Add animation support for WebP images

Source/WebCore/platform/image-decoders/webp/WEBPImageDecoder.cpp

Index: Source/WebCore/platform/image-decoders/webp/WEBPImageDecoder.cpp
diff --git a/Source/WebCore/platform/image-decoders/webp/WEBPImageDecoder.cpp b/Source/WebCore/platform/image-decoders/webp/WEBPImageDecoder.cpp
index ce858630dca47f6eba39ad888c457ff1c6b97b44..b1d43c994c9b66644403a10851a12afeb2e5caeb 100644
--- a/Source/WebCore/platform/image-decoders/webp/WEBPImageDecoder.cpp
+++ b/Source/WebCore/platform/image-decoders/webp/WEBPImageDecoder.cpp
@@ -35,11 +35,17 @@
 
 #ifdef QCMS_WEBP_COLOR_CORRECTION
 #include "qcms.h"
-#include "webp/demux.h"
+#include "webp/format_constants.h"
 #else
 #undef ICCP_FLAG
 #define ICCP_FLAG 0
-#endif
+#undef ALPHA_FLAG
+#if (WEBP_DECODER_ABI_VERSION >= 0x0163) // Alpha supported, but need to define flag.
+#define ALPHA_FLAG 0x00000010
+#else // Versions earlier than 0.1.99 don't support alpha.
+#define ALPHA_FLAG 0
+#endif // WEBP_DECODER_ABI_VERSION >= 0x0163
+#endif // QCMS_WEBP_COLOR_CORRECTION
 
 // Backward emulation for earlier versions than 0.1.99.
 #if (WEBP_DECODER_ABI_VERSION < 0x0163)
@@ -61,62 +67,228 @@ WEBPImageDecoder::WEBPImageDecoder(ImageSource::AlphaOption alphaOption,
                                    ImageSource::GammaAndColorProfileOption gammaAndColorProfileOption)
     : ImageDecoder(alphaOption, gammaAndColorProfileOption)
     , m_decoder(0)
-    , m_hasAlpha(false)
     , m_formatFlags(0)
 #ifdef QCMS_WEBP_COLOR_CORRECTION
+    , m_decodedHeight(0)
+    , m_haveAlreadyParsedThisData(false)
+    , m_demux(0)
+    , m_demuxState(WEBP_DEMUX_PARSING_HEADER)
     , m_haveReadProfile(false)
     , m_transform(0)
-    , m_decodedHeight(0)
+    , m_haveReadAnimParams(false)
+    , m_repetitionCount(cAnimationLoopOnce)
 #endif
 {
 }
 
 WEBPImageDecoder::~WEBPImageDecoder()
 {
-    clear();
+    clearAll();
 }
 
-void WEBPImageDecoder::clear()
+void WEBPImageDecoder::clearAll()
 {
 #ifdef QCMS_WEBP_COLOR_CORRECTION
     if (m_transform)
         qcms_transform_release(m_transform);
     m_transform = 0;
+    WebPDemuxDelete(m_demux);
+    m_demux = 0;
 #endif
-    if (m_decoder)
-        WebPIDelete(m_decoder);
+    clearDecoder();
+}
+
+void WEBPImageDecoder::clearDecoder()
+{
+    WebPIDelete(m_decoder);
     m_decoder = 0;
+#ifdef QCMS_WEBP_COLOR_CORRECTION
+    m_decodedHeight = 0;
+#endif
 }
 
 bool WEBPImageDecoder::isSizeAvailable()
 {
-    if (!ImageDecoder::isSizeAvailable())
-         decode(true);
-
+    if (!ImageDecoder::isSizeAvailable()) {
+#ifdef QCMS_WEBP_COLOR_CORRECTION
+        if (!updateDemuxer())
+            return 0;
+#else
+        decode(reinterpret_cast<const uint8_t*>(m_data->data()), m_data->size(), true, 0);
+#endif
+    }
     return ImageDecoder::isSizeAvailable();
 }
 
-ImageFrame* WEBPImageDecoder::frameBufferAtIndex(size_t index)
+size_t WEBPImageDecoder::frameCount()
 {
-    if (index)
+#ifdef QCMS_WEBP_COLOR_CORRECTION
+    if (!updateDemuxer())
         return 0;
-
+#else
     if (m_frameBufferCache.isEmpty()) {
         m_frameBufferCache.resize(1);
         m_frameBufferCache[0].setPremultiplyAlpha(m_premultiplyAlpha);
     }
+#endif
+    return m_frameBufferCache.size();
+}
 
-    ImageFrame& frame = m_frameBufferCache[0];
+ImageFrame* WEBPImageDecoder::frameBufferAtIndex(size_t index)
+{
+    if (index >= frameCount())
+        return 0;
+
+    ImageFrame& frame = m_frameBufferCache[index];
     if (frame.status() != ImageFrame::FrameComplete) {
+#ifdef QCMS_WEBP_COLOR_CORRECTION
+        if (index && (m_frameBufferCache[index - 1].status() != ImageFrame::FrameComplete))
+            return 0; // We haven't fully decoded the previous frame yet.
+        ASSERT(m_demux);
+        WebPIterator fIter;
+        if (!WebPDemuxGetFrame(m_demux, index + 1, &fIter))
+            return 0;
+        if (m_formatFlags & ANIMATION_FLAG) {
+            if (!initFrameBuffer(fIter, index))
+                return 0;
+        }
+        PlatformInstrumentation::willDecodeImage("WEBP");
+        decode(fIter.fragment.bytes, fIter.fragment.size, false, index);
+        PlatformInstrumentation::didDecodeImage();
+        WebPDemuxReleaseIterator(&fIter);
+#else
+        ASSERT(!index);
         PlatformInstrumentation::willDecodeImage("WEBP");
-        decode(false);
+        decode(reinterpret_cast<const uint8_t*>(m_data->data()), m_data->size(), false, index);
         PlatformInstrumentation::didDecodeImage();
+#endif
     }
     return &frame;
 }
 
 #ifdef QCMS_WEBP_COLOR_CORRECTION
 
+void WEBPImageDecoder::setData(SharedBuffer* data, bool allDataReceived)
+{
+    if (failed())
+        return;
+
+    ImageDecoder::setData(data, allDataReceived);
+
+    // Mark that we have new data.
+    if (m_demuxState != WEBP_DEMUX_DONE)
+        m_haveAlreadyParsedThisData = false;
+}
+
+bool WEBPImageDecoder::updateDemuxer()
+{
+    if (!m_haveAlreadyParsedThisData) {
+        WebPDemuxDelete(m_demux);
+        const uint8_t* dataBytes = reinterpret_cast<const uint8_t*>(m_data->data());
+        const size_t dataSize = m_data->size();
+
+        static const size_t minSizeForDemux = RIFF_HEADER_SIZE + CHUNK_HEADER_SIZE;
+        if (dataSize < minSizeForDemux)
+            return 0; // Wait for headers so that WebPDemuxPartial doesn't return null.
+
+        WebPData inputData = { dataBytes, dataSize };
+        m_demux = WebPDemuxPartial(&inputData, &m_demuxState);
+        if (!m_demux)
+            return setFailed(); // Must be a failure as we have at least 'minSizeForDemux' bytes.
+        if (m_demuxState >= WEBP_DEMUX_PARSED_HEADER) {
+            if (!ImageDecoder::isSizeAvailable()) {
+                if (!setSize(WebPDemuxGetI(m_demux, WEBP_FF_CANVAS_WIDTH), WebPDemuxGetI(m_demux, WEBP_FF_CANVAS_HEIGHT)))
+                    setFailed();
+                m_formatFlags = WebPDemuxGetI(m_demux, WEBP_FF_FORMAT_FLAGS);
+            }
+            ASSERT(ImageDecoder::isSizeAvailable());
+            const bool hasAnimation = (m_formatFlags & ANIMATION_FLAG);
+            const size_t newFrameCount = WebPDemuxGetI(m_demux, WEBP_FF_FRAME_COUNT);
+            if (hasAnimation && !m_haveReadAnimParams && (newFrameCount >= 1)) {
+                // As we have parsed at least one frame (even if partially),
+                // we must already have parsed the animation properties.
+                // This is because ANIM chunk always precedes ANMF chunks.
+                const uint32_t loopCount = WebPDemuxGetI(m_demux, WEBP_FF_LOOP_COUNT);
+                // Note: The following casts an 'unsigned int' to 'int'. But that is fine, because loop count is always <= 16 bits.
+                m_repetitionCount = (!loopCount) ? cAnimationLoopInfinite : loopCount;
+                m_haveReadAnimParams = true;
+            }
+            if (newFrameCount > m_frameBufferCache.size()) {
+                m_frameBufferCache.resize(newFrameCount);
+                for (size_t i = 0; i < newFrameCount; ++i)
+                    m_frameBufferCache[i].setPremultiplyAlpha(m_premultiplyAlpha);
+            }
+        }
+        m_haveAlreadyParsedThisData = true;
+    }
+    return true;
+}
+
+bool WEBPImageDecoder::initFrameBuffer(const WebPIterator& fIter, size_t frameIndex)
+{
+    ImageFrame& buffer = m_frameBufferCache[frameIndex];
+    if (buffer.status() != ImageFrame::FrameEmpty) // Already initialized.
+        return true;
+
+    // Initialize the frame rect in our buffer.
+    IntRect frameRect(fIter.x_offset, fIter.y_offset, fIter.width, fIter.height);
+
+    // Make sure the frameRect doesn't extend outside the buffer.
+    if (frameRect.maxX() > size().width())
+        frameRect.setWidth(size().width() - fIter.x_offset);
+    if (frameRect.maxY() > size().height())
+        frameRect.setHeight(size().height() - fIter.y_offset);
+
+    const int left = upperBoundScaledX(frameRect.x());
+    const int right = lowerBoundScaledX(frameRect.maxX(), left);
+    const int top = upperBoundScaledY(frameRect.y());
+    const int bottom = lowerBoundScaledY(frameRect.maxY(), top);
+    buffer.setOriginalFrameRect(IntRect(left, top, right - left, bottom - top));
+
+    buffer.setDisposalMethod(fIter.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND ? ImageFrame::DisposeOverwriteBgcolor : ImageFrame::DisposeKeep);
+    buffer.setDuration(fIter.duration);
+    buffer.setHasAlpha(m_formatFlags & ALPHA_FLAG);
+
+    if (!frameIndex) {
+        // This is the first frame, so we're not relying on any previous data.
+        if (!buffer.setSize(scaledSize().width(), scaledSize().height()))
+            return setFailed();
+    } else {
+        // The starting state for this frame depends on the previous frame's
+        // disposal method.
+        const ImageFrame& prevBuffer = m_frameBufferCache[frameIndex - 1];
+        ASSERT(prevBuffer.status() == ImageFrame::FrameComplete);
+        const IntRect& prevRect = prevBuffer.originalFrameRect();
+        const ImageFrame::FrameDisposalMethod prevMethod = prevBuffer.disposalMethod();
+        if ((prevMethod == ImageFrame::DisposeKeep) || (prevMethod == ImageFrame::DisposeNotSpecified)) {
+            // Preserve the last frame as the starting state for this frame.
+            if (!buffer.copyBitmapData(prevBuffer))
+                return setFailed();
+        } else { // prevMethod == ImageFrame::DisposeOverwriteBgcolor
+            // We want to clear the previous frame to transparent, without
+            // affecting pixels in the image outside of the frame.
+            // So, we copy the whole previous buffer, then clear just its frame.
+            if (!frameIndex || prevRect.contains(IntRect(IntPoint(), scaledSize()))) {
+                // Clearing the first frame, or a frame the size of the whole
+                // image, results in a completely empty image.
+                if (!buffer.setSize(scaledSize().width(), scaledSize().height()))
+                    return setFailed();
+            } else {
+                // Copy the whole previous buffer, then clear just its frame.
+                if (!buffer.copyBitmapData(prevBuffer))
+                    return setFailed();
+                for (int y = prevRect.y(); y < prevRect.maxY(); ++y) {
+                    for (int x = prevRect.x(); x < prevRect.maxX(); ++x)
+                        buffer.setRGBA(x, y, 0, 0, 0, 0);
+                }
+            }
+        }
+    }
+    // Update frame status to be partially complete.
+    buffer.setStatus(ImageFrame::FramePartial);
+    return true;
+}
+
 void WEBPImageDecoder::createColorTransform(const char* data, size_t size)
 {
     if (m_transform)
@@ -140,16 +312,11 @@ void WEBPImageDecoder::createColorTransform(const char* data, size_t size)
     qcms_profile_release(inputProfile);
 }
 
-void WEBPImageDecoder::readColorProfile(const uint8_t* data, size_t size)
+void WEBPImageDecoder::readColorProfile()
 {
     WebPChunkIterator chunkIterator;
-    WebPData inputData = { data, size };
-    WebPDemuxState state;
-
-    WebPDemuxer* demuxer = WebPDemuxPartial(&inputData, &state);
-    if (!WebPDemuxGetChunk(demuxer, "ICCP", 1, &chunkIterator)) {
+    if (!WebPDemuxGetChunk(m_demux, "ICCP", 1, &chunkIterator)) {
         WebPDemuxReleaseChunkIterator(&chunkIterator);
-        WebPDemuxDelete(demuxer);
         return;
     }
 
@@ -169,80 +336,129 @@ void WEBPImageDecoder::readColorProfile(const uint8_t* data, size_t size)
         createColorTransform(profileData, profileSize);
 
     WebPDemuxReleaseChunkIterator(&chunkIterator);
-    WebPDemuxDelete(demuxer);
 }
 
-void WEBPImageDecoder::applyColorProfile(const uint8_t* data, size_t size, ImageFrame& buffer)
+void WEBPImageDecoder::applyPostProcessing(size_t frameIndex)
 {
+    ImageFrame& buffer = m_frameBufferCache[frameIndex];
     int width;
+    int stride;
     int decodedHeight;
-    if (!WebPIDecGetRGB(m_decoder, &decodedHeight, &width, 0, 0))
+    if (!WebPIDecGetRGB(m_decoder, &decodedHeight, &width, 0, &stride))
         return; // See also https://bugs.webkit.org/show_bug.cgi?id=74062
     if (decodedHeight <= 0)
         return;
-
-    if (!m_haveReadProfile) {
-        readColorProfile(data, size);
-        m_haveReadProfile = true;
-    }
-
     ASSERT(width == scaledSize().width());
     ASSERT(decodedHeight <= scaledSize().height());
+    const int left = buffer.originalFrameRect().x();
+    const int top = buffer.originalFrameRect().y();
+
+    // Color Profile.
+    if ((m_formatFlags & ICCP_FLAG) && !ignoresGammaAndColorProfile()) {
+        if (!m_haveReadProfile) {
+            readColorProfile();
+            m_haveReadProfile = true;
+        }
+        for (int y = m_decodedHeight; y < decodedHeight; ++y) {
+            const int canvasY = top + y;
+            uint8_t* row = reinterpret_cast<uint8_t*>(buffer.getAddr(left, canvasY));
+            if (qcms_transform* transform = colorTransform())
+                qcms_transform_data_type(transform, row, row, width, QCMS_OUTPUT_RGBX);
+            uint8_t* pixel = row;
+            for (int x = 0; x < width; ++x, pixel += 4) {
+                const int canvasX = left + x;
+                buffer.setRGBA(canvasX, canvasY, pixel[0], pixel[1], pixel[2], pixel[3]);
+            }
+        }
+    }
 
-    for (int y = m_decodedHeight; y < decodedHeight; ++y) {
-        uint8_t* row = reinterpret_cast<uint8_t*>(buffer.getAddr(0, y));
-        if (qcms_transform* transform = colorTransform())
-            qcms_transform_data_type(transform, row, row, width, QCMS_OUTPUT_RGBX);
-        uint8_t* pixel = row;
-        for (int x = 0; x < width; ++x, pixel += 4)
-            buffer.setRGBA(x, y, pixel[0], pixel[1], pixel[2], pixel[3]);
+    // Frame disposal.
+    if ((m_formatFlags & ANIMATION_FLAG) && frameIndex) {
+        ImageFrame& prevBuffer = m_frameBufferCache[frameIndex - 1];
+        ImageFrame::FrameDisposalMethod prevMethod = prevBuffer.disposalMethod();
+        ASSERT(prevBuffer.status() == ImageFrame::FrameComplete);
+        if (prevMethod == ImageFrame::DisposeKeep) { // Restore transparent pixels to pixels in previous canvas.
+            for (int y = m_decodedHeight; y < decodedHeight; ++y) {
+                const int canvasY = top + y;
+                for (int x = 0; x < width; ++x) {
+                    const int canvasX = left + x;
+                    ImageFrame::PixelData& pixel = *buffer.getAddr(canvasX, canvasY);
+                    // FIXME: Use alpha-blending when alpha is between 0 and 255.
+                    // Alpha-blending is being implemented in: https://bugs.webkit.org/show_bug.cgi?id=17022
+                    if (!((pixel >> 24) & 0xff)) { // Need to restore.
+                        const ImageFrame::PixelData prevPixel = *prevBuffer.getAddr(canvasX, canvasY);
+                        pixel = prevPixel;
+                    }
+                }
+            }
+        } else if (prevMethod == ImageFrame::DisposeOverwriteBgcolor) {
+            const IntRect& prevRect = prevBuffer.originalFrameRect();
+            // We need to restore transparent pixels to as they were just after initFrame() call. That is:
+            //   * Transparent if it belongs to prevRect <-- This is a no-op.
+            //   * Pixel in the previous canvas otherwise <-- Need to restore.
+            for (int y = m_decodedHeight; y < decodedHeight; ++y) {
+                const int canvasY = top + y;
+                for (int x = 0; x < width; ++x) {
+                    const int canvasX = left + x;
+                    ImageFrame::PixelData& pixel = *buffer.getAddr(canvasX, canvasY);
+                    const ImageFrame::PixelData prevPixel = *prevBuffer.getAddr(canvasX, canvasY);
+                    if (!((pixel >> 24) & 0xff) && !prevRect.contains(IntPoint(canvasX, canvasY))) // Need to restore.
+                        pixel = prevPixel;
+                }
+            }
+        }
     }
 
     m_decodedHeight = decodedHeight;
 }
 
+void WEBPImageDecoder::clearFrameBufferCache(size_t clearBeforeFrame)
+{
+    // We always preserve at least one frame.
+    if (m_frameBufferCache.size() <= 1)
+        return;
+
+    // Find the last frame we need to preserve in the cache to facilitate
+    // the construction of next frames (needed by initFrame() and
+    // applyPostProcessing()) . This frame is either:
+    //   * The last decoded frame in cache, OR
+    //   * The first frame (if cache doesn't contain any decoded frames).
+    const int lastFrame = std::min(clearBeforeFrame, m_frameBufferCache.size() - 1);
+    Vector<ImageFrame>::iterator i(m_frameBufferCache.begin() + lastFrame);
+    while ((i != m_frameBufferCache.begin()) && (i->status() != ImageFrame::FrameComplete))
+        --i;
+
+    // Now |i| holds the last frame we need to preserve; clear prior frames.
+    for (Vector<ImageFrame>::iterator j(m_frameBufferCache.begin()); j != i; ++j) {
+        ASSERT(j->status() != ImageFrame::FramePartial);
+        if (j->status() != ImageFrame::FrameEmpty)
+            j->clearPixelData();
+    }
+}
+
 #endif // QCMS_WEBP_COLOR_CORRECTION
 
-bool WEBPImageDecoder::decode(bool onlySize)
+bool WEBPImageDecoder::decode(const uint8_t* dataBytes, size_t dataSize, bool onlySize, size_t frameIndex)
 {
     if (failed())
         return false;
 
-    const uint8_t* dataBytes = reinterpret_cast<const uint8_t*>(m_data->data());
-    const size_t dataSize = m_data->size();
-
     if (!ImageDecoder::isSizeAvailable()) {
         static const size_t imageHeaderSize = 30;
         if (dataSize < imageHeaderSize)
             return false;
         int width, height;
-#ifdef QCMS_WEBP_COLOR_CORRECTION
-        WebPData inputData = { dataBytes, dataSize };
-        WebPDemuxState state;
-        WebPDemuxer* demuxer = WebPDemuxPartial(&inputData, &state);
-        if (!demuxer)
-            return setFailed();
-
-        width = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_WIDTH);
-        height = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_HEIGHT);
-        m_formatFlags = WebPDemuxGetI(demuxer, WEBP_FF_FORMAT_FLAGS);
-        m_hasAlpha = !!(m_formatFlags & ALPHA_FLAG);
-
-        WebPDemuxDelete(demuxer);
-        if (state <= WEBP_DEMUX_PARSING_HEADER)
-            return false;
-#elif (WEBP_DECODER_ABI_VERSION >= 0x0163)
+#if (WEBP_DECODER_ABI_VERSION >= 0x0163)
         WebPBitstreamFeatures features;
         if (WebPGetFeatures(dataBytes, dataSize, &features) != VP8_STATUS_OK)
             return setFailed();
         width = features.width;
         height = features.height;
-        m_hasAlpha = features.has_alpha;
+        m_formatFlags = features.has_alpha ? ALPHA_FLAG : 0;
 #else
         // Earlier version won't be able to display WebP files with alpha.
         if (!WebPGetInfo(dataBytes, dataSize, &width, &height))
             return setFailed();
-        m_hasAlpha = false;
 #endif
         if (!setSize(width, height))
             return setFailed();
@@ -252,27 +468,28 @@ bool WEBPImageDecoder::decode(bool onlySize)
     if (onlySize)
         return true;
 
-    ASSERT(!m_frameBufferCache.isEmpty());
-    ImageFrame& buffer = m_frameBufferCache[0];
+    ASSERT(m_frameBufferCache.size() > frameIndex);
+    ImageFrame& buffer = m_frameBufferCache[frameIndex];
     ASSERT(buffer.status() != ImageFrame::FrameComplete);
 
     if (buffer.status() == ImageFrame::FrameEmpty) {
-        if (!buffer.setSize(size().width(), size().height()))
+        if (!buffer.setSize(scaledSize().width(), scaledSize().height()))
             return setFailed();
         buffer.setStatus(ImageFrame::FramePartial);
-        buffer.setHasAlpha(m_hasAlpha);
+        buffer.setHasAlpha(m_formatFlags & ALPHA_FLAG);
         buffer.setOriginalFrameRect(IntRect(IntPoint(), size()));
     }
 
     if (!m_decoder) {
-        WEBP_CSP_MODE mode = outputMode(m_hasAlpha);
+        WEBP_CSP_MODE mode = outputMode(m_formatFlags & ALPHA_FLAG);
         if (!m_premultiplyAlpha)
             mode = outputMode(false);
         if ((m_formatFlags & ICCP_FLAG) && !ignoresGammaAndColorProfile())
             mode = MODE_RGBA; // Decode to RGBA for input to libqcms.
         int rowStride = size().width() * sizeof(ImageFrame::PixelData);
-        uint8_t* output = reinterpret_cast<uint8_t*>(buffer.getAddr(0, 0));
-        int outputSize = size().height() * rowStride;
+        const IntRect& frameRect = buffer.originalFrameRect();
+        uint8_t* output = reinterpret_cast<uint8_t*>(buffer.getAddr(frameRect.x(), frameRect.y()));
+        int outputSize = frameRect.height() * rowStride;
         m_decoder = WebPINewRGB(mode, output, outputSize, rowStride);
         if (!m_decoder)
             return setFailed();
@@ -280,17 +497,15 @@ bool WEBPImageDecoder::decode(bool onlySize)
 
     switch (WebPIUpdate(m_decoder, dataBytes, dataSize)) {
     case VP8_STATUS_OK:
-        if ((m_formatFlags & ICCP_FLAG) && !ignoresGammaAndColorProfile()) 
-            applyColorProfile(dataBytes, dataSize, buffer);
+        applyPostProcessing(frameIndex);
         buffer.setStatus(ImageFrame::FrameComplete);
-        clear();
+        clearDecoder();
         return true;
     case VP8_STATUS_SUSPENDED:
-        if ((m_formatFlags & ICCP_FLAG) && !ignoresGammaAndColorProfile()) 
-            applyColorProfile(dataBytes, dataSize, buffer);
+        applyPostProcessing(frameIndex);
         return false;
     default:
-        clear();                         
+        clearAll();
         return setFailed();
     }
 }