Use SkImageCacherator in SkImages

include/core/SkBitmap.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 SkBitmap_DEFINED
 #define SkBitmap_DEFINED
 
@@ skipping 196 matching lines @@
     static bool ComputeIsOpaque(const SkBitmap&);
 
     /**
      *  Return the bitmap's bounds [0, 0, width, height] as an SkRect
      */
     void getBounds(SkRect* bounds) const;
     void getBounds(SkIRect* bounds) const;
 
     SkIRect bounds() const { return fInfo.bounds(); }
     SkISize dimensions() const { return fInfo.dimensions(); }
+    // Returns the bounds of this bitmap, offset by its pixelref origin.
+    SkIRect getSubset() const {
+        return SkIRect::MakeXYWH(fPixelRefOrigin.x(), fPixelRefOrigin.y(),
+                                 fInfo.width(), fInfo.height());
+    }
 
     bool setInfo(const SkImageInfo&, size_t rowBytes = 0);
 
     /**
      *  Allocate the bitmap's pixels to match the requested image info. If the Factory
      *  is non-null, call it to allcoate the pixelref. If the ImageInfo requires
      *  a colortable, then ColorTable must be non-null, and will be ref'd.
      *  On failure, the bitmap will be set to empty and return false.
      */
     bool SK_WARN_UNUSED_RESULT tryAllocPixels(const SkImageInfo&, SkPixelRefFactory*, SkColorTable*);
@@ skipping 574 matching lines @@
 
 inline SkPMColor SkBitmap::getIndex8Color(int x, int y) const {
     SkASSERT(fPixels);
     SkASSERT(kIndex_8_SkColorType == this->colorType());
     SkASSERT((unsigned)x < (unsigned)this->width() && (unsigned)y < (unsigned)this->height());
     SkASSERT(fColorTable);
     return (*fColorTable)[*((const uint8_t*)fPixels + y * fRowBytes + x)];
 }
 
 #endif