Don't swap buffers before the window is exposed.

At app startup there is often a delay between setting
a window visible and the window being exposed by the
window manager.

Add check to canvas->isExposed() before calling
swapbuffers.

Change-Id: I5e588ab334a72c4fe817da44eff4c3dc785d6b1f
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

diff --git a/src/quick/items/qquickwindowmanager.cpp b/src/quick/items/qquickwindowmanager.cpp
index 2022d24..3cfa871 100644 (file)
--- a/src/quick/items/qquickwindowmanager.cpp
+++ b/src/quick/items/qquickwindowmanager.cpp
@@ -706,7 +706,7 @@ void QQuickRenderThreadSingleContextWindowManager::run()
             printf("                RenderThread: --- wait for swap...\n");
 #endif
 
-            if (canvasData->isVisible)
+            if (canvasData->isVisible && canvas->isExposed())
                 gl->swapBuffers(canvas);
 
             canvasPrivate->fireFrameSwapped();