QQuickWindow FBO: fix dpr and rect when there is an actual window

QQuickWidget is the primary example of a third case of rendering with
QQuickWindow: here the content goes to an FBO via the rendercontrol,
but there is still a window associated (the top-level widget's window)
in a way, and therefore the devicePixelRatio must be taken into account.

This amends ab54d0cab57121055914ff9a750f5ad975fe7525

Task-number: QTBUG-58442
Change-Id: Ic90147646aa9bd9c1fc6a3492ae8c3087a12832b
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: Gunnar Sletta <gunnar@crimson.no>

1 files changed, 7 insertions, 2 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 660c5f8067..0e7c50ffcf 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -453,8 +453,13 @@ void QQuickWindowPrivate::renderSceneGraph(const QSize &size)
             fboId = renderTargetId;
             renderer->setDeviceRect(rect);
             renderer->setViewportRect(rect);
-            renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), rect.size()));
-            renderer->setDevicePixelRatio(1);
+            if (QQuickRenderControl::renderWindowFor(q)) {
+                renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), size));
+                renderer->setDevicePixelRatio(devicePixelRatio);
+            } else {
+                renderer->setProjectionMatrixToRect(QRect(QPoint(0, 0), rect.size()));
+                renderer->setDevicePixelRatio(1);
+            }
         } else {
             QRect rect(QPoint(0, 0), devicePixelRatio * size);
             renderer->setDeviceRect(rect);