QGraphicsItem::childrenBoundingRect behavior breaks QGraphicsEffect::sourceBoundingRect().

Context:
QGraphicsEffect::sourceBoundingRect() returns:
item->boundingRect() | item->childrenBoundingRect();

Problem was that item->childrenBoundingRect() adjusted the children's
bounding rect with the children's ancestor effects (child -> root item),
which means the source bounding rect was bigger than needed. We should
only account for effects downwards in the hierarchy.

   root (has effect)
    |
   item (has effect)
    |
  child
    |
grandChild

Auto test included.

Task-number: QT-3633, QT-3828
Reviewed-by: samuel

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
index 985d466358..07fa630066 100644
--- a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
+++ b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
@@ -288,6 +288,32 @@ void tst_QGraphicsEffect::boundingRect2()
     // Disable ItemClipsChildrenToShape; effect's bounding rect is no longer clipped.
     child->setFlag(QGraphicsItem::ItemClipsChildrenToShape, false);
     QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childRect | grandChildRect));
+
+    // Add root item to a scene, do the same tests as above. Results should be the same.
+    QGraphicsScene scene;
+    scene.addItem(root);
+
+    child->setFlag(QGraphicsItem::ItemClipsChildrenToShape);
+    QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childRect));
+
+    child->setFlag(QGraphicsItem::ItemClipsChildrenToShape, false);
+    QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childRect | grandChildRect));
+
+    // Now add the scene to a view, results should be the same.
+    QGraphicsView view(&scene);
+
+    child->setFlag(QGraphicsItem::ItemClipsChildrenToShape);
+    QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childRect));
+
+    child->setFlag(QGraphicsItem::ItemClipsChildrenToShape, false);
+    QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childRect | grandChildRect));
+
+    CustomEffect *childEffect = new CustomEffect;
+    child->setGraphicsEffect(childEffect);
+    QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childEffect->boundingRectFor(childRect | grandChildRect)));
+
+    child->setGraphicsEffect(0);
+    QCOMPARE(effect->boundingRect(), effect->boundingRectFor(childRect | grandChildRect));
 }
 
 void tst_QGraphicsEffect::draw()