Mac: Fixes painting artifacts in Graphics View

Problem was that pending updates were not dispatched properly on the
Mac, which is strongly required in order to get correct behavior wrt
QGraphicsItem::update().

Task-number: QTBUG-4160
Reviewed-by: bnilsen

1 files changed, 7 insertions, 0 deletions

diff --git a/src/gui/graphicsview/qgraphicsview_p.h b/src/gui/graphicsview/qgraphicsview_p.h
index 762cad1..cd161ad 100644
--- a/src/gui/graphicsview/qgraphicsview_p.h
+++ b/src/gui/graphicsview/qgraphicsview_p.h
@@ -172,10 +172,17 @@ public:
 
     inline void dispatchPendingUpdateRequests()
     {
+#ifndef Q_WS_MAC
+        // QWidget::update() works slightly different on the Mac; it's not part of
+        // our backing store so it needs special threatment.
         if (qt_widget_private(viewport)->paintOnScreen())
             QCoreApplication::sendPostedEvents(viewport, QEvent::UpdateRequest);
         else
             QCoreApplication::sendPostedEvents(viewport->window(), QEvent::UpdateRequest);
+#else
+        QCoreApplication::processEvents(QEventLoop::AllEvents | QEventLoop::ExcludeSocketNotifiers
+                                        | QEventLoop::ExcludeUserInputEvents);
+#endif
     }
 
     bool updateRect(const QRect &rect);