More QQuickCanvas cleanup handling.

Avoid calling into QQuickContext2D from QQuickContext2DTexture
after QQuickContext2D has been deleted. We acheive this by

1. Giving the texture a direct pointer to the gl context and
   and surface, so that it doesn't need to go through m_context
   to get to them (which may have been deleted).

2. Protect access to QQuickContext2DTexture::m_context with
   a mutex and make sure it is set to 0 in a safe manner
   when the QQuickContext2D object is deleted.

Change-Id: Ie0a30f9fc46f844224838a7cdf2f28a62e8ce322
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/quick/items/context2d/qquickcontext2dtexture_p.h b/src/quick/items/context2d/qquickcontext2dtexture_p.h
index 186863c1aa..e41a4809e4 100644
--- a/src/quick/items/context2d/qquickcontext2dtexture_p.h
+++ b/src/quick/items/context2d/qquickcontext2dtexture_p.h
@@ -113,6 +113,11 @@ public:
     virtual QSGTexture *textureForNextFrame(QSGTexture *lastFrame) = 0;
     bool event(QEvent *e);
 
+    void initializeOpenGL(QOpenGLContext *gl, QOffscreenSurface *s) {
+        m_gl = gl;
+        m_surface = s;
+    }
+
 Q_SIGNALS:
     void textureChanged();
 
@@ -135,7 +140,10 @@ protected:
     QRect createTiles(const QRect& window);
 
     QList<QQuickContext2DTile*> m_tiles;
-    QQuickContext2D* m_context;
+    QQuickContext2D *m_context;
+
+    QOpenGLContext *m_gl;
+    QSurface *m_surface;
 
     QQuickContext2D::State m_state;