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
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index 0000000000000000000000000000000000000000..03d103f34d5798d4cbda3c1f362b09d13caafc9f
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+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.h
@@ -0,0 +1,154 @@
+/*
+ * 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 initialOffset);
+  ~PNGImageReader();
+
+  struct FrameInfo {
+    // The offset where the frame data of this frame starts.
+    size_t startOffset;
+    // The number of bytes that contain frame data, starting at startOffset.
+    size_t byteLength;
+    size_t duration;
+    IntRect frameRect;
+    uint8_t disposalMethod;
+    uint8_t alphaBlend;
+  };
+
+  
+  // This method tries to parse the data stream in the SegmentReader, up to
+  // the point where the PNGParseQuery can be answered.
+  // @return true when the query is fulfilled.
+  //         false when:
+  //          A) not enough data provided
+  //          B) the data processing by libpng fails. In this case, it also
+  //             calls setFailed() 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);
+
+  // |m_parseCompleted| becomes true when
+  //  a) the png is determined to be non-animated, if no acTL chunk is found, or

[scroggo_chromium, 2016/11/11 21:31:06]

no acTL chunk is found prior to <IDAT, I think?>

[joostouwerling, 2016/11/21 20:27:44]

It does not check for an acTL after the IDAT anymore, yes :) (That'd be against
the APNG spec).

Clarified it.

+  //  b) when the IEND chunk is seen for animated pngs.
+  bool parseCompleted() { return m_parseCompleted; };

[scroggo_chromium, 2016/11/11 21:31:06]

nit: This method can be const.

[joostouwerling, 2016/11/21 20:27:44]

Done.

+
+  // This method is called when a frame with status ImageFrame::FramePartial 
+  // gets cleared in PNGImageDecoder.
+  //
+  // For |frameIndex| > 0, no action is necessary, since each decode call will
+  // decode the frame completely from start to end. 
+  // 
+  // For |frameIndex| == 0, |m_progressiveDecodeOffset| will be set to 0, to 
+  // make sure progressive decoding is started from the beginning of the frame.
+  void clearDecodeState(size_t frameIndex);
+
+  png_structp pngPtr() const { return m_png; }
+  png_infop infoPtr() const { return m_info; }
+
+  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]);
+  }
+  void clearInterlaceBuffer() { m_interlaceBuffer.reset(); }
+
+ private:
+  png_structp m_png;
+  png_infop m_info;
+  PNGImageDecoder* m_decoder;
+  // This indicates at what offset in the stream the PNG image starts.
+  const size_t m_initialOffset;
+  // This is used to keep track of how many bytes we've read during parsing.
+  size_t m_readOffset;
+
+  // This variable is used to do progressive decoding for the first frame. It
+  // keeps track of how many bytes have been processed so far.
+  size_t m_progressiveDecodeOffset;
+  // The offset where IDAT starts. This is used to re-use the complete set of
+  // info/header chunks when mimicking a png image for a frame.
+  size_t m_idatOffset;
+  bool m_hasAlpha;
+  // This flag is set to true when an fcTL chunk is encountered before the
+  // IDAT chunk(s). In that case, the IDAT data is the first frame. Otherwise,
+  // the IDAT is ignored.

[scroggo_chromium, 2016/11/11 21:31:06]

ignored for an animated image.

[joostouwerling, 2016/11/21 20:27:44]

Done.

+  bool m_idatIsPartOfAnimation;
+  bool m_isAnimated;
+  bool m_parsedSignature;
+  bool m_parseCompleted;
+
+  std::unique_ptr<png_byte[]> m_interlaceBuffer;
+  
+  Vector<FrameInfo, 1> m_frameInfo;
+  // This is used to temporarily store frame information, until it is pushed to
+  // |m_frameInfo|, when all frame data has been seen in the stream.
+  FrameInfo m_newFrame;
+
+  size_t processData(SegmentReader&, size_t offset, size_t length);
+  bool parseSize(SegmentReader&);
+  void parseFrameInfo(const png_byte* data);
+  void startFrameDecoding(SegmentReader&, size_t);
+  // @return true if the complete frame has been decoded
+  //         false  otherwise
+  bool progressivelyDecodeFirstFrame(SegmentReader&);
+  void decodeFrame(SegmentReader&, size_t);
+  void endFrameDecoding();
+
+};
+
+};
+
+#endif