Revert 7aee2a7054d1ca280f6dfc9c46b3fe2ce403ccb3, fix render bugs.

This change introduced an unexpected interdependency for scenes with
items that enable ItemStacksBehindParent, and that contain children
that are transformed. There's a manual test for this, called
clippingAndTransformations, which shows this problem.

The bug has been fixed and this change also includes an autotest that
covers exactly this problem.

3 files changed, 70 insertions, 18 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 7038c3d..7963ea1 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -5138,9 +5138,10 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
     // Calculate the full transform for this item.
     QRect viewBoundingRect;
     bool wasDirtyParentSceneTransform = false;
+    QTransform transform;
     if (item) {
         if (item->d_ptr->itemIsUntransformable()) {
-            transformTmp = item->deviceTransform(viewTransform);
+            transform = item->deviceTransform(viewTransform);
         } else {
             if (item->d_ptr->dirtySceneTransform) {
                 item->d_ptr->sceneTransform = item->d_ptr->parent ? item->d_ptr->parent->d_ptr->sceneTransform
@@ -5149,14 +5150,14 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
                 item->d_ptr->dirtySceneTransform = 0;
                 wasDirtyParentSceneTransform = true;
             }
-            transformTmp = item->d_ptr->sceneTransform;
-            transformTmp *= viewTransform;
+            transform = item->d_ptr->sceneTransform;
+            transform *= viewTransform;
         }
         
         QRectF brect = item->boundingRect();
         // ### This does not take the clip into account.
         _q_adjustRect(&brect);
-        viewBoundingRect = transformTmp.mapRect(brect).toRect();
+        viewBoundingRect = transform.mapRect(brect).toRect();
         item->d_ptr->paintedViewBoundingRects.insert(widget, viewBoundingRect);
         viewBoundingRect.adjust(-1, -1, 1, 1);
         if (exposedRegion)
@@ -5200,7 +5201,7 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
     // Clip children.
     if (childClip) {
         painter->save();
-        painter->setWorldTransform(transformTmp);
+        painter->setWorldTransform(transform);
         painter->setClipPath(item->shape(), Qt::IntersectClip);
     }
     
@@ -5234,14 +5235,14 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
 
     // Draw item
     if (!dontDrawItem) {
-        item->d_ptr->initStyleOption(&styleOptionTmp, transformTmp, exposedRegion ? *exposedRegion : QRegion(), exposedRegion == 0);
+        item->d_ptr->initStyleOption(&styleOptionTmp, transform, exposedRegion ? *exposedRegion : QRegion(), exposedRegion == 0);
 
         bool clipsToShape = (item->d_ptr->flags & QGraphicsItem::ItemClipsToShape);
         bool savePainter = clipsToShape || !(optimizationFlags & QGraphicsView::DontSavePainterState);
         if (savePainter)
             painter->save();
         if (!childClip)
-            painter->setWorldTransform(transformTmp);
+            painter->setWorldTransform(transform);
         if (clipsToShape)
             painter->setClipPath(item->shape(), Qt::IntersectClip);
         painter->setOpacity(opacity);
diff --git a/src/gui/graphicsview/qgraphicsscene_p.h b/src/gui/graphicsview/qgraphicsscene_p.h
index fd7decf..000e2ba 100644
--- a/src/gui/graphicsview/qgraphicsscene_p.h
+++ b/src/gui/graphicsview/qgraphicsscene_p.h
@@ -290,7 +290,6 @@ public:
     void updatePalette(const QPalette &palette);
 
     QStyleOptionGraphicsItem styleOptionTmp;
-    QTransform transformTmp;
 };
 
 QT_END_NAMESPACE
diff --git a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
index d6ecbba..621f2bf 100644
--- a/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
+++ b/tests/auto/qgraphicsitem/tst_qgraphicsitem.cpp
@@ -236,6 +236,9 @@ private slots:
     void task240400_clickOnTextItem();
     void task243707_addChildBeforeParent();
     void task197802_childrenVisibility();
+
+private:
+    QList<QGraphicsItem *> paintedItems;
 };
 
 void tst_QGraphicsItem::init()
@@ -5793,19 +5796,36 @@ void tst_QGraphicsItem::opacity2()
     QCOMPARE(grandChild->repaints, 0);
 }
 
+class StacksBehindParentHelper : public QGraphicsRectItem
+{
+public:
+    StacksBehindParentHelper(QList<QGraphicsItem *> *paintedItems, const QRectF &rect, QGraphicsItem *parent = 0)
+        : QGraphicsRectItem(rect, parent), paintedItems(paintedItems)
+    { }
+
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
+    {
+        QGraphicsRectItem::paint(painter, option, widget);
+        paintedItems->append(this);
+    }
+
+private:
+    QList<QGraphicsItem *> *paintedItems;
+};
+
 void tst_QGraphicsItem::itemStacksBehindParent()
 {
-    QGraphicsRectItem *parent1 = new QGraphicsRectItem(QRectF(0, 0, 100, 50));
-    QGraphicsRectItem *child11 = new QGraphicsRectItem(QRectF(-10, 10, 50, 50), parent1);
-    QGraphicsRectItem *grandChild111 = new QGraphicsRectItem(QRectF(-20, 20, 50, 50), child11);
-    QGraphicsRectItem *child12 = new QGraphicsRectItem(QRectF(60, 10, 50, 50), parent1);
-    QGraphicsRectItem *grandChild121 = new QGraphicsRectItem(QRectF(70, 20, 50, 50), child12);
+    StacksBehindParentHelper *parent1 = new StacksBehindParentHelper(&paintedItems, QRectF(0, 0, 100, 50));
+    StacksBehindParentHelper *child11 = new StacksBehindParentHelper(&paintedItems, QRectF(-10, 10, 50, 50), parent1);
+    StacksBehindParentHelper *grandChild111 = new StacksBehindParentHelper(&paintedItems, QRectF(-20, 20, 50, 50), child11);
+    StacksBehindParentHelper *child12 = new StacksBehindParentHelper(&paintedItems, QRectF(60, 10, 50, 50), parent1);
+    StacksBehindParentHelper *grandChild121 = new StacksBehindParentHelper(&paintedItems, QRectF(70, 20, 50, 50), child12);
 
-    QGraphicsRectItem *parent2 = new QGraphicsRectItem(QRectF(0, 0, 100, 50));
-    QGraphicsRectItem *child21 = new QGraphicsRectItem(QRectF(-10, 10, 50, 50), parent2);
-    QGraphicsRectItem *grandChild211 = new QGraphicsRectItem(QRectF(-20, 20, 50, 50), child21);
-    QGraphicsRectItem *child22 = new QGraphicsRectItem(QRectF(60, 10, 50, 50), parent2);
-    QGraphicsRectItem *grandChild221 = new QGraphicsRectItem(QRectF(70, 20, 50, 50), child22);
+    StacksBehindParentHelper *parent2 = new StacksBehindParentHelper(&paintedItems, QRectF(0, 0, 100, 50));
+    StacksBehindParentHelper *child21 = new StacksBehindParentHelper(&paintedItems, QRectF(-10, 10, 50, 50), parent2);
+    StacksBehindParentHelper *grandChild211 = new StacksBehindParentHelper(&paintedItems, QRectF(-20, 20, 50, 50), child21);
+    StacksBehindParentHelper *child22 = new StacksBehindParentHelper(&paintedItems, QRectF(60, 10, 50, 50), parent2);
+    StacksBehindParentHelper *grandChild221 = new StacksBehindParentHelper(&paintedItems, QRectF(70, 20, 50, 50), child22);
 
     parent1->setData(0, "parent1");
     child11->setData(0, "child11");
@@ -5827,25 +5847,57 @@ void tst_QGraphicsItem::itemStacksBehindParent()
     scene.addItem(parent1);
     scene.addItem(parent2);
 
+    paintedItems.clear();
+
+    QGraphicsView view(&scene);
+    view.show();
+#ifdef Q_WS_X11
+    qt_x11_wait_for_window_manager(&view);
+#endif
+    QTest::qWait(250);
+
     QCOMPARE(scene.items(0, 0, 100, 100), (QList<QGraphicsItem *>()
                                            << grandChild111 << child11
                                            << grandChild121 << child12 << parent1
                                            << grandChild211 << child21
                                            << grandChild221 << child22 << parent2));
+    QCOMPARE(paintedItems, QList<QGraphicsItem *>()
+             << parent2 << child22 << grandChild221
+             << child21 << grandChild211
+             << parent1 << child12 << grandChild121
+             << child11 << grandChild111);
 
     child11->setFlag(QGraphicsItem::ItemStacksBehindParent);
+    scene.update();
+    paintedItems.clear();
+    QTest::qWait(250);
+
     QCOMPARE(scene.items(0, 0, 100, 100), (QList<QGraphicsItem *>()
                                            << grandChild121 << child12 << parent1
                                            << grandChild111 << child11
                                            << grandChild211 << child21
                                            << grandChild221 << child22 << parent2));
+    QCOMPARE(paintedItems, QList<QGraphicsItem *>()
+             << parent2 << child22 << grandChild221
+             << child21 << grandChild211
+             << child11 << grandChild111
+             << parent1 << child12 << grandChild121);
 
     child12->setFlag(QGraphicsItem::ItemStacksBehindParent);
+    paintedItems.clear();
+    scene.update();
+    QTest::qWait(250);
+
     QCOMPARE(scene.items(0, 0, 100, 100), (QList<QGraphicsItem *>()
                                            << parent1 << grandChild111 << child11
                                            << grandChild121 << child12
                                            << grandChild211 << child21
                                            << grandChild221 << child22 << parent2));
+    QCOMPARE(paintedItems, QList<QGraphicsItem *>()
+             << parent2 << child22 << grandChild221
+             << child21 << grandChild211
+             << child12 << grandChild121
+             << child11 << grandChild111 << parent1);
 }
 
 class ClippingAndTransformsScene : public QGraphicsScene