QGraphicsWidget is painted twice on the inital show.

Problem occured when doing something in the polishEvent() which
eventually ended up as an update(). The problem was that in
QGraphicsScene::addItem we scheduled a polish event after scheduling
an update, resulting in update requests being processed before polish
requests.

Auto-test included.

Task-number: QTBUG-6956
Reviewed-by: alexis

4 files changed, 43 insertions, 8 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index ac10aa7..bdd8863 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -178,6 +178,7 @@ public:
         sequentialOrdering(1),
         updateDueToGraphicsEffect(0),
         scenePosDescendants(0),
+        pendingPolish(0),
         globalStackingOrder(-1),
         q_ptr(0)
     {
@@ -486,6 +487,7 @@ public:
     quint32 sequentialOrdering : 1;
     quint32 updateDueToGraphicsEffect : 1;
     quint32 scenePosDescendants : 1;
+    quint32 pendingPolish : 1;
 
     // Optional stacking order
     int globalStackingOrder;
diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 088a6b9..7e182d0 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -429,12 +429,13 @@ void QGraphicsScenePrivate::unregisterTopLevelItem(QGraphicsItem *item)
 */
 void QGraphicsScenePrivate::_q_polishItems()
 {
-    QSet<QGraphicsItem *>::Iterator it = unpolishedItems.begin();
+    QVector<QGraphicsItem *>::Iterator it = unpolishedItems.begin();
     const QVariant booleanTrueVariant(true);
     while (!unpolishedItems.isEmpty()) {
         QGraphicsItem *item = *it;
         it = unpolishedItems.erase(it);
         unpolishedItemsModified = false;
+        item->d_ptr->pendingPolish = false;
         if (!item->d_ptr->explicitlyHidden) {
             item->itemChange(QGraphicsItem::ItemVisibleChange, booleanTrueVariant);
             item->itemChange(QGraphicsItem::ItemVisibleHasChanged, booleanTrueVariant);
@@ -638,8 +639,14 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
     selectedItems.remove(item);
     hoverItems.removeAll(item);
     cachedItemsUnderMouse.removeAll(item);
-    unpolishedItems.remove(item);
-    unpolishedItemsModified = true;
+    if (item->d_ptr->pendingPolish) {
+        const int unpolishedIndex = unpolishedItems.indexOf(item);
+        if (unpolishedIndex != -1) {
+            unpolishedItems.remove(unpolishedIndex);
+            unpolishedItemsModified = true;
+        }
+        item->d_ptr->pendingPolish = false;
+    }
     resetDirtyItem(item);
 
     //We remove all references of item from the sceneEventFilter arrays
@@ -2501,6 +2508,11 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
         return;
     }
 
+    if (d->unpolishedItems.isEmpty())
+        QMetaObject::invokeMethod(this, "_q_polishItems", Qt::QueuedConnection);
+    d->unpolishedItems.append(item);
+    item->d_ptr->pendingPolish = true;
+
     // Detach this item from its parent if the parent's scene is different
     // from this scene.
     if (QGraphicsItem *itemParent = item->d_ptr->parent) {
@@ -2583,10 +2595,6 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
     item->d_ptr->resolveFont(d->font.resolve());
     item->d_ptr->resolvePalette(d->palette.resolve());
 
-    if (d->unpolishedItems.isEmpty())
-        QMetaObject::invokeMethod(this, "_q_polishItems", Qt::QueuedConnection);
-    d->unpolishedItems.insert(item);
-    d->unpolishedItemsModified = true;
 
     // Reenable selectionChanged() for individual items
     --d->selectionChanging;
diff --git a/src/gui/graphicsview/qgraphicsscene_p.h b/src/gui/graphicsview/qgraphicsscene_p.h
index d10811c..a3e36d0 100644
--- a/src/gui/graphicsview/qgraphicsscene_p.h
+++ b/src/gui/graphicsview/qgraphicsscene_p.h
@@ -108,7 +108,7 @@ public:
     QPainterPath selectionArea;
     int selectionChanging;
     QSet<QGraphicsItem *> selectedItems;
-    QSet<QGraphicsItem *> unpolishedItems;
+    QVector<QGraphicsItem *> unpolishedItems;
     QList<QGraphicsItem *> topLevelItems;
     bool needSortTopLevelItems;
     bool unpolishedItemsModified;
diff --git a/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp b/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp
index 909ea54..d3132fe 100644
--- a/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp
+++ b/tests/auto/qgraphicswidget/tst_qgraphicswidget.cpp
@@ -163,6 +163,7 @@ private slots:
     void addChildInpolishEvent();
     void polishEvent();
     void polishEvent2();
+    void initialShow();
 
     // Task fixes
     void task236127_bspTreeIndexFails();
@@ -2856,6 +2857,30 @@ void tst_QGraphicsWidget::polishEvent2()
     QVERIFY(widget->events.contains(QEvent::Polish));
 }
 
+void tst_QGraphicsWidget::initialShow()
+{
+    class MyGraphicsWidget : public QGraphicsWidget
+    { public:
+        MyGraphicsWidget() : repaints(0) {}
+        int repaints;
+        void paint(QPainter *, const QStyleOptionGraphicsItem *, QWidget*) { ++repaints; }
+        void polishEvent() { update(); }
+    };
+
+    QGraphicsScene scene;
+    MyGraphicsWidget *widget = new MyGraphicsWidget;
+
+    QGraphicsView view(&scene);
+    view.show();
+    QTest::qWaitForWindowShown(&view);
+
+    QTest::qWait(100);
+    scene.addItem(widget);
+    QTest::qWait(100);
+
+    QCOMPARE(widget->repaints, 1);
+}
+
 void tst_QGraphicsWidget::QT_BUG_6544_tabFocusFirstUnsetWhenRemovingItems()
 {
     QGraphicsScene scene;