Fixed a crash when QPixmaps are destroyed after the ~QApplication.

Destroying QPixmaps after the QApp destructor will leak native pixmap
objects on X11, and it's a general rule that all GUI objects must
be destroyed before the QApp destuctor is called.

Task-number: QTBUG-7746
Reviewed-by: Kim

2 files changed, 8 insertions, 3 deletions

diff --git a/src/gui/image/qpixmap_x11.cpp b/src/gui/image/qpixmap_x11.cpp
index 169a2ece26..e1e8a0db5e 100644
--- a/src/gui/image/qpixmap_x11.cpp
+++ b/src/gui/image/qpixmap_x11.cpp
@@ -1243,8 +1243,13 @@ void QX11PixmapData::release()
     delete pengine;
     pengine = 0;
 
-    if (!X11)
+    if (!X11) {
+#ifndef QT_NO_DEBUG
+        qWarning("~QX11PixmapData(): QPixmap objects must be destroyed before the QApplication"
+                 " object, otherwise the native pixmap object will be leaked.");
+#endif
         return;
+    }
 
     if (x11_mask) {
 #ifndef QT_NO_XRENDER
diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index cde6a2d6c9..bf12c6b584 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -7509,7 +7509,7 @@ QPaintDevice *QPainter::redirected(const QPaintDevice *device, QPoint *offset)
             return widgetPrivate->redirected(offset);
     }
 
-    if (*globalRedirectionAtomic() == 0)
+    if (!globalRedirectionAtomic() || *globalRedirectionAtomic() == 0)
         return 0;
 
     QMutexLocker locker(globalRedirectionsMutex());
@@ -7529,7 +7529,7 @@ QPaintDevice *QPainter::redirected(const QPaintDevice *device, QPoint *offset)
 
 void qt_painter_removePaintDevice(QPaintDevice *dev)
 {
-    if (*globalRedirectionAtomic() == 0)
+    if (!globalRedirectionAtomic() || *globalRedirectionAtomic() == 0)
         return;
 
     QMutex *mutex = 0;