Fix WaylandOutput.sizeFollowsWindow when window changes screen

If a QWaylandOutput's QWindow is moved from one screen to another and that
causes the devicePixelRatio to change, it may result in a new pixel size,
but QWindow::width and height may stay unchanged (because they're not in pixel
coordinates). This is a problem because the sizeFollowsWindow functionality of
QWaylandOutput relied on the widthChanged and heightChanged signals, which are
then not fired, although the pixel size did change.

There's no QWindow::devicePixelRatioChanged signal we can attach to, so to fix
this, we attach to screenChanged instead and then compute the new pixelSize
using QWindow::devicePixelRatio() and call the handler if it changed.

This also removes some duplication between the old width and height handlers.

Change-Id: Ibcbf10489b83498b4a0fee2b520f528f94cb9ce3
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 1 insertions, 2 deletions

diff --git a/src/compositor/compositor_api/qwaylandoutput.h b/src/compositor/compositor_api/qwaylandoutput.h
index f0bea809e..c7f2973b6 100644
--- a/src/compositor/compositor_api/qwaylandoutput.h
+++ b/src/compositor/compositor_api/qwaylandoutput.h
@@ -181,8 +181,7 @@ Q_SIGNALS:
     void windowDestroyed();
 
 private Q_SLOTS:
-    void handleSetWidth(int newWidth);
-    void handleSetHeight(int newHeight);
+    void handleMaybeWindowPixelSizeChanged();
     void handleWindowDestroyed();
 
 protected: