Scanline decoding for jpeg

src/codec/SkJpegCodec.h

Index: src/codec/SkJpegCodec.h
diff --git a/src/codec/SkJpegCodec.h b/src/codec/SkJpegCodec.h
index 51a741a525aa0936442aa7ac50c179f6e07db5fb..f75d16cd2e5c81840632fc5b3a38674e8d909bb7 100644
--- a/src/codec/SkJpegCodec.h
+++ b/src/codec/SkJpegCodec.h
@@ -56,6 +56,9 @@ protected:
         return kJPEG_SkEncodedFormat;
     }
 
+    SkScanlineDecoder* onGetScanlineDecoder(const SkImageInfo& dstInfo, const Options& options,
+            SkPMColor ctable[], int* ctableCount) override;
+
 private:
 
     /*
@@ -91,7 +94,27 @@ private:
      */
     SkJpegCodec(const SkImageInfo& srcInfo, SkStream* stream, JpegDecoderMgr* decoderMgr);
 
+    /*
+     * Handles rewinding the input stream if it is necessary
+     */
+    bool handleRewind();
+
+    /*
+     * Checks if we can scale to the requested dimensions and performs the scaling

[scroggo, 2015/04/24 13:14:28]

This doesn't actually scale, right? It just sets up the jpeg_decompress_struct
to scale in the future.

[msarett, 2015/04/24 15:08:44]

Yes this is unclear.  I changed the function name and comments.

+     */
+    bool handleScaling(const SkImageInfo& dstInfo);
+
+    /*
+     * Create the swizzler based on the encoded format
+     */
+    void initializeSwizzler(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
+            const Options& options);
+
     SkAutoTDelete<JpegDecoderMgr> fDecoderMgr;
+    SkAutoTDelete<SkSwizzler>     fSwizzler;
+    size_t                        fSrcRowBytes;
+
+    friend class SkJpegScanlineDecoder;
 
     typedef SkCodec INHERITED;
 };