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, 1 insertions, 2 deletions

diff --git a/src/quick/items/context2d/qquickcontext2d_p.h b/src/quick/items/context2d/qquickcontext2d_p.h
index bd1a83ce08..c679bc33cb 100644
--- a/src/quick/items/context2d/qquickcontext2d_p.h
+++ b/src/quick/items/context2d/qquickcontext2d_p.h
@@ -185,7 +185,6 @@ public:
 
     QQuickCanvasItem* canvas() const { return m_canvas; }
     QQuickContext2DCommandBuffer* buffer() const { return m_buffer; }
-    QQuickContext2DCommandBuffer* nextBuffer();
 
     bool bufferValid() const { return m_buffer != 0; }
     void popState();
@@ -255,7 +254,7 @@ public:
     QImage m_grabbedImage;
     bool m_grabbed:1;
 
-    QMutex m_mutex;
+    static QMutex mutex;
 };