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..aa97bb427a3f19508245e234782a1a73b3dde51e 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 +39,32 @@ public:
     PNGImageDecoder(AlphaOption, GammaAndColorProfileOption, size_t maxDecodedBytes, size_t offset = 0);
     ~PNGImageDecoder() override;
 
+    enum class PNGParseQuery { PNGSizeQuery, PNGFrameCountQuery, PNGFrameDataQuery };
+
     // ImageDecoder:
     String filenameExtension() const override { return "png"; }
+    size_t decodeFrameCount() override;
+    void parse(PNGParseQuery);

[scroggo_chromium, 2016/10/04 14:50:16]

I think this can be private? (It also does not fit into the pattern of
"overrides from ImageDecoder".)

[joostouwerling, 2016/10/11 16:31:06]

Acknowledged.

 
     // Callbacks from libpng
+    void frameHeaderAvailable() {};
     void headerAvailable();
     void rowAvailable(unsigned char* row, unsigned rowIndex, int);
     void complete();
 
+    // Additional methods used for APNG
+    bool isDecodedFrameCountAvailable() const;

[scroggo_chromium, 2016/10/04 14:50:16]

I think these can be private as well.

[joostouwerling, 2016/10/11 16:31:06]

Acknowledged.

+    void animationControlAvailable(size_t numFrames, size_t numRepetitions);
+
 private:
     // ImageDecoder:
-    void decodeSize() override { decode(true); }
-    void decode(size_t) override { decode(false); }
-
-    // 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 decodeSize() override { parse(PNGParseQuery::PNGSizeQuery); }
+    void decode(size_t) override { parse(PNGParseQuery::PNGFrameDataQuery); }
 
     std::unique_ptr<PNGImageReader> m_reader;
     const unsigned m_offset;
+    bool m_frameCountDecoded;
+    size_t m_frameCount;
 };
 
 } // namespace blink