1 files changed, 68 insertions, 13 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 13f70e5..69e08d1 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -351,6 +351,8 @@ QGraphicsScenePrivate::QGraphicsScenePrivate()
       dragDropItem(0),
       enterWidget(0),
       lastDropAction(Qt::IgnoreAction),
+      allItemsIgnoreHoverEvents(true),
+      allItemsUseDefaultCursor(true),
       painterStateProtection(true),
       sortCacheEnabled(false),
       updatingSortCache(false),
@@ -622,6 +624,30 @@ void QGraphicsScenePrivate::_q_emitUpdated()
 
 /*!
     \internal
+*/
+void QGraphicsScenePrivate::registerTopLevelItem(QGraphicsItem *item)
+{
+    item->d_ptr->siblingIndex = topLevelItems.size();
+    topLevelItems.append(item);
+}
+
+/*!
+    \internal
+*/
+void QGraphicsScenePrivate::unregisterTopLevelItem(QGraphicsItem *item)
+{
+    int idx = item->d_ptr->siblingIndex;
+    int size = topLevelItems.size();
+    for (int i = idx; i < size - 1; ++i) {
+        QGraphicsItem *p = topLevelItems[i + 1];
+        topLevelItems[i] = p;
+        p->d_ptr->siblingIndex = i;
+    }
+    topLevelItems.removeLast();
+}
+
+/*!
+    \internal
 
     Updates all items in the pending update list. At this point, the list is
     unlikely to contain partially constructed items.
@@ -756,10 +782,6 @@ void QGraphicsScenePrivate::_q_removeItemLater(QGraphicsItem *item)
         freeSceneTransformSlots.append(transformIndex);
     }
 
-    // Remove all children recursively.
-    foreach (QGraphicsItem *child, item->children())
-        _q_removeItemLater(child);
-
     // Reset the mouse grabber
     if (mouseGrabberItems.contains(item))
         ungrabMouse(item, /* item is dying */ true);
@@ -880,11 +902,18 @@ void QGraphicsScenePrivate::grabMouse(QGraphicsItem *item, bool implicit)
 {
     // Append to list of mouse grabber items, and send a mouse grab event.
     if (mouseGrabberItems.contains(item)) {
-        if (mouseGrabberItems.last() == item)
-            qWarning("QGraphicsItem::grabMouse: already a mouse grabber");
-        else
+        if (mouseGrabberItems.last() == item) {
+            Q_ASSERT(!implicit);
+            if (!lastMouseGrabberItemHasImplicitMouseGrab) {
+                qWarning("QGraphicsItem::grabMouse: already a mouse grabber");
+            } else {
+                // Upgrade to an explicit mouse grab
+                lastMouseGrabberItemHasImplicitMouseGrab = false;
+            }
+        } else {
             qWarning("QGraphicsItem::grabMouse: already blocked by mouse grabber: %p",
                      mouseGrabberItems.last());
+        }
         return;
     }
 
@@ -1036,6 +1065,12 @@ void QGraphicsScenePrivate::clearKeyboardGrabber()
         ungrabKeyboard(keyboardGrabberItems.first());
 }
 
+void QGraphicsScenePrivate::enableMouseTrackingOnViews()
+{
+    foreach (QGraphicsView *view, views)
+        view->viewport()->setMouseTracking(true);
+}
+
 /*!
     Returns all items for the screen position in \a event.
 */
@@ -1831,7 +1866,7 @@ inline bool qt_closestLeaf(const QGraphicsItem *item1, const QGraphicsItem *item
     if (f1 != f2) return f2;
     qreal z1 = d1->z;
     qreal z2 = d2->z;
-    return z1 != z2 ? z1 > z2 : item1 > item2;
+    return z1 != z2 ? z1 > z2 : d1->siblingIndex > d2->siblingIndex;
 }
 
 /*!
@@ -2747,12 +2782,13 @@ void QGraphicsScene::clear()
     }
     d->unindexedItems.clear();
     qDeleteAll(unindexedParents);
-
     d->indexedItems.clear();
     d->freeItemIndexes.clear();
     d->lastItemCount = 0;
     d->bspTree.clear();
     d->largestUntransformableItem = QRectF();
+    d->allItemsIgnoreHoverEvents = true;
+    d->allItemsUseDefaultCursor = true;
 }
 
 /*!
@@ -2856,7 +2892,6 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
         qWarning("QGraphicsScene::addItem: item has already been added to this scene");
         return;
     }
-
     // Remove this item from its existing scene
     if (QGraphicsScene *oldScene = item->scene())
         oldScene->removeItem(item);
@@ -2897,6 +2932,10 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
     item->d_func()->index = -1;
     d->startIndexTimer();
 
+    // Add to list of toplevels if this item is a toplevel.
+    if (!item->d_ptr->parent)
+        d->registerTopLevelItem(item);
+
     // Update the scene's sort cache settings.
     item->d_ptr->globalStackingOrder = -1;
     d->invalidateSortCache();
@@ -2914,6 +2953,17 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
     ++d->selectionChanging;
     int oldSelectedItemSize = d->selectedItems.size();
 
+    // Enable mouse tracking if the item accepts hover events or has a cursor set.
+    if (d->allItemsIgnoreHoverEvents && d->itemAcceptsHoverEvents_helper(item)) {
+        d->allItemsIgnoreHoverEvents = false;
+        d->enableMouseTrackingOnViews();
+    }
+    if (d->allItemsUseDefaultCursor && item->hasCursor()) {
+        d->allItemsUseDefaultCursor = false;
+        if (d->allItemsIgnoreHoverEvents) // already enabled otherwise
+            d->enableMouseTrackingOnViews();
+    }
+
     // Update selection lists
     if (item->isSelected())
         d->selectedItems << item;
@@ -3249,13 +3299,15 @@ void QGraphicsScene::removeItem(QGraphicsItem *item)
     // Set the item's scene ptr to 0.
     item->d_func()->scene = 0;
 
-    // Detach the item from its parent.
+    // Remove from parent, or unregister from toplevels.
     if (QGraphicsItem *parentItem = item->parentItem()) {
         if (parentItem->scene()) {
             Q_ASSERT_X(parentItem->scene() == this, "QGraphicsScene::removeItem",
                        "Parent item's scene is different from this item's scene");
             item->setParentItem(0);
         }
+    } else {
+        d->unregisterTopLevelItem(item);
     }
 
     // Remove from our item lists.
@@ -4214,6 +4266,9 @@ bool QGraphicsScenePrivate::itemAcceptsHoverEvents_helper(const QGraphicsItem *i
 */
 bool QGraphicsScenePrivate::dispatchHoverEvent(QGraphicsSceneHoverEvent *hoverEvent)
 {
+    if (allItemsIgnoreHoverEvents)
+        return false;
+
     // Find the first item that accepts hover events, reusing earlier
     // calculated data is possible.
     if (cachedItemsUnderMouse.isEmpty()) {
@@ -4613,7 +4668,7 @@ static void _q_paintItem(QGraphicsItem *item, QPainter *painter,
                                 ? proxy->widget()->windowOpacity() : 1.0;
     const qreal oldPainterOpacity = painter->opacity();
 
-    if (qFuzzyCompare(windowOpacity + 1, qreal(1.0)))
+    if (qFuzzyIsNull(windowOpacity))
         return;
     // Set new painter opacity.
     if (windowOpacity < 1.0)
@@ -5255,7 +5310,7 @@ void QGraphicsScene::itemUpdated(QGraphicsItem *item, const QRectF &rect)
     // Deliver the actual update.
     if (!d->updateAll) {
         if (d->views.isEmpty() || ((d->connectedSignals & d->changedSignalMask) && !item->d_ptr->itemIsUntransformable()
-                                   && qFuzzyCompare(item->boundingRegionGranularity(), qreal(0.0)))) {
+                                   && qFuzzyIsNull(item->boundingRegionGranularity()))) {
             // This block of code is kept for compatibility. Since 4.5, by default
             // QGraphicsView does not connect the signal and we use the below
             // method of delivering updates.