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diff --git a/canvas/source/vcl/bitmapbackbuffer.hxx b/canvas/source/vcl/bitmapbackbuffer.hxx
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+++ b/canvas/source/vcl/bitmapbackbuffer.hxx
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+/*************************************************************************
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Copyright 2000, 2010 Oracle and/or its affiliates.
+ *
+ * OpenOffice.org - a multi-platform office productivity suite
+ *
+ * This file is part of OpenOffice.org.
+ *
+ * OpenOffice.org is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3
+ * only, as published by the Free Software Foundation.
+ *
+ * OpenOffice.org is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License version 3 for more details
+ * (a copy is included in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * version 3 along with OpenOffice.org.  If not, see
+ * <http://www.openoffice.org/license.html>
+ * for a copy of the LGPLv3 License.
+ *
+ ************************************************************************/
+
+#ifndef _VCLCANVAS_BITMAPBACKBUFFER_HXX_
+#define _VCLCANVAS_BITMAPBACKBUFFER_HXX_
+
+#include <vcl/virdev.hxx>
+#include <vcl/bitmapex.hxx>
+
+#include <canvas/vclwrapper.hxx>
+#include "outdevprovider.hxx"
+
+#include <boost/shared_ptr.hpp>
+
+
+namespace vclcanvas
+{
+    /** Backbuffer implementation for canvas bitmap.
+
+        This class abstracts away the renderable bitmap for the bitmap
+        canvas. The actual VirtualDevice is only created when
+        necessary, which makes read-only bitmaps a lot smaller.
+    */
+    class BitmapBackBuffer : public OutDevProvider
+    {
+    public:
+        /** Create a backbuffer for given reference device
+         */
+        BitmapBackBuffer( const BitmapEx&       rBitmap,
+                          const OutputDevice&   rRefDevice );
+
+        ~BitmapBackBuffer();
+
+        virtual OutputDevice&       getOutDev();
+        virtual const OutputDevice& getOutDev() const;
+
+        /// Clear the underlying bitmap to white, all transparent
+        void clear();
+
+        /** Exposing our internal bitmap. Only to be used from
+            CanvasBitmapHelper
+
+            @internal
+        */
+        BitmapEx&                   getBitmapReference();
+        Size                        getBitmapSizePixel() const;
+
+    private:
+        void createVDev() const;
+        void updateVDev() const;
+
+        ::canvas::vcltools::VCLObject<BitmapEx> maBitmap;
+        mutable VirtualDevice*                  mpVDev; // created only on demand
+
+        const OutputDevice&                     mrRefDevice;
+
+        /** When true, the bitmap contains the last valid
+            content. When false, and mbVDevContentIsCurrent is true,
+            the VDev contains the last valid content (which must be
+            copied back to the bitmap, when getBitmapReference() is
+            called). When both are false, this object is just
+            initialized.
+         */
+        mutable bool                            mbBitmapContentIsCurrent;
+
+        /** When true, and mpVDev is non-NULL, the VDev contains the
+            last valid content. When false, and
+            mbBitmapContentIsCurrent is true, the bitmap contains the
+            last valid content. When both are false, this object is
+            just initialized.
+         */
+        mutable bool                            mbVDevContentIsCurrent;
+    };
+
+    typedef ::boost::shared_ptr< BitmapBackBuffer > BitmapBackBufferSharedPtr;
+
+}
+
+#endif /* #ifndef _VCLCANVAS_BITMAPBACKBUFFER_HXX_ */
+