Source/WebCore/platform/image-decoders/gif/GIFImageReader.h - WebKit - Git at Google

 /* -*- 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
  * 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 ***** */

 #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::DataSegment& 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::DataSegment> m_data;
     bool m_parseCompleted;
 };
	/* -- 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
	* 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 *** */

	#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::DataSegment& 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::DataSegment> m_data;
	bool m_parseCompleted;
	};