WIP: Implement APNG

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

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..78495406bc43e2a747ee5494559a3f6d6fe0b768
--- /dev/null
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2006 Apple Computer, Inc.
+ * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
+ *
+ * Portions are Copyright (C) 2001 mozilla.org
+ *
+ * Other contributors:
+ *   Stuart Parmenter <stuart@mozilla.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Alternatively, the contents of this file may be used under the terms
+ * of either the Mozilla Public License Version 1.1, found at
+ * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
+ * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
+ * (the "GPL"), in which case the provisions of the MPL or the GPL are
+ * applicable instead of those above.  If you wish to allow use of your
+ * version of this file only under the terms of one of those two
+ * licenses (the MPL or the GPL) and not to allow others to use your
+ * version of this file under the LGPL, indicate your decision by
+ * deletingthe provisions above and replace them with the notice and
+ * other provisions required by the MPL or the GPL, as the case may be.
+ * If you do not delete the provisions above, a recipient may use your
+ * version of this file under any of the LGPL, the MPL or the GPL.
+ */
+
+#include "platform/image-decoders/png/PNGImageReader.h"
+
+#include "platform/image-decoders/png/PNGImageDecoder.h"
+#include "png.h"
+#include "wtf/PtrUtil.h"
+#include <memory>
+
+#if !defined(PNG_LIBPNG_VER_MAJOR) || !defined(PNG_LIBPNG_VER_MINOR)
+#error version error: compile against a versioned libpng.
+#endif
+#if USE(QCMSLIB)
+#include "qcms.h"
+#endif
+
+#if PNG_LIBPNG_VER_MAJOR > 1 || (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 4)
+#define JMPBUF(png_ptr) png_jmpbuf(png_ptr)
+#else
+#define JMPBUF(png_ptr) png_ptr->jmpbuf
+#endif
+
+namespace {
+
+inline blink::PNGImageDecoder* imageDecoder(png_structp png)
+{
+    return static_cast<blink::PNGImageDecoder*>(png_get_progressive_ptr(png));
+}
+
+void PNGAPI pngFrameHeaderAvailable(png_structp png, png_infop)
+{
+    imageDecoder(png)->frameHeaderAvailable();
+}
+
+void PNGAPI pngHeaderAvailable(png_structp png, png_infop)
+{
+    imageDecoder(png)->headerAvailable();
+}
+
+void PNGAPI pngRowAvailable(png_structp png, png_bytep row, png_uint_32 rowIndex, int state)
+{
+    imageDecoder(png)->rowAvailable(row, rowIndex, state);
+}
+
+void PNGAPI pngComplete(png_structp png, png_infop)
+{
+    imageDecoder(png)->complete();
+}
+
+void PNGAPI pngFailed(png_structp png, png_const_charp)
+{
+    longjmp(JMPBUF(png), 1);
+}
+
+} // namespace
+
+namespace blink {
+
+// This is the callback function for unknown PNG chunks, which is used to
+// extract the animation chunks.
+static int readAnimationChunk(png_structp png_ptr, png_unknown_chunkp chunk)
+{
+    PNGImageReader* reader = (PNGImageReader*) png_get_user_chunk_ptr(png_ptr);
+    reader->readChunk((const char*) chunk->name, chunk->data, chunk->size);
+    return 1;
+}
+
+PNGImageReader::PNGImageReader(PNGImageDecoder* decoder, size_t readOffset)
+    : m_decoder(decoder)
+    , m_readOffset(readOffset)
+    , m_currentBufferSize(0)
+    , m_decodingSizeOnly(false)
+    , m_hasAlpha(false)
+#if USE(QCMSLIB)
+    , m_rowBuffer()
+#endif
+{
+    m_png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, pngFailed, 0);
+    m_info = png_create_info_struct(m_png);
+    png_set_progressive_read_fn(m_png, m_decoder, pngHeaderAvailable, pngRowAvailable, pngComplete);
+
+    // Keep the chunks which are of interest for APNG.
+    png_byte apngChunks[] = {"acTL\0fcTL\0fdAT\0"};
+    png_set_keep_unknown_chunks(m_png, 1, apngChunks, 3);
+    png_set_read_user_chunk_fn(m_png, (png_voidp) this, readAnimationChunk);
+}
+
+PNGImageReader::~PNGImageReader()
+{
+    png_destroy_read_struct(m_png ? &m_png : 0, m_info ? &m_info : 0, 0);
+    ASSERT(!m_png && !m_info);
+    m_readOffset = 0;

[scroggo_chromium, 2016/10/04 14:50:17]

No reason to set an integer variable in the destructor. No one will read it
after this.

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

Acknowledged.

+}
+
+bool PNGImageReader::parse(const SegmentReader& data, PNGImageDecoder::PNGParseQuery query)
+{
+
+    if (PNGImageDecoder::PNGParseQuery::PNGSizeQuery == query)
+        m_decodingSizeOnly = true;
+
+    if (setjmp(JMPBUF(m_png)))
+        return m_decoder->setFailed();
+
+    const char *segment;
+    while (size_t segmentLength = data.getSomeData(segment, m_readOffset)) {
+        m_readOffset += segmentLength;
+        m_currentBufferSize = m_readOffset;
+        png_process_data(m_png, m_info,
+                         reinterpret_cast<png_bytep>(const_cast<char*>(segment)),
+                         segmentLength);
+
+        if (PNGImageDecoder::PNGParseQuery::PNGSizeQuery == query

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

This sure looks like it should be a switch statement to me.

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

Acknowledged.

+            && m_decoder->isSizeAvailable())
+            return true;
+
+        if (PNGImageDecoder::PNGParseQuery::PNGFrameCountQuery == query
+            && m_decoder->isDecodedFrameCountAvailable())
+            return true;
+
+        if (PNGImageDecoder::PNGParseQuery::PNGFrameDataQuery == query
+            && m_decoder->frameIsCompleteAtIndex(0))

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

I don't understand PNGFrameDataQuery. What is it asking for? And why do we want
to know whether the first frame is complete?

[joostouwerling, 2016/10/04 17:48:31]

This is the query I want to use for decoding an actual frame. It needs to be
annotated (somehow) with the frame id. My guess is that I will extract decoding
a single frame into it's own method, in a later design.

The is-first-frame-complete check was merely to not break the static PNG
decoding at this point. 

+            return true;
+    }
+    return false;
+
+}
+
+bool PNGImageReader::readChunk(const char tag[], const void* data_chunk, size_t length)
+{
+    const png_byte* data = static_cast<const png_byte*>(data_chunk);
+
+    if (!strcmp(tag, "acTL")) {
+        ASSERT(length == 8);
+        return readAnimationControl(data);
+    }
+
+    return false;
+}
+
+inline bool PNGImageReader::readAnimationControl(const png_byte* data)
+{
+    png_uint_32 numFrames, numRepetitions;
+    numFrames = png_get_uint_32(data);

[scroggo_chromium, 2016/10/04 14:50:17]

Nit: I might call these frameCount and repetitionCount, to be consistent with
variable names elsewhere.

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

Acknowledged.

+    numRepetitions = png_get_uint_32(data);
+    m_decoder->animationControlAvailable(numFrames, numRepetitions);
+    return true;
+}
+
+}; // namespace blink