init

ui/qg_scrollbar.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 QG_SCROLLBAR_H
+#define QG_SCROLLBAR_H
+
+#include <QScrollBar>
+#include <QWheelEvent>
+
+/**
+ * A small wrapper for the Qt scrollbar. This class offers a slot
+ * for scroll events.
+ */
+class QG_ScrollBar: public QScrollBar {
+    Q_OBJECT
+
+public:
+    QG_ScrollBar(QWidget* parent=0)
+            : QScrollBar(parent) {
+        sizeHintCache = QScrollBar::sizeHint();
+    }
+    QG_ScrollBar(Qt::Orientation orientation,
+                 QWidget* parent=0)
+            : QScrollBar(orientation, parent) {
+        sizeHintCache = QScrollBar::sizeHint();
+    }
+
+    // This sizeHint caches the height value. Out of profiling (see #727),
+    // it appears that sizeHint calls all the way down to the underlying
+    // windowing system to check the size.
+    QSize sizeHint() const override final {
+        return sizeHintCache;
+    }
+
+public slots:
+    void slotWheelEvent(QWheelEvent* e) {
+        wheelEvent(e);
+    }
+
+    void resizeEvent(QResizeEvent* event) override {
+        sizeHintCache = QScrollBar::sizeHint();
+        QScrollBar::resizeEvent(event);
+    }
+
+private:
+    QSize sizeHintCache;
+
+};
+
+#endif
+