add encodeData() to SkImageEncoder, and add encoding to SkImage

src/image/SkImage_Raster.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImage_Base.h"
 #include "SkImagePriv.h"
 #include "SkBitmap.h"
@@ skipping 37 matching lines @@
         }
         return true;
     }
 
     static SkImage* NewEmpty();
 
     SkImage_Raster(const SkImage::Info&, SkData*, size_t rb);
     virtual ~SkImage_Raster();
 
     virtual void onDraw(SkCanvas*, SkScalar, SkScalar, const SkPaint*) SK_OVERRIDE;
+    virtual bool getROPixels(SkBitmap*) const SK_OVERRIDE;
 
     // exposed for SkSurface_Raster via SkNewImageFromPixelRef
     SkImage_Raster(const SkImage::Info&, SkPixelRef*, size_t rowBytes);
 
     SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
 
 private:
     SkImage_Raster() : INHERITED(0, 0) {}
 
     SkBitmap    fBitmap;
@@ skipping 33 matching lines @@
     fBitmap.setPixelRef(pr);
     fBitmap.setIsOpaque(isOpaque);
 }
 
 SkImage_Raster::~SkImage_Raster() {}
 
 void SkImage_Raster::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y, const SkPaint* paint) {
     canvas->drawBitmap(fBitmap, x, y, paint);
 }
 
+bool SkImage_Raster::getROPixels(SkBitmap* dst) const {
+    *dst = fBitmap;
+    return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 SkImage* SkImage::NewRasterCopy(const SkImage::Info& info, const void* pixels, size_t rowBytes) {
     if (!SkImage_Raster::ValidArgs(info, rowBytes)) {
         return NULL;
     }
     if (0 == info.fWidth && 0 == info.fHeight) {
         return SkImage_Raster::NewEmpty();
     }
     // check this after empty-check
@@ skipping 30 matching lines @@
 }
 
 SkImage* SkNewImageFromPixelRef(const SkImage::Info& info, SkPixelRef* pr,
                                 size_t rowBytes) {
     return SkNEW_ARGS(SkImage_Raster, (info, pr, rowBytes));
 }
 
 SkPixelRef* SkBitmapImageGetPixelRef(SkImage* image) {
     return ((SkImage_Raster*)image)->getPixelRef();
 }