QGraphicsView - fix rubberband to stay right on scroll

We should consider the scene-position when we are expanding
moving a rubberband. If the user does some auto-scroll
(Qt should support that itself, but that is another matter)
then the rubberband should not keep the (old) local position
to calculate the rubberband extension, but instead use the
scene-position that was actually clicked.

Change-Id: I04a2df6a1edae8b3587e1ac2104c7fe4ccfb7762
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Andreas Aardal Hanssen <andreas@hanssen.name>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

src/widgets/graphicsview/qgraphicsview.cpp

@@ -3238,7 +3238,7 @@ void QGraphicsView::mouseMoveEvent(QMouseEvent *event)
             }
 
             // Update rubberband position
-            const QPoint &mp = d->mousePressViewPoint;
+            const QPoint &mp = mapFromScene(d->mousePressScenePoint);
             QPoint ep = event->pos();
             d->rubberBandRect = QRect(qMin(mp.x(), ep.x()), qMin(mp.y(), ep.y()),
                                       qAbs(mp.x() - ep.x()) + 1, qAbs(mp.y() - ep.y()) + 1);

tests/manual/widgets/qgraphicsview/rubberband/rubberbandtest.cpp

@@ -0,0 +1,99 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Thorbjørn Lund Martsum - tmartsum[at]gmail.com
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtWidgets>
+
+class MyGraphicsItem : public QGraphicsRectItem
+{
+public:
+    MyGraphicsItem() : QGraphicsRectItem()
+    {
+        setFlags(QGraphicsItem::ItemIsSelectable);
+    }
+
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem * /* option*/, QWidget * /*widget*/)
+    {
+        if (isSelected())
+            painter->fillRect(rect(), QColor(255, 0, 0));
+        else
+            painter->fillRect(rect(), QColor(0, 255, 0));
+    }
+};
+
+class MyGraphicsView : public QGraphicsView
+{
+
+public:
+    MyGraphicsView() : QGraphicsView()
+    {
+        setDragMode(QGraphicsView::RubberBandDrag);
+    }
+protected:
+    void mouseMoveEvent(QMouseEvent *event)
+    {
+        int rightmostInView = viewport()->mapToGlobal(viewport()->geometry().topRight()).x();
+        int xglobal = event->globalX();
+        if (xglobal > rightmostInView)
+            horizontalScrollBar()->setValue(horizontalScrollBar()->value() + 10);
+        QGraphicsView::mouseMoveEvent(event);
+    }
+};
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+    MyGraphicsView v;
+
+    QGraphicsScene s(0.0, 0.0, 10000.0, 100.0);
+    v.setScene(&s);
+    v.setInteractive(true);
+    v.setRubberBandSelectionMode(Qt::IntersectsItemBoundingRect);
+    s.addRect( (qreal) 0.0, 0.0, 1000.0, 50.0, QPen(),QBrush(QColor(0,0,255)));
+
+    for (int u = 0; u < 100; ++u) {
+        MyGraphicsItem *item = new MyGraphicsItem();
+        item->setRect(QRectF(u * 100, 50.0, 50.0, 20.0));
+        s.addItem(item);
+    }
+    v.show();
+    app.exec();
+    return 0;
+}

tests/manual/widgets/qgraphicsview/rubberband/rubberbandtest.pro

@@ -0,0 +1,4 @@
+TEMPLATE = app
+SOURCES = rubberbandtest.cpp
+QT += gui widgets # core-private
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0