Skia side RGB to YUV gpu conversion

include/core/SkImageDecoder.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 SkImageDecoder_DEFINED
 #define SkImageDecoder_DEFINED
 
@@ skipping 28 matching lines @@
         kKTX_Format,
 
         kLastKnownFormat = kKTX_Format,
     };
 
     /** Return the format of image this decoder can decode. If this decoder can decode multiple
         formats, kUnknown_Format will be returned.
     */
     virtual Format getFormat() const;
 
+
+    /**  Returns the sizes of each component of the image
+    */
+    virtual bool getImageFormat(SkStream*, SkISize sizes[3]) {

[scroggo, 2014/07/18 21:52:40]

This name doesn't seem to match what it does. A better name might be
getComponentSizes?

+        return false;
+    }
+
+    /* If the decoder wants to support YUV based decoding, this method must be overridden.
+    */
+    virtual void setYUVBuffers(void* yuv[3], size_t rowBytes[3]) {}

[scroggo, 2014/07/18 21:52:40]

For both of these, why not have two functions:

void setYUVBuffers(...) {
  this->onSetYUVBuffers(...);
}

virtual void onSetYUVBuffers(...) {}

Then we've separated the interface from the implementation (we mostly follow
this convention in Skia).

+
     /** Return the format of the SkStreamRewindable or kUnknown_Format if it cannot be determined.
         Rewinds the stream before returning.
     */
     static Format GetStreamFormat(SkStreamRewindable*);
 
     /** Return a readable string of the Format provided.
     */
     static const char* GetFormatName(Format);
 
     /** Return a readable string of the value returned by getFormat().
@@ skipping 466 matching lines @@
 DECLARE_DECODER_CREATOR(WEBPImageDecoder);
 DECLARE_DECODER_CREATOR(PKMImageDecoder);
 DECLARE_DECODER_CREATOR(KTXImageDecoder);
 
 // Typedefs to make registering decoder and formatter callbacks easier.
 // These have to be defined outside SkImageDecoder. :(
 typedef SkTRegistry<SkImageDecoder*(*)(SkStreamRewindable*)>        SkImageDecoder_DecodeReg;
 typedef SkTRegistry<SkImageDecoder::Format(*)(SkStreamRewindable*)> SkImageDecoder_FormatReg;
 
 #endif