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/qquickimage.cpp b/src/quick/items/qquickimage.cpp
index 073b107753..1e389cfe38 100644
--- a/src/quick/items/qquickimage.cpp
+++ b/src/quick/items/qquickimage.cpp
@@ -152,13 +152,11 @@ QQuickImagePrivate::QQuickImagePrivate()
 QQuickImage::QQuickImage(QQuickItem *parent)
     : QQuickImageBase(*(new QQuickImagePrivate), parent)
 {
-    connect(this, SIGNAL(sceneGraphInvalidated()), this, SLOT(invalidateSG()));
 }
 
 QQuickImage::QQuickImage(QQuickImagePrivate &dd, QQuickItem *parent)
     : QQuickImageBase(dd, parent)
 {
-    connect(this, SIGNAL(sceneGraphInvalidated()), this, SLOT(invalidateSG()));
 }
 
 QQuickImage::~QQuickImage()
@@ -569,7 +567,7 @@ QSGTextureProvider *QQuickImage::textureProvider() const
     return d->provider;
 }
 
-void QQuickImage::invalidateSG()
+void QQuickImage::invalidateSceneGraph()
 {
     Q_D(QQuickImage);
     delete d->provider;