Don't allow backingstore flush to non-raster surfaces

Change-Id: I8e85706727a8c5f7585e34e3864c8a9f48481b92
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/gui/painting/qbackingstore.cpp b/src/gui/painting/qbackingstore.cpp
index 8d71d1c3a9..0dfb52e7c3 100644
--- a/src/gui/painting/qbackingstore.cpp
+++ b/src/gui/painting/qbackingstore.cpp
@@ -192,6 +192,17 @@ void QBackingStore::endPaint()
     d_ptr->platformBackingStore->endPaint();
 }
 
+static bool isRasterSurface(QWindow *window)
+{
+    switch (window->surfaceType()) {
+    case QSurface::RasterSurface:
+    case QSurface::RasterGLSurface:
+        return true;
+    default:
+        return false;
+    };
+}
+
 /*!
     Flushes the given \a region from the specified \a window onto the
     screen.
@@ -220,6 +231,13 @@ void QBackingStore::flush(const QRegion &region, QWindow *window, const QPoint &
         return;
     }
 
+    if (!isRasterSurface(window)) {
+        qWarning() << "Attempted flush to non-raster surface" << window << "of type" << window->surfaceType()
+            << (window->inherits("QWidgetWindow") ? "(consider using Qt::WA_PaintOnScreen to exclude "
+                                                   "from backingstore sync)" : "");
+        return;
+    }
+
 #ifdef QBACKINGSTORE_DEBUG
     if (window && window->isTopLevel() && !qt_window_private(window)->receivedExpose) {
         qWarning().nospace() << "QBackingStore::flush() called with non-exposed window "