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

2 files changed, 34 insertions, 7 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);
diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index e737773..ead240b 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -239,7 +239,7 @@ public:
     void removeChild(QGraphicsItem *child);
     void setParentItemHelper(QGraphicsItem *parent, const QVariant *newParentVariant,
                              const QVariant *thisPointerVariant);
-    void childrenBoundingRectHelper(QTransform *x, QRectF *rect);
+    void childrenBoundingRectHelper(QTransform *x, QRectF *rect, bool doClip = true);
     void initStyleOption(QStyleOptionGraphicsItem *option, const QTransform &worldTransform,
                          const QRegion &exposedRegion, bool allItems = false) const;
     QRectF effectiveBoundingRect() const;
@@ -580,7 +580,7 @@ class QGraphicsItemEffectSourcePrivate : public QGraphicsEffectSourcePrivate
 {
 public:
     QGraphicsItemEffectSourcePrivate(QGraphicsItem *i)
-        : QGraphicsEffectSourcePrivate(), item(i), info(0)
+        : QGraphicsEffectSourcePrivate(), dirtyChildrenBoundingRect(true), item(i), info(0)
     {}
 
     inline void detach()
@@ -631,6 +631,9 @@ public:
                    QGraphicsEffect::PixmapPadMode mode) const;
     QRect paddedEffectRect(Qt::CoordinateSystem system, QGraphicsEffect::PixmapPadMode mode, const QRectF &sourceRect, bool *unpadded = 0) const;
 
+    mutable bool dirtyChildrenBoundingRect;
+    mutable QRectF childrenBoundingRect;
+
     QGraphicsItem *item;
     QGraphicsItemPaintInfo *info;
     QTransform lastEffectTransform;
@@ -788,9 +791,12 @@ inline void QGraphicsItemPrivate::markParentDirty(bool updateBoundingRect)
 #ifndef QT_NO_GRAPHICSEFFECT
         if (parentp->graphicsEffect) {
             if (updateBoundingRect) {
+                QGraphicsItemEffectSourcePrivate *sourcep =
+                    static_cast<QGraphicsItemEffectSourcePrivate *>(parentp->graphicsEffect->d_func()
+                                                                    ->source->d_func());
+                parentp->dirtyChildrenBoundingRect = 1;
                 parentp->notifyInvalidated = 1;
-                static_cast<QGraphicsItemEffectSourcePrivate *>(parentp->graphicsEffect->d_func()
-                                                                ->source->d_func())->invalidateCache();
+                sourcep->invalidateCache();
             }
             if (parentp->graphicsEffect->isEnabled()) {
                 parentp->dirty = 1;