QWindowWindow: Avoid resize events from the ctor

When calling showFullScreen(), the setwindowStates call in the
QWindowsWindow constructor led to generating a resize event. This is
pretty bad for example when QOpenGLWindow is involved since the QWindow's
platformWindow member is not even set yet (handle() == nullptr) so
everything related to OpenGL contexts starts failing (as there is no
underlying platform window yet as far as the QWindow is concerned).

In short, generating geometry changes from the platformwindow ctor is a
bad idea. Use initialize() instead for that.

Task-number: QTBUG-67027
Change-Id: I35d11949213eb21f81b2ff2d4f2282cb36510210
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index d639f27c1a..9fff4b5e42 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -1107,7 +1107,6 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const QWindowsWindowData &data)
     updateDropSite(window()->isTopLevel());
 
     registerTouchWindow();
-    setWindowState(aWindow->windowStates());
     const qreal opacity = qt_window_private(aWindow)->opacity;
     if (!qFuzzyCompare(opacity, qreal(1.0)))
         setOpacity(opacity);
@@ -1136,9 +1135,11 @@ void QWindowsWindow::initialize()
     QWindowCreationContextPtr creationContext =
         QWindowsContext::instance()->setWindowCreationContext(QWindowCreationContextPtr());
 
+    QWindow *w = window();
+    setWindowState(w->windowStates());
+
     // Trigger geometry change (unless it has a special state in which case setWindowState()
     // will send the message) and screen change signals of QWindow.
-    QWindow *w = window();
     if (w->type() != Qt::Desktop) {
         const Qt::WindowState state = w->windowState();
         if (state != Qt::WindowMaximized && state != Qt::WindowFullScreen