JPEG YUV Decoding

include/core/SkImageDecoder.h

Index: include/core/SkImageDecoder.h
diff --git a/include/core/SkImageDecoder.h b/include/core/SkImageDecoder.h
index b258afedce184e79f3907c7cf8f29a6318c068ba..cf506e7ef191a2ec3b92a87e3b569d095d6ec768 100644
--- a/include/core/SkImageDecoder.h
+++ b/include/core/SkImageDecoder.h
@@ -46,6 +46,19 @@ public:
     */
     virtual Format getFormat() const;
 
+
+    /**  Returns the sizes of each component of the image
+    */
+    virtual bool getComponentSizes(SkStream* stream, SkISize sizes[3]) {
+        return this->onGetComponentSizes(stream, sizes);
+    }
+
+    /* Assigns buffers for YUV decoding
+    */
+    void setYUVBuffers(void* yuv[3], size_t rowBytes[3]) {
+        this->onSetYUVBuffers(yuv, rowBytes);
+    }
+
     /** Return the format of the SkStreamRewindable or kUnknown_Format if it cannot be determined.
         Rewinds the stream before returning.
     */
@@ -384,6 +397,16 @@ protected:
         return false;
     }
 
+    /* If the decoder wants to support YUV based decoding, this method must be overridden.
+    */
+    virtual void onSetYUVBuffers(void* yuv[3], size_t rowBytes[3]) {}

[scroggo, 2014/07/25 20:48:34]

Why not create a new entry point? Right now the client makes calls something
like:

  decoder->getComponentSIzes();
  decoder->setYUVBuffers();
  SkBitmap ignoredBitmap;
  decoder->decode(&ignoredBitmap); // Not meaningfully used but cannot be NULL

wouldn't it be cleaner if we had some function like

  SkImageDecoder::decodeIntoYUV();

?

+
+    /**  Returns the sizes of each component of the image
+    */
+    virtual bool onGetComponentSizes(SkStream*, SkISize sizes[3]) {
+        return false;
+    }
+
     /*
      * Crop a rectangle from the src Bitmap to the dest Bitmap. src and dst are
      * both sampled by sampleSize from an original Bitmap.