WIP: Implement APNG

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

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.h
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.h b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.h
new file mode 100644
index 0000000000000000000000000000000000000000..15aa86b1e61e273f8db7e37b2ffc20fc05a1ecea
--- /dev/null
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.h
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#include "platform/image-decoders/SegmentReader.h"
+#include "platform/image-decoders/png/PNGImageDecoder.h"
+#include "platform/PlatformExport.h"
+#include "png.h"
+#include "wtf/Allocator.h"
+#include "wtf/PtrUtil.h"
+
+#ifndef PNGImageReader_h
+#define PNGImageReader_h
+
+namespace blink {
+
+class FastSharedBufferReader;
+
+class PLATFORM_EXPORT PNGImageReader final {
+    USING_FAST_MALLOC(PNGImageReader);
+    WTF_MAKE_NONCOPYABLE(PNGImageReader);
+public:
+    PNGImageReader(PNGImageDecoder*, size_t readOffset);
+    ~PNGImageReader();
+
+    struct FrameInfo {
+        size_t readOffset;
+        size_t byteLength;
+        size_t duration;
+        IntPoint offset;

[scroggo_chromium, 2016/10/11 20:13:11]

Why not combine offset and size into an IntRect?

+        IntSize size;
+        ImageFrame::DisposalMethod disposalMethod;
+        ImageFrame::AlphaBlendSource alphaBlend;
+    };
+
+    /*
+     * This method tries to parse the data stream in the SegmentReader, up to
+     * the point where the PNGParseQuery can be answered. It returns true when

[scroggo_chromium, 2016/10/11 20:13:11]

I think some better formatting will make this easier to follow:

@return true when the query is fulfilled.
        false when:
        A) not enough data has been provided
        B) when the data processing by libpng fails. In
           this case, it also calls setFailed() on
           m_decoder

+     * the query is fulfilled. It returns false when 1) there is not enough data
+     * provided, or 2) when the data processing by libpng fails. In the case of
+     * 2), it also calls setFailed() at the m_decoder.

[scroggo_chromium, 2016/10/11 20:13:11]

nit: "on m_decoder"

+     */
+    bool parse(SegmentReader&, PNGImageDecoder::PNGParseQuery);
+
+    void decode(SegmentReader&, size_t);
+    const FrameInfo& frameInfo(size_t) const;
+
+    /*
+     * This will return the number of frames that have been detected in the
+     * stream so far. If an incomplete stream is provided, this number is not
+     * final. However, all frame info for the frames up to this number is
+     * available so it can be used by the client if it wants to.
+     */
+    size_t frameCount() const;
+
+    // This is a callback for libpng, when it encounters an unknown chunk.
+    void parseAnimationChunk(const char* tag, const void* dataChunk, size_t length);
+
+    png_structp pngPtr() const { return m_png; }
+    png_infop infoPtr() const { return m_info; }
+
+    size_t getReadOffset() const { return m_readOffset; }
+    void setReadOffset(size_t offset) { m_readOffset = offset; }
+    void setHasAlpha(bool hasAlpha) { m_hasAlpha = hasAlpha; }
+    bool hasAlpha() const { return m_hasAlpha; }
+
+    png_bytep interlaceBuffer() const { return m_interlaceBuffer.get(); }
+    void createInterlaceBuffer(int size) { m_interlaceBuffer = wrapArrayUnique(new png_byte[size]); }
+#if USE(QCMSLIB)
+    png_bytep rowBuffer() const { return m_rowBuffer.get(); }
+    void createRowBuffer(int size) { m_rowBuffer = wrapArrayUnique(new png_byte[size]); }
+#endif
+
+
+private:
+    png_structp m_png;
+    png_infop m_info;
+    PNGImageDecoder* m_decoder;
+    size_t m_readOffset;
+    bool m_hasAlpha;
+    bool m_idatPartOfAnimation;

[scroggo_chromium, 2016/10/11 20:13:11]

nit: I think this is more clear if you insert the word "is"

"m_idatIsPartOfAnimation"

It might be helpful to have an explanation of what that means, too.

+    bool m_parsedSignature;
+    std::unique_ptr<png_byte[]> m_interlaceBuffer;
+    
+    Vector<FrameInfo, 1> m_frameInfo;
+    FrameInfo m_newFrame;
+
+    // Before using this method, see the remarks at the definition.
+    png_byte* readAsPngBytep(const FastSharedBufferReader&, size_t offset, size_t length);
+    char m_readBuffer[26];
+
+    bool processData(SegmentReader&, size_t offset, size_t length);
+    bool parseSize(SegmentReader&);
+    void parseAnimationControl(const png_byte* data);
+    void parseFrameInfo(const png_byte* data);
+
+#if USE(QCMSLIB)
+    std::unique_ptr<png_byte[]> m_rowBuffer;
+#endif
+};
+
+};
+
+#endif