Implement SkBaseDevice snapshot support

include/core/SkCanvas.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 11 matching lines @@
 class SkBaseDevice;
 class SkCanvasClipVisitor;
 class SkDraw;
 class SkDrawable;
 class SkDrawFilter;
 class SkImage;
 class SkMetaData;
 class SkPicture;
 class SkRRect;
 class SkSurface;
-class SkSurface_Base;
 class SkTextBlob;
 class GrContext;
 class GrRenderTarget;
 
 class SkCanvasState;
 
 /** \class SkCanvas
 
     A Canvas encapsulates all of the state about drawing into a device (bitmap).
     This includes a reference to the device itself, and a stack of matrix/clip
@@ skipping 548 matching lines @@
 
     /**
      *  Helper method for drawing a color in SRC mode, completely replacing all the pixels
      *  in the current clip with this color.
      */
     void clear(SkColor color) {
         this->drawColor(color, SkXfermode::kSrc_Mode);
     }
 
     /**
-     * This makes the contents of the canvas undefined. Subsequent calls that
-     * require reading the canvas contents will produce undefined results. Examples
-     * include blending and readPixels. The actual implementation is backend-
-     * dependent and one legal implementation is to do nothing. Like clear(), this
-     * ignores the clip.
+     * This makes the contents of current layer of the canvas
+     * undefined. Subsequent calls that require reading the canvas contents will
+     * produce undefined results. Examples include blending and readPixels. The
+     * actual implementation is backend- dependent and one legal implementation
+     * is to do nothing. Like clear(), this ignores the clip.
      *
      * This function should only be called if the caller intends to subsequently
-     * draw to the canvas. The canvas may do real work at discard() time in order
+     * draw to the current layer. The canvas may do real work at discard() time in order
      * to optimize performance on subsequent draws. Thus, if you call this and then
      * never draw to the canvas subsequently you may pay a perfomance penalty.
      */
     void discard() { this->onDiscard(); }
 
     /**
      *  Fill the entire canvas' bitmap (restricted to the current clip) with the
      *  specified paint.
      *  @param paint    The paint used to fill the canvas
      */
@@ skipping 632 matching lines @@
     virtual SkCanvas* canvasForDrawIter();
 
     // Clip rectangle bounds. Called internally by saveLayer.
     // returns false if the entire rectangle is entirely clipped out
     // If non-NULL, The imageFilter parameter will be used to expand the clip
     // and offscreen bounds for any margin required by the filter DAG.
     bool clipRectBounds(const SkRect* bounds, SaveFlags flags,
                         SkIRect* intersection,
                         const SkImageFilter* imageFilter = NULL);
 
-    // notify our surface (if we have one) that we are about to draw, so it
-    // can perform copy-on-write or invalidate any cached images
-    void predrawNotify();
-
 private:
     class MCRec;
 
     SkAutoTUnref<SkClipStack> fClipStack;
     SkDeque     fMCStack;
     // points to top of stack
     MCRec*      fMCRec;
     // the first N recs that can fit here mean we won't call malloc
     uint32_t    fMCRecStorage[32];
 
     const SkSurfaceProps fProps;
 
     int         fSaveCount;         // value returned by getSaveCount()
 
     SkMetaData* fMetaData;
 
-    SkSurface_Base*  fSurfaceBase;
-    SkSurface_Base* getSurfaceBase() const { return fSurfaceBase; }
-    void setSurfaceBase(SkSurface_Base* sb) {
-        fSurfaceBase = sb;
-    }
     friend class SkSurface_Base;
     friend class SkSurface_Gpu;
 
     bool fDeviceCMDirty;            // cleared by updateDeviceCMCache()
     void updateDeviceCMCache();
 
     void doSave();
     void checkForDeferredSave();
 
     friend class SkDrawIter;        // needs setupDrawForLayerDevice()
@@ skipping 208 matching lines @@
 
 class SkCanvasClipVisitor {
 public:
     virtual ~SkCanvasClipVisitor();
     virtual void clipRect(const SkRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipRRect(const SkRRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) = 0;
 };
 
 #endif