Removed usage of CompositionMode_Source in QGraphicsView for X11.

Due to the rendering model in XRender ((src IN mask) OP dest) we can't
support the PorterDuff composition modes natively under X11. They
just behave differently than what we've defined them to do in QPainter,
and there is no apparent workaround.

Task-number: QTBUG-4829
Reviewed-by: Gunnar

1 files changed, 7 insertions, 1 deletions

diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index 710c745..8945f51 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -281,6 +281,7 @@ static const int QGRAPHICSVIEW_PREALLOC_STYLE_OPTIONS = 503; // largest prime <
 #include <QtGui/qstyleoption.h>
 #include <QtGui/qinputcontext.h>
 #ifdef Q_WS_X11
+#include <QtGui/qpaintengine.h>
 #include <private/qt_x11_p.h>
 #endif
 
@@ -3294,7 +3295,12 @@ void QGraphicsView::paintEvent(QPaintEvent *event)
             backgroundPainter.setClipRegion(d->backgroundPixmapExposed, Qt::ReplaceClip);
             if (viewTransformed)
                 backgroundPainter.setTransform(viewTransform);
-            backgroundPainter.setCompositionMode(QPainter::CompositionMode_Source);
+#ifdef Q_WS_X11
+#undef X11
+            if (backgroundPainter.paintEngine()->type() != QPaintEngine::X11)
+#define X11 qt_x11Data
+#endif
+                backgroundPainter.setCompositionMode(QPainter::CompositionMode_Source);
             drawBackground(&backgroundPainter, exposedSceneRect);
             d->backgroundPixmapExposed = QRegion();
         }