Client: Initialize mScale on creation instead of on show

At the time of creating a QPlatformWindow we will have a QScreen
assigned. It may not be the right one until we get a screen_entered
event, pointing instead to the primary screen.

When we get the screen_entered event we get the correct scale and call
handleWindowScreenChanged. However if it's the same screen as before
QWindowPrivate::setTopLevelScreen will no-op because from it's POV the
screen hasn't changed at all.

This leaves the window having the scale change without any notification.

This is notable with QQuickWidget which creates an FBO very early on
before the window is shown. This would then use the devicePixelRatio of
1 as it is currently unset and then not get any change notification.

Change-Id: Ia7e4072e0bd900abc558bf8930fef4e1e7d2c553
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
(cherry picked from commit 5ecf5215737ba3343a10310c0dff08763af737bc)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 7c2815f6..1127a07d 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -86,6 +86,8 @@ QWaylandWindow::QWaylandWindow(QWindow *window, QWaylandDisplay *display)
             mFrameCallbackTimeout = frameCallbackTimeout;
     }
 
+    mScale = waylandScreen() ? waylandScreen()->scale() : 1; // fallback to 1 if we don't have a real screen
+
     static WId id = 1;
     mWindowId = id++;
     initializeWlSurface();
@@ -182,8 +184,6 @@ void QWaylandWindow::initWindow()
         }
     }
 
-    mScale = waylandScreen() ? waylandScreen()->scale() : 1; // fallback to 1 if we don't have a real screen
-
     // Enable high-dpi rendering. Scale() returns the screen scale factor and will
     // typically be integer 1 (normal-dpi) or 2 (high-dpi). Call set_buffer_scale()
     // to inform the compositor that high-resolution buffers will be provided.