add readPixels() to SkBitmap

include/core/SkCanvas.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 SkCanvas_DEFINED
 #define SkCanvas_DEFINED
 
@@ skipping 216 matching lines @@
      *  returned address (and associated information).
      *
      *  On failure, returns NULL and the info and rowBytes parameters are
      *  ignored.
      */
     const void* peekPixels(SkImageInfo* info, size_t* rowBytes);
 
     /**
      *  Copy the pixels from the base-layer into the specified buffer (pixels + rowBytes),
      *  converting them into the requested format (SkImageInfo). The base-layer pixels are read
-     *  starting at the specified (x,y) location in the coordinate system of the base-layer.
+     *  starting at the specified (srcX,srcY) location in the coordinate system of the base-layer.
      *
-     *  The specified ImageInfo and (x,y) offset specifies a source rectangle
+     *  The specified ImageInfo and (srcX,srcY) offset specifies a source rectangle
      *
-     *      srcR(x, y, info.width(), info.height());
+     *      srcR.setXYWH(srcX, srcY, dstInfo.width(), dstInfo.height());
      *
-     *  SrcR is intersected with the bounds of the base-layer. If this intersection is not empty,
-     *  then we have two sets of pixels (of equal size), the "src" specified by base-layer at (x,y)
-     *  and the "dst" by info+pixels+rowBytes. Replace the dst pixels with the corresponding src
-     *  pixels, performing any colortype/alphatype transformations needed (in the case where the
-     *  src and dst have different colortypes or alphatypes).
+     *  srcR is intersected with the bounds of the base-layer. If this intersection is not empty,
+     *  then we have two sets of pixels (of equal size). Replace the dst pixels with the
+     *  corresponding src pixels, performing any colortype/alphatype transformations needed
+     *  (in the case where the src and dst have different colortypes or alphatypes).
      *
      *  This call can fail, returning false, for several reasons:
+     *  - If srcR does not intersect the base-layer bounds.
      *  - If the requested colortype/alphatype cannot be converted from the base-layer's types.
      *  - If this canvas is not backed by pixels (e.g. picture or PDF)
      */
-    bool readPixels(const SkImageInfo&, void* pixels, size_t rowBytes, int x, int y);
+    bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
+                    int srcX, int srcY);
 
     /**
      *  Helper for calling readPixels(info, ...). This call will check if bitmap has been allocated.
      *  If not, it will attempt to call allocPixels(). If this fails, it will return false. If not,
      *  it calls through to readPixels(info, ...) and returns its result.
      */
-    bool readPixels(SkBitmap* bitmap, int x, int y);
+    bool readPixels(SkBitmap* bitmap, int srcX, int srcY);
 
     /**
      *  Helper for allocating pixels and then calling readPixels(info, ...). The bitmap is resized
      *  to the intersection of srcRect and the base-layer bounds. On success, pixels will be
      *  allocated in bitmap and true returned. On failure, false is returned and bitmap will be
      *  set to empty.
      */
     bool readPixels(const SkIRect& srcRect, SkBitmap* bitmap);
 
     /**
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 class SkCanvasClipVisitor {
 public:
     virtual ~SkCanvasClipVisitor();
     virtual void clipRect(const SkRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipRRect(const SkRRect&, SkRegion::Op, bool antialias) = 0;
     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) = 0;
 };
 
 #endif