3 files changed, 36 insertions, 10 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 7971711..92be62f 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -885,6 +885,38 @@ void QGraphicsItemPrivate::setParentItemHelper(QGraphicsItem *newParent, bool de
 /*!
     \internal
 
+    Returns the bounding rect of this item's children (excluding itself).
+*/
+void QGraphicsItemPrivate::childrenBoundingRectHelper(QTransform *x, QRectF *rect)
+{
+    for (int i = 0; i < children.size(); ++i) {
+        QGraphicsItem *child = children.at(i);
+        QGraphicsItemPrivate *childd = child->d_ptr;
+        bool hasX = childd->hasTransform;
+        bool hasPos = !childd->pos.isNull();
+        if (hasPos || hasX) {
+            QTransform matrix;
+            if (hasX)
+                matrix = child->transform();
+            if (hasPos) {
+                const QPointF &p = childd->pos;
+                matrix *= QTransform::fromTranslate(p.x(), p.y());
+            }
+            matrix *= *x;
+            *rect |= matrix.mapRect(child->boundingRect());
+            if (!childd->children.isEmpty())
+                childd->childrenBoundingRectHelper(&matrix, rect);
+        } else {
+            *rect |= x->mapRect(child->boundingRect());
+            if (!childd->children.isEmpty())
+                childd->childrenBoundingRectHelper(x, rect);
+        }
+    }
+}
+
+/*!
+    \internal
+
     Empty all cached pixmaps from the pixmap cache.
 */
 void QGraphicsItemCache::purge()
@@ -3255,13 +3287,8 @@ void QGraphicsItem::setZValue(qreal z)
 QRectF QGraphicsItem::childrenBoundingRect() const
 {
     QRectF childRect;
-    foreach (QGraphicsItem *child, children()) {
-        QPointF childPos = child->pos();
-        QTransform matrix = child->transform();
-        if (!childPos.isNull())
-            matrix *= QTransform::fromTranslate(childPos.x(), childPos.y());
-        childRect |= matrix.mapRect(child->boundingRect() | child->childrenBoundingRect());
-    }
+    QTransform x;
+    d_ptr->childrenBoundingRectHelper(&x, &childRect);
     return childRect;
 }
 
diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index fb0bd2d..bcbd737 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -187,6 +187,7 @@ public:
     void addChild(QGraphicsItem *child);
     void removeChild(QGraphicsItem *child);
     void setParentItemHelper(QGraphicsItem *parent, bool deleting);
+    void childrenBoundingRectHelper(QTransform *x, QRectF *rect);
 
     virtual void resolveFont(uint inheritedMask)
     {
diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index a9d585c..7720a10 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -2809,9 +2809,7 @@ void QGraphicsView::setupViewport(QWidget *widget)
 
     const bool isGLWidget = widget->inherits("QGLWidget");
 
-    d->accelerateScrolling = !(isGLWidget
-                               || widget->testAttribute(Qt::WA_MSWindowsUseDirect3D)
-                               || qApp->testAttribute(Qt::AA_MSWindowsUseDirect3DByDefault));
+    d->accelerateScrolling = !(isGLWidget);
 
     widget->setFocusPolicy(Qt::StrongFocus);