QQuickWidget: Propagate screen changes.

This is required to make Qt Quick pick up changes
to the devicePixelRatio. Failure to do so prevents
a proper update of text nodes, as seen in the Qt
Creator welcome screen.

Propagate the new screen to the offscreenWindow,
offscreenSurface and context.

[ChangeLog][QtQuick] QQuickWidget now properly repaints
text on high-DPI screen changes.

Change-Id: I8f0b9f2f8768f99e293de018ae56d50ddf20b43a
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/quickwidgets/qquickwidget.cpp b/src/quickwidgets/qquickwidget.cpp
index 1a840b44bd..6709d88fa3 100644
--- a/src/quickwidgets/qquickwidget.cpp
+++ b/src/quickwidgets/qquickwidget.cpp
@@ -1217,6 +1217,17 @@ bool QQuickWidget::event(QEvent *e)
         break;
 
     case QEvent::ScreenChangeInternal:
+        if (QWindow *window = this->window()->windowHandle()) {
+            QScreen *newScreen = window->screen();
+
+            if (d->offscreenWindow)
+                d->offscreenWindow->setScreen(newScreen);
+            if (d->offscreenSurface)
+                d->offscreenSurface->setScreen(newScreen);
+            if (d->context)
+                d->context->setScreen(newScreen);
+        }
+
         if (d->fbo) {
             // This will check the size taking the devicePixelRatio into account
             // and recreate if needed.