add applyFilter() to SkImage

include/core/SkImage.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImage_DEFINED
 #define SkImage_DEFINED
 
@@ skipping 286 matching lines @@
      *  to empty.
      */
     bool asLegacyBitmap(SkBitmap*, LegacyBitmapMode) const;
     
     /**
      *  Returns true if the image is backed by an image-generator or other src that creates
      *  (and caches) its pixels / texture on-demand.
      */
     bool isLazyGenerated() const;
 
+    /**
+     *  Apply the specified filter to this image, and return the result as a new image.
+     *
+     *  if forceResultToOriginalSize is true, then the resulting image will be the same size as the
+     *  src, regardless of the normal output of the filter.
+     *
+     *  If offset is non-null, it is set to the relative offset needed to draw the resulting image
+     *  in the same logical place as the original.
+     *
+     *  e.g.
+     *      If the filter makes the result larger by a margin of 4 the output would be:
+     *          result->width() = this->width + 8
+     *          result->height() = this->height + 8
+     *          offset.x() == -4
+     *          offset.y() == -4
+     *
+     *  If the filter fails to create a resulting image, null is returned, and the offset parameter
+     *  (if specified) will be undefined.
+     */
+    SkImage* applyFilter(SkImageFilter* filter, SkIPoint* offset,
+                         bool forceResultToOriginalSize) const;
+
 protected:
     SkImage(int width, int height, uint32_t uniqueID);
 
 private:
     const int       fWidth;
     const int       fHeight;
     const uint32_t  fUniqueID;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif