Only use a translucent background if there is support for alpha

Change-Id: Ia8d9e543fac4b6e790fa38cf04c5a782d72d72df Reviewed-by: Eirik Aavitsland <[email protected]> Reviewed-by: Gatis Paeglis <[email protected]>
vellw · Oct 12, 2018 · dc5f9d0 · dc5f9d0
1 parent 091a386
commit dc5f9d0
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/src/plugins/platforms/xcb/nativepainting/qbackingstore_x11.cpp b/src/plugins/platforms/xcb/nativepainting/qbackingstore_x11.cpp
@@ -62,8 +62,10 @@ QXcbNativeBackingStore::QXcbNativeBackingStore(QWindow *window)
     : QPlatformBackingStore(window)
     , m_translucentBackground(false)
 {
-    if (QXcbWindow *w = static_cast<QXcbWindow *>(window->handle()))
-        m_translucentBackground = w->connection()->hasXRender() && QImage::toPixelFormat(w->imageFormat()).alphaSize() > 0;
+    if (QXcbWindow *w = static_cast<QXcbWindow *>(window->handle())) {
+        m_translucentBackground = w->connection()->hasXRender() &&
+            QImage::toPixelFormat(w->imageFormat()).alphaUsage() == QPixelFormat::UsesAlpha;
+    }
 }
 
 QXcbNativeBackingStore::~QXcbNativeBackingStore()