Scanline decoding for gifs

include/codec/SkScaledCodec.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkScaledCodec_DEFINED
 #define SkScaledCodec_DEFINED
 
 #include "SkCodec.h"
@@ skipping 23 matching lines @@
             return false;
         }
         // only support down sampling, dstWidth cannot be larger that srcWidth
         if(dstInfo.width() > srcInfo.width()) {
             return false;
         }
         return true;   
     }
 
     /*
+     * Converts the original dimension to a scaled output dimension using the
+     * sample factor.
+     */
+    static inline int GetScaledDimension(int srcDim, int sampleFactor);
+
+    /*
      * Returns the first coordinate that we will keep during sampling.
      * The output can be interpreted as an x-coordinate or a y-coordinate.
      */
     static inline int GetStartCoord(int sampleFactor);
 
     /*
      * Given a coordinate in the original image, this returns the corresponding
      * coordinate in the scaled image.  This function is meaningless if
      * IsCoordNecessary returns false.
      * The output can be interpreted as an x-coordinate or a y-coordinate.
@@ skipping 29 matching lines @@
 
 private:
 
     SkAutoTDelete<SkScanlineDecoder> fScanlineDecoder;
 
     explicit SkScaledCodec(SkScanlineDecoder*);
 
     typedef SkCodec INHERITED;
 };
 #endif // SkScaledCodec_DEFINED