| /* -*- Mode: C; tab-width: 4; 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 Communicator client 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): |
| * |
| * 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 |
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| * 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 ***** */ |
| |
| #pragma once |
| |
| // Define ourselves as the clientPtr. Mozilla just hacked their C++ callback class into this old C decoder, |
| // so we will too. |
| #include "GIFImageDecoder.h" |
| #include "SharedBuffer.h" |
| #include <wtf/Vector.h> |
| |
| #define MAX_LZW_BITS 12 |
| #define MAX_BYTES 4097 /* 2^MAX_LZW_BITS+1 */ |
| #define MAX_COLORS 256 |
| #define GIF_COLORS 3 |
| |
| const int cLoopCountNotSeen = -2; |
| |
| // List of possible parsing states. |
| enum GIFState { |
| GIFType, |
| GIFGlobalHeader, |
| GIFGlobalColormap, |
| GIFImageStart, |
| GIFImageHeader, |
| GIFImageColormap, |
| GIFImageBody, |
| GIFLZWStart, |
| GIFLZW, |
| GIFSubBlock, |
| GIFExtension, |
| GIFControlExtension, |
| GIFConsumeBlock, |
| GIFSkipBlock, |
| GIFDone, |
| GIFCommentExtension, |
| GIFApplicationExtension, |
| GIFNetscapeExtensionBlock, |
| GIFConsumeNetscapeExtension, |
| GIFConsumeComment |
| }; |
| |
| struct GIFFrameContext; |
| |
| // LZW decoder state machine. |
| class GIFLZWContext { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| GIFLZWContext(WebCore::GIFImageDecoder* client, const GIFFrameContext* frameContext) |
| : stackp(0) |
| , codesize(0) |
| , codemask(0) |
| , clearCode(0) |
| , avail(0) |
| , oldcode(0) |
| , firstchar(0) |
| , bits(0) |
| , datum(0) |
| , ipass(0) |
| , irow(0) |
| , rowPosition(0) |
| , rowsRemaining(0) |
| , m_client(client) |
| , m_frameContext(frameContext) |
| { } |
| |
| bool prepareToDecode(); |
| bool outputRow(); |
| bool doLZW(const unsigned char* block, size_t bytesInBlock); |
| bool hasRemainingRows() { return rowsRemaining; } |
| |
| private: |
| // LZW decoding states and output states. |
| size_t stackp; // Current stack pointer. |
| int codesize; |
| int codemask; |
| int clearCode; // Codeword used to trigger dictionary reset. |
| int avail; // Index of next available slot in dictionary. |
| int oldcode; |
| unsigned char firstchar; |
| int bits; // Number of unread bits in "datum". |
| int datum; // 32-bit input buffer. |
| int ipass; // Interlace pass; Ranges 1-4 if interlaced. |
| size_t irow; // Current output row, starting at zero. |
| size_t rowPosition; |
| size_t rowsRemaining; // Rows remaining to be output. |
| |
| Vector<unsigned short> prefix; |
| Vector<unsigned char> suffix; |
| Vector<unsigned char> stack; |
| Vector<unsigned char> rowBuffer; // Single scanline temporary buffer. |
| |
| // Initialized during construction and read-only. |
| WebCore::GIFImageDecoder* m_client; |
| const GIFFrameContext* m_frameContext; |
| }; |
| |
| // Data structure for one LZW block. |
| struct GIFLZWBlock { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| GIFLZWBlock(size_t position, size_t size) |
| : blockPosition(position) |
| , blockSize(size) |
| { |
| } |
| |
| size_t blockPosition; |
| size_t blockSize; |
| }; |
| |
| // Frame output state machine. |
| struct GIFFrameContext { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| // FIXME: Move these members to private section. |
| int frameId; |
| unsigned xOffset; |
| unsigned yOffset; // With respect to "screen" origin. |
| unsigned width; |
| unsigned height; |
| int tpixel; // Index of transparent pixel. |
| WebCore::ScalableImageDecoderFrame::DisposalMethod disposalMethod; // Restore to background, leave in place, etc. |
| size_t localColormapPosition; // Per-image colormap. |
| int localColormapSize; // Size of local colormap array. |
| int datasize; |
| |
| bool isLocalColormapDefined : 1; |
| bool progressiveDisplay : 1; // If true, do Haeberli interlace hack. |
| bool interlaced : 1; // True, if scanlines arrive interlaced order. |
| bool isTransparent : 1; // TRUE, if tpixel is valid. |
| |
| unsigned delayTime; // Display time, in milliseconds, for this image in a multi-image GIF. |
| |
| GIFFrameContext(int id) |
| : frameId(id) |
| , xOffset(0) |
| , yOffset(0) |
| , width(0) |
| , height(0) |
| , tpixel(0) |
| , disposalMethod(WebCore::ScalableImageDecoderFrame::DisposalMethod::Unspecified) |
| , localColormapPosition(0) |
| , localColormapSize(0) |
| , datasize(0) |
| , isLocalColormapDefined(false) |
| , progressiveDisplay(false) |
| , interlaced(false) |
| , isTransparent(false) |
| , delayTime(0) |
| , m_currentLzwBlock(0) |
| , m_isComplete(false) |
| , m_isHeaderDefined(false) |
| , m_isDataSizeDefined(false) |
| { |
| } |
| |
| void addLzwBlock(size_t position, size_t size) |
| { |
| m_lzwBlocks.append(GIFLZWBlock(position, size)); |
| } |
| |
| bool decode(const unsigned char* data, size_t length, WebCore::GIFImageDecoder* client, bool* frameDecoded); |
| |
| bool isComplete() const { return m_isComplete; } |
| void setComplete() { m_isComplete = true; } |
| bool isHeaderDefined() const { return m_isHeaderDefined; } |
| void setHeaderDefined() { m_isHeaderDefined = true; } |
| bool isDataSizeDefined() const { return m_isDataSizeDefined; } |
| void setDataSize(int size) |
| { |
| datasize = size; |
| m_isDataSizeDefined = true; |
| } |
| |
| private: |
| std::unique_ptr<GIFLZWContext> m_lzwContext; |
| Vector<GIFLZWBlock> m_lzwBlocks; // LZW blocks for this frame. |
| size_t m_currentLzwBlock; |
| bool m_isComplete; |
| bool m_isHeaderDefined; |
| bool m_isDataSizeDefined; |
| }; |
| |
| class GIFImageReader { |
| WTF_MAKE_FAST_ALLOCATED; |
| public: |
| GIFImageReader(WebCore::GIFImageDecoder* client = 0) |
| : m_client(client) |
| , m_state(GIFType) |
| , m_bytesToConsume(6) // Number of bytes for GIF type, either "GIF87a" or "GIF89a". |
| , m_bytesRead(0) |
| , m_screenBgcolor(0) |
| , m_version(0) |
| , m_screenWidth(0) |
| , m_screenHeight(0) |
| , m_isGlobalColormapDefined(false) |
| , m_globalColormapPosition(0) |
| , m_globalColormapSize(0) |
| , m_loopCount(cLoopCountNotSeen) |
| , m_currentDecodingFrame(0) |
| , m_parseCompleted(false) |
| { |
| } |
| |
| void setData(WebCore::SharedBuffer* data) { m_data = data; } |
| // FIXME: haltAtFrame should be size_t. |
| bool decode(WebCore::GIFImageDecoder::GIFQuery, unsigned haltAtFrame); |
| |
| size_t imagesCount() const |
| { |
| if (m_frames.isEmpty()) |
| return 0; |
| |
| // This avoids counting an empty frame when the file is truncated right after |
| // GIFControlExtension but before GIFImageHeader. |
| // FIXME: This extra complexity is not necessary and we should just report m_frames.size(). |
| return m_frames.last()->isHeaderDefined() ? m_frames.size() : m_frames.size() - 1; |
| } |
| int loopCount() const { return m_loopCount; } |
| |
| const unsigned char* globalColormap() const |
| { |
| return m_isGlobalColormapDefined ? data(m_globalColormapPosition) : 0; |
| } |
| int globalColormapSize() const |
| { |
| return m_isGlobalColormapDefined ? m_globalColormapSize : 0; |
| } |
| |
| const unsigned char* localColormap(const GIFFrameContext* frame) const |
| { |
| return frame->isLocalColormapDefined ? data(frame->localColormapPosition) : 0; |
| } |
| int localColormapSize(const GIFFrameContext* frame) const |
| { |
| return frame->isLocalColormapDefined ? frame->localColormapSize : 0; |
| } |
| |
| const GIFFrameContext* frameContext() const |
| { |
| return m_currentDecodingFrame < m_frames.size() ? m_frames[m_currentDecodingFrame].get() : 0; |
| } |
| |
| const GIFFrameContext* frameContext(size_t frame) const |
| { |
| return frame < m_frames.size() ? m_frames[frame].get() : nullptr; |
| } |
| |
| private: |
| bool parse(size_t dataPosition, size_t len, bool parseSizeOnly); |
| void setRemainingBytes(size_t); |
| |
| const unsigned char* data(size_t dataPosition) const |
| { |
| return reinterpret_cast<const unsigned char*>(m_data->data()) + dataPosition; |
| } |
| |
| void addFrameIfNecessary(); |
| bool currentFrameIsFirstFrame() const |
| { |
| return m_frames.isEmpty() || (m_frames.size() == 1u && !m_frames[0]->isComplete()); |
| } |
| |
| WebCore::GIFImageDecoder* m_client; |
| |
| // Parsing state machine. |
| GIFState m_state; // Current decoder master state. |
| size_t m_bytesToConsume; // Number of bytes to consume for next stage of parsing. |
| size_t m_bytesRead; // Number of bytes processed. |
| |
| // Global (multi-image) state. |
| int m_screenBgcolor; // Logical screen background color. |
| int m_version; // Either 89 for GIF89 or 87 for GIF87. |
| unsigned m_screenWidth; // Logical screen width & height. |
| unsigned m_screenHeight; |
| bool m_isGlobalColormapDefined; |
| size_t m_globalColormapPosition; // (3* MAX_COLORS in size) Default colormap if local not supplied, 3 bytes for each color. |
| int m_globalColormapSize; // Size of global colormap array. |
| int m_loopCount; // Netscape specific extension block to control the number of animation loops a GIF renders. |
| |
| Vector<std::unique_ptr<GIFFrameContext> > m_frames; |
| size_t m_currentDecodingFrame; |
| |
| RefPtr<WebCore::SharedBuffer> m_data; |
| bool m_parseCompleted; |
| }; |