Rendering artifacts when installing an effect on HasNoContents items.

QGraphicsItem::HasNoContents is documented to not paint anything when
the flag is set on an item, so all the update requests are ignored. However,
we cannot ignore update requests on such items when an effect is
installed on them, because when the effects changes parameters it calls
update on the item. We still don't paint the item, but we processes the
update request such that its children can be painted properly.

Reviewed-by: Andreas

1 files changed, 10 insertions, 5 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 2ac1dca..5dd71e2 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -4616,7 +4616,8 @@ void QGraphicsScenePrivate::markDirty(QGraphicsItem *item, const QRectF &rect, b
         return;
     }
 
-    bool hasNoContents = item->d_ptr->flags & QGraphicsItem::ItemHasNoContents;
+    bool hasNoContents = item->d_ptr->flags & QGraphicsItem::ItemHasNoContents
+                         && !item->d_ptr->graphicsEffect;
     if (!hasNoContents) {
         item->d_ptr->dirty = 1;
         if (fullItemUpdate)
@@ -4706,11 +4707,15 @@ void QGraphicsScenePrivate::processDirtyItemsRecursive(QGraphicsItem *item, bool
         return;
     }
 
-    const bool itemHasContents = !(item->d_ptr->flags & QGraphicsItem::ItemHasNoContents);
+    bool itemHasContents = !(item->d_ptr->flags & QGraphicsItem::ItemHasNoContents);
     const bool itemHasChildren = !item->d_ptr->children.isEmpty();
-    if (!itemHasContents && !itemHasChildren) {
-        resetDirtyItem(item);
-        return; // Item has neither contents nor children!(?)
+    if (!itemHasContents) {
+        if (!itemHasChildren) {
+            resetDirtyItem(item);
+            return; // Item has neither contents nor children!(?)
+        }
+        if (item->d_ptr->graphicsEffect)
+            itemHasContents = true;
     }
 
     const qreal opacity = item->d_ptr->combineOpacityFromParent(parentOpacity);