Fix offscreen rendering in QOpenGLWidget

Amends 68a4c5da9a080101cccd8a3b2edb1c908da0ca8e

In a case sharing QOpenGLContext,
offscreen renderings cannot get QOpenGLContext from Rhi.

Fixes: QTBUG-123005
Pick-to: 6.7 6.6 6.5
Change-Id: I9baae5e5c77878885f73ee39df5cd39117e8f1c2
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 5 insertions, 3 deletions

diff --git a/src/openglwidgets/qopenglwidget.cpp b/src/openglwidgets/qopenglwidget.cpp
index a7b760c379..4a0bf7f492 100644
--- a/src/openglwidgets/qopenglwidget.cpp
+++ b/src/openglwidgets/qopenglwidget.cpp
@@ -855,9 +855,11 @@ void QOpenGLWidgetPrivate::initialize()
 
     context = new QOpenGLContext;
     context->setFormat(requestedFormat);
-    if (contextFromRhi) {
-        context->setShareContext(contextFromRhi);
-        context->setScreen(contextFromRhi->screen());
+
+    QOpenGLContext *shareContext = contextFromRhi ? contextFromRhi : qt_gl_global_share_context();
+    if (shareContext) {
+        context->setShareContext(shareContext);
+        context->setScreen(shareContext->screen());
     }
     if (Q_UNLIKELY(!context->create())) {
         qWarning("QOpenGLWidget: Failed to create context");