Implement SkBaseDevice snapshot support

include/core/SkBitmapDevice.h

 
 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkBitmapDevice_DEFINED
 #define SkBitmapDevice_DEFINED
@@ skipping 16 matching lines @@
      *  Construct a new device with the specified bitmap as its backend. It is
      *  valid for the bitmap to have no pixels associated with it. In that case,
      *  any drawing to this device will have no effect.
     */
     SkBitmapDevice(const SkBitmap& bitmap, const SkDeviceProperties& deviceProperties);
     static SkBitmapDevice* Create(const SkImageInfo&, const SkDeviceProperties*);
 public:
     static SkBitmapDevice* Create(const SkImageInfo& info) {
         return Create(info, NULL);
     }
-
+    ~SkBitmapDevice();
     SkImageInfo imageInfo() const SK_OVERRIDE;
 
+    SkImage* newImageSnapshot() SK_OVERRIDE;
+    void discard() SK_OVERRIDE;
 protected:
     bool onShouldDisableLCD(const SkPaint&) const SK_OVERRIDE;
 
     /** These are called inside the per-device-layer loop for each draw call.
      When these are called, we have already applied any saveLayer operations,
      and are handling any looping from the paint, and any effects from the
      DrawFilter.
      */
     void drawPaint(const SkDraw&, const SkPaint& paint) SK_OVERRIDE;
     virtual void drawPoints(const SkDraw&, SkCanvas::PointMode mode, size_t count,
@@ skipping 80 matching lines @@
 
 private:
     friend class SkCanvas;
     friend struct DeviceCM; //for setMatrixClip
     friend class SkDraw;
     friend class SkDrawIter;
     friend class SkDeviceFilteredPaint;
     friend class SkDeviceImageFilterProxy;
 
     friend class SkSurface_Raster;
+    friend class SkRasterDevice;
 
     // used to change the backend's pixels (and possibly config/rowbytes)
     // but cannot change the width/height, so there should be no change to
     // any clip information.
-    void replaceBitmapBackendForRasterSurface(const SkBitmap&) SK_OVERRIDE;
+    void deepCopyBackendIfNeeded();
 
     SkBaseDevice* onCreateDevice(const CreateInfo&, const SkPaint*) SK_OVERRIDE;
+    virtual SkImage* onNewImageSnapshot();
 
     SkSurface* newSurface(const SkImageInfo&, const SkSurfaceProps&) SK_OVERRIDE;
     const void* peekPixels(SkImageInfo*, size_t* rowBytes) SK_OVERRIDE;
 
     SkImageFilter::Cache* getImageFilterCache() SK_OVERRIDE;
 
     SkBitmap    fBitmap;
-
+    SkAutoTUnref<SkImage> fSnapshot;
     typedef SkBaseDevice INHERITED;
 };
 
 #endif // SkBitmapDevice_DEFINED