No repaint when resizing graphics item with an effect.

Problem was that the item's cache was not invalidated from
prepareGeometryChange(). We did invalidate the cache for all the
ancestors, but not for the item itself. To avoid looping through the
whole parent chain twice, we invalidate the item's cache before
walking the parent chain. It would be nice to centralize the cache
invalidating mechanism, but for now it's OK to solve it like this.

Auto test included.

Task-number: QTBUG-9551
Reviewed-by: samuel

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
index dbd4a233f1..5dc0c9dd67 100644
--- a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
+++ b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
@@ -75,6 +75,7 @@ private slots:
     void inheritOpacity();
     void dropShadowClipping();
     void childrenVisibilityShouldInvalidateCache();
+    void prepareGeometryChangeInvalidateCache();
 };
 
 void tst_QGraphicsEffect::initTestCase()
@@ -647,6 +648,33 @@ void tst_QGraphicsEffect::childrenVisibilityShouldInvalidateCache()
     QCOMPARE(parent.nbPaint, 3);
 }
 
+void tst_QGraphicsEffect::prepareGeometryChangeInvalidateCache()
+{
+    MyGraphicsItem *item = new MyGraphicsItem;
+    item->resize(200, 200);
+
+    QGraphicsScene scene;
+    scene.addItem(item);
+
+    QGraphicsView view(&scene);
+    view.show();
+    QTest::qWaitForWindowShown(&view);
+    QTRY_COMPARE(item->nbPaint, 1);
+
+    item->nbPaint = 0;
+    item->setGraphicsEffect(new QGraphicsDropShadowEffect);
+    QTRY_COMPARE(item->nbPaint, 1);
+
+    item->nbPaint = 0;
+    item->resize(300, 300);
+    QTRY_COMPARE(item->nbPaint, 1);
+
+    item->nbPaint = 0;
+    item->setPos(item->pos() + QPointF(10, 10));
+    QTest::qWait(50);
+    QCOMPARE(item->nbPaint, 0);
+}
+
 QTEST_MAIN(tst_QGraphicsEffect)
 #include "tst_qgraphicseffect.moc"