     */
+	virtual std::vector<RS_Entity* > offsetTwoSides(const double& /*distance*/) const
+    {
+		return std::vector<RS_Entity* >();
+    }
+    /**
+          * implementations must revert the direction of an atomic entity
+          */
+    virtual void revertDirection(){}
+    /**
+     * Implementations must move the entity by the given vector.
+     */
+    virtual void move(const RS_Vector& offset) = 0;
+
+    /**
+     * Implementations must rotate the entity by the given angle around
+     * the given center.
+     */
+    virtual void rotate(const RS_Vector& center, const double& angle) = 0;
+    virtual void rotate(const RS_Vector& center, const RS_Vector& angleVector) = 0;
+
+    /**
+     * Implementations must scale the entity by the given factors.
+     */
+    virtual void scale(const RS_Vector& center, const RS_Vector& factor) = 0;
+
+    /**
+     * Acts like scale(RS_Vector) but with equal factors.
+     * Equal to scale(center, RS_Vector(factor, factor)).
+     */
+    virtual void scale(const RS_Vector& center, const double& factor) {
+        scale(center, RS_Vector(factor, factor));
+    }
+    virtual void scale(const RS_Vector& factor) {
+        scale(RS_Vector(0.,0.), factor);
+    }
+    /**
+     * Implementations must mirror the entity by the given axis.
+     */
+    virtual void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) = 0;
+
+    virtual void stretch(const RS_Vector& firstCorner,
+                         const RS_Vector& secondCorner,
+                         const RS_Vector& offset);
+
+    /**
+         * Implementations must drag the reference point(s) of all
+         * (sub-)entities that are very close to ref by offset.
+         */
+    virtual void moveRef(const RS_Vector& /*ref*/,
+                         const RS_Vector& /*offset*/) {
+        return;
+    }
+
+    /**
+         * Implementations must drag the reference point(s) of selected
+         * (sub-)entities that are very close to ref by offset.
+         */
+    virtual void moveSelectedRef(const RS_Vector& /*ref*/,
+                                 const RS_Vector& /*offset*/) {
+        return;
+    }
+
+
+    /** whether the entity's bounding box intersects with visible portion of graphic view */
+    virtual bool isVisibleInWindow(RS_GraphicView* view) const;
+    /**
+     * Implementations must draw the entity on the given device.
+     */
+    virtual void draw(RS_Painter* painter, RS_GraphicView* view,
+                      double& patternOffset ) = 0;
+
+    double getStyleFactor(RS_GraphicView* view);
+
+    QString getUserDefVar(const QString& key) const;
+	std::vector<QString> getAllKeys() const;
+    void setUserDefVar(QString key, QString val);
+    void delUserDefVar(QString key);
+
+    friend std::ostream& operator << (std::ostream& os, RS_Entity& e);
+
+    /** Recalculates the borders of this entity. */
+    virtual void calculateBorders() = 0;
+    /** whether the entity is on a constructionLayer */
+    //! constructionLayer contains entities of infinite length, constructionLayer doesn't show up in print
+    bool isConstruction(bool typeCheck = false) const; // ignore certain entity types for constructionLayer check
+    //! whether printing is enabled or disabled for the entity's layer
+    bool isPrint(void) const;
+    /** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+    virtual LC_Quadratic getQuadratic() const;
+    /**
+     * @brief areaLineIntegral, line integral for contour area calculation by Green's Theorem
+     * Contour Area =\oint x dy
+     * @return line integral \oint x dy along the entity
+     */
+	virtual double areaLineIntegral() const;
+
+    /**
+     * @brief trimmable, whether the entity type can be trimmed
+     * @return true, for trimmable entity types
+     * currently, trimmable types are: RS_Line, RS_Circle, RS_Arc, RS_Ellipse
+     */
+    bool trimmable() const;
+
+	/**
+	 * @brief isArc is the entity of type Arc, Circle, or Ellipse
+	 * @return true for Arc, Circle, or Ellipse
+	 */
+	virtual bool isArc() const;
+	/**
+	 * @brief isArcLine determine the entity is either Arc, Circle, or Line
+	 * @return true if entity is Arc, Circle, or Line
+	 */
+	virtual bool isArcCircleLine() const;
+
+protected:
+	//! Entity's parent entity or nullptr is this entity has no parent.
+	RS_EntityContainer* parent = nullptr;
+    //! minimum coordinates
+    RS_Vector minV;
+    //! maximum coordinates
+    RS_Vector maxV;
+
+    //! Pointer to layer
+    RS_Layer* layer;
+
+    //! Entity id
+    unsigned long int id;
+
+    //! pen (attributes) for this entity
+    RS_Pen pen;
+
+    //! auto updating enabled?
+    bool updateEnabled;
+
+private:
+	std::map<QString, QString> varList;
+};
+
+#endif

lib/engine/rs_entitycontainer.h

@@ -0,0 +1,259 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_ENTITYCONTAINER_H
+#define RS_ENTITYCONTAINER_H
+
+#include <vector>
+#include "rs_entity.h"
+
+/**
+ * Class representing a tree of entities.
+ * Typical entity containers are graphics, polylines, groups, texts, ...)
+ *
+ * @author Andrew Mustun
+ */
+class RS_EntityContainer : public RS_Entity {
+	typedef RS_Entity * value_type;
+
+public:
+
+	RS_EntityContainer(RS_EntityContainer* parent=nullptr, bool owner=true);
+    //RS_EntityContainer(const RS_EntityContainer& ec);
+	~RS_EntityContainer() override;
+
+	RS_Entity* clone() const override;
+	virtual void detach();
+
+    /** @return RS2::EntityContainer */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityContainer;
+    }
+
+	void reparent(RS_EntityContainer* parent) override;
+
+    /**
+     * @return true: because entities made from this class
+	 *         and subclasses are containers for other entities.
+     */
+	bool isContainer() const override{
+        return true;
+    }
+
+    /**
+     * @return false: because entities made from this class
+     *         and subclasses are containers for other entities.
+     */
+	bool isAtomic() const override{
+                return false;
+        }
+
+	double getLength() const override;
+
+	void setVisible(bool v) override;
+
+	bool setSelected(bool select=true) override;
+	bool toggleSelected() override;
+
+	virtual void selectWindow(RS_Vector v1, RS_Vector v2,
+				bool select=true, bool cross=false);
+
+    virtual void addEntity(RS_Entity* entity);
+    virtual void appendEntity(RS_Entity* entity);
+    virtual void prependEntity(RS_Entity* entity);
+	virtual void moveEntity(int index, QList<RS_Entity *>& entList);
+    virtual void insertEntity(int index, RS_Entity* entity);
+    virtual bool removeEntity(RS_Entity* entity);
+
+	//!
+	//! \brief addRectangle add four lines to form a rectangle by
+	//! the diagonal vertices v0,v1
+	//! \param v0,v1 diagonal vertices of the rectangle
+	//!
+	void addRectangle(RS_Vector const& v0, RS_Vector const& v1);
+
+    virtual RS_Entity* firstEntity(RS2::ResolveLevel level=RS2::ResolveNone);
+    virtual RS_Entity* lastEntity(RS2::ResolveLevel level=RS2::ResolveNone);
+    virtual RS_Entity* nextEntity(RS2::ResolveLevel level=RS2::ResolveNone);
+    virtual RS_Entity* prevEntity(RS2::ResolveLevel level=RS2::ResolveNone);
+    virtual RS_Entity* entityAt(int index);
+	virtual void setEntityAt(int index,RS_Entity* en);
+//RLZ unused	virtual int entityAt();
+		virtual int findEntity(RS_Entity const* const entity);
+    virtual void clear();
+
+    //virtual unsigned long int count() {
+        //	return count(false);
+        //}
+	virtual bool isEmpty() const{
+        return count()==0;
+	}
+	unsigned count() const override;
+	unsigned countDeep() const override;
+	//virtual unsigned long int countLayerEntities(RS_Layer* layer);
+	/** \brief countSelected number of selected
+	* @param deep count sub-containers, if true
+	* @param types if is not empty, only counts by types listed
+	*/
+	virtual unsigned countSelected(bool deep=true, std::initializer_list<RS2::EntityType> const& types = {});
+    virtual double totalSelectedLength();
+
+    /**
+     * Enables / disables automatic update of borders on entity removals
+     * and additions. By default this is turned on.
+     */
+    virtual void setAutoUpdateBorders(bool enable) {
+        autoUpdateBorders = enable;
+    }
+    virtual void adjustBorders(RS_Entity* entity);
+	void calculateBorders() override;
+	void forcedCalculateBorders();
+	void updateDimensions( bool autoText=true);
+    virtual void updateInserts();
+    virtual void updateSplines();
+	void update() override;
+	virtual void renameInserts(const QString& oldName,
+							   const QString& newName);
+
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist = nullptr)const override;
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist, RS_Entity** pEntity ) const;
+
+    RS_Entity* getNearestEntity(const RS_Vector& point,
+								double* dist = nullptr,
+								RS2::ResolveLevel level=RS2::ResolveAll) const;
+
+	RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+            bool onEntity = true,
+						double* dist = nullptr,
+			RS_Entity** entity=nullptr)const override;
+
+	RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = nullptr)const override;
+	RS_Vector getNearestMiddle(const RS_Vector& coord,
+									   double* dist = nullptr,
+                                       int middlePoints = 1
+									   )const override;
+	RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = nullptr) const override;
+	RS_Vector getNearestIntersection(const RS_Vector& coord,
+			double* dist = nullptr);
+    RS_Vector getNearestVirtualIntersection(const RS_Vector& coord,
+                                            const double& angle,
+                                            double* dist);
+	RS_Vector getNearestRef(const RS_Vector& coord,
+									 double* dist = nullptr) const override;
+	RS_Vector getNearestSelectedRef(const RS_Vector& coord,
+									 double* dist = nullptr) const override;
+
+	double getDistanceToPoint(const RS_Vector& coord,
+                                      RS_Entity** entity,
+                                      RS2::ResolveLevel level=RS2::ResolveNone,
+									  double solidDist = RS_MAXDOUBLE) const override;
+
+    virtual bool optimizeContours();
+
+	bool hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2) override;
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2a) override;
+
+	void stretch(const RS_Vector& firstCorner,
+                         const RS_Vector& secondCorner,
+						 const RS_Vector& offset) override;
+	void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+	void moveSelectedRef(const RS_Vector& ref, const RS_Vector& offset) override;
+	void revertDirection() override;
+
+
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+    friend std::ostream& operator << (std::ostream& os, RS_EntityContainer& ec);
+
+	bool isOwner() const {return autoDelete;}
+    void setOwner(bool owner) {autoDelete=owner;}
+    /**
+     * @brief areaLineIntegral, line integral for contour area calculation by Green's Theorem
+     * Contour Area =\oint x dy
+     * @return line integral \oint x dy along the entity
+     * returns absolute value
+     */
+    virtual double areaLineIntegral() const override;
+    /**
+	 * @brief ignoreForModification ignore this entity for entity catch for certain actions
+     * like catching circles to create tangent circles
+     * @return, true, indicate this entity container should be ignored
+     */
+    bool ignoredOnModification() const;
+
+	/**
+	 * @brief begin/end to support range based loop
+	 * @return iterator
+	 */
+	QList<RS_Entity *>::const_iterator begin() const;
+	QList<RS_Entity *>::const_iterator end() const;
+	QList<RS_Entity *>::iterator begin() ;
+	QList<RS_Entity *>::iterator end() ;
+	//! \{
+	//! first and last without resolving into children, assume the container is
+	//! not empty
+	RS_Entity* last() const;
+	RS_Entity* first() const;
+	//! \}
+
+    const QList<RS_Entity*>& getEntityList();
+
+protected:
+
+    /** entities in the container */
+    QList<RS_Entity *> entities;
+
+    /** sub container used only temporarily for iteration. */
+    RS_EntityContainer* subContainer;
+
+    /**
+     * Automatically update the borders of the container when entities
+     * are added or removed.
+     */
+    static bool autoUpdateBorders;
+
+private:
+	/**
+	 * @brief ignoredSnap whether snapping is ignored
+	 * @return true when entity of this container won't be considered for snapping points
+	 */
+	bool ignoredSnap() const;
+    int entIdx;
+    bool autoDelete;
+};
+
+#endif

lib/engine/rs_flags.cpp

@@ -0,0 +1,64 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 Dongxu Li (dongxuli2011@gmail.com)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include "rs_flags.h"
+
+/** Constructor with initialisation to the given flags. */
+RS_Flags::RS_Flags(unsigned f):
+	flags(f)
+{
+}
+
+
+unsigned RS_Flags::getFlags() const {
+	return flags;
+}
+
+void RS_Flags::resetFlags() {
+	flags=0;
+}
+
+void RS_Flags::setFlags(unsigned f) {
+	flags=f;
+}
+
+void RS_Flags::setFlag(unsigned f) {
+	flags |= f;
+}
+
+void RS_Flags::delFlag(unsigned f) {
+	flags &= ~f;
+}
+
+void RS_Flags::toggleFlag(unsigned f) {
+	flags ^= f;
+}
+
+bool RS_Flags::getFlag(unsigned f) const {
+	return flags&f;
+}
+

lib/engine/rs_flags.h

@@ -0,0 +1,60 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+#ifndef RS_FLAGS_H
+#define RS_FLAGS_H
+
+/**
+ * Base class for objects which have flags.
+ *
+ * @author Andrew Mustun
+ */
+struct RS_Flags {
+	//! \{Constructor with initialisation to the given flags.
+	//! Default sets all flags to 0
+	RS_Flags(unsigned f = 0);
+	//! \}
+
+	virtual ~RS_Flags() = default;
+
+	unsigned getFlags() const;
+
+	void resetFlags();
+
+	void setFlags(unsigned f);
+
+	void setFlag(unsigned f);
+
+	void delFlag(unsigned f);
+
+	void toggleFlag(unsigned f);
+
+	bool getFlag(unsigned f) const;
+
+private:
+	unsigned flags = 0;
+};
+
+#endif

lib/engine/rs_font.cpp

@@ -0,0 +1,463 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+
+#include <iostream>
+#include <QTextStream>
+#include <QTextCodec>
+
+#include "rs_font.h"
+#include "rs_arc.h"
+#include "rs_line.h"
+#include "rs_polyline.h"
+#include "rs_fontchar.h"
+#include "rs_system.h"
+#include "rs_math.h"
+#include "rs_debug.h"
+
+/**
+ * Constructor.
+ *
+ * @param owner true if the font owns the letters (blocks). Otherwise
+ *              the letters will be deleted when the font is deleted.
+ */
+RS_Font::RS_Font(const QString& fileName, bool owner)
+    :	letterList(owner), fileName(fileName), fileLicense("unknown") {
+    loaded = false;
+    letterSpacing = 3.0;
+    wordSpacing = 6.75;
+    lineSpacingFactor = 1.0;
+    rawLffFontList.clear();
+}
+
+
+
+/**
+ * Loads the font into memory.
+ *
+ * @retval true font was already loaded or is loaded now.
+ * @retval false font could not be loaded.
+ */
+bool RS_Font::loadFont() {
+    RS_DEBUG->print("RS_Font::loadFont");
+
+    if (loaded) {
+        return true;
+    }
+
+    QString path;
+
+    // Search for the appropriate font if we have only the name of the font:
+    if (!fileName.toLower().contains(".cxf") &&
+            !fileName.toLower().contains(".lff")) {
+        QStringList fonts = RS_SYSTEM->getNewFontList();
+        fonts.append(RS_SYSTEM->getFontList());
+
+        QFileInfo file;
+        for (QStringList::Iterator it = fonts.begin();
+             it!=fonts.end();
+             it++) {
+
+            if (QFileInfo(*it).baseName().toLower()==fileName.toLower()) {
+                path = *it;
+                break;
+            }
+        }
+    }
+
+    // We have the full path of the font:
+    else {
+        path = fileName;
+    }
+
+    // No font paths found:
+    if (path.isEmpty()) {
+        RS_DEBUG->print(RS_Debug::D_WARNING,
+                        "RS_Font::loadFont: No fonts available.");
+        return false;
+    }
+
+    // Open cxf file:
+    QFile f(path);
+    if (!f.open(QIODevice::ReadOnly)) {
+        RS_DEBUG->print(RS_Debug::D_WARNING,
+                        "RS_Font::loadFont: Cannot open font file: %s",
+                        path.toLatin1().data());
+        return false;
+    } else {
+        RS_DEBUG->print("RS_Font::loadFont: "
+                        "Successfully opened font file: %s",
+                        path.toLatin1().data());
+    }
+    f.close();
+
+    if (path.contains(".cxf"))
+        readCXF(path);
+    if (path.contains(".lff"))
+        readLFF(path);
+
+    RS_Block* bk = letterList.find(QChar(0xfffd));
+	if (!bk) {
+        // create new letter:
+		RS_FontChar* letter = new RS_FontChar(nullptr, QChar(0xfffd), RS_Vector(0.0, 0.0));
+        RS_Polyline* pline = new RS_Polyline(letter, RS_PolylineData());
+        pline->setPen(RS_Pen(RS2::FlagInvalid));
+		pline->setLayer(nullptr);
+        pline->addVertex(RS_Vector(1, 0), 0);
+        pline->addVertex(RS_Vector(0, 2), 0);
+        pline->addVertex(RS_Vector(1, 4), 0);
+        pline->addVertex(RS_Vector(2, 2), 0);
+        pline->addVertex(RS_Vector(1, 0), 0);
+        letter->addEntity(pline);
+        letter->calculateBorders();
+        letterList.add(letter);
+    }
+
+    loaded = true;
+
+    RS_DEBUG->print("RS_Font::loadFont OK");
+
+    return true;
+}
+
+
+void RS_Font::readCXF(QString path) {
+    QString line;
+    QFile f(path);
+    f.open(QIODevice::ReadOnly);
+    QTextStream ts(&f);
+
+    // Read line by line until we find a new letter:
+    while (!ts.atEnd()) {
+        line = ts.readLine();
+
+        if (line.isEmpty())
+            continue;
+
+        // Read font settings:
+        if (line.at(0)=='#') {
+            QStringList lst =
+                    ( line.right(line.length()-1) ).split(':', QString::SkipEmptyParts);
+            QStringList::Iterator it3 = lst.begin();
+
+            // RVT_PORT sometimes it happens that the size is < 2
+            if (lst.size()<2)
+                continue;
+
+            QString identifier = (*it3).trimmed();
+            it3++;
+            QString value = (*it3).trimmed();
+
+            if (identifier.toLower()=="letterspacing") {
+                letterSpacing = value.toDouble();
+            } else if (identifier.toLower()=="wordspacing") {
+                wordSpacing = value.toDouble();
+            } else if (identifier.toLower()=="linespacingfactor") {
+                lineSpacingFactor = value.toDouble();
+            } else if (identifier.toLower()=="author") {
+                authors.append(value);
+            } else if (identifier.toLower()=="name") {
+                names.append(value);
+            } else if (identifier.toLower()=="encoding") {
+                ts.setCodec(QTextCodec::codecForName(value.toLatin1()));
+                encoding = value;
+            }
+        }
+
+        // Add another letter to this font:
+        else if (line.at(0)=='[') {
+
+            // uniode character:
+            QChar ch;
+
+            // read unicode:
+            QRegExp regexp("[0-9A-Fa-f]{4,4}");
+            regexp.indexIn(line);
+            QString cap = regexp.cap();
+            if (!cap.isNull()) {
+				int uCode = cap.toInt(nullptr, 16);
+                ch = QChar(uCode);
+            }
+
+            // read UTF8 (LibreCAD 1 compatibility)
+            else if (line.indexOf(']')>=3) {
+                int i = line.indexOf(']');
+                QString mid = line.mid(1, i-1);
+                ch = QString::fromUtf8(mid.toLatin1()).at(0);
+            }
+
+            // read normal ascii character:
+            else {
+                ch = line.at(1);
+            }
+
+            // create new letter:
+            RS_FontChar* letter =
+					new RS_FontChar(nullptr, ch, RS_Vector(0.0, 0.0));
+
+            // Read entities of this letter:
+            QString coordsStr;
+            QStringList coords;
+            QStringList::Iterator it2;
+            do {
+                line = ts.readLine();
+
+                if (line.isEmpty()) {
+                    continue;
+                }
+
+                coordsStr = line.right(line.length()-2);
+                //                coords = QStringList::split(',', coordsStr);
+                coords = coordsStr.split(',', QString::SkipEmptyParts);
+                it2 = coords.begin();
+
+                // Line:
+                if (line.at(0)=='L') {
+                    double x1 = (*it2++).toDouble();
+                    double y1 = (*it2++).toDouble();
+                    double x2 = (*it2++).toDouble();
+                    double y2 = (*it2).toDouble();
+
+					RS_Line* line = new RS_Line{letter, {{x1, y1}, {x2, y2}}};
+                    line->setPen(RS_Pen(RS2::FlagInvalid));
+					line->setLayer(nullptr);
+                    letter->addEntity(line);
+                }
+
+                // Arc:
+                else if (line.at(0)=='A') {
+                    double cx = (*it2++).toDouble();
+                    double cy = (*it2++).toDouble();
+                    double r = (*it2++).toDouble();
+					double a1 = RS_Math::deg2rad((*it2++).toDouble());
+					double a2 = RS_Math::deg2rad((*it2).toDouble());
+                    bool reversed = (line.at(1)=='R');
+
+                    RS_ArcData ad(RS_Vector(cx,cy),
+                                  r, a1, a2, reversed);
+                    RS_Arc* arc = new RS_Arc(letter, ad);
+                    arc->setPen(RS_Pen(RS2::FlagInvalid));
+					arc->setLayer(nullptr);
+                    letter->addEntity(arc);
+                }
+            } while (!line.isEmpty());
+
+            if (letter->isEmpty()) {
+                delete letter;
+            } else {
+                letter->calculateBorders();
+                letterList.add(letter);
+            }
+        }
+    }
+    f.close();
+}
+
+void RS_Font::readLFF(QString path) {
+    QString line;
+    QFile f(path);
+    encoding = "UTF-8";
+    f.open(QIODevice::ReadOnly);
+    QTextStream ts(&f);
+
+    // Read line by line until we find a new letter:
+    while (!ts.atEnd()) {
+        line = ts.readLine();
+
+        if (line.isEmpty())
+            continue;
+
+        // Read font settings:
+        if (line.at(0)=='#') {
+            QStringList lst =line.remove(0,1).split(':', QString::SkipEmptyParts);
+            //if size is < 2 is a comentary not parameter
+            if (lst.size()<2)
+                continue;
+
+            QString identifier = lst.at(0).trimmed();
+            QString value = lst.at(1).trimmed();
+
+            if (identifier.toLower()=="letterspacing") {
+                letterSpacing = value.toDouble();
+            } else if (identifier.toLower()=="wordspacing") {
+                wordSpacing = value.toDouble();
+            } else if (identifier.toLower()=="linespacingfactor") {
+                lineSpacingFactor = value.toDouble();
+            } else if (identifier.toLower()=="author") {
+                authors.append(value);
+            } else if (identifier.toLower()=="name") {
+                names.append(value);
+            } else if (identifier.toLower()=="license") {
+                fileLicense = value;
+            } else if (identifier.toLower()=="encoding") {
+                ts.setCodec(QTextCodec::codecForName(value.toLatin1()));
+                encoding = value;
+            } else if (identifier.toLower()=="created") {
+                fileCreate = value;
+            }
+        }
+
+        // Add another letter to this font:
+        else if (line.at(0)=='[') {
+
+            // uniode character:
+            QChar ch;
+
+            // read unicode:
+            QRegExp regexp("[0-9A-Fa-f]{1,5}");
+            regexp.indexIn(line);
+            QString cap = regexp.cap();
+            if (!cap.isNull()) {
+				int uCode = cap.toInt(nullptr, 16);
+                ch = QChar(uCode);
+            }
+            // only unicode allowed
+            else {
+                RS_DEBUG->print(RS_Debug::D_WARNING,"Ignoring code from LFF font file: %s",qPrintable(line));
+                continue;
+            }
+
+            QStringList fontData;
+            do {
+                line = ts.readLine();
+                if(line.isEmpty()) break;
+                fontData.push_back(line);
+            } while(true);
+            if(fontData.size()>0) {
+                rawLffFontList[QString(ch)]=fontData;
+            }
+
+
+        }
+    }
+    f.close();
+}
+
+void RS_Font::generateAllFonts(){
+    QMap<QString, QStringList>::const_iterator i = rawLffFontList.constBegin();
+    while (i != rawLffFontList.constEnd()) {
+        generateLffFont(i.key());
+        ++i;
+    }
+}
+
+RS_Block* RS_Font::generateLffFont(const QString& ch){
+        if(rawLffFontList.contains(ch) == false ){
+                RS_DEBUG->print("RS_Font::generateLffFont(QChar %s ) : can not find the letter in given lff font file",qPrintable(ch));
+				return nullptr;
+        }
+    // create new letter:
+    RS_FontChar* letter =
+			new RS_FontChar(nullptr, ch, RS_Vector(0.0, 0.0));
+
+    // Read entities of this letter:
+    QStringList vertex;
+    QStringList coords;
+    QStringList fontData=rawLffFontList[ch];
+    QString line;
+
+    while(fontData.isEmpty() == false) {
+        line = fontData.takeFirst();
+
+        if (line.isEmpty()) {
+            continue;
+        }
+
+        // Defined char:
+        if (line.at(0)=='C') {
+            line.remove(0,1);
+			int uCode = line.toInt(nullptr, 16);
+            QChar ch = QChar(uCode);
+            RS_Block* bk = letterList.find(ch);
+			if (!bk && rawLffFontList.contains(ch)) {
+                generateLffFont(ch);
+                bk = letterList.find(ch);
+            }
+			if (bk) {
+                RS_Entity* bk2 = bk->clone();
+                bk2->setPen(RS_Pen(RS2::FlagInvalid));
+				bk2->setLayer(nullptr);
+                letter->addEntity(bk2);
+            }
+        }
+        //sequence:
+        else {
+            vertex = line.split(';', QString::SkipEmptyParts);
+            //at least is required two vertex
+            if (vertex.size()<2)
+                continue;
+            RS_Polyline* pline = new RS_Polyline(letter, RS_PolylineData());
+            pline->setPen(RS_Pen(RS2::FlagInvalid));
+			pline->setLayer(nullptr);
+            for (int i = 0; i < vertex.size(); ++i) {
+                double x1, y1;
+                double bulge = 0;
+
+                coords = vertex.at(i).split(',', QString::SkipEmptyParts);
+                //at least X,Y is required
+                if (coords.size()<2)
+                    continue;
+                x1 = coords.at(0).toDouble();
+                y1 = coords.at(1).toDouble();
+                //check presence of bulge
+                if (coords.size() == 3 && coords.at(2).at(0) == QChar('A')){
+                    QString bulgeStr = coords.at(2);
+                    bulge = bulgeStr.remove(0,1).toDouble();
+                }
+                pline->setNextBulge(bulge);
+                pline->addVertex(RS_Vector(x1, y1), bulge);
+            }
+            letter->addEntity(pline);
+        }
+
+    }
+
+    if (letter->isEmpty()) {
+        delete letter;
+			return nullptr;
+    } else {
+        letter->calculateBorders();
+        letterList.add(letter);
+        return letter;
+    }
+}
+
+RS_Block* RS_Font::findLetter(const QString& name) {
+    RS_Block* ret= letterList.find(name);
+	if (ret) return ret;
+    return generateLffFont(name);
+
+}
+/**
+ * Dumps the fonts data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Font& f) {
+    os << " Font file name: " << f.getFileName().toLatin1().data() << "\n";
+    //<< (RS_BlockList&)f << "\n";
+    return os;
+}
+

lib/engine/rs_font.h

@@ -0,0 +1,160 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_FONT_H
+#define RS_FONT_H
+
+#include <iosfwd>
+#include <QStringList>
+#include <QMap>
+#include "rs_blocklist.h"
+
+/**
+ * Class for representing a font. This is implemented as a RS_Graphic
+ * with a name (the font name) and several blocks, one for each letter
+ * in the font.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Font {
+public:
+    RS_Font(const QString& name, bool owner=true);
+    //RS_Font(const char* name);
+
+    /** @return the fileName of this font. */
+    QString getFileName() const {
+        return fileName;
+    }
+	
+    /** @return the fileLicense of this font. */
+    QString getFileLicense() const {
+        return fileLicense;
+    }
+
+    /** @return the creation date of this font. */
+    QString getFileCreate() const {
+        return fileCreate;
+    }
+
+    /** @return the encoding of this font. */
+    QString getEncoding() const {
+        return encoding;
+    }
+	
+    /** @return the alternative names of this font. */
+    const QStringList& getNames() const {
+        return names;
+    }
+	
+    /** @return the author(s) of this font. */
+    const QStringList& getAuthors() const {
+        return authors;
+    }
+
+    /** @return Default letter spacing for this font */
+    double getLetterSpacing() {
+        return letterSpacing;
+    }
+
+    /** @return Default word spacing for this font */
+    double getWordSpacing() {
+        return wordSpacing;
+    }
+
+    /** @return Default line spacing factor for this font */
+    double getLineSpacingFactor() {
+        return lineSpacingFactor;
+    }
+
+    bool loadFont();
+
+    void generateAllFonts();
+
+	// Wrappers for block list (letters) functions
+	RS_BlockList* getLetterList() {
+		return &letterList;
+	}
+    RS_Block* findLetter(const QString& name);
+//    RS_Block* findLetter(const QString& name) {
+//		return letterList.find(name);
+//	}
+    unsigned countLetters() {
+        return letterList.count();
+    }
+    RS_Block* letterAt(unsigned i) {
+		return letterList.at(i);
+	}
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Font& l);
+
+    friend class RS_FontList;
+
+private:
+    void readCXF(QString path);
+    void readLFF(QString path);
+    RS_Block* generateLffFont(const QString& ch);
+
+private:
+    //raw lff font file list, not processed into blocks yet
+    QMap<QString, QStringList> rawLffFontList;
+
+        //! block list (letters)
+        RS_BlockList letterList;
+
+    //! Font file name
+    QString fileName;
+	
+    //! Font file license
+    QString fileLicense;
+
+    //! Font file license
+    QString fileCreate;
+
+    //! Font encoding (see docu for QTextCodec)
+    QString encoding;
+
+	//! Font names
+        QStringList names;
+	
+	//! Authors
+        QStringList authors;
+
+    //! Is this font currently loaded into memory?
+    bool loaded;
+
+    //! Default letter spacing for this font
+    double letterSpacing;
+
+    //! Default word spacing for this font
+    double wordSpacing;
+
+    //! Default line spacing factor for this font
+    double lineSpacingFactor;
+};
+
+#endif
+

lib/engine/rs_fontchar.h

@@ -0,0 +1,71 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_FONTCHAR_H
+#define RS_FONTCHAR_H
+
+#include "rs_block.h"
+
+
+/**
+ * A character in a font is represented by this special block class.
+ *
+ * @author Andrew Mustun
+ */
+class RS_FontChar : public RS_Block {
+public:
+    /**
+     * @param parent The font this block belongs to.
+     * @param name The name of the letter (a unicode char) used as 
+     *        an identifier.
+     * @param basePoint Base point (offset) of the letter (usually 0/0).
+     */
+    RS_FontChar(RS_EntityContainer* parent,
+                const QString& name,
+                RS_Vector basePoint)
+            : RS_Block(parent, RS_BlockData(name, basePoint, false)) {}
+
+    virtual ~RS_FontChar() {}
+
+    /** @return RS2::EntityFontChar */
+    virtual RS2::EntityType rtti() const {
+        return RS2::EntityFontChar;
+    }
+
+
+    /*friend std::ostream& operator << (std::ostream& os, const RS_FontChar& b) {
+       	os << " name: " << b.getName().latin1() << "\n";
+    	os << " entities: " << (RS_EntityContainer&)b << "\n";
+       	return os;
+}*/
+
+
+protected:
+};
+
+
+#endif

lib/engine/rs_fontlist.cpp

@@ -0,0 +1,142 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include <iostream>
+#include <QHash>
+#include "rs_fontlist.h"
+#include "rs_debug.h"
+#include "rs_font.h"
+#include "rs_system.h"
+
+RS_FontList* RS_FontList::uniqueInstance = nullptr;
+
+RS_FontList* RS_FontList::instance() {
+	if (!uniqueInstance) {
+		uniqueInstance = new RS_FontList();
+	}
+	return uniqueInstance;
+}
+
+
+/**
+ * Initializes the font list by creating empty RS_Font 
+ * objects, one for each font that could be found.
+ */
+void RS_FontList::init() {
+    RS_DEBUG->print("RS_FontList::initFonts");
+
+    QStringList list = RS_SYSTEM->getNewFontList();
+    list.append(RS_SYSTEM->getFontList());
+    QHash<QString, int> added; //used to remember added fonts (avoid duplication)
+
+    for (int i = 0; i < list.size(); ++i) {
+        RS_DEBUG->print("font: %s:", list.at(i).toLatin1().data());
+
+        QFileInfo fi( list.at(i) );
+        if ( !added.contains(fi.baseName()) ) {
+			fonts.emplace_back(new RS_Font(fi.baseName()));
+            added.insert(fi.baseName(), 1);
+        }
+
+        RS_DEBUG->print("base: %s", fi.baseName().toLatin1().data());
+    }
+}
+
+size_t RS_FontList::countFonts() const{
+	return fonts.size();
+}
+
+std::vector<std::unique_ptr<RS_Font> >::const_iterator RS_FontList::begin() const
+{
+	return fonts.begin();
+}
+
+std::vector<std::unique_ptr<RS_Font> >::const_iterator RS_FontList::end() const
+{
+	return fonts.end();
+}
+
+/**
+ * Removes all fonts in the fontlist.
+ */
+void RS_FontList::clearFonts() {
+	fonts.clear();
+}
+
+/**
+ * @return Pointer to the font with the given name or
+ * \p NULL if no such font was found. The font will be loaded into
+ * memory if it's not already.
+ */
+RS_Font* RS_FontList::requestFont(const QString& name) {
+    RS_DEBUG->print("RS_FontList::requestFont %s",  name.toLatin1().data());
+
+    QString name2 = name.toLower();
+    RS_Font* foundFont = NULL;
+
+    // QCAD 1 compatibility:
+    if (name2.contains('#') && name2.contains('_')) {
+        name2 = name2.left(name2.indexOf('_'));
+    } else if (name2.contains('#')) {
+        name2 = name2.left(name2.indexOf('#'));
+    }
+
+    RS_DEBUG->print("name2: %s", name2.toLatin1().data());
+
+	// Search our list of available fonts:
+	for( auto const& f: fonts){
+
+        if (f->getFileName().toLower() == name2) {
+            // Make sure this font is loaded into memory:
+            f->loadFont();
+			foundFont = f.get();
+            break;
+        }
+    }
+
+	if (!foundFont && name!="standard") {
+        foundFont = requestFont("standard");
+    }
+
+    return foundFont;
+}
+
+/**
+ * Dumps the fonts to stdout.
+ */
+std::ostream& operator << (std::ostream& os, RS_FontList& l) {
+
+    os << "Fontlist: \n";
+	for(auto const& f: l.fonts){
+        os << *f << "\n";
+    }
+
+    return os;
+}
+
+
+
+

lib/engine/rs_fontlist.h

@@ -0,0 +1,70 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+#ifndef RS_FONTLIST_H
+#define RS_FONTLIST_H
+#include <memory>
+#include <vector>
+
+class RS_Font;
+
+#define RS_FONTLIST RS_FontList::instance()
+
+/**
+ * The global list of fonts. This is implemented as a singleton.
+ * Use RS_FontList::instance() to get a pointer to the object.
+ *
+ * @author Andrew Mustun
+ */
+class RS_FontList {
+
+public:
+    /**
+     * @return Instance to the unique font list.
+     */
+	static RS_FontList* instance();
+
+	virtual ~RS_FontList() = default;
+
+    void init();
+
+    void clearFonts();
+	size_t countFonts() const;
+    RS_Font* requestFont(const QString& name);
+	std::vector<std::unique_ptr<RS_Font> >::const_iterator begin() const;
+	std::vector<std::unique_ptr<RS_Font> >::const_iterator end() const;
+
+    friend std::ostream& operator << (std::ostream& os, RS_FontList& l);
+
+private:
+	RS_FontList()=default;
+	RS_FontList(RS_FontList const&)=delete;
+	RS_FontList& operator = (RS_FontList const&)=delete;
+	static RS_FontList* uniqueInstance;
+    //! fonts in the graphic
+	std::vector<std::unique_ptr<RS_Font>> fonts;
+};
+
+#endif

lib/engine/rs_graphic.h

@@ -0,0 +1,383 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_GRAPHIC_H
+#define RS_GRAPHIC_H
+
+#include <QDateTime>
+#include "rs_blocklist.h"
+#include "rs_layerlist.h"
+#include "rs_variabledict.h"
+#include "rs_document.h"
+#include "rs_units.h"
+
+class RS_VariableDict;
+class QG_LayerWidget;
+
+/**
+ * A graphic document which can contain entities layers and blocks.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Graphic : public RS_Document {
+public:
+    RS_Graphic(RS_EntityContainer* parent=NULL);
+    virtual ~RS_Graphic();
+
+    //virtual RS_Entity* clone() {
+    //	return new RS_Graphic(*this);
+    //}
+
+    /** @return RS2::EntityGraphic */
+    virtual RS2::EntityType rtti() const {
+        return RS2::EntityGraphic;
+    }
+
+    virtual unsigned long int countLayerEntities(RS_Layer* layer);
+
+    virtual RS_LayerList* getLayerList() {
+        return &layerList;
+    }
+    virtual RS_BlockList* getBlockList() {
+        return &blockList;
+    }
+
+    virtual void newDoc();
+    virtual bool save(bool isAutoSave = false);
+    virtual bool saveAs(const QString& filename, RS2::FormatType type, bool force = false);
+    virtual bool open(const QString& filename, RS2::FormatType type);
+    bool loadTemplate(const QString &filename, RS2::FormatType type);
+
+        // Wrappers for Layer functions:
+    void clearLayers() {
+        layerList.clear();
+    }
+    unsigned countLayers() const {
+        return layerList.count();
+    }
+    RS_Layer* layerAt(unsigned i) {
+        return layerList.at(i);
+    }
+    void activateLayer(const QString& name) {
+        layerList.activate(name);
+    }
+    void activateLayer(RS_Layer* layer) {
+        layerList.activate(layer);
+    }
+    RS_Layer* getActiveLayer() {
+        return layerList.getActive();
+    }
+    virtual void addLayer(RS_Layer* layer) {
+        layerList.add(layer);
+    }
+    virtual void addEntity(RS_Entity* entity);
+    virtual void removeLayer(RS_Layer* layer);
+    virtual void editLayer(RS_Layer* layer, const RS_Layer& source) {
+        layerList.edit(layer, source);
+    }
+    RS_Layer* findLayer(const QString& name) {
+        return layerList.find(name);
+    }
+    void toggleLayer(const QString& name) {
+        layerList.toggle(name);
+    }
+    void toggleLayer(RS_Layer* layer) {
+        layerList.toggle(layer);
+    }
+    void toggleLayerLock(RS_Layer* layer) {
+        layerList.toggleLock(layer);
+    }
+    void toggleLayerPrint(RS_Layer* layer) {
+        layerList.togglePrint(layer);
+    }
+    void toggleLayerConstruction(RS_Layer* layer) {
+        layerList.toggleConstruction(layer);
+    }
+    void freezeAllLayers(bool freeze) {
+        layerList.freezeAll(freeze);
+    }
+    void lockAllLayers(bool lock) {
+        layerList.lockAll(lock);
+    }
+
+    void addLayerListListener(RS_LayerListListener* listener) {
+        layerList.addListener(listener);
+    }
+    void removeLayerListListener(RS_LayerListListener* listener) {
+        layerList.removeListener(listener);
+    }
+
+
+        // Wrapper for block functions:
+    void clearBlocks() {
+        blockList.clear();
+    }
+    unsigned countBlocks() {
+        return blockList.count();
+    }
+    RS_Block* blockAt(unsigned i) {
+        return blockList.at(i);
+    }
+    void activateBlock(const QString& name) {
+        blockList.activate(name);
+    }
+    void activateBlock(RS_Block* block) {
+        blockList.activate(block);
+    }
+    RS_Block* getActiveBlock() {
+        return blockList.getActive();
+    }
+    virtual bool addBlock(RS_Block* block, bool notify=true) {
+        return blockList.add(block, notify);
+    }
+    virtual void addBlockNotification() {
+        blockList.addNotification();
+    }
+    virtual void removeBlock(RS_Block* block) {
+        blockList.remove(block);
+    }
+    RS_Block* findBlock(const QString& name) {
+        return blockList.find(name);
+    }
+    QString newBlockName() {
+        return blockList.newName();
+    }
+    void toggleBlock(const QString& name) {
+        blockList.toggle(name);
+    }
+    void toggleBlock(RS_Block* block) {
+        blockList.toggle(block);
+    }
+    void freezeAllBlocks(bool freeze) {
+        blockList.freezeAll(freeze);
+    }
+    void addBlockListListener(RS_BlockListListener* listener) {
+        blockList.addListener(listener);
+    }
+    void removeBlockListListener(RS_BlockListListener* listener) {
+        blockList.removeListener(listener);
+    }
+
+        // Wrappers for variable functions:
+    void clearVariables() {
+        variableDict.clear();
+    }
+    int countVariables() {
+        return variableDict.count();
+    }
+
+    void addVariable(const QString& key, const RS_Vector& value, int code) {
+        variableDict.add(key, value, code);
+    }
+    void addVariable(const QString& key, const QString& value, int code) {
+        variableDict.add(key, value, code);
+    }
+    void addVariable(const QString& key, int value, int code) {
+        variableDict.add(key, value, code);
+    }
+    void addVariable(const QString& key, double value, int code) {
+        variableDict.add(key, value, code);
+    }
+
+    RS_Vector getVariableVector(const QString& key, const RS_Vector& def) {
+        return variableDict.getVector(key, def);
+    }
+    QString getVariableString(const QString& key, const QString& def) {
+        return variableDict.getString(key, def);
+    }
+    int getVariableInt(const QString& key, int def) {
+        return variableDict.getInt(key, def);
+    }
+    double getVariableDouble(const QString& key, double def) {
+        return variableDict.getDouble(key, def);
+    }
+
+    void removeVariable(const QString& key) {
+        variableDict.remove(key);
+    }
+
+    QHash<QString, RS_Variable>& getVariableDict() {
+        return variableDict.getVariableDict();
+    }
+
+    RS2::LinearFormat getLinearFormat();
+    RS2::LinearFormat getLinearFormat(int f);
+    int getLinearPrecision();
+    RS2::AngleFormat getAngleFormat();
+    int getAnglePrecision();
+
+    RS_Vector getPaperSize();
+    void setPaperSize(const RS_Vector& s);
+    RS_Vector getPrintAreaSize(bool total=true);
+
+    RS_Vector getPaperInsertionBase();
+    void setPaperInsertionBase(const RS_Vector& p);
+
+    RS2::PaperFormat getPaperFormat(bool* landscape);
+    void setPaperFormat(RS2::PaperFormat f, bool landscape);
+
+    double getPaperScale();
+    void setPaperScale(double s);
+
+    virtual void setUnit(RS2::Unit u);
+    virtual RS2::Unit getUnit();
+
+    bool isGridOn();
+    void setGridOn(bool on);
+    bool isIsometricGrid();
+    void setIsometricGrid(bool on);
+    void setCrosshairType(RS2::CrosshairType chType);
+    RS2::CrosshairType getCrosshairType();
+
+    bool isDraftOn();
+    void setDraftOn(bool on);
+
+    /** Sets the unit of this graphic's dimensions to 'u' */
+    /*virtual void setDimensionUnit(RS2::Unit u) {
+            addVariable("$INSUNITS", (int)u, 70);
+    dimensionUnit = u;
+    }*/
+
+    /** Gets the unit of this graphic's dimension */
+    /*virtual RS2::Unit getDimensionUnit() {
+    return dimensionUnit;
+    }*/
+
+    void centerToPage();
+    bool fitToPage();
+
+    bool isBiggerThanPaper();
+
+    /**
+     * @retval true The document has been modified since it was last saved.
+     * @retval false The document has not been modified since it was last saved.
+     */
+    virtual bool isModified() const {
+        return modified || layerList.isModified() || blockList.isModified();
+    }
+
+    /**
+     * Sets the documents modified status to 'm'.
+     */
+    virtual void setModified(bool m) {
+        modified = m;
+        layerList.setModified(m);
+        blockList.setModified(m);
+    }
+    virtual QDateTime getModifyTime(void){
+        return modifiedTime;
+    }
+
+    //if set to true, will refuse to modify paper scale
+    void setPaperScaleFixed(bool fixed)
+    {
+        paperScaleFixed=fixed;
+    }
+    bool getPaperScaleFixed()
+    {
+        return paperScaleFixed;
+    }
+
+    /**
+     * Paper margins in millimeters
+     */
+    void setMargins(double left, double top, double right, double bottom)
+    {
+        if (left >= 0.0) marginLeft = left;
+        if (top >= 0.0) marginTop = top;
+        if (right >= 0.0) marginRight = right;
+        if (bottom >= 0.0) marginBottom = bottom;
+    }
+    double getMarginLeft() const
+    {
+        return marginLeft;
+    }
+    double getMarginTop() const
+    {
+        return marginTop;
+    }
+    double getMarginRight() const
+    {
+        return marginRight;
+    }
+    double getMarginBottom() const
+    {
+        return marginBottom;
+    }
+
+    /**
+     * Paper margins in graphic units
+     */
+    void setMarginsInUnits(double left, double top, double right, double bottom);
+    double getMarginLeftInUnits();
+    double getMarginTopInUnits();
+    double getMarginRightInUnits();
+    double getMarginBottomInUnits();
+
+    /**
+     * Number of pages drawing occupies
+     */
+    void setPagesNum(int horiz, int vert);
+    void setPagesNum(const QString &horizXvert);
+    int getPagesNumHoriz() {
+        return pagesNumH;
+    }
+    int getPagesNumVert() {
+        return pagesNumV;
+    }
+
+    friend std::ostream& operator << (std::ostream& os, RS_Graphic& g);
+
+    int clean();
+
+private:
+
+        bool BackupDrawingFile(const QString &filename);
+        QDateTime modifiedTime;
+        QString currentFileName; //keep a copy of filename for the modifiedTime
+
+        RS_LayerList layerList;
+        RS_BlockList blockList;
+        RS_VariableDict variableDict;
+        RS2::CrosshairType crosshairType; //crosshair type used by isometric grid
+        //if set to true, will refuse to modify paper scale
+        bool paperScaleFixed;
+
+        // Paper margins in millimeters
+        double marginLeft;
+        double marginTop;
+        double marginRight;
+        double marginBottom;
+
+        // Number of pages drawing occupies
+        int pagesNumH;
+        int pagesNumV;
+};
+
+
+#endif

lib/engine/rs_hatch.cpp

@@ -0,0 +1,788 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+#include <iostream>
+#include <cmath>
+#include <memory>
+#include <QPainterPath>
+#include <QBrush>
+#include <QString>
+#include "rs_hatch.h"
+
+#include "rs_arc.h"
+#include "rs_circle.h"
+#include "rs_ellipse.h"
+#include "rs_line.h"
+#include "rs_graphicview.h"
+#include "rs_dialogfactory.h"
+#include "rs_infoarea.h"
+
+#include "rs_information.h"
+#include "rs_painter.h"
+#include "rs_pattern.h"
+#include "rs_patternlist.h"
+#include "rs_math.h"
+#include "rs_debug.h"
+
+
+RS_HatchData::RS_HatchData(bool _solid,
+						   double _scale,
+						   double _angle,
+						   const QString& _pattern):
+	solid(_solid)
+  ,scale(_scale)
+  ,angle(_angle)
+  ,pattern(_pattern)
+{
+	//std::cout << "RS_HatchData: " << pattern.latin1() << "\n";
+}
+
+std::ostream& operator << (std::ostream& os, const RS_HatchData& td) {
+	os << "(" << td.pattern.toLatin1().data() << ")";
+	return os;
+}
+
+/**
+ * Constructor.
+ */
+RS_Hatch::RS_Hatch(RS_EntityContainer* parent,
+                   const RS_HatchData& d)
+        : RS_EntityContainer(parent), data(d)
+{
+
+	hatch = nullptr;
+    updateRunning = false;
+    needOptimization = true;
+    updateError = HATCH_UNDEFINED;
+}
+
+
+
+/**
+ * Validates the hatch.
+ */
+bool RS_Hatch::validate() {
+        bool ret = true;
+
+    // loops:
+		for(auto l: entities){
+
+        if (l->rtti()==RS2::EntityContainer) {
+            RS_EntityContainer* loop = (RS_EntityContainer*)l;
+
+            ret = loop->optimizeContours() && ret;
+        }
+    }
+
+        return ret;
+}
+
+
+
+RS_Entity* RS_Hatch::clone() const{
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::clone()");
+    RS_Hatch* t = new RS_Hatch(*this);
+    t->setOwner(isOwner());
+    t->initId();
+    t->detach();
+    t->update();
+//    t->hatch = nullptr;
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::clone(): OK");
+    return t;
+}
+
+
+/**
+ * @return Number of loops.
+ */
+int RS_Hatch::countLoops() const{
+    if (data.solid) {
+        return count();
+    } else {
+        return count() - 1;
+    }
+}
+
+bool RS_Hatch::isContainer() const {
+	return !isSolid();
+}
+
+/**
+ * Recalculates the borders of this hatch.
+ */
+void RS_Hatch::calculateBorders() {
+    RS_DEBUG->print("RS_Hatch::calculateBorders");
+
+    activateContour(true);
+
+    RS_EntityContainer::calculateBorders();
+
+        RS_DEBUG->print("RS_Hatch::calculateBorders: size: %f,%f",
+                getSize().x, getSize().y);
+
+    activateContour(false);
+}
+
+
+
+/**
+ * Updates the Hatch. Called when the
+ * hatch or it's data, position, alignment, .. changes.
+ *
+ * Refill hatch with pattern. Move, scale, rotate, trim, etc.
+ */
+void RS_Hatch::update() {
+
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update");
+
+    updateError = HATCH_OK;
+    if (updateRunning) {
+        RS_DEBUG->print(RS_Debug::D_NOTICE, "RS_Hatch::update: skip hatch in updating process");
+        return;
+    }
+
+    if (updateEnabled==false) {
+        RS_DEBUG->print(RS_Debug::D_NOTICE, "RS_Hatch::update: skip hatch forbidden to update");
+        return;
+    }
+
+    if (data.solid==true) {
+        RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: processing solid hatch");
+        calculateBorders();
+        return;
+    }
+
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: contour has %d loops", count());
+    updateRunning = true;
+
+    // save attributes for the current hatch
+    RS_Layer* hatch_layer = this->getLayer();
+    RS_Pen hatch_pen = this->getPen();
+
+    // delete old hatch:
+    if (hatch) {
+        removeEntity(hatch);
+		hatch = nullptr;
+    }
+
+    if (isUndone()) {
+        RS_DEBUG->print(RS_Debug::D_NOTICE, "RS_Hatch::update: skip undone hatch");
+        updateRunning = false;
+        return;
+    }
+
+    if (!validate()) {
+        RS_DEBUG->print(RS_Debug::D_ERROR, "RS_Hatch::update: invalid contour in hatch found");
+        updateRunning = false;
+        updateError = HATCH_INVALID_CONTOUR;
+        return;
+    }
+
+    // search for pattern
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: requesting pattern");
+    RS_Pattern* pat = RS_PATTERNLIST->requestPattern(data.pattern);
+	if (!pat) {
+        updateRunning = false;
+        RS_DEBUG->print(RS_Debug::D_ERROR, "RS_Hatch::update: requesting pattern: not found");
+        updateError = HATCH_PATTERN_NOT_FOUND;
+        return;
+    } else {
+        RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: requesting pattern: OK");
+        // make a working copy of hatch pattern
+        RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: cloning pattern");
+        pat = (RS_Pattern*)pat->clone();
+        if (pat) {
+            RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: cloning pattern: OK");
+        } else {
+            RS_DEBUG->print(RS_Debug::D_ERROR, "RS_Hatch::update: error while cloning hatch pattern");
+            return;
+        }
+    }
+
+    // scale pattern
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: scaling pattern");
+    pat->scale(RS_Vector(0.0,0.0), RS_Vector(data.scale, data.scale));
+    pat->calculateBorders();
+    forcedCalculateBorders();
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: scaling pattern: OK");
+
+    // find out how many pattern-instances we need in x/y:
+    int px1, py1, px2, py2;
+    double f;
+    RS_Hatch* copy = (RS_Hatch*)this->clone();
+    copy->rotate(RS_Vector(0.0,0.0), -data.angle);
+    copy->forcedCalculateBorders();
+
+    // create a pattern over the whole contour.
+    RS_Vector pSize = pat->getSize();
+    RS_Vector rot_center=pat->getMin();
+//    RS_Vector cPos = getMin();
+    RS_Vector cSize = getSize();
+
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: pattern size: %f/%f", pSize.x, pSize.y);
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: contour size: %f/%f", cSize.x, cSize.y);
+
+    // check pattern sizes for sanity
+    if (cSize.x<1.0e-6 || cSize.y<1.0e-6 ||
+            pSize.x<1.0e-6 || pSize.y<1.0e-6 ||
+            cSize.x>RS_MAXDOUBLE-1 || cSize.y>RS_MAXDOUBLE-1 ||
+            pSize.x>RS_MAXDOUBLE-1 || pSize.y>RS_MAXDOUBLE-1) {
+        delete pat;
+        delete copy;
+        updateRunning = false;
+        RS_DEBUG->print(RS_Debug::D_ERROR, "RS_Hatch::update: contour size or pattern size too small");
+        updateError = HATCH_TOO_SMALL;
+        return;
+    }
+    // avoid huge memory consumption:
+    else if ( cSize.x* cSize.y/(pSize.x*pSize.y)>1e4) {
+        RS_DEBUG->print(RS_Debug::D_ERROR, "RS_Hatch::update: contour size too large or pattern size too small");
+        delete pat;
+        delete copy;
+        updateError = HATCH_AREA_TOO_BIG;
+        return;
+    }
+
+    // calculate pattern pieces quantity
+    f = copy->getMin().x/pSize.x;
+    px1 = (int)floor(f);
+    f = copy->getMin().y/pSize.y;
+    py1 = (int)floor(f);
+    f = copy->getMax().x/pSize.x;
+    px2 = (int)ceil(f);
+    f = copy->getMax().y/pSize.y;
+    py2 = (int)ceil(f);
+    RS_Vector dvx=RS_Vector(data.angle)*pSize.x;
+    RS_Vector dvy=RS_Vector(data.angle+M_PI*0.5)*pSize.y;
+    pat->rotate(rot_center, data.angle);
+    pat->move(-rot_center);
+
+    RS_EntityContainer tmp;   // container for untrimmed lines
+
+    // adding array of patterns to tmp:
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: creating pattern carpet");
+    for (int px=px1; px<px2; px++) {
+		for (int py=py1; py<py2; py++) {
+			for(auto e: *pat){
+                RS_Entity* te=e->clone();
+                te->move(dvx*px + dvy*py);
+                tmp.addEntity(te);
+            }
+        }
+    }
+
+    // clean memory
+    delete pat;
+    pat = nullptr;
+    delete copy;
+    copy = nullptr;
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: creating pattern carpet: OK");
+
+    // cut pattern to contour shape
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: cutting pattern carpet");
+    RS_EntityContainer tmp2;   // container for small cut lines
+	RS_Line* line = nullptr;
+	RS_Arc* arc = nullptr;
+	RS_Circle* circle = nullptr;
+	RS_Ellipse* ellipse = nullptr;
+
+    for(auto e: tmp) {
+
+        if (!e) {
+            RS_DEBUG->print(RS_Debug::D_WARNING, "RS_Hatch::update: nullptr entity found");
+            continue;
+        }
+
+		line = nullptr;
+		arc = nullptr;
+		circle = nullptr;
+		ellipse = nullptr;
+
+        RS_Vector startPoint;
+        RS_Vector endPoint;
+        RS_Vector center = RS_Vector(false);
+        bool reversed=false;
+
+        switch(e->rtti()) {
+            case RS2::EntityLine:
+                line=static_cast<RS_Line*>(e);
+                startPoint = line->getStartpoint();
+                endPoint = line->getEndpoint();
+                break;
+            case RS2::EntityArc:
+                arc=static_cast<RS_Arc*>(e);
+                startPoint = arc->getStartpoint();
+                endPoint = arc->getEndpoint();
+                center = arc->getCenter();
+                reversed = arc->isReversed();
+                break;
+            case RS2::EntityCircle:
+                circle=static_cast<RS_Circle*>(e);
+                startPoint = circle->getCenter()
+                        + RS_Vector(circle->getRadius(), 0.0);
+                endPoint = startPoint;
+                center = circle->getCenter();
+                break;
+            case RS2::EntityEllipse:
+                ellipse = static_cast<RS_Ellipse*>(e);
+                startPoint = ellipse->getStartpoint();
+                endPoint = ellipse->getEndpoint();
+                center = ellipse->getCenter();
+                reversed = ellipse->isReversed();
+                break;
+            default:
+                continue;
+        }
+
+        // getting all intersections of this pattern line with the contour:
+		QList<RS_Vector> is;
+
+		for(auto loop: entities){
+
+            if (loop->isContainer()) {
+				for(auto p: * static_cast<RS_EntityContainer*>(loop)){
+
+                    RS_VectorSolutions sol =
+                        RS_Information::getIntersection(e, p, true);
+
+                    for (const RS_Vector& vp: sol) {
+						if (vp.valid) {
+							is.append(vp);
+                            RS_DEBUG->print(RS_Debug::D_DEBUGGING, "  pattern line intersection: %f/%f", vp.x, vp.y);
+						}
+					}
+				}
+			}
+		}
+
+        QList<RS_Vector> is2;       //to be filled with sorted intersections
+		is2.append(startPoint);
+
+        // sort the intersection points into is2 (only if there are intersections):
+        if(is.size() == 1) {        //only one intersection
+            is2.append(is.first());
+        }
+        else if(is.size() > 1) {
+            RS_Vector sp = startPoint;
+            double sa = center.angleTo(sp);
+			if(ellipse ) sa=ellipse->getEllipseAngle(sp);
+            bool done;
+            double minDist;
+            double dist = 0.0;
+			RS_Vector av;
+			RS_Vector v;
+			RS_Vector last{};
+            do {    // very long while(!done) loop
+                done = true;
+                minDist = RS_MAXDOUBLE;
+				av.valid = false;
+                for (int i = 0; i < is.size(); ++i) {
+                    v = is.at(i);
+                    double a;
+                    switch(e->rtti()){
+                    case RS2::EntityLine:
+						dist = sp.distanceTo(v);
+                        break;
+                    case RS2::EntityArc:
+                    case RS2::EntityCircle:
+						a = center.angleTo(v);
+                        dist = reversed?
+                                    fmod(sa - a + 2.*M_PI,2.*M_PI):
+                                    fmod(a - sa + 2.*M_PI,2.*M_PI);
+                        break;
+                    case RS2::EntityEllipse:
+						a = ellipse->getEllipseAngle(v);
+                        dist = reversed?
+                                    fmod(sa - a + 2.*M_PI,2.*M_PI):
+                                    fmod(a - sa + 2.*M_PI,2.*M_PI);
+                        break;
+                    default:
+                        break;
+
+                    }
+
+                    if (dist<minDist) {
+                        minDist = dist;
+                        done = false;
+                        av = v;
+                    }
+                }
+
+                // copy to sorted list, removing double points
+				if (!done && av) {
+					if (last.valid==false || last.distanceTo(av)>RS_TOLERANCE) {
+						is2.append(av);
+						last = av;
+                    }
+                    is.removeOne(av);
+
+					av.valid = false;
+                }
+            } while(!done);
+        }
+
+		is2.append(endPoint);
+
+        // add small cut lines / arcs to tmp2:
+        for (int i = 1; i < is2.size(); ++i) {
+            auto v1 = is2.at(i-1);
+            auto v2 = is2.at(i);
+
+
+            if (line) {
+
+                tmp2.addEntity(new RS_Line{&tmp2, v1, v2});
+            } else if (arc || circle) {
+                if(fabs(center.angleTo(v2)-center.angleTo(v1)) > RS_TOLERANCE_ANGLE)
+                {//don't create an arc with a too small angle
+                    tmp2.addEntity(new RS_Arc(&tmp2,
+                                              RS_ArcData(center,
+                                                         center.distanceTo(v1),
+                                                         center.angleTo(v1),
+                                                         center.angleTo(v2),
+                                                         reversed)));
+                }
+            }
+        }
+    } // end for very very long for(auto e: tmp) loop
+
+    // updating hatch / adding entities that are inside
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: cutting pattern carpet: OK");
+
+    //RS_EntityContainer* rubbish = new RS_EntityContainer(getGraphic());
+
+    // add the hatch pattern entities
+    hatch = new RS_EntityContainer(this);
+    hatch->setPen(hatch_pen);
+    hatch->setLayer(hatch_layer);
+    hatch->setFlag(RS2::FlagTemp);
+
+    //calculateBorders();
+	for(auto e: tmp2){
+
+        RS_Vector middlePoint;
+        RS_Vector middlePoint2;
+        if (e->rtti()==RS2::EntityLine) {
+			RS_Line* line = static_cast<RS_Line*>(e);
+            middlePoint = line->getMiddlePoint();
+            middlePoint2 = line->getNearestDist(line->getLength()/2.1,
+                                                line->getStartpoint());
+        } else if (e->rtti()==RS2::EntityArc) {
+			RS_Arc* arc = static_cast<RS_Arc*>(e);
+            middlePoint = arc->getMiddlePoint();
+            middlePoint2 = arc->getNearestDist(arc->getLength()/2.1,
+                                               arc->getStartpoint());
+        } else {
+			middlePoint = RS_Vector{false};
+			middlePoint2 = RS_Vector{false};
+        }
+
+        if (middlePoint.valid) {
+            bool onContour=false;
+
+            if (RS_Information::isPointInsideContour(
+                        middlePoint,
+                        this, &onContour) ||
+                    RS_Information::isPointInsideContour(middlePoint2, this)) {
+
+                RS_Entity* te = e->clone();
+                te->setPen(hatch_pen);
+                te->setLayer(hatch_layer);
+                te->reparent(hatch);
+                hatch->addEntity(te);
+            }
+        }
+    }
+
+    addEntity(hatch);
+    //getGraphic()->addEntity(rubbish);
+
+    forcedCalculateBorders();
+
+    // deactivate contour:
+    activateContour(false);
+
+    updateRunning = false;
+
+    RS_DEBUG->print(RS_Debug::D_DEBUGGING, "RS_Hatch::update: OK");
+}
+
+
+
+/**
+ * Activates of deactivates the hatch boundary.
+ */
+void RS_Hatch::activateContour(bool on) {
+        RS_DEBUG->print("RS_Hatch::activateContour: %d", (int)on);
+		for(auto e: entities){
+        if (!e->isUndone()) {
+            if (!e->getFlag(RS2::FlagTemp)) {
+                                RS_DEBUG->print("RS_Hatch::activateContour: set visible");
+                e->setVisible(on);
+            }
+                        else {
+                                RS_DEBUG->print("RS_Hatch::activateContour: entity temp");
+                        }
+        }
+                else {
+                        RS_DEBUG->print("RS_Hatch::activateContour: entity undone");
+                }
+    }
+        RS_DEBUG->print("RS_Hatch::activateContour: OK");
+}
+
+/**
+ * Overrides drawing of subentities. This is only ever called for solid fills.
+ */
+void RS_Hatch::draw(RS_Painter* painter, RS_GraphicView* view, double& /*patternOffset*/) {
+
+    if (!data.solid) {
+        foreach (auto se, entities){
+
+            view->drawEntity(painter,se);
+        }
+        return;
+    }
+
+    //area of solid fill. Use polygon approximation, except trivial cases
+    QPainterPath path;
+    QList<QPolygon> paClosed;
+    QPolygon pa;
+
+    if (needOptimization==true) {
+        foreach (auto l, entities){
+
+            if (l->rtti()==RS2::EntityContainer) {
+                RS_EntityContainer* loop = (RS_EntityContainer*)l;
+
+                loop->optimizeContours();
+            }
+        }
+        needOptimization = false;
+    }
+
+    foreach (auto l, entities){
+        l->setLayer(getLayer());
+
+        if (l->rtti()==RS2::EntityContainer) {
+            RS_EntityContainer* loop = (RS_EntityContainer*)l;
+
+            // edges:
+            for(auto e: *loop){
+
+                e->setLayer(getLayer());
+                switch (e->rtti()) {
+                case RS2::EntityLine: {
+                    QPoint pt1(RS_Math::round(view->toGuiX(e->getStartpoint().x)),
+                               RS_Math::round(view->toGuiY(e->getStartpoint().y)));
+                    QPoint pt2(RS_Math::round(view->toGuiX(e->getEndpoint().x)),
+                               RS_Math::round(view->toGuiY(e->getEndpoint().y)));
+
+                    if(!pa.size() || (pa.last() - pt1).manhattanLength() >= 1) {
+                        pa << pt1;
+                    }
+                    pa << pt2;
+                }
+                    break;
+
+                case RS2::EntityArc: {
+                    QPolygon pa2;
+                    RS_Arc* arc=static_cast<RS_Arc*>(e);
+
+                    painter->createArc(pa2, view->toGui(arc->getCenter()),
+                                       view->toGuiDX(arc->getRadius())
+                                       ,arc->getAngle1(),arc->getAngle2(),arc->isReversed());
+                    if(pa.size() &&pa2.size()&&(pa.last()-pa2.first()).manhattanLength()<1)
+                        pa2.remove(0,1);
+                    pa<<pa2;
+
+                }
+                    break;
+
+                case RS2::EntityCircle: {
+                    RS_Circle* circle = static_cast<RS_Circle*>(e);
+                    RS_Vector c=view->toGui(circle->getCenter());
+                    double r=view->toGuiDX(circle->getRadius());
+                    path.addEllipse(QPoint(c.x,c.y),r,r);
+                }
+                    break;
+                case RS2::EntityEllipse:
+                if(static_cast<RS_Ellipse*>(e)->isArc()) {
+                    QPolygon pa2;
+                    auto ellipse=static_cast<RS_Ellipse*>(e);
+
+                    painter->createEllipse(pa2,
+                                           view->toGui(ellipse->getCenter()),
+                                           view->toGuiDX(ellipse->getMajorRadius()),
+                                           view->toGuiDX(ellipse->getMinorRadius()),
+                                           ellipse->getAngle()
+                                           ,ellipse->getAngle1(),ellipse->getAngle2(),ellipse->isReversed()
+                                           );
+
+                    if(pa.size() && pa2.size()&&(pa.last()-pa2.first()).manhattanLength()<1)
+                        pa2.remove(0,1);
+                    pa<<pa2;
+                }else{
+                    QPolygon pa2;
+                    auto ellipse=static_cast<RS_Ellipse*>(e);
+                    painter->createEllipse(pa2,
+                                           view->toGui(ellipse->getCenter()),
+                                           view->toGuiDX(ellipse->getMajorRadius()),
+                                           view->toGuiDX(ellipse->getMinorRadius()),
+                                           ellipse->getAngle(),
+                                           ellipse->getAngle1(), ellipse->getAngle2(),
+                                           ellipse->isReversed()
+                                           );
+                    path.addPolygon(pa2);
+                }
+                    break;
+                default:
+                    break;
+                }
+
+                if( pa.size()>2 && pa.first() == pa.last()) {
+                    paClosed<<pa;
+                    pa.clear();
+                }
+
+            }
+
+        }
+    }
+    if(pa.size()>2){
+        pa<<pa.first();
+        paClosed<<pa;
+    }
+
+    for(auto& p:paClosed){
+        path.addPolygon(p);
+    }
+
+    //bug#474, restore brush after solid fill
+    const QBrush brush(painter->brush());
+    const RS_Pen pen=painter->getPen();
+    painter->setBrush(pen.getColor());
+    painter->disablePen();
+    painter->drawPath(path);
+    painter->setBrush(brush);
+    painter->setPen(pen);
+}
+
+//must be called after update()
+double RS_Hatch::getTotalArea() {
+
+    double totalArea=0.;
+
+    // loops:
+	for(auto l: entities){
+
+        if (l!=hatch && l->rtti()==RS2::EntityContainer) {
+            totalArea += l->areaLineIntegral();
+        }
+    }
+    return totalArea;
+}
+
+double RS_Hatch::getDistanceToPoint(
+    const RS_Vector& coord,
+    RS_Entity** entity,
+    RS2::ResolveLevel level,
+    double solidDist) const {
+
+    if (data.solid==true) {
+        if (entity) {
+            *entity = const_cast<RS_Hatch*>(this);
+        }
+
+        bool onContour;
+        if (RS_Information::isPointInsideContour(
+                    coord,
+                     const_cast<RS_Hatch*>(this), &onContour)) {
+
+            // distance is the snap range:
+            return solidDist;
+        }
+
+        return RS_MAXDOUBLE;
+    } else {
+        return RS_EntityContainer::getDistanceToPoint(coord, entity,
+                level, solidDist);
+    }
+}
+
+
+
+void RS_Hatch::move(const RS_Vector& offset) {
+    RS_EntityContainer::move(offset);
+    update();
+}
+
+
+
+void RS_Hatch::rotate(const RS_Vector& center, const double& angle) {
+    RS_EntityContainer::rotate(center, angle);
+    data.angle = RS_Math::correctAngle(data.angle+angle);
+    update();
+}
+
+
+void RS_Hatch::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_EntityContainer::rotate(center, angleVector);
+    data.angle = RS_Math::correctAngle(data.angle+angleVector.angle());
+    update();
+}
+
+void RS_Hatch::scale(const RS_Vector& center, const RS_Vector& factor) {
+    RS_EntityContainer::scale(center, factor);
+    data.scale *= factor.x;
+    update();
+}
+
+
+
+void RS_Hatch::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    RS_EntityContainer::mirror(axisPoint1, axisPoint2);
+    double ang = axisPoint1.angleTo(axisPoint2);
+    data.angle = RS_Math::correctAngle(data.angle + ang*2.0);
+    update();
+}
+
+
+void RS_Hatch::stretch(const RS_Vector& firstCorner,
+                       const RS_Vector& secondCorner,
+                       const RS_Vector& offset) {
+
+    RS_EntityContainer::stretch(firstCorner, secondCorner, offset);
+    update();
+}
+
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Hatch& p) {
+    os << " Hatch: " << p.getData() << "\n";
+    return os;
+}

lib/engine/rs_hatch.h

@@ -0,0 +1,175 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_HATCH_H
+#define RS_HATCH_H
+
+#include "rs_entity.h"
+#include "rs_entitycontainer.h"
+
+/**
+ * Holds the data that defines a hatch entity.
+ */
+struct RS_HatchData {
+    /**
+     * Default constructor. Leaves the data object uninitialized.
+     */
+	RS_HatchData() = default;
+	~RS_HatchData() = default;
+
+        /**
+         * @param solid true: solid fill, false: pattern.
+         * @param scale Pattern scale or spacing.
+         * @param pattern Pattern name.
+         */
+	RS_HatchData(bool solid,
+				 double scale,
+				 double angle,
+				 const QString& pattern);
+
+
+	bool solid;
+	double scale;
+	double angle;
+	QString pattern;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_HatchData& td);
+
+
+
+/**
+ * Class for a hatch entity.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Hatch : public RS_EntityContainer {
+public:
+    enum RS_HatchError { HATCH_UNDEFINED = -1,
+                         HATCH_OK,
+                         HATCH_INVALID_CONTOUR,
+                         HATCH_PATTERN_NOT_FOUND,
+                         HATCH_TOO_SMALL,
+                         HATCH_AREA_TOO_BIG };
+
+	RS_Hatch() = default;
+
+    RS_Hatch(RS_EntityContainer* parent,
+            const RS_HatchData& d);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityHatch */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityHatch;
+    }
+
+    /**
+     * @return true: if this is a hatch with lines (hatch pattern),
+     *         false: if this is filled with a solid color.
+     */
+	bool isContainer() const override;
+
+    /** @return Copy of data that defines the hatch. */
+    RS_HatchData getData() const {
+        return data;
+    }
+
+        bool validate();
+
+		int countLoops() const;
+
+        /** @return true if this is a solid fill. false if it is a pattern hatch. */
+        bool isSolid() const {
+                return data.solid;
+        }
+        void setSolid(bool solid) {
+                data.solid = solid;
+        }
+
+        QString getPattern() {
+                return data.pattern;
+        }
+        void setPattern(const QString& pattern) {
+                data.pattern = pattern;
+        }
+
+        double getScale() {
+                return data.scale;
+        }
+        void setScale(double scale) {
+                data.scale = scale;
+        }
+
+        double getAngle() {
+                return data.angle;
+        }
+        void setAngle(double angle) {
+                data.angle = angle;
+        }
+		double getTotalArea();
+
+		void calculateBorders() override;
+		void update() override;
+        int getUpdateError() {
+                return updateError;
+        }
+        void activateContour(bool on);
+
+		void draw(RS_Painter* painter, RS_GraphicView* view,
+						  double& patternOffset) override;
+
+		//	double getLength() {
+        //		return -1.0;
+        //	}
+
+		double getDistanceToPoint(const RS_Vector& coord,
+                                          RS_Entity** entity = NULL,
+                                          RS2::ResolveLevel level = RS2::ResolveNone,
+										  double solidDist = RS_MAXDOUBLE) const override;
+
+
+		void move(const RS_Vector& offset) override;
+		void rotate(const RS_Vector& center, const double& angle) override;
+		void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+		void scale(const RS_Vector& center, const RS_Vector& factor) override;
+		void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+		void stretch(const RS_Vector& firstCorner,
+                             const RS_Vector& secondCorner,
+							 const RS_Vector& offset) override;
+
+        friend std::ostream& operator << (std::ostream& os, const RS_Hatch& p);
+
+protected:
+        RS_HatchData data;
+        RS_EntityContainer* hatch;
+        bool updateRunning;
+        bool needOptimization;
+        int  updateError;
+};
+
+#endif

lib/engine/rs_image.cpp

@@ -0,0 +1,418 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+#include<iostream>
+#include <QImage>
+#include "rs_image.h"
+#include "rs_line.h"
+#include "rs_settings.h"
+
+#include "rs_constructionline.h"
+#include "rs_debug.h"
+#include "rs_graphicview.h"
+#include "rs_painterqt.h"
+#include "rs_math.h"
+
+RS_ImageData::RS_ImageData(int _handle,
+						   const RS_Vector& _insertionPoint,
+						   const RS_Vector& _uVector,
+						   const RS_Vector& _vVector,
+						   const RS_Vector& _size,
+						   const QString& _file,
+						   int _brightness,
+						   int _contrast,
+						   int _fade):
+	handle(_handle)
+  , insertionPoint(_insertionPoint)
+  , uVector(_uVector)
+  , vVector(_vVector)
+  , size(_size)
+  , file(_file)
+  , brightness(_brightness)
+  , contrast(_contrast)
+  , fade(_fade)
+{
+}
+
+std::ostream& operator << (std::ostream& os, const RS_ImageData& ld) {
+	os << "(" << ld.insertionPoint << ")";
+	return os;
+}
+
+/**
+ * Constructor.
+ */
+RS_Image::RS_Image(RS_EntityContainer* parent,
+                   const RS_ImageData& d)
+        :RS_AtomicEntity(parent), data(d) {
+
+    update();
+    calculateBorders();
+}
+
+RS_Image::RS_Image(const RS_Image& _image):
+	RS_AtomicEntity(_image.getParent())
+  ,data(_image.data)
+  ,img(_image.img.get()?new QImage(*_image.img):nullptr)
+{
+}
+
+RS_Image& RS_Image::operator = (const RS_Image& _image)
+{
+	data=_image.data;
+	if(_image.img.get()){
+		img.reset(new QImage(*_image.img));
+	}else{
+		img.reset();
+	}
+	return *this;
+}
+
+RS_Image::RS_Image(RS_Image&& _image):
+	RS_AtomicEntity(_image.getParent())
+  ,data(std::move(_image.data))
+  ,img(std::move(_image.img))
+{
+}
+
+RS_Image& RS_Image::operator = (RS_Image&& _image)
+{
+	data=_image.data;
+	img = std::move(_image.img);
+	return *this;
+}
+
+
+RS_Entity* RS_Image::clone() const {
+    RS_Image* i = new RS_Image(*this);
+        i->setHandle(getHandle());
+    i->initId();
+    i->update();
+    return i;
+}
+
+
+void RS_Image::updateData(RS_Vector size, RS_Vector Uv, RS_Vector Vv) {
+    data.size = size;
+    data.uVector = Uv;
+    data.vVector = Vv;
+    update();
+    calculateBorders();
+}
+
+
+void RS_Image::update() {
+
+    RS_DEBUG->print("RS_Image::update");
+
+    // the whole image:
+    //QImage image = QImage(data.file);
+	img.reset(new QImage(data.file));
+	if (!img->isNull()) {
+		data.size = RS_Vector(img->width(), img->height());
+		calculateBorders(); // image update need this.
+    }
+
+    RS_DEBUG->print("RS_Image::update: OK");
+
+    /*
+    // number of small images:
+    nx = image.width()/100;
+    ny = image.height()/100;
+
+    // create small images:
+    img = new QImage*[nx];
+    QPixmap pm;
+    int w,h;
+    for (int x = 0; x<nx; ++x) {
+        img[x] = new QImage[ny];
+        for (int y = 0; y<ny; ++y) {
+                if (x<nx-1) {
+                        w = 100;
+                }
+                else {
+                        w = image.width()%100;
+                }
+
+                if (y<ny-1) {
+                        h = 100;
+                }
+                else {
+                        h = image.height()%100;
+                }
+
+                pm = QPixmap(w, h);
+                RS_PainterQt painter(&pm);
+                painter.drawImage(-x*100, -y*100, image);
+                img[x][y] = pm.convertToImage();
+        }
+    }
+    */
+}
+
+
+
+void RS_Image::calculateBorders() {
+
+    RS_VectorSolutions sol = getCorners();
+        minV =  RS_Vector::minimum(
+                RS_Vector::minimum(sol.get(0), sol.get(1)),
+                RS_Vector::minimum(sol.get(2), sol.get(3))
+                    );
+        maxV =  RS_Vector::maximum(
+                RS_Vector::maximum(sol.get(0), sol.get(1)),
+                RS_Vector::maximum(sol.get(2), sol.get(3))
+                    );
+}
+
+RS_VectorSolutions RS_Image::getCorners() const {
+        RS_VectorSolutions sol(4);
+
+        sol.set(0, data.insertionPoint);
+        sol.set(1,
+                data.insertionPoint + data.uVector*RS_Math::round(data.size.x));
+        sol.set(3,
+                data.insertionPoint + data.vVector*RS_Math::round(data.size.y));
+        sol.set(2, sol.get(3) + data.uVector*RS_Math::round(data.size.x));
+
+        return sol;
+}
+
+/**
+  * whether a given point is within image region
+  *@ coord, a point
+  *@ returns true, if the point is within borders of image
+  */
+bool RS_Image::containsPoint(const RS_Vector& coord) const{
+    QPolygonF paf;
+    RS_VectorSolutions corners =getCorners();
+	for(const RS_Vector& vp: corners){
+		paf.push_back(QPointF(vp.x, vp.y));
+    }
+    paf.push_back(paf.at(0));
+    return paf.containsPoint(QPointF(coord.x,coord.y),Qt::OddEvenFill);
+}
+
+RS_Vector RS_Image::getNearestEndpoint(const RS_Vector& coord,
+                                       double* dist) const {
+    RS_VectorSolutions corners =getCorners();
+    return corners.getClosest(coord, dist);
+}
+
+
+
+RS_Vector RS_Image::getNearestPointOnEntity(const RS_Vector& coord,
+        bool onEntity, double* dist, RS_Entity** entity) const{
+
+    if (entity) {
+        *entity = const_cast<RS_Image*>(this);
+    }
+
+	RS_VectorSolutions const& corners =getCorners();
+    //allow selecting image by clicking within images, bug#3464626
+    if(containsPoint(coord)){
+        //if coord is within image
+        if(dist) *dist=0.;
+        return coord;
+    }
+	RS_VectorSolutions points;
+	for (size_t i=0; i < corners.size(); ++i){
+		size_t const j = (i+1)%corners.size();
+		RS_Line const l{corners.at(i), corners.at(j)};
+		RS_Vector const vp = l.getNearestPointOnEntity(coord, onEntity);
+		points.push_back(vp);
+	}
+
+	return points.getClosest(coord, dist);
+}
+
+
+
+RS_Vector RS_Image::getNearestCenter(const RS_Vector& coord,
+									 double* dist) const{
+
+	RS_VectorSolutions const& corners{getCorners()};
+    //bug#485, there's no clear reason to ignore snapping to center within an image
+//    if(containsPoint(coord)){
+//        //if coord is within image
+//        if(dist) *dist=0.;
+//        return coord;
+//    }
+
+	RS_VectorSolutions points;
+	for (size_t i=0; i < corners.size(); ++i) {
+		size_t const j = (i+1)%corners.size();
+		points.push_back((corners.get(i) + corners.get(j))*0.5);
+	}
+	points.push_back((corners.get(0) + corners.get(2))*0.5);
+
+    return points.getClosest(coord, dist);
+}
+
+
+/*
+ * ToDo, implement middlePoints
+ */
+RS_Vector RS_Image::getNearestMiddle(const RS_Vector& coord,
+                                     double* dist,
+                                     const int /*middlePoints*/) const{
+	return getNearestCenter(coord, dist);
+}
+
+
+
+RS_Vector RS_Image::getNearestDist(double distance,
+                                   const RS_Vector& coord,
+								   double* dist) const{
+
+	RS_VectorSolutions const& corners = getCorners();
+	RS_VectorSolutions points;
+
+	for (size_t i = 0; i < corners.size(); ++i){
+		size_t const j = (i+1)%corners.size();
+		RS_Line const l{corners.get(i), corners.get(j)};
+		RS_Vector const& vp = l.getNearestDist(distance, coord, dist);
+		points.push_back(vp);
+	}
+
+    return points.getClosest(coord, dist);
+}
+
+
+
+double RS_Image::getDistanceToPoint(const RS_Vector& coord,
+                                    RS_Entity** entity,
+                                    RS2::ResolveLevel /*level*/,
+                                                                        double /*solidDist*/) const{
+    if (entity) {
+        *entity = const_cast<RS_Image*>(this);
+    }
+
+    RS_VectorSolutions corners = getCorners();
+
+    //allow selecting image by clicking within images, bug#3464626
+	if(containsPoint(coord)){
+		//if coord is on image
+
+		RS_SETTINGS->beginGroup("/Appearance");
+		bool draftMode = (bool)RS_SETTINGS->readNumEntry("/DraftMode", 0);
+		RS_SETTINGS->endGroup();
+		if(!draftMode) return double(0.);
+	}
+    //continue to allow selecting by image edges
+    double minDist = RS_MAXDOUBLE;
+
+	for (size_t i = 0; i < corners.size(); ++i){
+		size_t const j = (i+1)%corners.size();
+		RS_Line const l{corners.get(i), corners.get(j)};
+		double const dist = l.getDistanceToPoint(coord, nullptr);
+		minDist = std::min(minDist, dist);
+	}
+
+    return minDist;
+}
+
+
+
+void RS_Image::move(const RS_Vector& offset) {
+    data.insertionPoint.move(offset);
+    moveBorders(offset);
+}
+
+
+
+void RS_Image::rotate(const RS_Vector& center, const double& angle) {
+    RS_Vector angleVector(angle);
+    data.insertionPoint.rotate(center, angleVector);
+    data.uVector.rotate(angleVector);
+    data.vVector.rotate(angleVector);
+    calculateBorders();
+}
+
+void RS_Image::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    data.insertionPoint.rotate(center, angleVector);
+    data.uVector.rotate(angleVector);
+    data.vVector.rotate(angleVector);
+    calculateBorders();
+}
+
+
+void RS_Image::scale(const RS_Vector& center, const RS_Vector& factor) {
+    data.insertionPoint.scale(center, factor);
+    data.uVector.scale(factor);
+    data.vVector.scale(factor);
+    scaleBorders(center,factor);
+}
+
+
+
+void RS_Image::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    data.insertionPoint.mirror(axisPoint1, axisPoint2);
+    RS_Vector vp0(0.,0.);
+    RS_Vector vp1( axisPoint2-axisPoint1 );
+    data.uVector.mirror(vp0,vp1);
+    data.vVector.mirror(vp0,vp1);
+    calculateBorders();
+}
+
+
+
+void RS_Image::draw(RS_Painter* painter, RS_GraphicView* view, double& /*patternOffset*/) {
+	if (!(painter && view) || !img.get() || img->isNull())
+		return;
+
+    // erase image:
+    //if (painter->getPen().getColor()==view->getBackground()) {
+    //	RS_VectorSolutions sol = getCorners();
+    //
+    //}
+
+	RS_Vector scale{view->toGuiDX(data.uVector.magnitude()),
+								view->toGuiDY(data.vVector.magnitude())};
+    double angle = data.uVector.angle();
+
+	painter->drawImg(*img,
+                     view->toGui(data.insertionPoint),
+                     angle, scale);
+
+    if (isSelected() && !(view->isPrinting() || view->isPrintPreview())) {
+        RS_VectorSolutions sol = getCorners();
+		for (size_t i = 0; i < sol.size(); ++i){
+			size_t const j = (i+1)%sol.size();
+			painter->drawLine(view->toGui(sol.get(i)), view->toGui(sol.get(j)));
+		}
+    }
+}
+
+
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Image& i) {
+    os << " Image: " << i.getData() << "\n";
+    return os;
+}
+

lib/engine/rs_image.h

@@ -0,0 +1,229 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+#ifndef RS_IMAGE_H
+#define RS_IMAGE_H
+
+#include <memory>
+#include "rs_atomicentity.h"
+
+class QImage;
+
+/**
+ * Holds the data that defines a line.
+ */
+struct RS_ImageData {
+    /**
+     * Default constructor. Leaves the data object uninitialized.
+     */
+	RS_ImageData() = default;
+
+    RS_ImageData(int handle,
+                                const RS_Vector& insertionPoint,
+                const RS_Vector& uVector,
+                                const RS_Vector& vVector,
+                                const RS_Vector& size,
+                                const QString& file,
+                                int brightness,
+                                int contrast,
+								int fade);
+
+	/** Handle of image definition. */
+	int handle;
+	/** Insertion point. */
+	RS_Vector insertionPoint;
+	/** u vector. Points along visual bottom of image. */
+	RS_Vector uVector;
+	/** v vector. Points along visual left of image. */
+	RS_Vector vVector;
+	/** Image size in pixel. */
+	RS_Vector size;
+	/** Path to image file. */
+	QString file;
+	/** Brightness (0..100, default: 50). */
+	int brightness;
+	/** Contrast (0..100, default: 50). */
+	int contrast;
+	/** Fade (0..100, default: 0). */
+	int fade;
+};
+
+
+
+/**
+ * Class for a line entity.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Image : public RS_AtomicEntity {
+public:
+    RS_Image(RS_EntityContainer* parent,
+            const RS_ImageData& d);
+	RS_Image(const RS_Image& _image);
+	RS_Image(RS_Image&& _image);
+	RS_Image& operator = (const RS_Image& _image);
+	RS_Image& operator = (RS_Image&& _image);
+
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityImage */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityImage;
+    }
+
+		void update() override;
+
+    /** @return Copy of data that defines the image. */
+    RS_ImageData getData() const {
+        return data;
+    }
+
+    /** @return Insertion point of the entity */
+	RS_Vector getInsertionPoint() const {
+        return data.insertionPoint;
+    }
+    /** Sets the insertion point for the image. */
+    void setInsertionPoint(RS_Vector ip) {
+        data.insertionPoint = ip;
+        calculateBorders();
+    }
+
+    /** Update image data ONLY for plugins. */
+    void updateData(RS_Vector size, RS_Vector Uv, RS_Vector Vv);
+
+        /** @return File name of the image. */
+        QString getFile() const {
+                return data.file;
+        }
+
+        /** Sets the file name of the image.  */
+        void setFile(const QString& file) {
+                data.file = file;
+        }
+
+        /** @return u Vector. Points along bottom, 1 pixel long. */
+        RS_Vector getUVector() const {
+                return data.uVector;
+        }
+        /** @return v Vector. Points along left, 1 pixel long. */
+        RS_Vector getVVector() const {
+                return data.vVector;
+        }
+        /** @return Width of image in pixels. */
+        int getWidth() const {
+                return (int)data.size.x;
+        }
+        /** @return Height of image in pixels. */
+        int getHeight() const {
+                return (int)data.size.y;
+        }
+        /** @return Brightness. */
+        int getBrightness() const {
+                return data.brightness;
+        }
+        /** @return Contrast. */
+        int getContrast() const {
+                return data.contrast;
+        }
+        /** @return Fade. */
+        int getFade() const {
+                return data.fade;
+        }
+        /** @return Image definition handle. */
+        int getHandle() const {
+                return data.handle;
+        }
+        /** Sets the image definition handle. */
+        void setHandle(int h) {
+                data.handle = h;
+        }
+
+
+        /** @return The four corners. **/
+        RS_VectorSolutions getCorners() const;
+
+        /**
+         * @return image with in graphic units.
+         */
+        double getImageWidth() {
+                return data.size.x * data.uVector.magnitude();
+        }
+
+        /**
+         * @return image height in graphic units.
+         */
+        double getImageHeight() {
+                return data.size.y * data.vVector.magnitude();
+        }
+
+
+	RS_Vector getNearestEndpoint(const RS_Vector& coord,
+										 double* dist = NULL)const override;
+	RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+			bool onEntity=true, double* dist = NULL, RS_Entity** entity=NULL)const override;
+	RS_Vector getNearestCenter(const RS_Vector& coord,
+									   double* dist = NULL)const override;
+	RS_Vector getNearestMiddle(const RS_Vector& coord,
+                                       double* dist = NULL,
+									   int middlePoints=1)const override;
+	RS_Vector getNearestDist(double distance,
+                                     const RS_Vector& coord,
+									 double* dist = NULL)const override;
+	double getDistanceToPoint(const RS_Vector& coord,
+                                      RS_Entity** entity=NULL,
+                                      RS2::ResolveLevel level=RS2::ResolveNone,
+							  double solidDist = RS_MAXDOUBLE) const override;
+
+//        double getLength() const {
+//                return -1.0;
+//        }
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	/*void stretch(RS_Vector firstCorner,
+                         RS_Vector secondCorner,
+                         RS_Vector offset);*/
+
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Image& l);
+
+	void calculateBorders() override;
+
+
+protected:
+	// whether the point is within image
+	bool containsPoint(const RS_Vector& coord) const;
+	RS_ImageData data;
+	std::unique_ptr<QImage> img;
+        //QImage** img;
+        //int nx;
+        //int ny;
+};
+
+#endif

lib/engine/rs_insert.cpp

@@ -0,0 +1,397 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include<cmath>
+#include "rs_insert.h"
+
+#include "rs_arc.h"
+#include "rs_circle.h"
+#include "rs_ellipse.h"
+#include "rs_block.h"
+#include "rs_graphic.h"
+#include "rs_layer.h"
+#include "rs_math.h"
+#include "rs_debug.h"
+
+RS_InsertData::RS_InsertData(const QString& _name,
+							 RS_Vector _insertionPoint,
+							 RS_Vector _scaleFactor,
+							 double _angle,
+							 int _cols, int _rows, RS_Vector _spacing,
+							 RS_BlockList* _blockSource ,
+							 RS2::UpdateMode _updateMode ):
+	name(_name)
+  ,insertionPoint(_insertionPoint)
+  ,scaleFactor(_scaleFactor)
+  ,angle(_angle)
+  ,cols(_cols)
+  ,rows(_rows)
+  ,spacing(_spacing)
+  ,blockSource(_blockSource)
+  ,updateMode(_updateMode)
+{
+}
+
+std::ostream& operator << (std::ostream& os,
+									 const RS_InsertData& d) {
+	   os << "(" << d.name.toLatin1().data() << ")";
+	   return os;
+   }
+/**
+ * @param parent The graphic this block belongs to.
+ */
+RS_Insert::RS_Insert(RS_EntityContainer* parent,
+                     const RS_InsertData& d)
+        : RS_EntityContainer(parent), data(d) {
+
+		block = nullptr;
+
+    if (data.updateMode!=RS2::NoUpdate) {
+        update();
+        //calculateBorders();
+    }
+}
+
+
+RS_Entity* RS_Insert::clone() const{
+	RS_Insert* i = new RS_Insert(*this);
+	i->setOwner(isOwner());
+	i->initId();
+	i->detach();
+	return i;
+}
+
+
+/**
+ * Updates the entity buffer of this insert entity. This method
+ * needs to be called whenever the block this insert is based on changes.
+ */
+void RS_Insert::update() {
+
+        RS_DEBUG->print("RS_Insert::update");
+        RS_DEBUG->print("RS_Insert::update: name: %s", data.name.toLatin1().data());
+//        RS_DEBUG->print("RS_Insert::update: insertionPoint: %f/%f",
+//                data.insertionPoint.x, data.insertionPoint.y);
+
+        if (updateEnabled==false) {
+                return;
+        }
+
+    clear();
+
+    RS_Block* blk = getBlockForInsert();
+	if (!blk) {
+		//return nullptr;
+				RS_DEBUG->print("RS_Insert::update: Block is nullptr");
+        return;
+    }
+
+    if (isUndone()) {
+                RS_DEBUG->print("RS_Insert::update: Insert is in undo list");
+        return;
+    }
+
+        if (fabs(data.scaleFactor.x)<1.0e-6 || fabs(data.scaleFactor.y)<1.0e-6) {
+                RS_DEBUG->print("RS_Insert::update: scale factor is 0");
+                return;
+        }
+
+    RS_Pen tmpPen;
+
+        /*QListIterator<RS_Entity> it = createIterator();
+    RS_Entity* e;
+	while ( (e = it.current())  ) {
+        ++it;*/
+
+        RS_DEBUG->print("RS_Insert::update: cols: %d, rows: %d",
+                data.cols, data.rows);
+        RS_DEBUG->print("RS_Insert::update: block has %d entities",
+                blk->count());
+//int i_en_counts=0;
+		for(auto e: *blk){
+        for (int c=0; c<data.cols; ++c) {
+//            RS_DEBUG->print("RS_Insert::update: col %d", c);
+            for (int r=0; r<data.rows; ++r) {
+//                i_en_counts++;
+//                RS_DEBUG->print("RS_Insert::update: row %d", r);
+
+                if (e->rtti()==RS2::EntityInsert &&
+                    data.updateMode!=RS2::PreviewUpdate) {
+
+//                                        RS_DEBUG->print("RS_Insert::update: updating sub-insert");
+					static_cast<RS_Insert*>(e)->update();
+                }
+
+//                                RS_DEBUG->print("RS_Insert::update: cloning entity");
+
+                RS_Entity* ne;
+                if ( (data.scaleFactor.x - data.scaleFactor.y)>1.0e-6) {
+                    if (e->rtti()== RS2::EntityArc) {
+						RS_Arc* a= static_cast<RS_Arc*>(e);
+						ne = new RS_Ellipse{this,
+						{a->getCenter(), {a->getRadius(), 0.},
+								1, a->getAngle1(), a->getAngle2(),
+								a->isReversed()}
+					};
+                        ne->setLayer(e->getLayer());
+                        ne->setPen(e->getPen(false));
+                    } else if (e->rtti()== RS2::EntityCircle) {
+						RS_Circle* a= static_cast<RS_Circle*>(e);
+						ne = new RS_Ellipse{this,
+						{ a->getCenter(), {a->getRadius(), 0.}, 1, 0., 2.*M_PI, false}
+					};
+                        ne->setLayer(e->getLayer());
+                        ne->setPen(e->getPen(false));
+                    } else
+                        ne = e->clone();
+                } else
+                    ne = e->clone();
+                ne->initId();
+                ne->setUpdateEnabled(false);
+                // if entity layer are 0 set to insert layer to allow "1 layer control" bug ID #3602152
+                RS_Layer *l= ne->getLayer();//special fontchar block don't have
+				if (l  && ne->getLayer()->getName() == "0")
+                    ne->setLayer(this->getLayer());
+                ne->setParent(this);
+                ne->setVisible(getFlag(RS2::FlagVisible));
+
+//                                RS_DEBUG->print("RS_Insert::update: transforming entity");
+
+                // Move:
+//                                RS_DEBUG->print("RS_Insert::update: move 1");
+                if (fabs(data.scaleFactor.x)>1.0e-6 &&
+                        fabs(data.scaleFactor.y)>1.0e-6) {
+                    ne->move(data.insertionPoint +
+                             RS_Vector(data.spacing.x/data.scaleFactor.x*c,
+                                       data.spacing.y/data.scaleFactor.y*r));
+                }
+                else {
+                    ne->move(data.insertionPoint);
+                }
+                // Move because of block base point:
+//                                RS_DEBUG->print("RS_Insert::update: move 2");
+                ne->move(blk->getBasePoint()*-1);
+                // Scale:
+//                                RS_DEBUG->print("RS_Insert::update: scale");
+                ne->scale(data.insertionPoint, data.scaleFactor);
+                // Rotate:
+//                                RS_DEBUG->print("RS_Insert::update: rotate");
+                ne->rotate(data.insertionPoint, data.angle);
+                // Select:
+                ne->setSelected(isSelected());
+
+                // individual entities can be on indiv. layers
+                tmpPen = ne->getPen(false);
+
+                // color from block (free floating):
+                if (tmpPen.getColor()==RS_Color(RS2::FlagByBlock)) {
+                    tmpPen.setColor(getPen().getColor());
+                }
+
+                // line width from block (free floating):
+                if (tmpPen.getWidth()==RS2::WidthByBlock) {
+                    tmpPen.setWidth(getPen().getWidth());
+                }
+
+                // line type from block (free floating):
+                if (tmpPen.getLineType()==RS2::LineByBlock) {
+                    tmpPen.setLineType(getPen().getLineType());
+                }
+
+                // now that we've evaluated all flags, let's strip them:
+                // TODO: strip all flags (width, line type)
+                //tmpPen.setColor(tmpPen.getColor().stripFlags());
+
+                ne->setPen(tmpPen);
+
+                ne->setUpdateEnabled(true);
+
+                // insert must be updated even in preview mode
+                if (data.updateMode != RS2::PreviewUpdate
+                        || ne->rtti() == RS2::EntityInsert) {
+                    //RS_DEBUG->print("RS_Insert::update: updating new entity");
+                    ne->update();
+                }
+
+//                                RS_DEBUG->print("RS_Insert::update: adding new entity");
+                appendEntity(ne);
+//                std::cout<<"done # of entity: "<<i_en_counts<<std::endl;
+            }
+        }
+    }
+    calculateBorders();
+
+        RS_DEBUG->print("RS_Insert::update: OK");
+}
+
+
+
+/**
+ * @return Pointer to the block associated with this Insert or
+ *   nullptr if the block couldn't be found. Blocks are requested
+ *   from the blockSource if one was supplied and otherwise from
+ *   the closest parent graphic.
+ */
+RS_Block* RS_Insert::getBlockForInsert() const{
+	RS_Block* blk = nullptr;
+		if (block) {
+			blk=block;
+			return blk;
+        }
+
+    RS_BlockList* blkList;
+
+	if (!data.blockSource) {
+		if (getGraphic()) {
+            blkList = getGraphic()->getBlockList();
+        } else {
+			blkList = nullptr;
+        }
+    } else {
+        blkList = data.blockSource;
+    }
+
+	if (blkList) {
+        blk = blkList->find(data.name);
+    }
+
+	if (blk) {
+    }
+
+        block = blk;
+
+    return blk;
+}
+
+
+/**
+ * Is this insert visible? (re-implementation from RS_Entity)
+ *
+ * @return true Only if the entity and the block and the layer it is on
+ * are visible.
+ * The Layer might also be nullptr. In that case the layer visibility
+ * is ignored.
+ * The Block might also be nullptr. In that case the block visibility
+ * is ignored.
+ */
+bool RS_Insert::isVisible() const
+{
+    RS_Block* blk = getBlockForInsert();
+	if (blk) {
+        if (blk->isFrozen()) {
+            return false;
+        }
+    }
+
+    return RS_Entity::isVisible();
+}
+
+
+RS_VectorSolutions RS_Insert::getRefPoints() const
+{
+	return RS_VectorSolutions{data.insertionPoint};
+}
+
+
+
+RS_Vector RS_Insert::getNearestRef(const RS_Vector& coord,
+									 double* dist) const{
+
+        return getRefPoints().getClosest(coord, dist);
+}
+
+
+
+void RS_Insert::move(const RS_Vector& offset) {
+        RS_DEBUG->print("RS_Insert::move: offset: %f/%f",
+                offset.x, offset.y);
+        RS_DEBUG->print("RS_Insert::move1: insertionPoint: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y);
+    data.insertionPoint.move(offset);
+        RS_DEBUG->print("RS_Insert::move2: insertionPoint: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y);
+    update();
+}
+
+
+
+void RS_Insert::rotate(const RS_Vector& center, const double& angle) {
+        RS_DEBUG->print("RS_Insert::rotate1: insertionPoint: %f/%f "
+            "/ center: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y,
+                center.x, center.y);
+    data.insertionPoint.rotate(center, angle);
+    data.angle = RS_Math::correctAngle(data.angle+angle);
+        RS_DEBUG->print("RS_Insert::rotate2: insertionPoint: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y);
+    update();
+}
+void RS_Insert::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+        RS_DEBUG->print("RS_Insert::rotate1: insertionPoint: %f/%f "
+            "/ center: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y,
+                center.x, center.y);
+    data.insertionPoint.rotate(center, angleVector);
+    data.angle = RS_Math::correctAngle(data.angle+angleVector.angle());
+        RS_DEBUG->print("RS_Insert::rotate2: insertionPoint: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y);
+    update();
+}
+
+
+
+void RS_Insert::scale(const RS_Vector& center, const RS_Vector& factor) {
+        RS_DEBUG->print("RS_Insert::scale1: insertionPoint: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y);
+    data.insertionPoint.scale(center, factor);
+    data.scaleFactor.scale(RS_Vector(0.0, 0.0), factor);
+    data.spacing.scale(RS_Vector(0.0, 0.0), factor);
+        RS_DEBUG->print("RS_Insert::scale2: insertionPoint: %f/%f",
+                data.insertionPoint.x, data.insertionPoint.y);
+    update();
+}
+
+
+
+void RS_Insert::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    data.insertionPoint.mirror(axisPoint1, axisPoint2);
+
+		RS_Vector vec = RS_Vector::polar(1.0, data.angle);
+        vec.mirror(RS_Vector(0.0,0.0), axisPoint2-axisPoint1);
+        data.angle = RS_Math::correctAngle(vec.angle()-M_PI);
+
+        data.scaleFactor.x*=-1;
+
+    update();
+}
+
+
+std::ostream& operator << (std::ostream& os, const RS_Insert& i) {
+    os << " Insert: " << i.getData() << std::endl;
+    return os;
+}
+

lib/engine/rs_insert.h

@@ -0,0 +1,197 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_INSERT_H
+#define RS_INSERT_H
+
+#include "rs_entitycontainer.h"
+
+class RS_BlockList;
+
+/**
+ * Holds the data that defines an insert.
+ */
+struct RS_InsertData {
+	/**
+		 * Default constructor.
+		 */
+	RS_InsertData() = default;
+	~RS_InsertData() = default;
+
+	/**
+	 * @param name The name of the block used as an identifier.
+	 * @param insertionPoint Insertion point of the block.
+	 * @param scaleFactor Scale factor in x / y.
+	 * @param angle Rotation angle.
+	 * @param cols Number of cols if we insert a whole array.
+	 * @param rows Number of rows if we insert a whole array.
+	 * @param spacing Spacing between rows and cols.
+	 * @param blockSource Source for the block to insert if other than parent.
+	 *    Normally blocks are requested from the entity's parent but the
+	 *    block can also come from another resource. RS_Text uses that
+	 *    to share the blocks (letters) from a font.
+	 * @param updateMode RS2::Update will update the insert entity instantly
+	 *    RS2::NoUpdate will not update the insert. You can update
+	 *	  it later manually using the update() method. This is
+	 *    often the case since you might want to adjust attributes
+	 *    after creating an insert entity.
+	 */
+	RS_InsertData(const QString& name,
+				  RS_Vector insertionPoint,
+				  RS_Vector scaleFactor,
+				  double angle,
+				  int cols, int rows, RS_Vector spacing,
+				  RS_BlockList* blockSource = NULL,
+				  RS2::UpdateMode updateMode = RS2::Update);
+
+	QString name;
+	RS_Vector insertionPoint;
+	RS_Vector scaleFactor;
+	double angle;
+	int cols, rows;
+	RS_Vector spacing;
+	RS_BlockList* blockSource;
+	RS2::UpdateMode updateMode;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_InsertData& d);
+
+/**
+ * An insert inserts a block into the drawing at a certain location
+ * with certain attributes (angle, scale, ...).
+ * Inserts don't really contain other entities internally. They just
+ * refer to a block. However, to the outside world they act exactly
+ * like EntityContainer.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Insert : public RS_EntityContainer {
+public:
+    RS_Insert(RS_EntityContainer* parent,
+              const RS_InsertData& d);
+	virtual ~RS_Insert() = default;
+
+	virtual RS_Entity* clone() const;
+
+    /** @return RS2::EntityInsert */
+    virtual RS2::EntityType rtti() const {
+        return RS2::EntityInsert;
+    }
+
+    /** @return Copy of data that defines the insert. **/
+    RS_InsertData getData() const {
+        return data;
+    }
+
+        /**
+         * Reimplementation of reparent. Invalidates block cache pointer.
+         */
+    virtual void reparent(RS_EntityContainer* parent) {
+                RS_Entity::reparent(parent);
+                block = NULL;
+    }
+
+	RS_Block* getBlockForInsert() const;
+
+    virtual void update();
+
+    QString getName() const {
+        return data.name;
+    }
+
+        void setName(const QString& newName) {
+                data.name = newName;
+                update();
+        }
+
+    RS_Vector getInsertionPoint() const {
+        return data.insertionPoint;
+    }
+    void setInsertionPoint(const RS_Vector& i) {
+        data.insertionPoint = i;
+    }
+
+    RS_Vector getScale() const {
+        return data.scaleFactor;
+    }
+
+        void setScale(const RS_Vector& s) {
+                data.scaleFactor = s;
+        }
+
+    double getAngle() const {
+        return data.angle;
+    }
+    void setAngle(double a) {
+        data.angle = a;
+    }
+
+    int getCols() const {
+        return data.cols;
+    }
+        void setCols(int c) {
+                data.cols = c;
+        }
+
+    int getRows() const {
+        return data.rows;
+    }
+        void setRows(int r) {
+                data.rows = r;
+        }
+
+    RS_Vector getSpacing() const {
+        return data.spacing;
+    }
+        void setSpacing(const RS_Vector& s) {
+                data.spacing = s;
+        }
+
+	virtual bool isVisible() const;
+
+	virtual RS_VectorSolutions getRefPoints() const;
+    virtual RS_Vector getMiddlePoint(void) const{
+            return RS_Vector(false);
+    }
+    virtual RS_Vector getNearestRef(const RS_Vector& coord,
+									 double* dist = nullptr) const;
+
+    virtual void move(const RS_Vector& offset);
+    virtual void rotate(const RS_Vector& center, const double& angle);
+    virtual void rotate(const RS_Vector& center, const RS_Vector& angleVector);
+    virtual void scale(const RS_Vector& center, const RS_Vector& factor);
+    virtual void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2);
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Insert& i);
+
+protected:
+    RS_InsertData data;
+	mutable RS_Block* block;
+};
+
+
+#endif

lib/engine/rs_layer.cpp

@@ -0,0 +1,233 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include <iostream>
+#include <QString>
+#include "rs_layer.h"
+
+RS_LayerData::RS_LayerData(const QString& name,
+						   const RS_Pen& pen,
+						   bool frozen,
+						   bool locked):
+	name(name)
+  ,pen(pen)
+  ,frozen(frozen)
+  ,locked(locked)
+{
+}
+
+/**
+ * Constructor.
+ */
+RS_Layer::RS_Layer(const QString& name):
+	data(name, RS_Pen(Qt::black, RS2::Width00,RS2::SolidLine), false, false)
+{
+}
+
+RS_Layer* RS_Layer::clone() const{
+	return new RS_Layer(*this);
+}
+
+/** sets a new name for this layer. */
+void RS_Layer::setName(const QString& name) {
+	data.name = name;
+}
+
+/** @return the name of this layer. */
+QString RS_Layer::getName() const {
+	return data.name;
+}
+
+/** sets the default pen for this layer. */
+void RS_Layer::setPen(const RS_Pen& pen) {
+	data.pen = pen;
+}
+
+/** @return default pen for this layer. */
+RS_Pen RS_Layer::getPen() const {
+	return data.pen;
+}
+
+/**
+ * @retval true if this layer is frozen (invisible)
+ * @retval false if this layer isn't frozen (visible)
+ */
+bool RS_Layer::isFrozen() const {
+	return data.frozen;
+	//getFlag(RS2::FlagFrozen);
+}
+
+/**
+ * @retval true the layer has been converted already
+ * @retval false the layer still needs to be converted
+ */
+bool RS_Layer::isConverted() const {
+	return data.converted;
+}
+
+/**
+ * Sets the converted flag
+ */
+void RS_Layer::setConverted(bool c) {
+	data.converted = c;
+}
+
+/**
+ * Toggles the visibility of this layer.
+ * Freezes the layer if it's not frozen, thaws the layer otherwise
+ */
+void RS_Layer::toggle() {
+	//toggleFlag(RS2::FlagFrozen);
+	data.frozen = !data.frozen;
+}
+
+/**
+ * (De-)freezes this layer.
+ *
+ * @param freeze true: freeze, false: defreeze
+ */
+void RS_Layer::freeze(bool freeze) {
+	data.frozen = freeze;
+}
+
+/**
+ * Toggles the lock of this layer.
+ */
+void RS_Layer::toggleLock() {
+	//toggleFlag(RS2::FlagFrozen);
+	data.locked = !data.locked;
+}
+
+/**
+ * Toggles printing of this layer on / off.
+ */
+void RS_Layer::togglePrint() {
+	data.print = !data.print;
+}
+
+/**
+ * Toggles construction attribute of this layer on / off.
+ */
+void RS_Layer::toggleConstruction() {
+	data.construction = !data.construction;
+}
+
+/**
+ * Locks/Unlocks this layer.
+ *
+ * @param l true: lock, false: unlock
+ */
+void RS_Layer::lock(bool l) {
+	data.locked = l;
+}
+
+/**
+ * return the LOCK state of the Layer
+ */
+bool RS_Layer::isLocked() const{
+	return data.locked;
+}
+
+/**
+ * set visibility of layer in layer list
+ *
+ * @param l true: visible, false: invisible
+ */
+void RS_Layer::visibleInLayerList(bool l) {
+	data.visibleInLayerList = l;
+}
+
+/**
+ * return the visibility of the Layer in layer list
+ */
+bool RS_Layer::isVisibleInLayerList() const{
+	return data.visibleInLayerList;
+}
+
+/**
+ * set selection state of the layer in layer list
+ *
+ * @param val true: selected, false: deselected
+ */
+void RS_Layer::selectedInLayerList(bool val) {
+	data.selectedInLayerList = val;
+}
+
+/**
+ * return selection state of the layer in layer list
+ */
+bool RS_Layer::isSelectedInLayerList() const {
+	return data.selectedInLayerList;
+}
+
+/**
+ * set the PRINT state of the Layer
+ *
+ * @param print true: print layer, false: don't print layer
+ */
+bool RS_Layer::setPrint( const bool print) {
+	return data.print = print;
+}
+
+/**
+ * return the PRINT state of the Layer
+ */
+bool RS_Layer::isPrint() const{
+	return data.print;
+}
+
+/**
+ * whether the layer is a construction layer
+ * The construction layer property is stored
+ * in extended data in the DXF layer table
+ */
+bool RS_Layer::isConstruction() const{
+	return data.construction;
+}
+
+/**
+ * set the construction attribute for the layer
+ *
+ * @param construction true: infinite lines, false: normal layer
+ */
+bool RS_Layer::setConstruction( const bool construction){
+	data.construction = construction;
+	return construction;
+}
+
+/**
+ * Dumps the layers data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Layer& l) {
+    os << " name: " << l.getName().toLatin1().data()
+    << " pen: " << l.getPen()
+    << " frozen: " << (int)l.isFrozen()
+    << " address: " << &l
+    << std::endl;
+    return os;
+}
+

lib/engine/rs_layer.h

@@ -0,0 +1,206 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_LAYER_H
+#define RS_LAYER_H
+
+#ifdef __hpux
+#include <sys/_size_t.h>
+#endif
+
+#include <iosfwd>
+
+#include "rs_pen.h"
+
+class QString;
+
+/**
+ * Holds the data that defines a layer.
+ */
+struct RS_LayerData {
+    RS_LayerData() = default;
+
+    RS_LayerData(const QString& name,
+                 const RS_Pen& pen,
+                 bool frozen,
+                 bool locked);
+
+    QString name;                   //!< Layer name
+    RS_Pen pen;                     //!< default pen for this layer
+    bool frozen {false};            //!< Frozen flag
+    bool locked {false};            //!< Locked flag
+    bool print {true};              //!< Print flag
+    bool converted {false};         //!< Converted flag (CAM)
+    bool construction {false};      //!< a construction layer has entities of infinite length
+                                    //!< and will never be printed out
+    bool visibleInLayerList {true}; //!< visible in layer list
+    bool selectedInLayerList {false}; //!< selected in layer list
+};
+
+
+
+/**
+ * Class for representing a layer
+ *
+ * @author Andrew Mustun
+ */
+class RS_Layer {
+public:
+    explicit RS_Layer(const QString& name);
+    //RS_Layer(const char* name);
+
+	RS_Layer* clone() const;
+
+    /** sets a new name for this layer. */
+	void setName(const QString& name);
+
+    /** @return the name of this layer. */
+	QString getName() const;
+
+    /** sets the default pen for this layer. */
+	void setPen(const RS_Pen& pen);
+
+    /** @return default pen for this layer. */
+	RS_Pen getPen() const;
+
+    /**
+     * @retval true if this layer is frozen (invisible)
+     * @retval false if this layer isn't frozen (visible)
+     */
+	bool isFrozen() const;
+
+    /**
+     * @retval true the layer has been converted already
+     * @retval false the layer still needs to be converted
+     */
+	bool isConverted() const;
+
+    /**
+     * Sets the converted flag
+     */
+	void setConverted(bool c);
+
+    /**
+     * Toggles the visibility of this layer.
+     * Freezes the layer if it's not frozen, thaws the layer otherwise
+     */
+	void toggle();
+
+    /**
+     * (De-)freezes this layer.
+     *
+     * @param freeze true: freeze, false: defreeze
+     */
+	void freeze(bool freeze);
+
+    /**
+     * Toggles the lock of this layer.
+     */
+	void toggleLock();
+
+    /**
+     * Toggles printing of this layer on / off.
+     */
+	void togglePrint();
+
+    /**
+     * Toggles construction attribute of this layer on / off.
+     */
+	void toggleConstruction();
+
+    /**
+     * Locks/Unlocks this layer.
+     *
+     * @param l true: lock, false: unlock
+     */
+	void lock(bool l);
+
+    /**
+     * return the LOCK state of the Layer
+     */
+	bool isLocked() const;
+
+    /**
+     * set visibility of layer in layer list
+     *
+     * @param l true: visible, false: invisible
+     */
+	void visibleInLayerList(bool l);
+
+    /**
+     * return the visibility of the Layer in layer list
+     */
+	bool isVisibleInLayerList() const;
+
+    /**
+     * set selection state of the layer in layer list
+     *
+     * @param val true: selected, false: deselected
+     */
+    void selectedInLayerList(bool val);
+
+    /**
+     * return selection state of the layer in layer list
+     */
+    bool isSelectedInLayerList() const;
+
+    /**
+     * set the PRINT state of the Layer
+     *
+     * @param print true: print layer, false: don't print layer
+     */
+	bool setPrint( const bool print);
+
+    /**
+     * return the PRINT state of the Layer
+     */
+	bool isPrint() const;
+
+    /**
+     * whether the layer is a construction layer
+     * The construction layer property is stored
+     * in extended data in the DXF layer table
+     */
+	bool isConstruction() const;
+
+    /**
+     * set the construction attribute for the layer
+     *
+     * @param construction true: infinite lines, false: normal layer
+     */
+	bool setConstruction( const bool construction);
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Layer& l);
+
+private:
+    //! Layer data
+    RS_LayerData data;
+
+};
+
+#endif

lib/engine/rs_layerlist.cpp

@@ -0,0 +1,496 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include<iostream>
+#include "rs_debug.h"
+#include "rs_layerlist.h"
+#include "rs_layer.h"
+#include "rs_layerlistlistener.h"
+
+/**
+ * Default constructor.
+ */
+RS_LayerList::RS_LayerList() {
+    activeLayer = NULL;
+	setModified(false);
+}
+
+
+
+/**
+ * Removes all layers in the layerlist.
+ */
+void RS_LayerList::clear() {
+    layers.clear();
+	setModified(true);
+}
+
+
+QList<RS_Layer*>::iterator RS_LayerList::begin()
+{
+    return layers.begin();
+}
+
+QList<RS_Layer*>::iterator RS_LayerList::end()
+{
+    return layers.end();
+}
+
+QList<RS_Layer*>::const_iterator RS_LayerList::begin()const
+{
+    return layers.begin();
+}
+
+QList<RS_Layer*>::const_iterator RS_LayerList::end()const
+{
+    return layers.end();
+}
+
+
+
+/**
+ * Activates the given layer.
+ * 
+ * @param notify Notify listeners.
+ */
+void RS_LayerList::activate(const QString& name, bool notify) {
+    RS_DEBUG->print("RS_LayerList::activate: %s, notify: %d begin",
+                                    name.toLatin1().data(), notify);
+
+    activate(find(name), notify);
+    /*
+    if (activeLayer==NULL) {
+        RS_DEBUG->print("activeLayer is NULL");
+} else {
+        RS_DEBUG->print("activeLayer is %s", activeLayer->getName().latin1());
+}
+    */
+
+    RS_DEBUG->print("RS_LayerList::activate: %s end", name.toLatin1().data());
+}
+
+
+
+/**
+ * Activates the given layer.
+ * 
+ * @param notify Notify listeners.
+ */
+void RS_LayerList::activate(RS_Layer* layer, bool notify) {
+    RS_DEBUG->print("RS_LayerList::activate notify: %d begin", notify);
+
+    /*if (layer) {
+        RS_DEBUG->print("RS_LayerList::activate: %s",
+                        layer->getName().latin1());
+} else {
+        RS_DEBUG->print("RS_LayerList::activate: NULL");
+}*/
+
+    activeLayer = layer;
+
+    if (notify) {
+       for (int i=0; i<layerListListeners.size(); ++i) {
+           RS_LayerListListener* l = layerListListeners.at(i);
+
+           l->layerActivated(activeLayer);
+		   RS_DEBUG->print("RS_LayerList::activate listener notified");
+       }
+    }
+
+    RS_DEBUG->print("RS_LayerList::activate end");
+}
+
+
+/**
+ * @brief sort by layer names
+ */
+void RS_LayerList::sort()
+{
+    std::stable_sort(layers.begin(), layers.end(), [](const RS_Layer* l0, const RS_Layer* l1 )->bool{
+                         return l0->getName() < l1->getName();
+                     });
+}
+
+/**
+ * Adds a layer to the layer list.
+ * If there is already a layer with the same name, no layer is 
+ * added. In that case the layer passed to the method will be deleted!
+ * If no layer was active so far, the new layer becomes the active one.
+ *
+ * Listeners are notified.
+ */
+void RS_LayerList::add(RS_Layer* layer) {
+    RS_DEBUG->print("RS_LayerList::addLayer()");
+
+    if (layer==NULL) {
+        return;
+    }
+
+    // check if layer already exists:
+    RS_Layer* l = find(layer->getName());
+    if (l==NULL) {
+        layers.append(layer);
+        this->sort();
+        // notify listeners
+        for (int i=0; i<layerListListeners.size(); ++i) {
+            RS_LayerListListener* l = layerListListeners.at(i);
+            l->layerAdded(layer);
+        }
+		setModified(true);
+
+        // if there was no active layer so far, activate this one.
+        if (activeLayer==NULL) {
+            activate(layer);
+        }
+    } else {
+        // if there was no active layer so far, activate this one.
+        if (activeLayer==NULL) {
+            activate(l);
+        }
+
+        l->freeze( layer->isFrozen());
+        l->lock( layer->isLocked());
+        l->setPrint( layer->isPrint());
+        l->setConverted( layer->isConverted());
+        l->setConstruction( layer->isConstruction());
+        l->visibleInLayerList( layer->isVisibleInLayerList());
+        l->setPen(layer->getPen());
+
+        delete layer;
+        layer = NULL;
+    }
+}
+
+
+
+/**
+ * Removes a layer from the list.
+ * Listeners are notified after the layer was removed from 
+ * the list but before it gets deleted.
+ */
+void RS_LayerList::remove(RS_Layer* layer) {
+    RS_DEBUG->print("RS_LayerList::removeLayer()");
+    if (layer==NULL) {
+        return;
+    }
+
+    // here the layer is removed from the list but not deleted
+    layers.removeOne(layer);
+
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+        l->layerRemoved(layer);
+    }
+		
+	setModified(true);
+
+    // activate an other layer if necessary:
+    if (activeLayer==layer) {
+        activate(layers.first());
+    }
+
+    // now it's save to delete the layer
+    delete layer;
+}
+
+
+
+/**
+ * Changes a layer's attributes. The attributes of layer 'layer'
+ * are copied from layer 'source'.
+ * Listeners are notified.
+ */
+void RS_LayerList::edit(RS_Layer* layer, const RS_Layer& source) {
+    if (layer==NULL) {
+        return;
+    }
+
+    *layer = source;
+
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+
+        l->layerEdited(layer);
+    }
+	
+	setModified(true);
+}
+
+
+
+/**
+ * @return Pointer to the layer with the given name or
+ * \p NULL if no such layer was found.
+ */
+RS_Layer* RS_LayerList::find(const QString& name) {
+    //RS_DEBUG->print("RS_LayerList::find begin");
+
+    RS_Layer* ret = NULL;
+
+    for (int i=0; i<layers.size(); ++i) {
+        RS_Layer* l = layers.at(i);
+        if (l->getName()==name) {
+            ret = l;
+            break;
+        }
+    }
+
+    //RS_DEBUG->print("RS_LayerList::find end");
+
+    return ret;
+}
+
+
+
+/**
+ * @return Index of the given layer in the layer list or -1 if the layer
+ * was not found.
+ */
+int RS_LayerList::getIndex(const QString& name) {
+    //RS_DEBUG->print("RS_LayerList::find begin");
+
+    int ret = -1;
+
+    for (int i=0; i<layers.size(); i++) {
+        RS_Layer* l = layers.at(i);
+
+        if (l->getName()==name) {
+            ret = i;
+            break;
+        }
+    }
+
+    //RS_DEBUG->print("RS_LayerList::find end");
+
+    return ret;
+}
+
+
+/**
+ * @return Index of the given layer in the layer list or -1 if the layer
+ * was not found.
+ */
+int RS_LayerList::getIndex(RS_Layer* layer) {
+    //RS_DEBUG->print("RS_LayerList::find begin");
+    return layers.indexOf(layer);
+}
+
+
+/**
+ * Switches on / off the given layer. 
+ * Listeners are notified.
+ */
+void RS_LayerList::toggle(const QString& name) {
+    toggle(find(name));
+}
+
+
+
+/**
+ * Switches on / off the given layer. 
+ * Listeners are notified.
+ */
+void RS_LayerList::toggle(RS_Layer* layer) {
+
+    if (!layer) {
+        RS_DEBUG->print(RS_Debug::D_ERROR, "RS_LayerList::toggle: nullptr layer");
+        return;
+    }
+
+    // set flags
+    layer->toggle();
+    setModified(true);
+
+    // Notify listeners:
+    for (auto *i : layerListListeners) {
+
+        if (!i) {
+            RS_DEBUG->print(RS_Debug::D_WARNING, "RS_LayerList::toggle: nullptr layer listener");
+            continue;
+        }
+
+        RS_LayerListListener *l = (RS_LayerListListener *)i;
+        l->layerToggled(layer);
+    }
+}
+
+
+
+/**
+ * Locks or unlocks the given layer.
+ * Listeners are notified.
+ */
+void RS_LayerList::toggleLock(RS_Layer* layer) {
+    if (layer==NULL) {
+        return;
+    }
+
+    layer->toggleLock();
+    setModified(true);
+
+    // Notify listeners:
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+        l->layerToggledLock(layer);
+    }
+}
+
+
+
+/**
+ * Switch printing for the given layer on / off.
+ * Listeners are notified.
+ */
+void RS_LayerList::togglePrint(RS_Layer* layer) {
+    if (layer==NULL) {
+        return;
+    }
+
+    layer->togglePrint();
+    setModified(true);
+
+    // Notify listeners:
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+        l->layerToggledPrint(layer);
+    }
+}
+
+
+/**
+ * Switch construction attribute for the given layer on / off.
+ * Listeners are notified.
+ */
+void RS_LayerList::toggleConstruction(RS_Layer* layer) {
+    if (layer==NULL) {
+        return;
+    }
+
+    layer->toggleConstruction();
+    setModified(true);
+
+    // Notify listeners:
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+        l->layerToggledConstruction(layer);
+    }
+}
+
+
+
+/**
+ * Freezes or defreezes all layers.
+ *
+ * @param freeze true: freeze, false: defreeze
+ */
+void RS_LayerList::freezeAll(bool freeze) {
+
+    for (unsigned l=0; l<count(); l++) {
+        if (at(l)->isVisibleInLayerList()) {
+             at(l)->freeze(freeze);
+         }
+    }
+    setModified(true);
+
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+        l->layerToggled(NULL);
+    }
+}
+
+
+
+/**
+ * Locks or unlocks all layers.
+ *
+ * @param lock true: lock, false: unlock
+ */
+void RS_LayerList::lockAll(bool lock) {
+
+    for (unsigned l=0; l<count(); l++) {
+        if (at(l)->isVisibleInLayerList()) {
+             at(l)->lock(lock);
+         }
+    }
+    setModified(true);
+
+    for (int i=0; i<layerListListeners.size(); ++i) {
+        RS_LayerListListener* l = layerListListeners.at(i);
+        l->layerToggled(NULL);
+    }
+}
+
+
+
+/**
+ * adds a LayerListListener to the list of listeners. Listeners
+ * are notified when the layer list changes.
+ *
+ * Typical listeners are: layer list widgets, pen toolbar, graphic view
+ */
+void RS_LayerList::addListener(RS_LayerListListener* listener) {
+    layerListListeners.append(listener);
+}
+
+
+
+/**
+ * removes a LayerListListener from the list of listeners. 
+ */
+void RS_LayerList::removeListener(RS_LayerListListener* listener) {
+    layerListListeners.removeOne(listener);
+}
+
+
+
+/**
+ * Dumps the layers to stdout.
+ */
+std::ostream& operator << (std::ostream& os, RS_LayerList& l) {
+
+    os << "Layerlist: \n";
+    for (unsigned i=0; i<l.count(); i++) {
+        os << *(l.at(i)) << "\n";
+    }
+
+    return os;
+}
+
+
+/**
+ * Sets the layer lists modified status to 'm'.
+ * Listeners are notified.
+ */
+void RS_LayerList::setModified(bool m) {
+    modified = m;
+
+    // Notify listeners
+    for (auto l: layerListListeners) {
+        l->layerListModified(m);
+    }
+}
+

lib/engine/rs_layerlist.h

@@ -0,0 +1,141 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_LAYERLIST_H
+#define RS_LAYERLIST_H
+
+#include <QList>
+#include "rs_layer.h"
+
+class RS_LayerListListener;
+class QG_LayerWidget;
+
+/**
+ * A list of layers.
+ *
+ * @author Andrew Mustun
+ */
+class RS_LayerList {
+public:
+    RS_LayerList();
+	virtual ~RS_LayerList() = default;
+
+    void clear();
+
+    /**
+     * @return Number of layers in the list.
+     */
+    unsigned int count() const {
+        return layers.count();
+    }
+
+    /**
+     * @return Layer at given position or NULL if i is out of range.
+     */
+    RS_Layer* at(unsigned int i) {
+        return layers.at(i);
+    }
+    QList<RS_Layer*>::iterator begin();
+    QList<RS_Layer*>::iterator end();
+    QList<RS_Layer*>::const_iterator begin()const;
+    QList<RS_Layer*>::const_iterator end()const;
+
+    void activate(const QString& name, bool notify = false);
+    void activate(RS_Layer* layer, bool notify = false);
+    //! @return The active layer of NULL if no layer is activated.
+    RS_Layer* getActive() {
+        return activeLayer;
+    }
+    virtual void add(RS_Layer* layer);
+    virtual void remove(RS_Layer* layer);
+    virtual void edit(RS_Layer* layer, const RS_Layer& source);
+    RS_Layer* find(const QString& name);
+    int getIndex(const QString& name);
+    int getIndex(RS_Layer* layer);
+    void toggle(const QString& name);
+    void toggle(RS_Layer* layer);
+    void toggleLock(RS_Layer* layer);
+    void togglePrint(RS_Layer* layer);
+    void toggleConstruction(RS_Layer* layer);
+    void freezeAll(bool freeze);
+    void lockAll(bool lock);
+
+    //! sets the layerWidget pointer in RS_LayerListClass
+    void setLayerWitget(QG_LayerWidget * lw) {
+        layerWidget=lw;
+    }
+    //! @return the layerWidget pointer inside the RS_LayerListClass
+    QG_LayerWidget* getLayerWitget() {
+        return layerWidget;
+    }
+    //! @return First layer of the list.
+    //RS_Layer* firstLayer() {
+    //    return layers.first();
+    //}
+    /** @return Next layer from the list after
+     * calling firstLayer() or nextLayer().
+     */
+    //RS_Layer* nextLayer() {
+    //    return layers.next();
+    //}
+
+    void addListener(RS_LayerListListener* listener);
+    void removeListener(RS_LayerListListener* listener);
+
+    /**
+     * Sets the layer lists modified status to 'm'.
+     */
+    void setModified(bool m);
+
+    /**
+     * @retval true The layer list has been modified.
+     * @retval false The layer list has not been modified.
+     */
+    virtual bool isModified() const {
+        return modified;
+    }
+    /**
+     * @brief sort by layer names
+     */
+    void sort();
+
+    friend std::ostream& operator << (std::ostream& os, RS_LayerList& l);
+
+private:
+    //! layers in the graphic
+    QList<RS_Layer*> layers;
+    //! List of registered LayerListListeners
+    QList<RS_LayerListListener*> layerListListeners;
+    QG_LayerWidget* layerWidget;
+    //! Currently active layer
+    RS_Layer* activeLayer;
+    /** Flag set if the layer list was modified and not yet saved. */
+    bool modified;
+};
+
+#endif

lib/engine/rs_layerlistlistener.h

@@ -0,0 +1,90 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_LAYERLISTLISTENER_H
+#define RS_LAYERLISTLISTENER_H
+
+#include "rs_layer.h"
+
+/**
+ * This class is an interface for classes that are interested in
+ * knowing about changes in the layer list. 
+ */
+class RS_LayerListListener {
+public:
+    RS_LayerListListener() {}
+    virtual ~RS_LayerListListener() {}
+
+    /**
+     * Called when the active layer changes.
+     */
+    virtual void layerActivated(RS_Layer*) {}
+
+    /**
+     * Called when a new layer is added to the list.
+     */
+    virtual void layerAdded(RS_Layer*) {}
+
+    /**
+     * Called when a layer is removed from the list.
+     */
+    virtual void layerRemoved(RS_Layer*) {}
+
+    /**
+     * Called when a layer's attributes are modified.
+     */
+    virtual void layerEdited(RS_Layer*) {}
+
+    /**
+     * Called when a layer's visibility is toggled.
+     */
+    virtual void layerToggled(RS_Layer*) {}
+
+    /**
+     * Called when a layer's lock attribute is toggled.
+     */
+    virtual void layerToggledLock(RS_Layer*) {}
+
+    /**
+     * Called when a layer's printing attribute is toggled.
+     */
+    virtual void layerToggledPrint(RS_Layer*) {}
+
+    /**
+     * Called when a layer's construction attribute is toggled.
+     */
+    virtual void layerToggledConstruction(RS_Layer*) {}
+
+    /**
+     * Called when layer list is modified.
+     */
+    virtual void layerListModified(bool) {}
+}
+;
+
+#endif

lib/engine/rs_leader.cpp

@@ -0,0 +1,214 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include "rs_leader.h"
+
+#include "rs_debug.h"
+#include "rs_line.h"
+#include "rs_solid.h"
+
+
+/**
+ * Constructor.
+ */
+RS_Leader::RS_Leader(RS_EntityContainer* parent)
+		:RS_EntityContainer(parent)
+		,empty(true)
+{
+}
+
+
+/**
+ * Constructor.
+ * @param d Leader data
+ */
+RS_Leader::RS_Leader(RS_EntityContainer* parent,
+                     const RS_LeaderData& d)
+        :RS_EntityContainer(parent), data(d) {
+    empty = true;
+}
+
+RS_Entity* RS_Leader::clone() const{
+	RS_Leader* p = new RS_Leader(*this);
+	p->setOwner(isOwner());
+	p->initId();
+	p->detach();
+	return p;
+}
+
+/**
+ * Implementation of update. Updates the arrow.
+ */
+void RS_Leader::update() {
+
+    // find and delete arrow:
+	for(auto e: entities){
+        if (e->rtti()==RS2::EntitySolid) {
+            removeEntity(e);
+            break;
+        }
+    }
+
+        if (isUndone()) {
+                return;
+        }
+
+    RS_Entity* fe = firstEntity();
+    if (fe && fe->isAtomic()) {
+        RS_Vector p1 = ((RS_AtomicEntity*)fe)->getStartpoint();
+        RS_Vector p2 = ((RS_AtomicEntity*)fe)->getEndpoint();
+
+        // first entity must be the line which gets the arrow:
+        if (hasArrowHead()) {
+            RS_Solid* s = new RS_Solid(this, RS_SolidData());
+            s->shapeArrow(p1,
+                          p2.angleTo(p1),
+                          getGraphicVariableDouble("$DIMASZ", 2.5)* getGraphicVariableDouble("$DIMSCALE", 1.0));
+            s->setPen(RS_Pen(RS2::FlagInvalid));
+			s->setLayer(nullptr);
+            RS_EntityContainer::addEntity(s);
+        }
+    }
+    calculateBorders();
+}
+
+
+
+/**
+ * Adds a vertex from the endpoint of the last element or
+ * sets the startpoint to the point 'v'.
+ *
+ * The very first vertex added is the starting point.
+ *
+ * @param v vertex coordinate
+ *
+ * @return Pointer to the entity that was added or nullptr if this
+ *         was the first vertex added.
+ */
+RS_Entity* RS_Leader::addVertex(const RS_Vector& v) {
+
+	RS_Entity* entity{nullptr};
+	static RS_Vector last = RS_Vector{false};
+
+    if (empty) {
+        last = v;
+        empty = false;
+    } else {
+        // add line to the leader:
+		entity = new RS_Line{this, {last, v}};
+        entity->setPen(RS_Pen(RS2::FlagInvalid));
+		entity->setLayer(nullptr);
+        RS_EntityContainer::addEntity(entity);
+
+                if (count()==1 && hasArrowHead()) {
+                        update();
+                }
+
+        last = v;
+    }
+
+    return entity;
+}
+
+
+
+/**
+ * Reimplementation of the addEntity method for a normal container.
+ * This reimplementation deletes the given entity!
+ *
+ * To add entities use addVertex() instead.
+ */
+void RS_Leader::addEntity(RS_Entity* entity) {
+    RS_DEBUG->print(RS_Debug::D_WARNING, "RS_Leader::addEntity:"
+                    " should never be called");
+
+	if (!entity) return;
+
+	delete entity;
+}
+
+
+
+void RS_Leader::move(const RS_Vector& offset) {
+    RS_EntityContainer::move(offset);
+    update();
+}
+
+
+
+void RS_Leader::rotate(const RS_Vector& center, const double& angle) {
+    RS_EntityContainer::rotate(center, angle);
+    update();
+}
+
+
+void RS_Leader::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_EntityContainer::rotate(center, angleVector);
+    update();
+}
+
+
+void RS_Leader::scale(const RS_Vector& center, const RS_Vector& factor) {
+    RS_EntityContainer::scale(center, factor);
+    update();
+}
+
+
+
+void RS_Leader::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    RS_EntityContainer::mirror(axisPoint1, axisPoint2);
+    update();
+}
+
+
+void RS_Leader::stretch(const RS_Vector& firstCorner,
+                       const RS_Vector& secondCorner,
+                       const RS_Vector& offset) {
+
+    RS_EntityContainer::stretch(firstCorner, secondCorner, offset);
+    update();
+}
+
+/**
+ * Dumps the leader's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Leader& l) {
+    os << " Leader: " << l.getData() << " {\n";
+
+    os << (RS_EntityContainer&)l;
+
+    os << "\n}\n";
+
+    return os;
+}
+
+std::ostream& operator << (std::ostream& os,
+                                      const RS_LeaderData& /*ld*/) {
+        os << "(Leader)";
+        return os;
+}
+

lib/engine/rs_leader.h

@@ -0,0 +1,109 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_LEADER_H
+#define RS_LEADER_H
+
+#include "rs_entity.h"
+#include "rs_entitycontainer.h"
+
+
+
+/**
+ * Holds the data that defines a leader.
+ */
+class RS_LeaderData {
+public:
+	RS_LeaderData() = default;
+	RS_LeaderData(bool arrowHeadFlag) {
+		arrowHead = arrowHeadFlag;
+	}
+
+	friend std::ostream& operator << (std::ostream& os,
+									  const RS_LeaderData& /*ld*/);
+
+	/** true: leader has an arrow head. false: no arrow. */
+	bool arrowHead;
+};
+
+
+
+/**
+ * Class for a leader entity (kind of a polyline arrow).
+ *
+ * @author Andrew Mustun
+ */
+class RS_Leader : public RS_EntityContainer {
+public:
+	RS_Leader(RS_EntityContainer* parent=NULL);
+	RS_Leader(RS_EntityContainer* parent,
+			  const RS_LeaderData& d);
+
+	RS_Entity* clone() const override;
+
+	/**	@return RS2::EntityDimLeader */
+	RS2::EntityType rtti() const override{
+		return RS2::EntityDimLeader;
+	}
+
+	void update() override;
+
+	/** @return Copy of data that defines the leader. */
+	RS_LeaderData getData() const {
+		return data;
+	}
+
+	/** @return true: if this leader has an arrow at the beginning. */
+	bool hasArrowHead() {
+		return data.arrowHead;
+	}
+
+	RS_Entity* addVertex(const RS_Vector& v);
+	void addEntity(RS_Entity* entity) override;
+
+	//	double getLength() const {
+	//		return -1.0;
+	//	}
+
+
+	void move(const RS_Vector& offset) override;
+	void rotate(const RS_Vector& center, const double& angle) override;
+	void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+	void scale(const RS_Vector& center, const RS_Vector& factor) override;
+	void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+	void stretch(const RS_Vector& firstCorner,
+				 const RS_Vector& secondCorner,
+				 const RS_Vector& offset) override;
+
+	friend std::ostream& operator << (std::ostream& os, const RS_Leader& l);
+
+protected:
+	RS_LeaderData data;
+	bool empty;
+};
+
+#endif

lib/engine/rs_line.cpp

@@ -0,0 +1,789 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2015-2018 A. Stebich (librecad@mail.lordofbikes.de)
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include "rs_line.h"
+
+#include "rs_debug.h"
+#include "rs_graphicview.h"
+#include "rs_painter.h"
+#include "rs_graphic.h"
+#include "rs_linetypepattern.h"
+#include "rs_information.h"
+#include "lc_quadratic.h"
+#include "rs_painterqt.h"
+#include "rs_circle.h"
+#include "lc_rect.h"
+
+#ifdef EMU_C99
+#include "emu_c99.h"
+#endif
+
+std::ostream& operator << (std::ostream& os, const RS_LineData& ld) {
+	os << "RS_LINE: ((" << ld.startpoint <<
+		  ")(" << ld.endpoint <<
+		  "))";
+	return os;
+}
+
+/**
+ * Constructor.
+ */
+RS_Line::RS_Line(RS_EntityContainer* parent,
+                 const RS_LineData& d)
+    :RS_AtomicEntity(parent), data(d) {
+    calculateBorders();
+}
+
+////construct a line from two endpoints
+RS_Line::RS_Line(RS_EntityContainer* parent, const RS_Vector& pStart, const RS_Vector& pEnd)
+	:RS_AtomicEntity(parent), data({pStart,pEnd}) {
+    calculateBorders();
+}
+
+////construct a line from two endpoints, to be used for construction
+RS_Line::RS_Line(const RS_Vector& pStart, const RS_Vector& pEnd)
+	:RS_AtomicEntity(nullptr), data({pStart,pEnd}) {
+    calculateBorders();
+}
+
+
+RS_Entity* RS_Line::clone() const {
+	RS_Line* l = new RS_Line(*this);
+	l->initId();
+	return l;
+}
+
+
+
+void RS_Line::calculateBorders() {
+    minV = RS_Vector::minimum(data.startpoint, data.endpoint);
+    maxV = RS_Vector::maximum(data.startpoint, data.endpoint);
+}
+
+
+
+RS_VectorSolutions RS_Line::getRefPoints() const
+{
+	return RS_VectorSolutions({data.startpoint, data.endpoint});
+}
+
+
+RS_Vector RS_Line::getNearestEndpoint(const RS_Vector& coord,
+                                      double* dist)const {
+    double dist1((data.startpoint-coord).squared());
+    double dist2((data.endpoint-coord).squared());
+
+    if (dist2<dist1) {
+		if (dist) {
+            *dist = sqrt(dist2);
+        }
+        return data.endpoint;
+    } else {
+		if (dist) {
+            *dist = sqrt(dist1);
+        }
+        return data.startpoint;
+    }
+
+}
+
+/**
+ *  This is similar to getNearestPointOnEntity, but only returns the value of
+ *  the position of the projection.  The value may be negative, or greater than
+ *  the length of the line since there are no bounds checking.  The absolute
+ *  value of the return value represents a physical distance from the
+ *  startpoint.
+ *
+ *  @param coord The point which will be projected onto the line.
+ */
+double RS_Line::getProjectionValueAlongLine(const RS_Vector& coord) const
+{
+    RS_Vector direction {data.endpoint - data.startpoint};
+    RS_Vector vpc {coord - data.startpoint};
+    double direction_magnitude {direction.magnitude()};
+    double v = 0.0;
+
+    if(direction_magnitude > RS_TOLERANCE2) {
+        //find projection on line
+        v = RS_Vector::dotP(vpc, direction) / direction_magnitude;
+    }
+
+    return v;
+}
+
+RS_Vector RS_Line::getNearestPointOnEntity(const RS_Vector& coord,
+                                           bool onEntity,
+                                           double* dist,
+                                           RS_Entity** entity) const
+{
+    if (entity) {
+        *entity = const_cast<RS_Line*>(this);
+    }
+
+    RS_Vector direction {data.endpoint - data.startpoint};
+    RS_Vector vpc {coord - data.startpoint};
+    double a {direction.squared()};
+
+    if( a < RS_TOLERANCE2) {
+        //line too short
+        vpc = getMiddlePoint();
+    }
+    else {
+        //find projection on line
+        const double t {RS_Vector::dotP( vpc, direction) / a};
+        if( !isConstruction()
+            && onEntity
+            && ( t <= -RS_TOLERANCE
+                 || t >= 1. + RS_TOLERANCE ) ) {
+            //projection point not within range, find the nearest endpoint
+            return getNearestEndpoint( coord, dist);
+        }
+
+        vpc = data.startpoint + direction * t;
+    }
+
+    if (dist) {
+        *dist = vpc.distanceTo( coord);
+    }
+
+    return vpc;
+}
+
+/*
+RS_Vector RS_Line::getPointOnEntityAlongLine(const RS_Vector& coord,const double angle,
+                                           bool onEntity,
+                                           double* dist,
+                                           RS_Entity** entity) const
+{
+    if (entity)
+    {
+        *entity = const_cast<RS_Line*>(this);
+    }
+
+
+    RS_Vector direction {data.endpoint - data.startpoint};
+    RS_Vector vpc {coord - data.startpoint};
+    double a {direction.squared()};
+
+    if( a < RS_TOLERANCE2)
+    {
+        //line too short
+        vpc = getMiddlePoint();
+    }
+    else
+    {
+        //find projection on line
+        const double t {RS_Vector::dotP( vpc, direction) / a};
+        if( !isConstruction()   && onEntity  && ( t <= -RS_TOLERANCE || t >= 1. + RS_TOLERANCE ) )
+        {
+            //projection point not within range, find the nearest endpoint
+            return getNearestEndpoint( coord, dist);
+        }
+
+        vpc = data.startpoint + direction * t;
+    }
+
+    if (dist)
+    {
+        *dist = vpc.distanceTo( coord);
+    }
+
+    return vpc;
+}
+*/
+
+
+RS_Vector RS_Line::getMiddlePoint()const
+{
+        return (getStartpoint() + getEndpoint())*0.5;
+}
+    /** @return the nearest of equidistant middle points of the line. */
+    RS_Vector RS_Line::getNearestMiddle(const RS_Vector& coord,
+                                        double* dist,
+                                        int middlePoints
+                                        )const {
+//        RS_DEBUG->print("RS_Line::getNearestMiddle(): begin\n");
+        RS_Vector dvp(getEndpoint() - getStartpoint());
+        double l=dvp.magnitude();
+        if( l<= RS_TOLERANCE) {
+            //line too short
+            return const_cast<RS_Line*>(this)->getNearestCenter(coord, dist);
+        }
+        RS_Vector vp0(getNearestPointOnEntity(coord,true,dist));
+        int counts=middlePoints+1;
+        int i( static_cast<int>(vp0.distanceTo(getStartpoint())/l*counts+0.5));
+        if(!i) i++; // remove end points
+        if(i==counts) i--;
+        vp0=getStartpoint() + dvp*(double(i)/double(counts));
+
+		if (dist) {
+            *dist=vp0.distanceTo(coord);
+        }
+//        RS_DEBUG->print("RS_Line::getNearestMiddle(): end\n");
+        return vp0;
+    }
+
+
+//RS_Vector RS_Line::getNearestCenter(const RS_Vector& coord,
+//                                    double* dist) {
+
+//    RS_Vector p = (data.startpoint + data.endpoint)*0.5;
+
+//    if (dist) {
+//        *dist = p.distanceTo(coord);
+//    }
+
+//    return p;
+//}
+
+
+RS_Vector RS_Line::getNearestDist(double distance,
+                                  const RS_Vector& coord,
+								  double* dist) const{
+
+	RS_Vector dv = RS_Vector::polar(distance, getAngle1());
+
+    RS_Vector ret;
+    //if(coord.distanceTo(getStartpoint()) < coord.distanceTo(getEndpoint())) {
+    if( (coord-getStartpoint()).squared()<  (coord-getEndpoint()).squared() ) {
+        ret = getStartpoint() + dv;
+    }else{
+        ret = getEndpoint() - dv;
+    }
+	if (dist)
+        *dist=coord.distanceTo(ret);
+
+    return ret;
+}
+
+
+
+RS_Vector RS_Line::getNearestDist(double distance,
+								  bool startp) const{
+
+    double a1 = getAngle1();
+
+	RS_Vector dv = RS_Vector::polar(distance, a1);
+    RS_Vector ret;
+
+    if (startp) {
+        ret = data.startpoint + dv;
+    }
+    else {
+        ret = data.endpoint - dv;
+    }
+
+    return ret;
+
+}
+
+
+/*RS_Vector RS_Line::getNearestRef(const RS_Vector& coord,
+                                 double* dist) {
+    double d1, d2, d;
+    RS_Vector p;
+    RS_Vector p1 = getNearestEndpoint(coord, &d1);
+    RS_Vector p2 = getNearestMiddle(coord, &d2);
+
+    if (d1<d2) {
+        d = d1;
+        p = p1;
+    } else {
+        d = d2;
+        p = p2;
+    }
+
+	if (dist) {
+        *dist = d;
+    }
+
+    return p;
+}*/
+
+
+
+/** return the equation of the entity
+for quadratic,
+
+return a vector contains:
+m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+
+for linear:
+m0 x + m1 y + m2 =0
+**/
+LC_Quadratic RS_Line::getQuadratic() const
+{
+    std::vector<double> ce(3,0.);
+	auto dvp=data.endpoint - data.startpoint;
+    RS_Vector normal(-dvp.y,dvp.x);
+    ce[0]=normal.x;
+    ce[1]=normal.y;
+    ce[2]= -normal.dotP(data.endpoint);
+    return LC_Quadratic(ce);
+}
+
+double RS_Line::areaLineIntegral() const
+{
+    return 0.5*(data.endpoint.y - data.startpoint.y)*(data.startpoint.x + data.endpoint.x);
+}
+
+
+RS_Vector  RS_Line::getTangentDirection(const RS_Vector& /*point*/)const{
+        return getEndpoint() - getStartpoint();
+}
+
+void RS_Line::moveStartpoint(const RS_Vector& pos) {
+    data.startpoint = pos;
+    calculateBorders();
+}
+
+
+
+void RS_Line::moveEndpoint(const RS_Vector& pos) {
+    data.endpoint = pos;
+    calculateBorders();
+}
+
+
+
+RS_Vector RS_Line::prepareTrim(const RS_Vector& trimCoord,
+                               const RS_VectorSolutions& trimSol) {
+//prepare trimming for multiple intersections
+    if ( ! trimSol.hasValid()) return(RS_Vector(false));
+    if ( trimSol.getNumber() == 1 ) return(trimSol.get(0));
+	auto vp0=trimSol.getClosest(trimCoord, nullptr, 0);
+
+    double dr2=trimCoord.squaredTo(vp0);
+    //the trim point found is closer to mouse location (trimCoord) than both end points, return this trim point
+    if(dr2 < trimCoord.squaredTo(getStartpoint()) && dr2 < trimCoord.squaredTo(getEndpoint())) return vp0;
+    //the closer endpoint to trimCoord
+    RS_Vector vp1=(trimCoord.squaredTo(getStartpoint()) <= trimCoord.squaredTo(getEndpoint()))?getStartpoint():getEndpoint();
+
+    //searching for intersection in the direction of the closer end point
+	auto dvp1=vp1 - trimCoord;
+    RS_VectorSolutions sol1;
+    for(size_t i=0; i<trimSol.size(); i++){
+		auto dvp2=trimSol.at(i) - trimCoord;
+		if( RS_Vector::dotP(dvp1, dvp2) > RS_TOLERANCE)
+			sol1.push_back(trimSol.at(i));
+    }
+    //if found intersection in direction, return the closest to trimCoord from it
+	if(sol1.size())
+		return sol1.getClosest(trimCoord, nullptr, 0);
+
+    //no intersection by direction, return previously found closest intersection
+    return vp0;
+}
+
+RS2::Ending RS_Line::getTrimPoint(const RS_Vector& trimCoord,
+                                  const RS_Vector& trimPoint) {
+    RS_Vector vp1=getStartpoint() - trimCoord;
+    RS_Vector vp2=trimPoint - trimCoord;
+    if ( RS_Vector::dotP(vp1,vp2) < 0 ) {
+        return RS2::EndingEnd;
+    } else {
+        return RS2::EndingStart;
+    }
+}
+
+
+void RS_Line::reverse() {
+    std::swap(data.startpoint, data.endpoint);
+}
+
+
+
+bool RS_Line::hasEndpointsWithinWindow(const RS_Vector& firstCorner, const RS_Vector& secondCorner) {
+    RS_Vector vLow( std::min(firstCorner.x, secondCorner.x), std::min(firstCorner.y, secondCorner.y));
+    RS_Vector vHigh( std::max(firstCorner.x, secondCorner.x), std::max(firstCorner.y, secondCorner.y));
+
+    return data.startpoint.isInWindowOrdered(vLow, vHigh)
+            || data.endpoint.isInWindowOrdered(vLow, vHigh);
+
+}
+
+/**
+  * this function creates offset
+  *@coord, position indicates the direction of offset
+  *@distance, distance of offset
+  * return true, if success, otherwise, false
+  *
+  *Author: Dongxu Li
+  */
+bool RS_Line::offset(const RS_Vector& coord, const double& distance) {
+	RS_Vector direction{getEndpoint()-getStartpoint()};
+    double ds(direction.magnitude());
+    if(ds< RS_TOLERANCE) return false;
+    direction /= ds;
+    RS_Vector vp(coord-getStartpoint());
+//    RS_Vector vp1(getStartpoint() + direction*(RS_Vector::dotP(direction,vp))); //projection
+    direction.set(-direction.y,direction.x); //rotate pi/2
+    if(RS_Vector::dotP(direction,vp)<0.) {
+        direction *= -1.;
+    }
+    direction*=distance;
+    move(direction);
+    return true;
+}
+
+bool RS_Line::isTangent(const RS_CircleData&  circleData) const{
+    double d;
+	getNearestPointOnEntity(circleData.center,false,&d);
+	if(fabs(d-circleData.radius)<20.*RS_TOLERANCE) return true;
+    return false;
+}
+
+RS_Vector RS_Line::getNormalVector() const
+{
+    RS_Vector vp=data.endpoint  - data.startpoint; //direction vector
+	double r=vp.magnitude();
+	if (r< RS_TOLERANCE) return RS_Vector{false};
+	return RS_Vector{-vp.y,vp.x}/r;
+}
+
+std::vector<RS_Entity* > RS_Line::offsetTwoSides(const double& distance) const
+{
+	std::vector<RS_Entity*> ret(0);
+	RS_Vector const& vp=getNormalVector()*distance;
+	ret.push_back(new RS_Line{data.startpoint+vp,data.endpoint+vp});
+	ret.push_back(new RS_Line{data.startpoint-vp,data.endpoint-vp});
+	return ret;
+}
+
+/**
+  * revert the direction of line
+  */
+void RS_Line::revertDirection(){
+    std::swap(data.startpoint,data.endpoint);
+}
+
+void RS_Line::move(const RS_Vector& offset) {
+//    RS_DEBUG->print("RS_Line::move1: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+
+//    RS_DEBUG->print("RS_Line::move1: offset: %f/%f", offset.x, offset.y);
+
+    data.startpoint.move(offset);
+    data.endpoint.move(offset);
+    moveBorders(offset);
+//    RS_DEBUG->print("RS_Line::move2: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+}
+
+void RS_Line::rotate(const double& angle) {
+//    RS_DEBUG->print("RS_Line::rotate");
+//    RS_DEBUG->print("RS_Line::rotate1: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    RS_Vector rvp(angle);
+    data.startpoint.rotate(rvp);
+    data.endpoint.rotate(rvp);
+//    RS_DEBUG->print("RS_Line::rotate2: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    calculateBorders();
+//    RS_DEBUG->print("RS_Line::rotate: OK");
+}
+
+
+
+void RS_Line::rotate(const RS_Vector& center, const double& angle) {
+//    RS_DEBUG->print("RS_Line::rotate");
+//    RS_DEBUG->print("RS_Line::rotate1: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    RS_Vector rvp(angle);
+    data.startpoint.rotate(center, rvp);
+    data.endpoint.rotate(center, rvp);
+//    RS_DEBUG->print("RS_Line::rotate2: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    calculateBorders();
+//    RS_DEBUG->print("RS_Line::rotate: OK");
+}
+
+void RS_Line::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    data.startpoint.rotate(center, angleVector);
+    data.endpoint.rotate(center, angleVector);
+    calculateBorders();
+}
+
+/*scale the line around origin (0,0)
+  *
+  */
+void RS_Line::scale(const RS_Vector& factor) {
+//    RS_DEBUG->print("RS_Line::scale1: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    data.startpoint.scale(factor);
+    data.endpoint.scale(factor);
+//    RS_DEBUG->print("RS_Line::scale2: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    calculateBorders();
+}
+
+
+void RS_Line::scale(const RS_Vector& center, const RS_Vector& factor) {
+//    RS_DEBUG->print("RS_Line::scale1: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    data.startpoint.scale(center, factor);
+    data.endpoint.scale(center, factor);
+//    RS_DEBUG->print("RS_Line::scale2: sp: %f/%f, ep: %f/%f",
+//                    data.startpoint.x, data.startpoint.y,
+//                    data.endpoint.x, data.endpoint.y);
+    calculateBorders();
+}
+
+
+
+void RS_Line::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    data.startpoint.mirror(axisPoint1, axisPoint2);
+    data.endpoint.mirror(axisPoint1, axisPoint2);
+    calculateBorders();
+}
+
+
+/**
+ * Stretches the given range of the entity by the given offset.
+ */
+void RS_Line::stretch(const RS_Vector& firstCorner,
+                      const RS_Vector& secondCorner,
+                      const RS_Vector& offset) {
+
+	RS_Vector const vLow{std::min(firstCorner.x, secondCorner.x),
+				std::min(firstCorner.y, secondCorner.y)
+				  };
+	RS_Vector const vHigh{std::max(firstCorner.x, secondCorner.x),
+				std::max(firstCorner.y, secondCorner.y)
+				   };
+
+    if (getStartpoint().isInWindowOrdered(vLow, vHigh)) {
+        moveStartpoint(getStartpoint() + offset);
+    }
+    if (getEndpoint().isInWindowOrdered(vLow, vHigh)) {
+        moveEndpoint(getEndpoint() + offset);
+    }
+}
+
+
+
+void RS_Line::moveRef(const RS_Vector& ref, const RS_Vector& offset) {
+    if(  fabs(data.startpoint.x -ref.x)<1.0e-4 &&
+         fabs(data.startpoint.y -ref.y)<1.0e-4 ) {
+        moveStartpoint(data.startpoint+offset);
+    }
+    if(  fabs(data.endpoint.x -ref.x)<1.0e-4 &&
+         fabs(data.endpoint.y -ref.y)<1.0e-4 ) {
+        moveEndpoint(data.endpoint+offset);
+    }
+}
+
+
+void RS_Line::draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) {
+	if (! (painter && view)) {
+        return;
+    }
+
+    auto viewportRect = view->getViewRect();
+    RS_VectorSolutions endPoints(0);
+    endPoints.push_back(getStartpoint());
+    endPoints.push_back(getEndpoint());
+
+    RS_EntityContainer ec(nullptr);
+    ec.addRectangle(viewportRect.minP(), viewportRect.maxP());
+
+//    if (viewportRect.inArea(getStartpoint(), RS_TOLERANCE))
+//         endPoints.push_back(getStartpoint());
+//    if (viewportRect.inArea(getEndpoint(), RS_TOLERANCE))
+//         endPoints.push_back(getEndpoint());
+
+//    if (endPoints.size() < 2){
+//        RS_VectorSolutions vpIts;
+//        for(auto p: ec) {
+//            auto const sol=RS_Information::getIntersection(this, p, true);
+//            for (auto const& vp: sol) {
+//                if (vpIts.getClosestDistance(vp) <= RS_TOLERANCE * 10.)
+//                    continue;
+//                vpIts.push_back(vp);
+//            }
+//        }
+//        for (auto const& vp: vpIts) {
+//            if (endPoints.getClosestDistance(vp) <= RS_TOLERANCE * 10.)
+//                continue;
+//            endPoints.push_back(vp);
+//        }
+//    }
+
+//    if (endPoints.size()<2) return;
+
+    if ((endPoints[0] - getStartpoint()).squared() >
+            (endPoints[1] - getStartpoint()).squared() )
+    {
+        std::swap(endPoints[0],endPoints[1]);
+    }
+
+	RS_Vector pStart{view->toGui(endPoints.at(0))};
+	RS_Vector pEnd{view->toGui(endPoints.at(1))};
+    //    std::cout<<"draw line: "<<pStart<<" to "<<pEnd<<std::endl;
+	RS_Vector direction = pEnd-pStart;
+
+	if (isConstruction(true) && direction.squared() > RS_TOLERANCE){
+        //extend line on a construction layer to fill the whole view
+		RS_VectorSolutions vpIts;
+		for(auto p: ec) {
+            auto const sol=RS_Information::getIntersection(this, p, true);
+			for (auto const& vp: sol) {
+				if (vpIts.getClosestDistance(vp) <= RS_TOLERANCE * 10.)
+					continue;
+				vpIts.push_back(vp);
+			}
+		}
+
+		//draw construction lines up to viewport border
+		switch (vpIts.size()) {
+		case 2:
+			// no need to sort intersections
+			break;
+		case 3:
+		case 4: {
+			// will use the inner two points
+			size_t i{0};
+			for (size_t j = 0; j < vpIts.size(); ++j)
+				if (viewportRect.inArea(vpIts.at(j), RS_TOLERANCE * 10.))
+					std::swap(vpIts[j], vpIts[i++]);
+
+		}
+			break;
+		default:
+			//should not happen
+			return;
+		}
+		pStart=view->toGui(vpIts.get(0));
+		pEnd=view->toGui(vpIts.get(1));
+		direction=pEnd-pStart;
+    }
+
+    bool drawAsSelected = isSelected() && !(view->isPrinting() || view->isPrintPreview());
+
+    double  length=direction.magnitude();
+    patternOffset -= length;
+    if (( !drawAsSelected && (
+              getPen().getLineType()==RS2::SolidLine ||
+              view->getDrawingMode()==RS2::ModePreview)) ) {
+        //if length is too small, attempt to draw the line, could be a potential bug
+        painter->drawLine(pStart,pEnd);
+        return;
+    }
+    //    double styleFactor = getStyleFactor(view);
+
+
+    // Pattern:
+    const RS_LineTypePattern* pat;
+    if (drawAsSelected) {
+//        styleFactor=1.;
+        pat = &RS_LineTypePattern::patternSelected;
+
+    } else {
+        pat = view->getPattern(getPen().getLineType());
+    }
+	if (!pat) {
+//        patternOffset -= length;
+        RS_DEBUG->print(RS_Debug::D_WARNING,
+                        "RS_Line::draw: Invalid line pattern");
+        painter->drawLine(pStart,pEnd);
+        return;
+    }
+//    patternOffset = remainder(patternOffset - length-0.5*pat->totalLength,pat->totalLength)+0.5*pat->totalLength;
+    if(length<=RS_TOLERANCE){
+        painter->drawLine(pStart,pEnd);
+        return; //avoid division by zero
+    }
+    direction/=length; //cos(angle), sin(angle)
+    // Pen to draw pattern is always solid:
+    RS_Pen pen = painter->getPen();
+
+    pen.setLineType(RS2::SolidLine);
+    painter->setPen(pen);
+
+	if (pat->num <= 0) {
+		RS_DEBUG->print(RS_Debug::D_WARNING,"invalid line pattern for line, draw solid line instead");
+		painter->drawLine(view->toGui(getStartpoint()),
+						  view->toGui(getEndpoint()));
+		return;
+	}
+
+	// pattern segment length:
+	double patternSegmentLength = pat->totalLength;
+
+	// create pattern:
+	std::vector<RS_Vector> dp(pat->num);
+	std::vector<double> ds(pat->num);
+	double dpmm=static_cast<RS_PainterQt*>(painter)->getDpmm();
+	for (size_t i=0; i < pat->num; ++i) {
+		//        ds[j]=pat->pattern[i] * styleFactor;
+		//fixme, styleFactor support needed
+
+		ds[i]=dpmm*pat->pattern[i];
+		if (fabs(ds[i]) < 1. ) ds[i] = copysign(1., ds[i]);
+		dp[i] = direction*fabs(ds[i]);
+	}
+	double total= remainder(patternOffset-0.5*patternSegmentLength,patternSegmentLength) -0.5*patternSegmentLength;
+    //    double total= patternOffset-patternSegmentLength;
+
+	RS_Vector curP{pStart+direction*total};
+	for (int j=0; total<length; j=(j+1)%pat->num) {
+
+        // line segment (otherwise space segment)
+		double const t2=total+fabs(ds[j]);
+		RS_Vector const& p3=curP+dp[j];
+        if (ds[j]>0.0 && t2 > 0.0) {
+            // drop the whole pattern segment line, for ds[i]<0:
+            // trim end points of pattern segment line to line
+			RS_Vector const& p1 =(total > -0.5)?curP:pStart;
+			RS_Vector const& p2 =(t2 < length+0.5)?p3:pEnd;
+            painter->drawLine(p1,p2);
+        }
+        total=t2;
+        curP=p3;
+	}
+
+}
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_Line& l) {
+    os << " Line: " << l.getData() << "\n";
+    return os;
+}
+
+

lib/engine/rs_line.h

@@ -0,0 +1,234 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_LINE_H
+#define RS_LINE_H
+
+#include "rs_atomicentity.h"
+
+class LC_Quadratic;
+
+/**
+ * Holds the data that defines a line.
+ */
+struct RS_LineData {
+    RS_LineData() :
+        startpoint( false),
+        endpoint( false)
+    {}
+
+    RS_LineData(const RS_Vector& point1,
+                const RS_Vector& point2) :
+        startpoint( point1),
+        endpoint( point2)
+    {}
+
+    RS_Vector startpoint;
+    RS_Vector endpoint;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_LineData& ld);
+
+/**
+ * Class for a line entity.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Line : public RS_AtomicEntity {
+public:
+    RS_Line() = default;
+    RS_Line(RS_EntityContainer* parent,
+            const RS_LineData& d);
+    RS_Line(RS_EntityContainer* parent, const RS_Vector& pStart, const RS_Vector& pEnd);
+    RS_Line(const RS_Vector& pStart, const RS_Vector& pEnd);
+
+    RS_Entity* clone() const override;
+
+    /** @return RS2::EntityLine */
+    RS2::EntityType rtti() const override{
+        return RS2::EntityLine;
+    }
+    /** @return true */
+    bool isEdge() const override{
+        return true;
+    }
+
+    /** @return Copy of data that defines the line. */
+    RS_LineData getData() const{
+        return data;
+    }
+
+    RS_VectorSolutions getRefPoints() const override;
+
+    /** @return Start point of the entity */
+    RS_Vector getStartpoint() const override{
+        return data.startpoint;
+    }
+    /** @return End point of the entity */
+    RS_Vector getEndpoint() const override{
+        return data.endpoint;
+    }
+    /** Sets the startpoint */
+    void setStartpoint(RS_Vector s) {
+        data.startpoint = s;
+        calculateBorders();
+    }
+    /** Sets the endpoint */
+    void setEndpoint(RS_Vector e) {
+        data.endpoint = e;
+        calculateBorders();
+    }
+    /**
+     * @return Direction 1. The angle at which the line starts at
+     * the startpoint.
+     */
+    double getDirection1() const override{
+        return getAngle1();
+    }
+    /**
+     * @return Direction 2. The angle at which the line starts at
+     * the endpoint.
+     */
+    double getDirection2() const override{
+        return getAngle2();
+    }
+    RS_Vector getTangentDirection(const RS_Vector& point)const override;
+
+    void moveStartpoint(const RS_Vector& pos) override;
+    void moveEndpoint(const RS_Vector& pos) override;
+    RS2::Ending getTrimPoint(const RS_Vector& trimCoord,
+                             const RS_Vector& trimPoint) override;
+    RS_Vector prepareTrim(const RS_Vector& trimCoord,
+                          const RS_VectorSolutions& trimSol) override;
+    void reverse() override;
+    /** Sets the y coordinate of the startpoint */
+    void setStartpointY(double val) {
+        data.startpoint.y = val;
+        calculateBorders();
+    }
+    /** Sets the y coordinate of the endpoint */
+    void setEndpointY(double val) {
+        data.endpoint.y = val;
+        calculateBorders();
+    }
+    bool hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2) override;
+
+    /**
+     * @return The length of the line.
+     */
+    double getLength() const override{
+        return data.startpoint.distanceTo(data.endpoint);
+    }
+
+    /**
+     * @return The angle of the line (from start to endpoint).
+     */
+    double getAngle1() const{
+        return data.startpoint.angleTo(data.endpoint);
+    }
+
+    /**
+     * @return The angle of the line (from end to startpoint).
+     */
+    double getAngle2() const{
+        return data.endpoint.angleTo(data.startpoint);
+    }
+    bool isTangent(const RS_CircleData&  circleData) const override;
+
+    /**
+     * @return a perpendicular vector
+     */
+    RS_Vector getNormalVector() const;
+    double getProjectionValueAlongLine(const RS_Vector& coord) const;
+    RS_Vector getMiddlePoint() const override;
+    RS_Vector getNearestEndpoint(const RS_Vector& coord,
+                                 double* dist = nullptr) const override;
+    RS_Vector getNearestPointOnEntity(const RS_Vector& coord,
+                                      bool onEntity = true,
+                                      double* dist = nullptr,
+                                      RS_Entity** entity=nullptr) const override;
+    //RS_Vector getPointOnEntityAlongLine(const RS_Vector& coord,const double angle,bool onEntity,double* dist,RS_Entity** entity) const;
+    RS_Vector getNearestMiddle(const RS_Vector& coord,
+                               double* dist = nullptr,
+                               int middlePoints = 1) const override;
+    RS_Vector getNearestDist(double distance,
+                             const RS_Vector& coord,
+                             double* dist = nullptr) const override;
+    RS_Vector getNearestDist(double distance,
+                             bool startp) const override;
+
+    /**
+     * implementations must revert the direction of an atomic entity
+     */
+    void revertDirection() override;
+    std::vector<RS_Entity* > offsetTwoSides(const double& distance) const override;
+    /**
+     * the modify offset action
+     */
+    bool offset(const RS_Vector& coord, const double& distance) override;
+    void move(const RS_Vector& offset) override;
+    void rotate(const double& angle);
+    void rotate(const RS_Vector& center, const double& angle) override;
+    void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+    void scale(const RS_Vector& factor) override;
+    void scale(const RS_Vector& center, const RS_Vector& factor) override;
+    void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+    void stretch(const RS_Vector& firstCorner,
+                 const RS_Vector& secondCorner,
+                 const RS_Vector& offset) override;
+    void moveRef(const RS_Vector& ref, const RS_Vector& offset) override;
+
+    /** whether the entity's bounding box intersects with visible portion of graphic view */
+    void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Line& l);
+
+    void calculateBorders() override;
+    /**
+     * @brief getQuadratic() returns the equation of the entity
+     * for quadratic,
+     *
+     * return a vector contains:
+     * m0 x^2 + m1 xy + m2 y^2 + m3 x + m4 y + m5 =0
+     *
+     * for linear:
+     * m0 x + m1 y + m2 =0
+     */
+    LC_Quadratic getQuadratic() const override;
+    /**
+     * @brief areaLineIntegral line integral for contour area calculation by Green's Theorem
+     * Contour Area =\oint x dy
+     * @return line integral \oint x dy along the entity
+     * \oint x dy = 0.5*(x0+x1)*(y1-y0)
+     */
+    double areaLineIntegral() const override;
+
+protected:
+    RS_LineData data;
+};
+
+#endif

lib/engine/rs_mtext.cpp

@@ -0,0 +1,692 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include<cmath>
+#include "rs_font.h"
+#include "rs_mtext.h"
+
+#include "rs_fontlist.h"
+#include "rs_insert.h"
+#include "rs_math.h"
+#include "rs_debug.h"
+#include "rs_graphicview.h"
+#include "rs_painter.h"
+
+RS_MTextData::RS_MTextData(const RS_Vector& _insertionPoint,
+			double _height,
+			double _width,
+			VAlign _valign,
+			HAlign _halign,
+			MTextDrawingDirection _drawingDirection,
+			MTextLineSpacingStyle _lineSpacingStyle,
+			double _lineSpacingFactor,
+			const QString& _text,
+			const QString& _style,
+			double _angle,
+			RS2::UpdateMode _updateMode):
+	insertionPoint(_insertionPoint)
+	,height(_height)
+	,width(_width)
+	,valign(_valign)
+	,halign(_halign)
+	,drawingDirection(_drawingDirection)
+	,lineSpacingStyle(_lineSpacingStyle)
+	,lineSpacingFactor(_lineSpacingFactor)
+	,text(_text)
+	,style(_style)
+	,angle(_angle)
+	,updateMode(_updateMode)
+{
+}
+
+std::ostream& operator << (std::ostream& os, const RS_MTextData& td) {
+	os << "("
+	   <<td.insertionPoint<<','
+	  <<td.height<<','
+	 <<td.width<<','
+	<<td.valign<<','
+	<<td.halign<<','
+	<<td.drawingDirection<<','
+	<<td.lineSpacingStyle<<','
+	<<td.lineSpacingFactor<<','
+	<<td.text.toLatin1().data() <<','
+	<<td.style.toLatin1().data()<<','
+	<<td.angle<<','
+	<<td.updateMode<<','
+	<<")";
+	return os;
+}
+
+/**
+ * Constructor.
+ */
+RS_MText::RS_MText(RS_EntityContainer* parent,
+                 const RS_MTextData& d)
+        : RS_EntityContainer(parent), data(d) {
+
+    usedTextHeight = 0.0;
+    usedTextWidth = 0.0;
+    setText(data.text);
+}
+
+RS_Entity* RS_MText::clone() const{
+	RS_MText* t = new RS_MText(*this);
+	t->setOwner(isOwner());
+	t->initId();
+	t->detach();
+	return t;
+}
+
+/**
+ * Sets a new text. The entities representing the
+ * text are updated.
+ */
+void RS_MText::setText(const QString& t) {
+    data.text = t;
+
+    // handle some special flags embedded in the text:
+    if (data.text.left(4)=="\\A0;") {
+        data.text = data.text.mid(4);
+        data.valign = RS_MTextData::VABottom;
+    } else if (data.text.left(4)=="\\A1;") {
+        data.text = data.text.mid(4);
+        data.valign = RS_MTextData::VAMiddle;
+    } else if (data.text.left(4)=="\\A2;") {
+        data.text = data.text.mid(4);
+        data.valign = RS_MTextData::VATop;
+    }
+
+    if (data.updateMode==RS2::Update) {
+        update();
+        //calculateBorders();
+    }
+}
+
+
+
+/**
+ * Gets the alignment as an int.
+ *
+ * @return  1: top left ... 9: bottom right
+ */
+int RS_MText::getAlignment() {
+    if (data.valign==RS_MTextData::VATop) {
+        if (data.halign==RS_MTextData::HALeft) {
+            return 1;
+        } else if (data.halign==RS_MTextData::HACenter) {
+            return 2;
+        } else if (data.halign==RS_MTextData::HARight) {
+            return 3;
+        }
+    } else if (data.valign==RS_MTextData::VAMiddle) {
+        if (data.halign==RS_MTextData::HALeft) {
+            return 4;
+        } else if (data.halign==RS_MTextData::HACenter) {
+            return 5;
+        } else if (data.halign==RS_MTextData::HARight) {
+            return 6;
+        }
+    } else if (data.valign==RS_MTextData::VABottom) {
+        if (data.halign==RS_MTextData::HALeft) {
+            return 7;
+        } else if (data.halign==RS_MTextData::HACenter) {
+            return 8;
+        } else if (data.halign==RS_MTextData::HARight) {
+            return 9;
+        }
+    }
+
+    return 1;
+}
+
+
+
+/**
+ * Sets the alignment from an int.
+ *
+ * @param a 1: top left ... 9: bottom right
+ */
+void RS_MText::setAlignment(int a) {
+    switch (a%3) {
+    default:
+    case 1:
+        data.halign = RS_MTextData::HALeft;
+        break;
+    case 2:
+        data.halign = RS_MTextData::HACenter;
+        break;
+    case 0:
+        data.halign = RS_MTextData::HARight;
+        break;
+    }
+
+    switch ((int)ceil(a/3.0)) {
+    default:
+    case 1:
+        data.valign = RS_MTextData::VATop;
+        break;
+    case 2:
+        data.valign = RS_MTextData::VAMiddle;
+        break;
+    case 3:
+        data.valign = RS_MTextData::VABottom;
+        break;
+    }
+
+}
+
+
+
+/**
+ * @return Number of lines in this text entity.
+ */
+int RS_MText::getNumberOfLines() {
+    int c=1;
+
+    for (int i=0; i<(int)data.text.length(); ++i) {
+        if (data.text.at(i).unicode()==0x0A) {
+            c++;
+        }
+    }
+
+    return c;
+}
+
+
+
+
+/**
+ * Updates the Inserts (letters) of this text. Called when the
+ * text or it's data, position, alignment, .. changes.
+ * This method also updates the usedTextWidth / usedTextHeight property.
+ */
+void RS_MText::update()
+{
+    RS_DEBUG->print("RS_MText::update");
+
+    clear();
+    if (isUndone()) {
+        return;
+    }
+
+    usedTextWidth = 0.0;
+    usedTextHeight = 0.0;
+
+    RS_Font* font {RS_FONTLIST->requestFont( data.style)};
+    if (nullptr == font) {
+        return;
+    }
+
+    RS_Vector letterPos {RS_Vector( 0.0, -9.0)};
+    RS_Vector letterSpace {RS_Vector( font->getLetterSpacing(), 0.0)};
+    RS_Vector space {RS_Vector( font->getWordSpacing(), 0.0)};
+    int lineCounter {0};
+
+    // Every single text line gets stored in this entity container
+    // so we can move the whole line around easily:
+    RS_EntityContainer* oneLine {new RS_EntityContainer(this)};
+
+    // First every text line is created with
+    //   alignment: top left
+    //   angle: 0
+    //   height: 9.0
+    // Rotation, scaling and centering is done later
+
+    // For every letter:
+    for (int i = 0; i < static_cast<int>(data.text.length()); ++i) {
+        bool handled {false};
+
+        switch (data.text.at(i).unicode()) {
+        case 0x0A:
+            // line feed:
+            updateAddLine( oneLine, lineCounter++);
+            oneLine = new RS_EntityContainer(this);
+            letterPos = RS_Vector( 0.0, -9.0);
+            break;
+
+        case 0x20:
+            // Space:
+            letterPos += space;
+            break;
+
+        case 0x5C: {
+            // code (e.g. \S, \P, ..)
+            ++i;
+            if (static_cast<int>(data.text.length()) <= i) {
+                continue;
+            }
+            int ch {data.text.at(i).unicode()};
+            switch (ch) {
+            case 'P':
+                updateAddLine( oneLine, lineCounter++);
+                oneLine = new RS_EntityContainer(this);
+                letterPos = RS_Vector( 0.0, -9.0);
+                handled = true;
+                break;
+
+            case 'f':
+            case 'F': {
+                //font change
+                // \f{symbol} changes font to symbol
+                // \f{} sets font to standard
+                ++i;
+                if ('{' != data.text.at(i).unicode()) {
+                    --i;
+                    continue;
+                }
+
+                int j {data.text.indexOf( '}', i)};
+                if (j > i) {
+                    QString fontName;
+                    if (i + 1 == j) {
+                        fontName = "standard";
+                    }
+                    else {
+                        fontName = data.text.mid( i + 1, j - i - 1);
+                    }
+
+                    RS_Font* fontNew {RS_FONTLIST->requestFont( fontName)};
+                    if (nullptr != fontNew) {
+                        font = fontNew;
+                    }
+                    if (nullptr == font) {
+                        font = RS_FONTLIST->requestFont( "standard");
+                    }
+                    i = j;
+                }
+                continue;
+            } // inner case 'f','F'
+
+            case 'S': {
+                QString upperText;
+                QString lowerText;
+
+                // get upper string:
+                ++i;
+                while (static_cast<int>(data.text.length()) > i
+                       && data.text.at(i).unicode()!='^'
+                       && data.text.at(i).unicode()!='\\') {
+                    upperText += data.text.at(i);
+                    ++i;
+                }
+
+                ++i;
+                if (static_cast<int>(data.text.length()) > i
+                        && '^' == data.text.at(i - 1).unicode()
+                        && ' ' == data.text.at(i).unicode() ) {
+                    ++i;
+                }
+
+                // get lower string:
+                while (static_cast<int>(data.text.length()) > i
+                       && ';' != data.text.at(i).unicode()) {
+                    lowerText += data.text.at(i);
+                    ++i;
+                }
+
+                // add texts:
+                double upperWidth {0.0};
+                if (! upperText.isEmpty()) {
+                    RS_MText* upper { new RS_MText( oneLine,
+                                                    RS_MTextData( letterPos + RS_Vector( 0.0, 9.0),
+                                                                  4.0,
+                                                                  100.0,
+                                                                  RS_MTextData::VATop,
+                                                                  RS_MTextData::HALeft,
+                                                                  RS_MTextData::LeftToRight,
+                                                                  RS_MTextData::Exact,
+                                                                  1.0,
+                                                                  upperText,
+                                                                  data.style,
+                                                                  0.0,
+                                                                  RS2::Update)) };
+                    upper->setLayer( nullptr);
+                    upper->setPen( RS_Pen( RS2::FlagInvalid));
+                    upper->calculateBorders();
+                    oneLine->addEntity(upper);
+                    upperWidth = upper->getSize().x;
+                }
+
+                double lowerWidth {0.0};
+                if (! lowerText.isEmpty()) {
+                    RS_MText* lower { new RS_MText( oneLine,
+                                                    RS_MTextData( letterPos + RS_Vector( 0.0, 4.0),
+                                                                  4.0,
+                                                                  100.0,
+                                                                  RS_MTextData::VATop,
+                                                                  RS_MTextData::HALeft,
+                                                                  RS_MTextData::LeftToRight,
+                                                                  RS_MTextData::Exact,
+                                                                  1.0,
+                                                                  lowerText,
+                                                                  data.style,
+                                                                  0.0,
+                                                                  RS2::Update)) };
+                    lower->setLayer( nullptr);
+                    lower->setPen( RS_Pen( RS2::FlagInvalid));
+                    lower->calculateBorders();
+                    oneLine->addEntity(lower);
+                    lowerWidth = lower->getSize().x;
+                }
+
+                if (upperWidth > lowerWidth) {
+                    letterPos += RS_Vector( upperWidth, 0.0);
+                }
+                else {
+                    letterPos += RS_Vector( lowerWidth, 0.0);
+                }
+                letterPos += letterSpace;
+                handled = true;
+
+                break;
+            } // inner case 'S'
+
+            default:
+                --i;
+                break;
+            } // inner switch (ch)
+
+            if (handled) {
+                break;
+            }
+        } // outer case 0x5C
+
+            // if char is not handled
+            // fall-through
+        default: {
+            // One Letter:
+            QString letterText {QString(data.text.at(i))};
+            if (nullptr == font->findLetter( letterText)) {
+                RS_DEBUG->print("RS_MText::update: missing font for letter( %s ), replaced it with QChar(0xfffd)",
+                                qPrintable( letterText));
+                letterText = QChar( 0xfffd);
+            }
+
+            RS_DEBUG->print("RS_MText::update: insert a letter at pos: %f/%f", letterPos.x, letterPos.y);
+
+            RS_InsertData d( letterText,
+                             letterPos,
+                             RS_Vector( 1.0, 1.0),
+                             0.0,
+                             1,
+                             1,
+                             RS_Vector( 0.0, 0.0),
+                             font->getLetterList(),
+                             RS2::NoUpdate);
+
+            RS_Insert* letter {new RS_Insert(this, d)};
+            RS_Vector letterWidth;
+            letter->setPen( RS_Pen( RS2::FlagInvalid));
+            letter->setLayer( nullptr);
+            letter->update();
+            letter->forcedCalculateBorders();
+
+            letterWidth = RS_Vector( letter->getMax().x - letterPos.x, 0.0);
+            if (0 > letterWidth.x) {
+                letterWidth.x = -letterSpace.x;
+            }
+
+            oneLine->addEntity( letter);
+
+            // next letter position:
+            letterPos += letterWidth;
+            letterPos += letterSpace;
+
+            break;
+        } // outer default
+        } // outer switch (data.text.at(i).unicode())
+    } // for (i) loop
+
+    double tt {updateAddLine( oneLine, lineCounter)};
+    if (RS_MTextData::VABottom == data.valign) {
+        RS_Vector ot {RS_Vector( 0.0, -tt).rotate( data.angle)};
+        RS_EntityContainer::move( ot);
+    }
+
+    usedTextHeight -= data.height * data.lineSpacingFactor * 5.0 / 3.0 - data.height;
+    forcedCalculateBorders();
+
+    RS_DEBUG->print("RS_MText::update: OK");
+}
+
+
+
+/**
+ * Used internally by update() to add a text line created with
+ * default values and alignment to this text container.
+ *
+ * @param textLine The text line.
+ * @param lineCounter Line number.
+ *
+ * @return  distance over the text base-line
+ */
+double RS_MText::updateAddLine(RS_EntityContainer* textLine, int lineCounter) {
+    double ls =5.0/3.0;
+
+    RS_DEBUG->print("RS_MText::updateAddLine: width: %f", textLine->getSize().x);
+
+        //textLine->forcedCalculateBorders();
+    //RS_DEBUG->print("RS_MText::updateAddLine: width 2: %f", textLine->getSize().x);
+
+    // Move to correct line position:
+    textLine->move(RS_Vector(0.0, -9.0 * lineCounter
+                             * data.lineSpacingFactor * ls));
+
+    if( ! RS_EntityContainer::autoUpdateBorders) {
+        //only update borders when needed
+        textLine->forcedCalculateBorders();
+    }
+    RS_Vector textSize = textLine->getSize();
+
+        RS_DEBUG->print("RS_MText::updateAddLine: width 2: %f", textSize.x);
+
+    // Horizontal Align:
+    switch (data.halign) {
+    case RS_MTextData::HACenter:
+                RS_DEBUG->print("RS_MText::updateAddLine: move by: %f", -textSize.x/2.0);
+        textLine->move(RS_Vector(-textSize.x/2.0, 0.0));
+        break;
+
+    case RS_MTextData::HARight:
+        textLine->move(RS_Vector(-textSize.x, 0.0));
+        break;
+
+    default:
+        break;
+    }
+
+    // Vertical Align:
+    double vSize = getNumberOfLines()*9.0*data.lineSpacingFactor*ls
+                   - (9.0*data.lineSpacingFactor*ls - 9.0);
+
+    switch (data.valign) {
+    case RS_MTextData::VAMiddle:
+        textLine->move(RS_Vector(0.0, vSize/2.0));
+        break;
+
+    case RS_MTextData::VABottom:
+        textLine->move(RS_Vector(0.0, vSize));
+        break;
+
+    default:
+        break;
+    }
+
+    // Scale:
+    textLine->scale(RS_Vector(0.0,0.0),
+                    RS_Vector(data.height/9.0, data.height/9.0));
+
+    textLine->forcedCalculateBorders();
+
+    // Update actual text size (before rotating, after scaling!):
+    if (textLine->getSize().x>usedTextWidth) {
+        usedTextWidth = textLine->getSize().x;
+    }
+
+    usedTextHeight += data.height*data.lineSpacingFactor*ls;
+
+    // Gets the distance over text base-line (before rotating, after scaling!):
+    double textTail = textLine->getMin().y;
+
+    // Rotate:
+    textLine->rotate(RS_Vector(0.0,0.0), data.angle);
+
+    // Move:
+    textLine->move(data.insertionPoint);
+    textLine->setPen(RS_Pen(RS2::FlagInvalid));
+    textLine->setLayer(NULL);
+    textLine->forcedCalculateBorders();
+
+    addEntity(textLine);
+    return textTail;
+}
+
+
+RS_Vector RS_MText::getNearestEndpoint(const RS_Vector& coord, double* dist)const {
+    if (dist) {
+        *dist = data.insertionPoint.distanceTo(coord);
+    }
+    return data.insertionPoint;
+}
+
+
+RS_VectorSolutions RS_MText::getRefPoints() const{
+		return RS_VectorSolutions({data.insertionPoint});
+}
+
+void RS_MText::move(const RS_Vector& offset) {
+    RS_EntityContainer::move(offset);
+    data.insertionPoint.move(offset);
+//    update();
+}
+
+
+
+void RS_MText::rotate(const RS_Vector& center, const double& angle) {
+    RS_Vector angleVector(angle);
+    RS_EntityContainer::rotate(center, angleVector);
+    data.insertionPoint.rotate(center, angleVector);
+    data.angle = RS_Math::correctAngle(data.angle+angle);
+//    update();
+}
+void RS_MText::rotate(const RS_Vector& center, const RS_Vector& angleVector) {
+    RS_EntityContainer::rotate(center, angleVector);
+    data.insertionPoint.rotate(center, angleVector);
+    data.angle = RS_Math::correctAngle(data.angle+angleVector.angle());
+//    update();
+}
+
+
+
+void RS_MText::scale(const RS_Vector& center, const RS_Vector& factor) {
+    data.insertionPoint.scale(center, factor);
+    data.width*=factor.x;
+    data.height*=factor.x;
+    update();
+}
+
+
+
+void RS_MText::mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) {
+    data.insertionPoint.mirror(axisPoint1, axisPoint2);
+    //double ang = axisPoint1.angleTo(axisPoint2);
+    bool readable = RS_Math::isAngleReadable(data.angle);
+
+	RS_Vector vec = RS_Vector::polar(1.0, data.angle);
+    vec.mirror(RS_Vector(0.0,0.0), axisPoint2-axisPoint1);
+    data.angle = vec.angle();
+
+    bool corr;
+    data.angle = RS_Math::makeAngleReadable(data.angle, readable, &corr);
+
+    if (corr) {
+        if (data.halign==RS_MTextData::HALeft) {
+            data.halign=RS_MTextData::HARight;
+        } else if (data.halign==RS_MTextData::HARight) {
+            data.halign=RS_MTextData::HALeft;
+        }
+    } else {
+        if (data.valign==RS_MTextData::VATop) {
+            data.valign=RS_MTextData::VABottom;
+        } else if (data.valign==RS_MTextData::VABottom) {
+            data.valign=RS_MTextData::VATop;
+        }
+    }
+    update();
+}
+
+
+
+bool RS_MText::hasEndpointsWithinWindow(const RS_Vector& /*v1*/, const RS_Vector& /*v2*/) {
+    return false;
+}
+
+
+
+/**
+ * Implementations must stretch the given range of the entity
+ * by the given offset.
+ */
+void RS_MText::stretch(const RS_Vector& firstCorner, const RS_Vector& secondCorner, const RS_Vector& offset) {
+
+    if (getMin().isInWindow(firstCorner, secondCorner) &&
+            getMax().isInWindow(firstCorner, secondCorner)) {
+
+        move(offset);
+    }
+}
+
+
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_MText& p) {
+    os << " Text: " << p.getData() << "\n";
+    return os;
+}
+
+void RS_MText::draw(RS_Painter* painter, RS_GraphicView* view, double& /*patternOffset*/)
+{
+    if (!(painter && view)) {
+        return;
+    }
+
+    if (!view->isPrintPreview() && !view->isPrinting())
+    {
+        if (view->isPanning() || view->toGuiDY(getHeight()) < 4)
+        {
+            painter->drawRect(view->toGui(getMin()), view->toGui(getMax()));
+            return;
+        }
+    }
+
+    foreach (auto e, entities)
+    {
+        view->drawEntity(painter, e);
+    }
+}

lib/engine/rs_mtext.h

@@ -0,0 +1,276 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_MTEXT_H
+#define RS_MTEXT_H
+
+#include "rs_entitycontainer.h"
+
+/**
+ * Holds the data that defines a text entity.
+ */
+struct RS_MTextData {
+	/**
+	 * Vertical alignments.
+	 */
+	enum VAlign {
+		VATop,      /**< Top. */
+		VAMiddle,   /**< Middle */
+		VABottom    /**< Bottom */
+	};
+
+	/**
+	 * Horizontal alignments.
+	 */
+	enum HAlign {
+		HALeft,     /**< Left */
+		HACenter,   /**< Centered */
+		HARight     /**< Right */
+	};
+
+	/**
+	 * MText drawing direction.
+	 */
+	enum MTextDrawingDirection {
+		LeftToRight,     /**< Left to right */
+		TopToBottom,     /**< Top to bottom */
+		ByStyle          /**< Inherited from associated text style */
+	};
+
+	/**
+	 * Line spacing style for MTexts.
+	 */
+	enum MTextLineSpacingStyle {
+		AtLeast,        /**< Taller characters will override */
+		Exact           /**< Taller characters will not override */
+	};
+
+	/**
+	 * Default constructor. Leaves the data object uninitialized.
+	 */
+	RS_MTextData() = default;
+
+	/**
+	 * Constructor with initialisation.
+	 *
+	 * @param insertionPoint Insertion point
+	 * @param height Nominal (initial) text height
+	 * @param width Reference rectangle width
+	 * @param valign Vertical alignment
+	 * @param halign Horizontal alignment
+	 * @param drawingDirection Drawing direction
+	 * @param lineSpacingStyle Line spacing style
+	 * @param lineSpacingFactor Line spacing factor
+	 * @param text Text string
+	 * @param style Text style name
+	 * @param angle Rotation angle
+	 * @param updateMode RS2::Update will update the text entity instantly
+	 *    RS2::NoUpdate will not update the entity. You can update
+	 *    it later manually using the update() method. This is
+	 *    often the case since you might want to adjust attributes
+	 *    after creating a text entity.
+	 */
+	RS_MTextData(const RS_Vector& insertionPoint,
+				 double height,
+				 double width,
+				 VAlign valign,
+				 HAlign halign,
+				 MTextDrawingDirection drawingDirection,
+				 MTextLineSpacingStyle lineSpacingStyle,
+				 double lineSpacingFactor,
+				 const QString& text,
+				 const QString& style,
+				 double angle,
+				 RS2::UpdateMode updateMode = RS2::Update);
+
+	/** Insertion point */
+	RS_Vector insertionPoint;
+	/** Nominal (initial) text height */
+	double height;
+	/** Reference rectangle width */
+	double width;
+	/** Vertical alignment */
+	VAlign valign;
+	/** Horizontal alignment */
+	HAlign halign;
+	/** Drawing direction */
+	MTextDrawingDirection drawingDirection;
+	/** Line spacing style */
+	MTextLineSpacingStyle lineSpacingStyle;
+	/** Line spacing factor */
+	double lineSpacingFactor;
+	/** Text string */
+	QString text;
+	/** Text style name */
+	QString style;
+	/** Rotation angle */
+	double angle;
+	/** Update mode */
+	RS2::UpdateMode updateMode;
+};
+
+std::ostream& operator << (std::ostream& os, const RS_MTextData& td);
+
+
+/**
+ * Class for a text entity.
+ * Please note that text strings can contain special
+ * characters such as %%c for a diameter sign as well as unicode
+ * characters. Line feeds are stored as real line feeds in the string.
+ *
+ * @author Andrew Mustun
+ */
+class RS_MText : public RS_EntityContainer {
+public:
+    RS_MText(RS_EntityContainer* parent,
+            const RS_MTextData& d);
+	virtual ~RS_MText() = default;
+
+    virtual RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityText */
+    virtual RS2::EntityType rtti() const override{
+        return RS2::EntityMText;
+    }
+
+    /** @return Copy of data that defines the text. */
+    RS_MTextData getData() const {
+        return data;
+    }
+
+    void update() override;
+
+    int getNumberOfLines();
+
+
+    RS_Vector getInsertionPoint() {
+        return data.insertionPoint;
+    }
+    double getHeight() {
+        return data.height;
+    }
+    void setHeight(double h) {
+        data.height = h;
+    }
+    double getWidth() {
+        return data.width;
+    }
+    void setAlignment(int a);
+    int getAlignment();
+    RS_MTextData::VAlign getVAlign() {
+        return data.valign;
+    }
+    void setVAlign(RS_MTextData::VAlign va) {
+        data.valign = va;
+    }
+    RS_MTextData::HAlign getHAlign() {
+        return data.halign;
+    }
+    void setHAlign(RS_MTextData::HAlign ha) {
+        data.halign = ha;
+    }
+    RS_MTextData::MTextDrawingDirection getDrawingDirection() {
+        return data.drawingDirection;
+    }
+    RS_MTextData::MTextLineSpacingStyle getLineSpacingStyle() {
+        return data.lineSpacingStyle;
+    }
+    void setLineSpacingFactor(double f) {
+        data.lineSpacingFactor = f;
+    }
+    double getLineSpacingFactor() {
+        return data.lineSpacingFactor;
+    }
+    void setText(const QString& t);
+    QString getText() {
+        return data.text;
+    }
+    void setStyle(const QString& s) {
+        data.style = s;
+    }
+    QString getStyle() {
+        return data.style;
+    }
+    void setAngle(double a) {
+        data.angle = a;
+    }
+    double getAngle() {
+        return data.angle;
+    }
+    double getUsedTextWidth() {
+        return usedTextWidth;
+    }
+    double getUsedTextHeight() {
+        return usedTextHeight;
+    }
+
+//	virtual double getLength() const {
+//		return -1.0;
+//	}
+
+    /**
+     * @return The insertion point as endpoint.
+     */
+    virtual RS_Vector getNearestEndpoint(const RS_Vector& coord,
+                                         double* dist = NULL)const override;
+    virtual RS_VectorSolutions getRefPoints() const override;
+
+    virtual void move(const RS_Vector& offset) override;
+    virtual void rotate(const RS_Vector& center, const double& angle) override;
+    virtual void rotate(const RS_Vector& center, const RS_Vector& angleVector) override;
+    virtual void scale(const RS_Vector& center, const RS_Vector& factor) override;
+    virtual void mirror(const RS_Vector& axisPoint1, const RS_Vector& axisPoint2) override;
+    virtual bool hasEndpointsWithinWindow(const RS_Vector& v1, const RS_Vector& v2) override;
+    virtual void stretch(const RS_Vector& firstCorner,
+                         const RS_Vector& secondCorner,
+                         const RS_Vector& offset) override;
+
+    friend std::ostream& operator << (std::ostream& os, const RS_Text& p);
+
+    void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+private:
+    double updateAddLine(RS_EntityContainer* textLine, int lineCounter);
+
+protected:
+    RS_MTextData data;
+
+    /**
+     * Text width used by the current contents of this text entity.
+     * This property is updated by the update method.
+     * @see update
+     */
+    double usedTextWidth;
+    /**
+     * Text height used by the current contents of this text entity.
+     * This property is updated by the update method.
+     * @see update
+     */
+    double usedTextHeight;
+};
+
+#endif

lib/engine/rs_overlaybox.cpp

@@ -0,0 +1,93 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+#include<iostream>
+#include "rs_overlaybox.h"
+
+#include "rs_debug.h"
+#include "rs_graphicview.h"
+#include "rs_painter.h"
+#include "rs_graphic.h"
+#include <QBrush>
+
+/**
+ * Constructor.
+ */
+RS_OverlayBox::RS_OverlayBox(RS_EntityContainer* parent,
+                             const RS_OverlayBoxData& d)
+    :RS_AtomicEntity(parent), data(d) {
+}
+
+RS_Entity* RS_OverlayBox::clone() const{
+    RS_OverlayBox* l = new RS_OverlayBox(*this);
+    l->initId();
+    return l;
+}
+
+void RS_OverlayBox::draw(RS_Painter* painter, RS_GraphicView* view, double& /*patternOffset*/) {
+    if (painter==NULL || view==NULL) {
+        return;
+    }
+
+    RS_Vector v1=view->toGui(getCorner1());
+    RS_Vector v2=view->toGui(getCorner2());
+
+    QRectF selectRect(
+                v1.x,
+                v1.y,
+                v2.x - v1.x,
+                v2.y - v1.y);
+
+    if (v1.x > v2.x) {
+        RS_Pen p(RS_Color(50,255,50),RS2::Width00,RS2::DashLine);
+        painter->setPen(p);
+//        painter->setPen(QColor(50, 255, 50));
+        painter->fillRect(selectRect, RS_Color(9, 255, 9, 90));
+    }
+    else {
+        painter->setPen(QColor(50, 50, 255));
+        painter->fillRect(selectRect, RS_Color(9, 9, 255, 90));
+    }
+
+    painter->drawRect(v1, v2);
+}
+
+/**
+ * Dumps the point's data to stdout.
+ */
+std::ostream& operator << (std::ostream& os, const RS_OverlayBox& l) {
+    os << " Line: " << l.getData() << "\n";
+    return os;
+}
+
+std::ostream& operator << (std::ostream& os, const RS_OverlayBoxData& ld) {
+        os << "(" << ld.corner1 <<
+              "/" << ld.corner2 <<
+              ")";
+        return os;
+}
+
+

lib/engine/rs_overlaybox.h

@@ -0,0 +1,104 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#ifndef RS_OVERLAYBOX_H
+#define RS_OVERLAYBOX_H
+
+#include "rs_atomicentity.h"
+
+/**
+ * Holds the data that defines a line.
+ */
+class RS_OverlayBoxData {
+public:
+    /**
+     * Default constructor. Leaves the data object uninitialized.
+     */
+	RS_OverlayBoxData() = default;
+
+    RS_OverlayBoxData(const RS_Vector& corner1, const RS_Vector& corner2)
+                     : corner1(corner1), corner2(corner2) {}
+
+    friend class RS_OverlayBox;
+
+    friend std::ostream& operator << (std::ostream& os, const RS_OverlayBoxData& ld);
+
+public:
+    RS_Vector corner1;
+    RS_Vector corner2;
+};
+
+
+/**
+ * Class for a line entity.
+ *
+ * @author R. van Twisk
+ */
+class RS_OverlayBox : public RS_AtomicEntity {
+public:
+    RS_OverlayBox(RS_EntityContainer* parent, const RS_OverlayBoxData& d);
+	RS_Entity* clone() const override;
+
+    /**	@return RS2::EntityLine */
+	RS2::EntityType rtti() const override{
+        return RS2::EntityOverlayBox;
+    }
+	void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+    /** @return Start point of the entity */
+	RS_Vector getCorner1() const {
+        return data.corner1;
+    }
+    /** @return End point of the entity */
+	RS_Vector getCorner2() const {
+        return data.corner2;
+    }
+    /** @return Copy of data that defines the line. */
+    RS_OverlayBoxData getData() const {
+        return data;
+    }
+
+    /** We should make a separate drawing mechanism for overlays and not use entities */
+	void move(const RS_Vector& /*offset*/)override{}
+	void rotate(const RS_Vector& /*center*/, const double& /*angle*/)override{}
+	void rotate(const RS_Vector& /*center*/, const RS_Vector& /*angleVector*/)override{}
+	void scale(const RS_Vector& /*center*/, const RS_Vector& /*factor*/)override{}
+	void mirror(const RS_Vector& /*axisPoint1*/, const RS_Vector& /*axisPoint2*/)override{}
+	void calculateBorders() override{}
+	RS_Vector getNearestEndpoint(const RS_Vector&, double*)const override{return {};}
+	RS_Vector getNearestPointOnEntity(const RS_Vector&, bool, double*, RS_Entity**)const override{return {};}
+	RS_Vector getNearestCenter(const RS_Vector&, double*)const override{return {};}
+	RS_Vector getNearestMiddle(const RS_Vector&, double*,int)const override{return {};}
+	RS_Vector getNearestDist(double, const RS_Vector&, double*)const override{return {};}
+	double getDistanceToPoint(const RS_Vector&, RS_Entity**, RS2::ResolveLevel, double)const override{return -1;}//is -1 right here
+
+protected:
+    RS_OverlayBoxData data;
+}
+;
+
+#endif

lib/engine/rs_overlayline.cpp

@@ -0,0 +1,48 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include "rs_overlayline.h"
+#include "rs_painter.h"
+
+/**
+ * Constructor.
+ */
+RS_OverlayLine::RS_OverlayLine(RS_EntityContainer* parent,
+                 const RS_LineData& d)
+        :RS_Line(parent, d) {
+}
+
+
+void RS_OverlayLine::draw(RS_Painter* painter, RS_GraphicView* view, double& /*patternOffset*/) {
+    if (painter==NULL || view==NULL) {
+        return;
+    }
+
+        painter->drawLine(getStartpoint(),
+                                          getEndpoint());
+
+}

lib/engine/rs_overlayline.h

@@ -0,0 +1,53 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_OVERLAYLINE_H
+#define RS_OVERLAYLINE_H
+
+#include "rs_line.h"
+
+
+
+/**
+ * Class for a overlay line entity. It's used to draw lines on the overlay paint event
+ * The main difference is that the coordinates are actual screen coordinates and not real world coordinates
+ *
+ * @author R. van Twisk
+ */
+class RS_OverlayLine : public RS_Line {
+public:
+	RS_OverlayLine(RS_EntityContainer* parent, const RS_LineData& d);
+	
+    virtual void draw(RS_Painter* painter, RS_GraphicView* view, double& patternOffset) override;
+
+    RS2::EntityType rtti() const override{
+        return RS2::EntityOverlayLine;
+    }
+}
+;
+
+#endif

lib/engine/rs_pattern.cpp

@@ -0,0 +1,119 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!
+**
+**********************************************************************/
+
+
+#include "rs_pattern.h"
+
+#include "rs_system.h"
+#include "rs_fileio.h"
+#include "rs_layer.h"
+#include "rs_debug.h"
+
+
+/**
+ * Constructor.
+ *
+ * @param fileName File name of a DXF file defining the pattern
+ */
+RS_Pattern::RS_Pattern(const QString& fileName)
+		: RS_EntityContainer(NULL)
+		,fileName(fileName)
+		,loaded(false)
+{
+	RS_DEBUG->print("RS_Pattern::RS_Pattern() ");
+}
+
+
+/**
+ * Loads the given pattern file into this pattern.
+ * Entities other than lines are ignored.
+ *
+ * @param filename File name of the pattern file (without path and
+ * extension or full path.
+ */
+bool RS_Pattern::loadPattern() {
+    if (loaded) {
+        return true;
+    }
+
+    RS_DEBUG->print("RS_Pattern::loadPattern");
+
+    QString path;
+
+    // Search for the appropriate pattern if we have only the name of the pattern:
+    if (!fileName.toLower().contains(".dxf")) {
+        QStringList patterns = RS_SYSTEM->getPatternList();
+        QFileInfo file;
+        for (QStringList::Iterator it = patterns.begin();
+                it!=patterns.end();
+                it++) {
+
+            if (QFileInfo(*it).baseName().toLower()==fileName.toLower()) {
+                path = *it;
+                RS_DEBUG->print("Pattern found: %s", path.toLatin1().data());
+                break;
+            }
+        }
+    }
+
+    // We have the full path of the pattern:
+    else {
+        path = fileName;
+    }
+
+    // No pattern paths found:
+    if (path.isEmpty()) {
+        RS_DEBUG->print("No pattern \"%s\"available.", fileName.toLatin1().data());
+        return false;
+    }
+
+	RS_Graphic gr;
+	RS_FileIO::instance()->fileImport(gr, path);
+	for(auto e: gr){
+		if (e->rtti()==RS2::EntityLine ||
+				e->rtti()==RS2::EntityArc||
+				e->rtti()==RS2::EntityEllipse
+				) {
+            RS_Layer* l = e->getLayer();
+            RS_Entity* cl = e->clone();
+            cl->reparent(this);
+			if (l) {
+                cl->setLayer(l->getName());
+            }
+            addEntity(cl);
+        }
+	}
+
+    loaded = true;
+    RS_DEBUG->print("RS_Pattern::loadPattern: OK");
+
+    return true;
+}
+
+QString RS_Pattern::getFileName() const {
+	return fileName;
+}
+

lib/engine/rs_pattern.h

@@ -0,0 +1,65 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_PATTERN_H
+#define RS_PATTERN_H
+
+#include "rs_entitycontainer.h"
+
+class RS_PatternList;
+
+/**
+ * Patterns are used for hatches. They are stored in a RS_PatternList.
+ * Use RS_PatternList to access a pattern.
+ *
+ * @author Andrew Mustun
+ */
+class RS_Pattern : public RS_EntityContainer {
+public:
+    RS_Pattern(const QString& fileName);
+	virtual ~RS_Pattern()=default;
+	RS2::EntityType rtti() const{
+		return RS2::EntityPattern;
+	}
+
+    virtual bool loadPattern();
+	
+    /** @return the fileName of this pattern. */
+	QString getFileName() const;
+
+protected:
+    //! Pattern file name
+    QString fileName;
+
+    //! Is this pattern currently loaded into memory?
+    bool loaded;
+
+	
+};
+
+
+#endif

lib/engine/rs_patternlist.cpp

@@ -0,0 +1,112 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+#include<iostream>
+#include<QString>
+#include "rs_patternlist.h"
+
+#include "rs_system.h"
+#include "rs_pattern.h"
+#include "rs_debug.h"
+
+RS_PatternList* RS_PatternList::instance() {
+	static RS_PatternList instance;
+	return &instance;
+}
+
+
+RS_PatternList::~RS_PatternList() = default;
+
+/**
+ * Initializes the pattern list by creating empty RS_Pattern 
+ * objects, one for each pattern that could be found.
+ */
+void RS_PatternList::init() {
+    RS_DEBUG->print("RS_PatternList::initPatterns");
+
+	QStringList list = RS_SYSTEM->getPatternList();
+
+	patterns.clear();
+
+	for (auto const& s: list) {
+		RS_DEBUG->print("pattern: %s:", s.toLatin1().data());
+
+		QFileInfo fi(s);
+		QString const name = fi.baseName().toLower();
+		patterns[name] = std::unique_ptr<RS_Pattern>{};
+
+		RS_DEBUG->print("base: %s", name.toLatin1().data());
+    }
+}
+
+
+/**
+ * @return Pointer to the pattern with the given name or
+ * \p NULL if no such pattern was found. The pattern will be loaded into
+ * memory if it's not already.
+ */
+RS_Pattern* RS_PatternList::requestPattern(const QString& name) {
+    RS_DEBUG->print("RS_PatternList::requestPattern %s", name.toLatin1().data());
+
+    QString name2 = name.toLower();
+
+	RS_DEBUG->print("name2: %s", name2.toLatin1().data());
+	if (patterns.count(name2)) {
+		if (!patterns[name2]) {
+			RS_Pattern* p = new RS_Pattern(name2);
+			p->loadPattern();
+			patterns[name2].reset(p);
+		}
+		RS_DEBUG->print("name2: %s, size= %d", name2.toLatin1().data(),
+						patterns[name2]->countDeep());
+		return patterns[name2].get();
+	}
+
+	return nullptr;
+
+}
+
+	
+bool RS_PatternList::contains(const QString& name) const {
+
+	return patterns.count(name.toLower());
+
+}
+
+
+/**
+ * Dumps the patterns to stdout.
+ */
+std::ostream& operator << (std::ostream& os, RS_PatternList& l) {
+
+    os << "Patternlist: \n";
+	for (auto const& pa: l.patterns)
+		if (pa.second)
+			os<< *pa.second << '\n';
+
+    return os;
+}
+

lib/engine/rs_patternlist.h

@@ -0,0 +1,94 @@
+/****************************************************************************
+**
+** This file is part of the LibreCAD project, a 2D CAD program
+**
+** Copyright (C) 2010 R. van Twisk (librecad@rvt.dds.nl)
+** Copyright (C) 2001-2003 RibbonSoft. All rights reserved.
+**
+**
+** This file may be distributed and/or modified under the terms of the
+** GNU General Public License version 2 as published by the Free Software 
+** Foundation and appearing in the file gpl-2.0.txt included in the
+** packaging of this file.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+** 
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+**
+** This copyright notice MUST APPEAR in all copies of the script!  
+**
+**********************************************************************/
+
+
+#ifndef RS_PATTERNLIST_H
+#define RS_PATTERNLIST_H
+
+#include<map>
+#include<memory>
+
+class RS_Pattern;
+class QString;
+
+#define RS_PATTERNLIST RS_PatternList::instance()
+
+/**
+ * The global list of patterns. This is implemented as a singleton.
+ * Use RS_PatternList::instance() to get a pointer to the object.
+ *
+ * @author Andrew Mustun
+ */
+class RS_PatternList {
+	using PTN_MAP = std::map<QString, std::unique_ptr<RS_Pattern>>;
+	RS_PatternList() = default;
+
+public:
+    /**
+     * @return Instance to the unique pattern list.
+     */
+	static RS_PatternList* instance();
+
+	~RS_PatternList();
+	RS_PatternList(RS_PatternList const&) = delete;
+	RS_PatternList& operator = (RS_PatternList const&) = delete;
+	RS_PatternList(RS_PatternList &&) = delete;
+	RS_PatternList& operator = (RS_PatternList &&) = delete;
+
+	void init();
+
+	int countPatterns() const {
+		return patterns.size();
+    }
+
+	//! \{ range based loop support
+	PTN_MAP::iterator begin() {
+		return patterns.begin();
+	}
+	PTN_MAP::const_iterator begin() const{
+		return patterns.begin();
+	}
+	PTN_MAP::iterator end() {
+		return patterns.end();
+	}
+	PTN_MAP::const_iterator end() const{
+		return patterns.end();
+	}
+	//! \}
+
+	RS_Pattern* requestPattern(const QString& name);
+
+	bool contains(const QString& name) const;
+
+    friend std::ostream& operator << (std::ostream& os, RS_PatternList& l);
+
+
+private:
+    //! patterns in the graphic
+	PTN_MAP patterns;
+};
+
+#endif