Fix issue sharing OpenGL context from render thread on OS X

On OS X when running in QtQuick 2 examples in debug mode we fail an
assert because we try to set a dynamic property using
QObject::setProperty from the render thread, while the object exists in
the main thread.  Now we call setProperty from the correct thread.

Change-Id: I3f26ead0f68fadcded472bf5c9014a4025f0a03e
Reviewed-by: Christian Stromme <christian.stromme@digia.com>
Reviewed-by: Jason Barron <jason.barron@digia.com>

2 files changed, 24 insertions, 1 deletions

diff --git a/src/imports/multimedia/qdeclarativevideooutput_render.cpp b/src/imports/multimedia/qdeclarativevideooutput_render.cpp
index b74898f90..f65e0512c 100644
--- a/src/imports/multimedia/qdeclarativevideooutput_render.cpp
+++ b/src/imports/multimedia/qdeclarativevideooutput_render.cpp
@@ -171,7 +171,7 @@ QSGNode *QDeclarativeVideoRendererBackend::updatePaintNode(QSGNode *oldNode,
 
     if (!m_glContext) {
         m_glContext = QOpenGLContext::currentContext();
-        m_surface->setProperty("GLContext", QVariant::fromValue<QObject*>(m_glContext));
+        m_surface->scheduleOpenGLContextUpdate();
     }
 
     if (m_frameChanged) {
@@ -223,6 +223,11 @@ QAbstractVideoSurface *QDeclarativeVideoRendererBackend::videoSurface() const
     return m_surface;
 }
 
+QOpenGLContext *QDeclarativeVideoRendererBackend::glContext() const
+{
+    return m_glContext;
+}
+
 void QDeclarativeVideoRendererBackend::present(const QVideoFrame &frame)
 {
     m_frameMutex.lock();
@@ -287,4 +292,16 @@ bool QSGVideoItemSurface::present(const QVideoFrame &frame)
     return true;
 }
 
+void QSGVideoItemSurface::scheduleOpenGLContextUpdate()
+{
+    //This method is called from render thread
+    QMetaObject::invokeMethod(this, "updateOpenGLContext");
+}
+
+void QSGVideoItemSurface::updateOpenGLContext()
+{
+    //Set a dynamic property to access the OpenGL context in Qt Quick render thread.
+    this->setProperty("GLContext", QVariant::fromValue<QObject*>(m_backend->glContext()));
+}
+
 QT_END_NAMESPACE
diff --git a/src/imports/multimedia/qdeclarativevideooutput_render_p.h b/src/imports/multimedia/qdeclarativevideooutput_render_p.h
index e78094341..373ed213e 100644
--- a/src/imports/multimedia/qdeclarativevideooutput_render_p.h
+++ b/src/imports/multimedia/qdeclarativevideooutput_render_p.h
@@ -71,6 +71,7 @@ public:
     void updateGeometry();
     QSGNode *updatePaintNode(QSGNode *oldNode, QQuickItem::UpdatePaintNodeData *data);
     QAbstractVideoSurface *videoSurface() const;
+    QOpenGLContext *glContext() const;
 
     friend class QSGVideoItemSurface;
     void present(const QVideoFrame &frame);
@@ -93,6 +94,7 @@ private:
 
 class QSGVideoItemSurface : public QAbstractVideoSurface
 {
+    Q_OBJECT
 public:
     explicit QSGVideoItemSurface(QDeclarativeVideoRendererBackend *backend, QObject *parent = 0);
     ~QSGVideoItemSurface();
@@ -100,6 +102,10 @@ public:
     bool start(const QVideoSurfaceFormat &format);
     void stop();
     bool present(const QVideoFrame &frame);
+    void scheduleOpenGLContextUpdate();
+
+private slots:
+    void updateOpenGLContext();
 
 private:
     QDeclarativeVideoRendererBackend *m_backend;