Fix tlw source rect transformation for backingstore blit.

The srcRect is already in device window coordinates. Converting it
again via deviceRect(QRect, QWindow) causes it to be overly large.

Task-number: QTBUG-50613
Change-Id: Iaae390499c0d1add842bde6eec22fb07c8de663b
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gui/painting/qplatformbackingstore.cpp b/src/gui/painting/qplatformbackingstore.cpp
index 83b75ae605..8e40eb6dff 100644
--- a/src/gui/painting/qplatformbackingstore.cpp
+++ b/src/gui/painting/qplatformbackingstore.cpp
@@ -385,7 +385,7 @@ void QPlatformBackingStore::composeAndFlush(QWindow *window, const QRegion &regi
         // The backingstore is for the entire tlw.
         // In case of native children offset tells the position relative to the tlw.
         const QRect srcRect = toBottomLeftRect(deviceWindowRect.translated(offset), d_ptr->textureSize.height());
-        const QMatrix3x3 source = QOpenGLTextureBlitter::sourceTransform(deviceRect(srcRect, window),
+        const QMatrix3x3 source = QOpenGLTextureBlitter::sourceTransform(srcRect,
                                                                          d_ptr->textureSize,
                                                                          origin);
         d_ptr->blitter->blit(textureId, QMatrix4x4(), source);