Only delete all child nodes twice if effectRefEffectivelyChanged is set.

We already handle ChildrenUpdateMask again in the general case below, so this
second clear doesn't make sense, *but* for the fact that we are modifying
groupNode here when effectRefEffectivelyChanged is set. So keep doing it for
that case.

As a nice side-effect, this means that groupNode is not always allocated.

Also, don't fetch groupNode redundantly if we are clearing nodes.

Task-number: QTBUG-34255
Change-Id: Icc01b942d3c09c17300e19d61e9a65f220004796
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 990c339630..bf79158442 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -2720,16 +2720,21 @@ void QQuickWindowPrivate::updateDirtyNode(QQuickItem *item)
         }
     }
 
-    if (dirty & QQuickItemPrivate::ChildrenUpdateMask)
-        itemPriv->childContainerNode()->removeAllChildNodes();
-
     if (effectRefEffectivelyChanged) {
+        QSGNode *child = 0;
+
+        if (dirty & QQuickItemPrivate::ChildrenUpdateMask) {
+            child = itemPriv->childContainerNode();
+            child->removeAllChildNodes();
+        } else {
+            child = itemPriv->groupNode;
+        }
+
         QSGNode *parent = itemPriv->clipNode();
         if (!parent)
             parent = itemPriv->opacityNode();
         if (!parent)
             parent = itemPriv->itemNode();
-        QSGNode *child = itemPriv->groupNode;
 
         if (itemPriv->extra.isAllocated() && itemPriv->extra->effectRefCount) {
             Q_ASSERT(itemPriv->rootNode() == 0);