Warn when drawPixmapFragments is called with an invalid source rect

When drawPixmapFragments() is called with fragments that has invalid
source rects in it, then usually it causes the pixmap drawn on screen
to appear corrupted.  However it has been reported that a crash can
occur (not reproducable locally) so by adding a warning in debug mode
only means that this can hopefully be caught at development time.

Reviewed-by: Trond

1 files changed, 9 insertions, 0 deletions

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index 2ea6673..9dadbd5 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -8969,6 +8969,15 @@ void QPainter::drawPixmapFragments(const PixmapFragment *fragments, int fragment
     if (!d->engine)
         return;
 
+#ifndef QT_NO_DEBUG
+    for (int i = 0; i < fragmentCount; ++i) {
+        QRectF sourceRect(fragments[i].sourceLeft, fragments[i].sourceTop,
+                          fragments[i].width, fragments[i].height);
+        if (!(QRectF(pixmap.rect()).contains(sourceRect)))
+            qWarning("QPainter::drawPixmapFragments - the source rect is not contained by the pixmap's rectangle");
+    }
+#endif
+
     if (d->engine->isExtended()) {
         d->extended->drawPixmapFragments(fragments, fragmentCount, pixmap, hints);
     } else {