rename SkCanvasDrawable to SkDrawable, and make public

include/core/SkDrawable.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
-#ifndef SkCanvasDrawable_DEFINED
-#define SkCanvasDrawable_DEFINED
+#ifndef SkDrawable_DEFINED
+#define SkDrawable_DEFINED
 
 #include "SkRefCnt.h"
 
 class SkCanvas;
 class SkPicture;
 struct SkRect;
 
 /**
  *  Base-class for objects that draw into SkCanvas.
  *
  *  The object has a generation ID, which is guaranteed to be unique across all drawables. To
  *  allow for clients of the drawable that may want to cache the results, the drawable must
  *  change its generation ID whenever its internal state changes such that it will draw differently.
  */
-class SkCanvasDrawable : public SkRefCnt {
+class SkDrawable : public SkRefCnt {
 public:
-    SkCanvasDrawable();
+    SkDrawable();
 
     /**
      *  Draws into the specified content. The drawing sequence will be balanced upon return
      *  (i.e. the saveLevel() on the canvas will match what it was when draw() was called,
      *  and the current matrix and clip settings will not be changed.
      */
     void draw(SkCanvas*);
 
     SkPicture* newPictureSnapshot();
 
@@ skipping 16 matching lines @@
     /**
      *  Calling this invalidates the previous generation ID, and causes a new one to be computed
      *  the next time getGenerationID() is called. Typically this is called by the object itself,
      *  in response to its internal state changing.
      */
     void notifyDrawingChanged();
 
 protected:
     virtual SkRect onGetBounds() = 0;
     virtual void onDraw(SkCanvas*) = 0;
+    
+    /**
+     *  Default implementation calls onDraw() with a canvas that records into a picture. Subclasses
+     *  may override if they have a more efficient way to return a picture for the current state
+     *  of their drawable. Note: this picture must draw the same as what would be drawn from
+     *  onDraw().
+     */
     virtual SkPicture* onNewPictureSnapshot();
 
 private:
     int32_t fGenerationID;
 };
 
 #endif