Invalidate the cache of QGraphicsEffect if a child becomes visible.

The effect might rely on a child to draw itself. So we need to redraw if
a child become visible or invisible.

Task-number:QTBUG-7843
Reviewed-by:janarve

1 files changed, 43 insertions, 0 deletions

diff --git a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
index 1007d618c2..02899ae786 100644
--- a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
+++ b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
@@ -46,6 +46,7 @@
 #include <QtGui/qgraphicsview.h>
 #include <QtGui/qgraphicsscene.h>
 #include <QtGui/qgraphicsitem.h>
+#include <QtGui/qgraphicswidget.h>
 #include <QtGui/qstyleoption.h>
 
 #include "../../shared/util.h"
@@ -73,6 +74,7 @@ private slots:
     void deviceCoordinateTranslateCaching();
     void inheritOpacity();
     void dropShadowClipping();
+    void childrenVisibilityShouldInvalidateCache();
 };
 
 void tst_QGraphicsEffect::initTestCase()
@@ -613,6 +615,47 @@ void tst_QGraphicsEffect::dropShadowClipping()
             QCOMPARE(img.pixel(x, y), img.pixel(x, y-1));
 }
 
+class MyGraphicsItem : public QGraphicsWidget
+{
+public:
+    MyGraphicsItem(QGraphicsItem *parent = 0) :
+            QGraphicsWidget(parent), nbPaint(0)
+    {}
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
+    {
+        nbPaint++;
+        QGraphicsWidget::paint(painter, option, widget);
+    }
+    int nbPaint;
+};
+
+void tst_QGraphicsEffect::childrenVisibilityShouldInvalidateCache()
+{
+    QGraphicsScene scene;
+    MyGraphicsItem parent;
+    parent.resize(200, 200);
+    QGraphicsWidget child(&parent);
+    child.resize(200, 200);
+    child.setVisible(false);
+    scene.addItem(&parent);
+    QGraphicsView view(&scene);
+    view.show();
+    QApplication::setActiveWindow(&view);
+    QTest::qWaitForWindowShown(&view);
+    QCOMPARE(parent.nbPaint, 1);
+    //we set an effect on the parent
+    parent.setGraphicsEffect(new QGraphicsDropShadowEffect(&parent));
+    //flush the events
+    QApplication::processEvents();
+    //new effect applied->repaint
+    QCOMPARE(parent.nbPaint, 2);
+    child.setVisible(true);
+    //flush the events
+    QApplication::processEvents();
+    //a new child appears we need to redraw the effect.
+    QCOMPARE(parent.nbPaint, 3);
+}
+
 QTEST_MAIN(tst_QGraphicsEffect)
 #include "tst_qgraphicseffect.moc"