Fix performance regression caused by SG signals in QQuickItem.

For a testcase with thosands of items, I measured an increase
in shutdown time from 800ms to 7500ms, all spent in disconnect().
This is not acceptible, so we're choosing a different approach.

If items implement a invalidateSceneGraph slot, this function
will be called during shutdown. It should be made a proper virtual
in Qt 6. This approach costs very little.

Change-Id: I5970143cc0a0744955687e17586f0bb00c9afb26
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/src/quick/items/qquickpainteditem.cpp b/src/quick/items/qquickpainteditem.cpp
index bc148c5bca..a79f0b523c 100644
--- a/src/quick/items/qquickpainteditem.cpp
+++ b/src/quick/items/qquickpainteditem.cpp
@@ -140,7 +140,6 @@ QQuickPaintedItem::QQuickPaintedItem(QQuickItem *parent)
     : QQuickItem(*(new QQuickPaintedItemPrivate), parent)
 {
     setFlag(ItemHasContents);
-    connect(this, SIGNAL(sceneGraphInvalidated()), this, SLOT(invalidateSG()));
 }
 
 /*!
@@ -150,7 +149,6 @@ QQuickPaintedItem::QQuickPaintedItem(QQuickPaintedItemPrivate &dd, QQuickItem *p
     : QQuickItem(dd, parent)
 {
     setFlag(ItemHasContents);
-    connect(this, SIGNAL(sceneGraphInvalidated()), this, SLOT(invalidateSG()));
 }
 
 /*!
@@ -561,7 +559,7 @@ void QQuickPaintedItem::releaseResources()
     d->node = 0; // Managed by the scene graph, just clear the pointer.
 }
 
-void QQuickPaintedItem::invalidateSG()
+void QQuickPaintedItem::invalidateSceneGraph()
 {
     Q_D(QQuickPaintedItem);
     delete d->textureProvider;