WIP: Implement APNG

third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.h

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.h
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.h b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.h
index c0c9ca872b0ab94e8fb7bf03370a5c2441ca247f..5e96be02b3bffb47f835c44eabdbf33b9fa4f015 100644
--- a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.h
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.h
@@ -39,26 +39,44 @@ public:
     PNGImageDecoder(AlphaOption, GammaAndColorProfileOption, size_t maxDecodedBytes, size_t offset = 0);
     ~PNGImageDecoder() override;
 
+    enum class PNGParseQuery { PNGSizeQuery, PNGMetaDataQuery };
+
     // ImageDecoder:
     String filenameExtension() const override { return "png"; }
+    int repetitionCount() const override;
+    bool frameIsCompleteAtIndex(size_t) const override;
+    float frameDurationAtIndex(size_t) const override;
 
     // Callbacks from libpng
     void headerAvailable();
     void rowAvailable(unsigned char* row, unsigned rowIndex, int);
     void complete();
 
+    // Additional methods used for APNG
+    void setRepetitionCount(size_t);
+    // This is called by PNGImageReader when it encounters the IEND chunk
+    // while parsing PNGMetaDataQuery. If m_metaDataDecoded is true, the decoder
+    // does not need to query for meta data again.
+    void setMetaDataDecoded() { m_metaDataDecoded = true; };
+    
 private:
     // ImageDecoder:
-    void decodeSize() override { decode(true); }
-    void decode(size_t) override { decode(false); }
+    void decodeSize() override { parse(PNGParseQuery::PNGSizeQuery); }
+    void decode(size_t) override; 
+    size_t decodeFrameCount() override;
+    void initializeNewFrame(size_t) override;
 
-    // Decodes the image.  If |onlySize| is true, stops decoding after
-    // calculating the image size.  If decoding fails but there is no more
-    // data coming, sets the "decode failure" flag.
-    void decode(bool onlySize);
+    void parse(PNGParseQuery);
 
     std::unique_ptr<PNGImageReader> m_reader;
     const unsigned m_offset;
+    bool m_metaDataDecoded;
+    size_t m_frameCount;
+    size_t m_currentFrame;
+    // m_repetitionCount is set to cAnimationLoopOnce by default, so the
+    // DeferredImageDecoder takes into account that this may be an animated
+    // image, but we don't know for sure yet.
+    int m_repetitionCount;
 };
 
 } // namespace blink