Moving GraphicsContext and dependencies from core to platform.

Source/core/platform/image-decoders/gif/GIFImageReader.cpp

Index: Source/core/platform/image-decoders/gif/GIFImageReader.cpp
diff --git a/Source/core/platform/image-decoders/gif/GIFImageReader.cpp b/Source/core/platform/image-decoders/gif/GIFImageReader.cpp
deleted file mode 100644
index 2a025351596c2e0a5157ef4848d0e1f13a3d968f..0000000000000000000000000000000000000000
--- a/Source/core/platform/image-decoders/gif/GIFImageReader.cpp
+++ /dev/null
@@ -1,800 +0,0 @@
-/* -*- Mode: C; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is mozilla.org code.
- *
- * The Initial Developer of the Original Code is
- * Netscape Communications Corporation.
- * Portions created by the Initial Developer are Copyright (C) 1998
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   Chris Saari <saari@netscape.com>
- *   Apple Computer
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either the GNU General Public License Version 2 or later (the "GPL"), or
- * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-/*
-The Graphics Interchange Format(c) is the copyright property of CompuServe
-Incorporated. Only CompuServe Incorporated is authorized to define, redefine,
-enhance, alter, modify or change in any way the definition of the format.
-
-CompuServe Incorporated hereby grants a limited, non-exclusive, royalty-free
-license for the use of the Graphics Interchange Format(sm) in computer
-software; computer software utilizing GIF(sm) must acknowledge ownership of the
-Graphics Interchange Format and its Service Mark by CompuServe Incorporated, in
-User and Technical Documentation. Computer software utilizing GIF, which is
-distributed or may be distributed without User or Technical Documentation must
-display to the screen or printer a message acknowledging ownership of the
-Graphics Interchange Format and the Service Mark by CompuServe Incorporated; in
-this case, the acknowledgement may be displayed in an opening screen or leading
-banner, or a closing screen or trailing banner. A message such as the following
-may be used:
-
-    "The Graphics Interchange Format(c) is the Copyright property of
-    CompuServe Incorporated. GIF(sm) is a Service Mark property of
-    CompuServe Incorporated."
-
-For further information, please contact :
-
-    CompuServe Incorporated
-    Graphics Technology Department
-    5000 Arlington Center Boulevard
-    Columbus, Ohio  43220
-    U. S. A.
-
-CompuServe Incorporated maintains a mailing list with all those individuals and
-organizations who wish to receive copies of this document when it is corrected
-or revised. This service is offered free of charge; please provide us with your
-mailing address.
-*/
-
-#include "config.h"
-#include "core/platform/image-decoders/gif/GIFImageReader.h"
-
-#include <string.h>
-#include "core/platform/graphics/ImageSource.h"
-
-using WebCore::GIFImageDecoder;
-
-// GETN(n, s) requests at least 'n' bytes available from 'q', at start of state 's'.
-//
-// Note, the hold will never need to be bigger than 256 bytes to gather up in the hold,
-// as each GIF block (except colormaps) can never be bigger than 256 bytes.
-// Colormaps are directly copied in the resp. global_colormap or dynamically allocated local_colormap.
-// So a fixed buffer in GIFImageReader is good enough.
-// This buffer is only needed to copy left-over data from one GifWrite call to the next
-#define GETN(n, s) \
-    do { \
-        m_bytesToConsume = (n); \
-        m_state = (s); \
-    } while (0)
-
-// Get a 16-bit value stored in little-endian format.
-#define GETINT16(p)   ((p)[1]<<8|(p)[0])
-
-// Send the data to the display front-end.
-bool GIFLZWContext::outputRow(GIFRow::const_iterator rowBegin)
-{
-    int drowStart = irow;
-    int drowEnd = irow;
-
-    // Haeberli-inspired hack for interlaced GIFs: Replicate lines while
-    // displaying to diminish the "venetian-blind" effect as the image is
-    // loaded. Adjust pixel vertical positions to avoid the appearance of the
-    // image crawling up the screen as successive passes are drawn.
-    if (m_frameContext->progressiveDisplay() && m_frameContext->interlaced() && ipass < 4) {
-        unsigned rowDup = 0;
-        unsigned rowShift = 0;
-
-        switch (ipass) {
-        case 1:
-            rowDup = 7;
-            rowShift = 3;
-            break;
-        case 2:
-            rowDup = 3;
-            rowShift = 1;
-            break;
-        case 3:
-            rowDup = 1;
-            rowShift = 0;
-            break;
-        default:
-            break;
-        }
-
-        drowStart -= rowShift;
-        drowEnd = drowStart + rowDup;
-
-        // Extend if bottom edge isn't covered because of the shift upward.
-        if (((m_frameContext->height() - 1) - drowEnd) <= rowShift)
-            drowEnd = m_frameContext->height() - 1;
-
-        // Clamp first and last rows to upper and lower edge of image.
-        if (drowStart < 0)
-            drowStart = 0;
-
-        if ((unsigned)drowEnd >= m_frameContext->height())
-            drowEnd = m_frameContext->height() - 1;
-    }
-
-    // Protect against too much image data.
-    if ((unsigned)drowStart >= m_frameContext->height())
-        return true;
-
-    // CALLBACK: Let the client know we have decoded a row.
-    if (!m_client->haveDecodedRow(m_frameContext->frameId(), rowBegin, m_frameContext->width(),
-        drowStart, drowEnd - drowStart + 1, m_frameContext->progressiveDisplay() && m_frameContext->interlaced() && ipass > 1))
-        return false;
-
-    if (!m_frameContext->interlaced())
-        irow++;
-    else {
-        do {
-            switch (ipass) {
-            case 1:
-                irow += 8;
-                if (irow >= m_frameContext->height()) {
-                    ipass++;
-                    irow = 4;
-                }
-                break;
-
-            case 2:
-                irow += 8;
-                if (irow >= m_frameContext->height()) {
-                    ipass++;
-                    irow = 2;
-                }
-                break;
-
-            case 3:
-                irow += 4;
-                if (irow >= m_frameContext->height()) {
-                    ipass++;
-                    irow = 1;
-                }
-                break;
-
-            case 4:
-                irow += 2;
-                if (irow >= m_frameContext->height()) {
-                    ipass++;
-                    irow = 0;
-                }
-                break;
-
-            default:
-                break;
-            }
-        } while (irow > (m_frameContext->height() - 1));
-    }
-    return true;
-}
-
-// Perform Lempel-Ziv-Welch decoding.
-// Returns true if decoding was successful. In this case the block will have been completely consumed and/or rowsRemaining will be 0.
-// Otherwise, decoding failed; returns false in this case, which will always cause the GIFImageReader to set the "decode failed" flag.
-bool GIFLZWContext::doLZW(const unsigned char* block, size_t bytesInBlock)
-{
-    const size_t width = m_frameContext->width();
-
-    if (rowIter == rowBuffer.end())
-        return true;
-
-    for (const unsigned char* ch = block; bytesInBlock-- > 0; ch++) {
-        // Feed the next byte into the decoder's 32-bit input buffer.
-        datum += ((int) *ch) << bits;
-        bits += 8;
-
-        // Check for underflow of decoder's 32-bit input buffer.
-        while (bits >= codesize) {
-            // Get the leading variable-length symbol from the data stream.
-            int code = datum & codemask;
-            datum >>= codesize;
-            bits -= codesize;
-
-            // Reset the dictionary to its original state, if requested.
-            if (code == clearCode) {
-                codesize = m_frameContext->dataSize() + 1;
-                codemask = (1 << codesize) - 1;
-                avail = clearCode + 2;
-                oldcode = -1;
-                continue;
-            }
-
-            // Check for explicit end-of-stream code.
-            if (code == (clearCode + 1)) {
-                // end-of-stream should only appear after all image data.
-                if (!rowsRemaining)
-                    return true;
-                return false;
-            }
-
-            const int tempCode = code;
-            unsigned short codeLength = 0;
-            if (code < avail) {
-                // This is a pre-existing code, so we already know what it
-                // encodes.
-                codeLength = suffixLength[code];
-                rowIter += codeLength;
-            } else if (code == avail && oldcode != -1) {
-                // This is a new code just being added to the dictionary.
-                // It must encode the contents of the previous code, plus
-                // the first character of the previous code again.
-                codeLength = suffixLength[oldcode] + 1;
-                rowIter += codeLength;
-                *--rowIter = firstchar;
-                code = oldcode;
-            } else {
-                // This is an invalid code. The dictionary is just initialized
-                // and the code is incomplete. We don't know how to handle
-                // this case.
-                return false;
-            }
-
-            while (code >= clearCode) {
-                *--rowIter = suffix[code];
-                code = prefix[code];
-            }
-
-            *--rowIter = firstchar = suffix[code];
-
-            // Define a new codeword in the dictionary as long as we've read
-            // more than one value from the stream.
-            if (avail < MAX_DICTIONARY_ENTRIES && oldcode != -1) {
-                prefix[avail] = oldcode;
-                suffix[avail] = firstchar;
-                suffixLength[avail] = suffixLength[oldcode] + 1;
-                ++avail;
-
-                // If we've used up all the codewords of a given length
-                // increase the length of codewords by one bit, but don't
-                // exceed the specified maximum codeword size.
-                if (!(avail & codemask) && avail < MAX_DICTIONARY_ENTRIES) {
-                    ++codesize;
-                    codemask += avail;
-                }
-            }
-            oldcode = tempCode;
-            rowIter += codeLength;
-
-            // Output as many rows as possible.
-            GIFRow::iterator rowBegin = rowBuffer.begin();
-            for (; rowBegin + width <= rowIter; rowBegin += width) {
-                if (!outputRow(rowBegin))
-                    return false;
-                rowsRemaining--;
-                if (!rowsRemaining)
-                    return true;
-            }
-
-            if (rowBegin != rowBuffer.begin()) {
-                // Move the remaining bytes to the beginning of the buffer.
-                const size_t bytesToCopy = rowIter - rowBegin;
-                memcpy(rowBuffer.begin(), rowBegin, bytesToCopy);
-                rowIter = rowBuffer.begin() + bytesToCopy;
-            }
-        }
-    }
-    return true;
-}
-
-void GIFColorMap::buildTable(const unsigned char* data, size_t length)
-{
-    if (!m_isDefined || !m_table.isEmpty())
-        return;
-
-    RELEASE_ASSERT(m_position + m_colors * BYTES_PER_COLORMAP_ENTRY <= length);
-    const unsigned char* srcColormap = data + m_position;
-    m_table.resize(m_colors);
-    for (Table::iterator iter = m_table.begin(); iter != m_table.end(); ++iter) {
-        *iter = SkPackARGB32NoCheck(255, srcColormap[0], srcColormap[1], srcColormap[2]);
-        srcColormap += BYTES_PER_COLORMAP_ENTRY;
-    }
-}
-
-// Perform decoding for this frame. frameDecoded will be true if the entire frame is decoded.
-// Returns false if a decoding error occurred. This is a fatal error and causes the GIFImageReader to set the "decode failed" flag.
-// Otherwise, either not enough data is available to decode further than before, or the new data has been decoded successfully; returns true in this case.
-bool GIFFrameContext::decode(const unsigned char* data, size_t length, WebCore::GIFImageDecoder* client, bool* frameDecoded)
-{
-    m_localColorMap.buildTable(data, length);
-
-    *frameDecoded = false;
-    if (!m_lzwContext) {
-        // Wait for more data to properly initialize GIFLZWContext.
-        if (!isDataSizeDefined() || !isHeaderDefined())
-            return true;
-
-        m_lzwContext = adoptPtr(new GIFLZWContext(client, this));
-        if (!m_lzwContext->prepareToDecode()) {
-            m_lzwContext.clear();
-            return false;
-        }
-
-        m_currentLzwBlock = 0;
-    }
-
-    // Some bad GIFs have extra blocks beyond the last row, which we don't want to decode.
-    while (m_currentLzwBlock < m_lzwBlocks.size() && m_lzwContext->hasRemainingRows()) {
-        size_t blockPosition = m_lzwBlocks[m_currentLzwBlock].blockPosition;
-        size_t blockSize = m_lzwBlocks[m_currentLzwBlock].blockSize;
-        if (blockPosition + blockSize > length)
-            return false;
-        if (!m_lzwContext->doLZW(data + blockPosition, blockSize))
-            return false;
-        ++m_currentLzwBlock;
-    }
-
-    // If this frame is data complete then the previous loop must have completely decoded all LZW blocks.
-    // There will be no more decoding for this frame so it's time to cleanup.
-    if (isComplete()) {
-        *frameDecoded = true;
-        m_lzwContext.clear();
-    }
-    return true;
-}
-
-// Decode a frame.
-// This method uses GIFFrameContext:decode() to decode the frame; decoding error is reported to client as a critical failure.
-// Return true if decoding has progressed. Return false if an error has occurred.
-bool GIFImageReader::decode(size_t frameIndex)
-{
-    m_globalColorMap.buildTable(data(0), m_data->size());
-
-    bool frameDecoded = false;
-    GIFFrameContext* currentFrame = m_frames[frameIndex].get();
-
-    return currentFrame->decode(data(0), m_data->size(), m_client, &frameDecoded)
-        && (!frameDecoded || m_client->frameComplete(frameIndex));
-}
-
-bool GIFImageReader::parse(GIFImageDecoder::GIFParseQuery query)
-{
-    ASSERT(m_bytesRead <= m_data->size());
-
-    return parseData(m_bytesRead, m_data->size() - m_bytesRead, query);
-}
-
-// Parse incoming GIF data stream into internal data structures.
-// Return true if parsing has progressed or there is not enough data.
-// Return false if a fatal error is encountered.
-bool GIFImageReader::parseData(size_t dataPosition, size_t len, GIFImageDecoder::GIFParseQuery query)
-{
-    if (!len) {
-        // No new data has come in since the last call, just ignore this call.
-        return true;
-    }
-
-    if (len < m_bytesToConsume)
-        return true;
-
-    // This loop reads as many components from |m_data| as possible.
-    // At the beginning of each iteration, dataPosition will be advanced by m_bytesToConsume to
-    // point to the next component. len will be decremented accordingly.
-    while (len >= m_bytesToConsume) {
-        const size_t currentComponentPosition = dataPosition;
-        const unsigned char* currentComponent = data(dataPosition);
-
-        // Mark the current component as consumed. Note that currentComponent will remain pointed at this
-        // component until the next loop iteration.
-        dataPosition += m_bytesToConsume;
-        len -= m_bytesToConsume;
-
-        switch (m_state) {
-        case GIFLZW:
-            ASSERT(!m_frames.isEmpty());
-            // m_bytesToConsume is the current component size because it hasn't been updated.
-            m_frames.last()->addLzwBlock(currentComponentPosition, m_bytesToConsume);
-            GETN(1, GIFSubBlock);
-            break;
-
-        case GIFLZWStart: {
-            ASSERT(!m_frames.isEmpty());
-            m_frames.last()->setDataSize(*currentComponent);
-            GETN(1, GIFSubBlock);
-            break;
-        }
-
-        case GIFType: {
-            // All GIF files begin with "GIF87a" or "GIF89a".
-            if (!strncmp((char*)currentComponent, "GIF89a", 6))
-                m_version = 89;
-            else if (!strncmp((char*)currentComponent, "GIF87a", 6))
-                m_version = 87;
-            else
-                return false;
-            GETN(7, GIFGlobalHeader);
-            break;
-        }
-
-        case GIFGlobalHeader: {
-            // This is the height and width of the "screen" or frame into which images are rendered. The
-            // individual images can be smaller than the screen size and located with an origin anywhere
-            // within the screen.
-            m_screenWidth = GETINT16(currentComponent);
-            m_screenHeight = GETINT16(currentComponent + 2);
-
-            // CALLBACK: Inform the decoderplugin of our size.
-            // Note: A subsequent frame might have dimensions larger than the "screen" dimensions.
-            if (m_client && !m_client->setSize(m_screenWidth, m_screenHeight))
-                return false;
-
-            const size_t globalColorMapColors = 2 << (currentComponent[4] & 0x07);
-
-            if ((currentComponent[4] & 0x80) && globalColorMapColors > 0) { /* global map */
-                m_globalColorMap.setTablePositionAndSize(dataPosition, globalColorMapColors);
-                GETN(BYTES_PER_COLORMAP_ENTRY * globalColorMapColors, GIFGlobalColormap);
-                break;
-            }
-
-            GETN(1, GIFImageStart);
-            break;
-        }
-
-        case GIFGlobalColormap: {
-            m_globalColorMap.setDefined();
-            GETN(1, GIFImageStart);
-            break;
-        }
-
-        case GIFImageStart: {
-            if (*currentComponent == '!') { // extension.
-                GETN(2, GIFExtension);
-                break;
-            }
-
-            if (*currentComponent == ',') { // image separator.
-                GETN(9, GIFImageHeader);
-                break;
-            }
-
-            // If we get anything other than ',' (image separator), '!'
-            // (extension), or ';' (trailer), there is extraneous data
-            // between blocks. The GIF87a spec tells us to keep reading
-            // until we find an image separator, but GIF89a says such
-            // a file is corrupt. We follow Mozilla's implementation and
-            // proceed as if the file were correctly terminated, so the
-            // GIF will display.
-            GETN(0, GIFDone);
-            break;
-        }
-
-        case GIFExtension: {
-            size_t bytesInBlock = currentComponent[1];
-            GIFState exceptionState = GIFSkipBlock;
-
-            switch (*currentComponent) {
-            case 0xf9:
-                exceptionState = GIFControlExtension;
-                // The GIF spec mandates that the GIFControlExtension header block length is 4 bytes,
-                // and the parser for this block reads 4 bytes, so we must enforce that the buffer
-                // contains at least this many bytes. If the GIF specifies a different length, we
-                // allow that, so long as it's larger; the additional data will simply be ignored.
-                bytesInBlock = std::max(bytesInBlock, static_cast<size_t>(4));
-                break;
-
-            // The GIF spec also specifies the lengths of the following two extensions' headers
-            // (as 12 and 11 bytes, respectively). Because we ignore the plain text extension entirely
-            // and sanity-check the actual length of the application extension header before reading it,
-            // we allow GIFs to deviate from these values in either direction. This is important for
-            // real-world compatibility, as GIFs in the wild exist with application extension headers
-            // that are both shorter and longer than 11 bytes.
-            case 0x01:
-                // ignoring plain text extension
-                break;
-
-            case 0xff:
-                exceptionState = GIFApplicationExtension;
-                break;
-
-            case 0xfe:
-                exceptionState = GIFConsumeComment;
-                break;
-            }
-
-            if (bytesInBlock)
-                GETN(bytesInBlock, exceptionState);
-            else
-                GETN(1, GIFImageStart);
-            break;
-        }
-
-        case GIFConsumeBlock: {
-            if (!*currentComponent)
-                GETN(1, GIFImageStart);
-            else
-                GETN(*currentComponent, GIFSkipBlock);
-            break;
-        }
-
-        case GIFSkipBlock: {
-            GETN(1, GIFConsumeBlock);
-            break;
-        }
-
-        case GIFControlExtension: {
-            addFrameIfNecessary();
-            GIFFrameContext* currentFrame = m_frames.last().get();
-            if (*currentComponent & 0x1)
-                currentFrame->setTransparentPixel(currentComponent[3]);
-
-            // We ignore the "user input" bit.
-
-            // NOTE: This relies on the values in the FrameDisposalMethod enum
-            // matching those in the GIF spec!
-            int disposalMethod = ((*currentComponent) >> 2) & 0x7;
-            if (disposalMethod < 4) {
-                currentFrame->setDisposalMethod(static_cast<WebCore::ImageFrame::DisposalMethod>(disposalMethod));
-            } else if (disposalMethod == 4) {
-                // Some specs say that disposal method 3 is "overwrite previous", others that setting
-                // the third bit of the field (i.e. method 4) is. We map both to the same value.
-                currentFrame->setDisposalMethod(WebCore::ImageFrame::DisposeOverwritePrevious);
-            }
-            currentFrame->setDelayTime(GETINT16(currentComponent + 1) * 10);
-            GETN(1, GIFConsumeBlock);
-            break;
-        }
-
-        case GIFCommentExtension: {
-            if (*currentComponent)
-                GETN(*currentComponent, GIFConsumeComment);
-            else
-                GETN(1, GIFImageStart);
-            break;
-        }
-
-        case GIFConsumeComment: {
-            GETN(1, GIFCommentExtension);
-            break;
-        }
-
-        case GIFApplicationExtension: {
-            // Check for netscape application extension.
-            if (m_bytesToConsume == 11
-                && (!strncmp((char*)currentComponent, "NETSCAPE2.0", 11) || !strncmp((char*)currentComponent, "ANIMEXTS1.0", 11)))
-                GETN(1, GIFNetscapeExtensionBlock);
-            else
-                GETN(1, GIFConsumeBlock);
-            break;
-        }
-
-        // Netscape-specific GIF extension: animation looping.
-        case GIFNetscapeExtensionBlock: {
-            // GIFConsumeNetscapeExtension always reads 3 bytes from the stream; we should at least wait for this amount.
-            if (*currentComponent)
-                GETN(std::max(3, static_cast<int>(*currentComponent)), GIFConsumeNetscapeExtension);
-            else
-                GETN(1, GIFImageStart);
-            break;
-        }
-
-        // Parse netscape-specific application extensions
-        case GIFConsumeNetscapeExtension: {
-            int netscapeExtension = currentComponent[0] & 7;
-
-            // Loop entire animation specified # of times. Only read the loop count during the first iteration.
-            if (netscapeExtension == 1) {
-                m_loopCount = GETINT16(currentComponent + 1);
-
-                // Zero loop count is infinite animation loop request.
-                if (!m_loopCount)
-                    m_loopCount = WebCore::cAnimationLoopInfinite;
-
-                GETN(1, GIFNetscapeExtensionBlock);
-            } else if (netscapeExtension == 2) {
-                // Wait for specified # of bytes to enter buffer.
-
-                // Don't do this, this extension doesn't exist (isn't used at all)
-                // and doesn't do anything, as our streaming/buffering takes care of it all...
-                // See: http://semmix.pl/color/exgraf/eeg24.htm
-                GETN(1, GIFNetscapeExtensionBlock);
-            } else {
-                // 0,3-7 are yet to be defined netscape extension codes
-                return false;
-            }
-            break;
-        }
-
-        case GIFImageHeader: {
-            unsigned height, width, xOffset, yOffset;
-
-            /* Get image offsets, with respect to the screen origin */
-            xOffset = GETINT16(currentComponent);
-            yOffset = GETINT16(currentComponent + 2);
-
-            /* Get image width and height. */
-            width  = GETINT16(currentComponent + 4);
-            height = GETINT16(currentComponent + 6);
-
-            /* Work around broken GIF files where the logical screen
-             * size has weird width or height.  We assume that GIF87a
-             * files don't contain animations.
-             */
-            if (currentFrameIsFirstFrame()
-                && ((m_screenHeight < height) || (m_screenWidth < width) || (m_version == 87))) {
-                m_screenHeight = height;
-                m_screenWidth = width;
-                xOffset = 0;
-                yOffset = 0;
-
-                // CALLBACK: Inform the decoderplugin of our size.
-                if (m_client && !m_client->setSize(m_screenWidth, m_screenHeight))
-                    return false;
-            }
-
-            // Work around more broken GIF files that have zero image width or height
-            if (!height || !width) {
-                height = m_screenHeight;
-                width = m_screenWidth;
-                if (!height || !width)
-                    return false;
-            }
-
-            if (query == GIFImageDecoder::GIFSizeQuery) {
-                // The decoder needs to stop. Hand back the number of bytes we consumed from
-                // buffer minus 9 (the amount we consumed to read the header).
-                setRemainingBytes(len + 9);
-                GETN(9, GIFImageHeader);
-                return true;
-            }
-
-            addFrameIfNecessary();
-            GIFFrameContext* currentFrame = m_frames.last().get();
-
-            currentFrame->setHeaderDefined();
-            currentFrame->setRect(xOffset, yOffset, width, height);
-            m_screenWidth = std::max(m_screenWidth, width);
-            m_screenHeight = std::max(m_screenHeight, height);
-            currentFrame->setInterlaced(currentComponent[8] & 0x40);
-
-            // Overlaying interlaced, transparent GIFs over
-            // existing image data using the Haeberli display hack
-            // requires saving the underlying image in order to
-            // avoid jaggies at the transparency edges. We are
-            // unprepared to deal with that, so don't display such
-            // images progressively. Which means only the first
-            // frame can be progressively displayed.
-            // FIXME: It is possible that a non-transparent frame
-            // can be interlaced and progressively displayed.
-            currentFrame->setProgressiveDisplay(currentFrameIsFirstFrame());
-
-            const bool isLocalColormapDefined = currentComponent[8] & 0x80;
-            if (isLocalColormapDefined) {
-                // The three low-order bits of currentComponent[8] specify the bits per pixel.
-                const size_t numColors = 2 << (currentComponent[8] & 0x7);
-                currentFrame->localColorMap().setTablePositionAndSize(dataPosition, numColors);
-                GETN(BYTES_PER_COLORMAP_ENTRY * numColors, GIFImageColormap);
-                break;
-            }
-
-            GETN(1, GIFLZWStart);
-            break;
-        }
-
-        case GIFImageColormap: {
-            ASSERT(!m_frames.isEmpty());
-            m_frames.last()->localColorMap().setDefined();
-            GETN(1, GIFLZWStart);
-            break;
-        }
-
-        case GIFSubBlock: {
-            const size_t bytesInBlock = *currentComponent;
-            if (bytesInBlock)
-                GETN(bytesInBlock, GIFLZW);
-            else {
-                // Finished parsing one frame; Process next frame.
-                ASSERT(!m_frames.isEmpty());
-                // Note that some broken GIF files do not have enough LZW blocks to fully
-                // decode all rows but we treat it as frame complete.
-                m_frames.last()->setComplete();
-                GETN(1, GIFImageStart);
-            }
-            break;
-        }
-
-        case GIFDone: {
-            m_parseCompleted = true;
-            return true;
-        }
-
-        default:
-            // We shouldn't ever get here.
-            return false;
-            break;
-        }
-    }
-
-    setRemainingBytes(len);
-    return true;
-}
-
-void GIFImageReader::setRemainingBytes(size_t remainingBytes)
-{
-    ASSERT(remainingBytes <= m_data->size());
-    m_bytesRead = m_data->size() - remainingBytes;
-}
-
-void GIFImageReader::addFrameIfNecessary()
-{
-    if (m_frames.isEmpty() || m_frames.last()->isComplete())
-        m_frames.append(adoptPtr(new GIFFrameContext(m_frames.size())));
-}
-
-// FIXME: Move this method to close to doLZW().
-bool GIFLZWContext::prepareToDecode()
-{
-    ASSERT(m_frameContext->isDataSizeDefined() && m_frameContext->isHeaderDefined());
-
-    // Since we use a codesize of 1 more than the datasize, we need to ensure
-    // that our datasize is strictly less than the MAX_DICTIONARY_ENTRY_BITS.
-    if (m_frameContext->dataSize() >= MAX_DICTIONARY_ENTRY_BITS)
-        return false;
-    clearCode = 1 << m_frameContext->dataSize();
-    avail = clearCode + 2;
-    oldcode = -1;
-    codesize = m_frameContext->dataSize() + 1;
-    codemask = (1 << codesize) - 1;
-    datum = bits = 0;
-    ipass = m_frameContext->interlaced() ? 1 : 0;
-    irow = 0;
-
-    // We want to know the longest sequence encodable by a dictionary with
-    // MAX_DICTIONARY_ENTRIES entries. If we ignore the need to encode the base
-    // values themselves at the beginning of the dictionary, as well as the need
-    // for a clear code or a termination code, we could use every entry to
-    // encode a series of multiple values. If the input value stream looked
-    // like "AAAAA..." (a long string of just one value), the first dictionary
-    // entry would encode AA, the next AAA, the next AAAA, and so forth. Thus
-    // the longest sequence would be MAX_DICTIONARY_ENTRIES + 1 values.
-    //
-    // However, we have to account for reserved entries. The first |datasize|
-    // bits are reserved for the base values, and the next two entries are
-    // reserved for the clear code and termination code. In theory a GIF can
-    // set the datasize to 0, meaning we have just two reserved entries, making
-    // the longest sequence (MAX_DICTIONARY_ENTIRES + 1) - 2 values long. Since
-    // each value is a byte, this is also the number of bytes in the longest
-    // encodable sequence.
-    const size_t maxBytes = MAX_DICTIONARY_ENTRIES - 1;
-
-    // Now allocate the output buffer. We decode directly into this buffer
-    // until we have at least one row worth of data, then call outputRow().
-    // This means worst case we may have (row width - 1) bytes in the buffer
-    // and then decode a sequence |maxBytes| long to append.
-    rowBuffer.resize(m_frameContext->width() - 1 + maxBytes);
-    rowIter = rowBuffer.begin();
-    rowsRemaining = m_frameContext->height();
-
-    // Clearing the whole suffix table lets us be more tolerant of bad data.
-    for (int i = 0; i < clearCode; ++i) {
-        suffix[i] = i;
-        suffixLength[i] = 1;
-    }
-    return true;
-}