Merge branch '4.6'

1 files changed, 24 insertions, 1 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 5504803..83a6b9c 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -4688,8 +4688,31 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
         if (sourced->currentCachedSystem() != Qt::LogicalCoordinates
             && sourced->lastEffectTransform != painter->worldTransform())
         {
+            bool unclipped = false;
+            if (sourced->lastEffectTransform.type() <= QTransform::TxTranslate
+                && painter->worldTransform().type() <= QTransform::TxTranslate)
+            {
+                QRectF itemRect = item->boundingRect();
+                if (!item->d_ptr->children.isEmpty())
+                    itemRect |= item->childrenBoundingRect();
+
+                QRectF oldSourceRect = sourced->lastEffectTransform.mapRect(itemRect);
+                QRectF newSourceRect = painter->worldTransform().mapRect(itemRect);
+
+                QRect oldEffectRect = sourced->paddedEffectRect(sourced->currentCachedSystem(), sourced->currentCachedMode(), oldSourceRect);
+                QRect newEffectRect = sourced->paddedEffectRect(sourced->currentCachedSystem(), sourced->currentCachedMode(), newSourceRect);
+
+                QRect deviceRect(0, 0, painter->device()->width(), painter->device()->height());
+                if (deviceRect.contains(oldEffectRect) && deviceRect.contains(newEffectRect)) {
+                    sourced->setCachedOffset(newEffectRect.topLeft());
+                    unclipped = true;
+                }
+            }
+
             sourced->lastEffectTransform = painter->worldTransform();
-            sourced->invalidateCache(QGraphicsEffectSourcePrivate::TransformChanged);
+
+            if (!unclipped)
+                sourced->invalidateCache(QGraphicsEffectSourcePrivate::TransformChanged);
         }
 
         item->d_ptr->graphicsEffect->draw(painter);