Add methods for finding out if scene graph context has been initialized

We cannot rely on the OpenGL context for that as there may be
non-OpenGL scene graphs. In order for those to announce their readiness
QSGRenderContext::isValid() has to be virtual.

Change-Id: Ica35d8590e3f06edb54d57d93898d52e753f0407
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

3 files changed, 11 insertions, 1 deletions

diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 6c6b343080..ca0a81f2f4 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -2926,6 +2926,15 @@ QOpenGLContext *QQuickWindow::openglContext() const
 }
 
 /*!
+    Returns true if the scene graph has been initialized; otherwise returns false.
+ */
+bool QQuickWindow::isSceneGraphInitialized() const
+{
+    Q_D(const QQuickWindow);
+    return d->context != 0 && d->context->isValid();
+}
+
+/*!
     \fn void QQuickWindow::frameSwapped()
 
     This signal is emitted when the frame buffers have been swapped.
diff --git a/src/quick/items/qquickwindow.h b/src/quick/items/qquickwindow.h
index 108bcec589..82f2e29d9d 100644
--- a/src/quick/items/qquickwindow.h
+++ b/src/quick/items/qquickwindow.h
@@ -139,6 +139,7 @@ public:
     bool isPersistentSceneGraph() const;
 
     QOpenGLContext *openglContext() const;
+    bool isSceneGraphInitialized() const;
 
     void scheduleRenderJob(QRunnable *job, RenderStage schedule);
 
diff --git a/src/quick/scenegraph/qsgcontext_p.h b/src/quick/scenegraph/qsgcontext_p.h
index 184b8248d5..91788d82d4 100644
--- a/src/quick/scenegraph/qsgcontext_p.h
+++ b/src/quick/scenegraph/qsgcontext_p.h
@@ -93,7 +93,7 @@ public:
 
     QOpenGLContext *openglContext() const { return m_gl; }
     QSGContext *sceneGraphContext() const { return m_sg; }
-    bool isValid() const { return m_gl; }
+    virtual bool isValid() const { return m_gl; }
 
     virtual void initialize(QOpenGLContext *context);
     virtual void invalidate();