Fixes painting issues when scaling a QGraphicsView.

The problem was that the 'exposed rectangle' passed to the Item's paint() function was rounded to Int values, whereas the one passed to drawBackground and drawForeground was not.

Autotest included.

Task-number: QTBUG-5859
Reviewed-by: bnilsen

2 files changed, 40 insertions, 1 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 3f6dff2..710048e 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -1240,7 +1240,7 @@ void QGraphicsItemPrivate::initStyleOption(QStyleOptionGraphicsItem *option, con
         const QTransform reverseMap = worldTransform.inverted();
         const QVector<QRect> exposedRects(exposedRegion.rects());
         for (int i = 0; i < exposedRects.size(); ++i) {
-            option->exposedRect |= reverseMap.mapRect(exposedRects.at(i));
+            option->exposedRect |= reverseMap.mapRect(QRectF(exposedRects.at(i)));
             if (option->exposedRect.contains(brect))
                 break;
         }
diff --git a/tests/auto/qgraphicsview/tst_qgraphicsview.cpp b/tests/auto/qgraphicsview/tst_qgraphicsview.cpp
index 1ff06c2..797e1fb 100644
--- a/tests/auto/qgraphicsview/tst_qgraphicsview.cpp
+++ b/tests/auto/qgraphicsview/tst_qgraphicsview.cpp
@@ -235,6 +235,7 @@ private slots:
     void task259503_scrollingArtifacts();
     void QTBUG_4151_clipAndIgnore_data();
     void QTBUG_4151_clipAndIgnore();
+    void QTBUG_5859_exposedRect();
 };
 
 void tst_QGraphicsView::initTestCase()
@@ -3867,5 +3868,43 @@ void tst_QGraphicsView::QTBUG_4151_clipAndIgnore()
     QCOMPARE(view.items(view.rect()).size(), numItems);
 }
 
+void tst_QGraphicsView::QTBUG_5859_exposedRect()
+{
+    class CustomScene : public QGraphicsScene
+    {
+    public:
+        CustomScene(const QRectF &rect) : QGraphicsScene(rect) { }
+        void drawBackground(QPainter *painter, const QRectF &rect)
+        { lastBackgroundExposedRect = rect; }
+        QRectF lastBackgroundExposedRect;
+    };
+    
+    class CustomRectItem : public QGraphicsRectItem
+    {
+    public:
+        CustomRectItem(const QRectF &rect) : QGraphicsRectItem(rect)
+        { setFlag(QGraphicsItem::ItemUsesExtendedStyleOption); }
+        void paint(QPainter * painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0)
+        { lastExposedRect = option->exposedRect; }
+        QRectF lastExposedRect;
+    };
+
+    CustomScene scene(QRectF(0,0,50,50));
+
+    CustomRectItem item(scene.sceneRect());
+
+    scene.addItem(&item);
+
+    QGraphicsView view(&scene);
+    view.scale(4.15, 4.15);
+    view.show();
+    QTest::qWaitForWindowShown(&view);
+
+    view.viewport()->repaint(10,10,20,20);
+    QApplication::processEvents();
+
+    QCOMPARE(item.lastExposedRect, scene.lastBackgroundExposedRect);
+}
+
 QTEST_MAIN(tst_QGraphicsView)
 #include "tst_qgraphicsview.moc"