add SkImage::newSurface

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
 
 #include "SkImageInfo.h"
 #include "SkImageEncoder.h"
 #include "SkRefCnt.h"
 #include "SkScalar.h"
 #include "SkShader.h"
 
 class SkData;
 class SkCanvas;
 class SkImageGenerator;
 class SkPaint;
+class SkSurface;
+class SkSurfaceProps;
 class GrContext;
 class GrTexture;
 
 /**
  *  SkImage is an abstraction for drawing a rectagle of pixels, though the
  *  particular type of image could be actually storing its data on the GPU, or
  *  as drawing commands (picture or PDF or otherwise), ready to be played back
  *  into another canvas.
  *
  *  The content of SkImage is always immutable, though the actual storage may
@@ skipping 54 matching lines @@
     /**
      *  Encode the image's pixels and return the result as a new SkData, which
      *  the caller must manage (i.e. call unref() when they are done).
      *
      *  If the image type cannot be encoded, or the requested encoder type is
      *  not supported, this will return NULL.
      */
     SkData* encode(SkImageEncoder::Type t = SkImageEncoder::kPNG_Type,
                    int quality = 80) const;
 
+    /**
+     *  Return a new surface that is compatible with this image's internal representation
+     *  (e.g. raster or gpu).
+     *
+     *  If no surfaceprops are specified, the image will attempt to match the props of when it
+     *  was created (if it came from a surface).
+     */
+    SkSurface* newSurface(const SkImageInfo&, const SkSurfaceProps* = NULL) const;
+
 protected:
     SkImage(int width, int height) :
         fWidth(width),
         fHeight(height),
         fUniqueID(NextUniqueID()) {
 
         SkASSERT(width >= 0);
         SkASSERT(height >= 0);
     }
 
@@ skipping 37 matching lines @@
      *  On failure, false will be returned, and bitmap will unmodified.
      */
     // On ice for now:
     // - should it respect the particular colortype/alphatype of the src
     // - should it have separate entrypoints for preallocated and not bitmaps?
     // - isn't it enough to allow the caller to draw() the image into a canvas?
     bool readPixels(SkBitmap* bitmap, const SkIRect* subset = NULL) const;
 };
 
 #endif