Fixed missing clip when computing the graphics item effect source rect.

If item clips children to shape we should take that into account when
computing the source rect, to avoid creating unnecessary large source
pixmaps which might have a significant performance impact.

Task-number: QT-3551
Reviewed-by: Gunnar
Reviewed-by: Trond

1 files changed, 24 insertions, 3 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 074e571..88e9952 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -1205,8 +1205,14 @@ void QGraphicsItemPrivate::setParentItemHelper(QGraphicsItem *newParent, const Q
 
     Returns the bounding rect of this item's children (excluding itself).
 */
-void QGraphicsItemPrivate::childrenBoundingRectHelper(QTransform *x, QRectF *rect)
+void QGraphicsItemPrivate::childrenBoundingRectHelper(QTransform *x, QRectF *rect, bool doClip)
 {
+    Q_Q(QGraphicsItem);
+
+    QRectF childrenRect;
+    QRectF *result = rect;
+    rect = &childrenRect;
+
     for (int i = 0; i < children.size(); ++i) {
         QGraphicsItem *child = children.at(i);
         QGraphicsItemPrivate *childd = child->d_ptr.data();
@@ -1228,6 +1234,15 @@ void QGraphicsItemPrivate::childrenBoundingRectHelper(QTransform *x, QRectF *rec
                 childd->childrenBoundingRectHelper(x, rect);
         }
     }
+
+    if (doClip && (flags & QGraphicsItem::ItemClipsChildrenToShape)){
+        if (x)
+            *rect &= x->mapRect(q->boundingRect());
+        else
+            *rect &= q->boundingRect();
+    }
+
+    *result |= *rect;
 }
 
 void QGraphicsItemPrivate::initStyleOption(QStyleOptionGraphicsItem *option, const QTransform &worldTransform,
@@ -10816,8 +10831,14 @@ QRectF QGraphicsItemEffectSourcePrivate::boundingRect(Qt::CoordinateSystem syste
     }
 
     QRectF rect = item->boundingRect();
-    if (!item->d_ptr->children.isEmpty())
-        rect |= item->childrenBoundingRect();
+    if (!item->d_ptr->children.isEmpty()) {
+        if (dirtyChildrenBoundingRect) {
+            childrenBoundingRect = QRectF();
+            item->d_ptr->childrenBoundingRectHelper(0, &childrenBoundingRect, true);
+            dirtyChildrenBoundingRect = false;
+        }
+        rect |= childrenBoundingRect;
+    }
 
     if (deviceCoordinates) {
         Q_ASSERT(info->painter);