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src/Source/FreeImage/PluginGIF.cpp  view on Meta::CPAN

// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================

#ifdef _MSC_VER 
#pragma warning (disable : 4786) // identifier was truncated to 'number' characters
#endif

#include "FreeImage.h"
#include "Utilities.h"
#include "../Metadata/FreeImageTag.h"

// ==========================================================
//   Metadata declarations
// ==========================================================

#define GIF_DISPOSAL_UNSPECIFIED	0
#define GIF_DISPOSAL_LEAVE			1
#define GIF_DISPOSAL_BACKGROUND		2
#define GIF_DISPOSAL_PREVIOUS		3

// ==========================================================
//   Constant/Typedef declarations
// ==========================================================


struct GIFinfo {
	BOOL read;
	//only really used when reading
	size_t global_color_table_offset;
	int global_color_table_size;
	BYTE background_color;
	std::vector<size_t> application_extension_offsets;
	std::vector<size_t> comment_extension_offsets;
	std::vector<size_t> graphic_control_extension_offsets;
	std::vector<size_t> image_descriptor_offsets;

	GIFinfo() : read(0), global_color_table_offset(0), global_color_table_size(0), background_color(0)
	{
	}
};

struct PageInfo {
	PageInfo(int d, int l, int t, int w, int h) { 
		disposal_method = d; left = (WORD)l; top = (WORD)t; width = (WORD)w; height = (WORD)h; 
	}
	int disposal_method;
	WORD left, top, width, height;
};

//GIF defines a max of 12 bits per code
#define MAX_LZW_CODE			4096

class StringTable
{
public:
	StringTable();
	~StringTable();
	void Initialize(int minCodeSize);
	BYTE *FillInputBuffer(int len);
	void CompressStart(int bpp, int width);
	int CompressEnd(BYTE *buf); //0-4 bytes
	bool Compress(BYTE *buf, int *len);
	bool Decompress(BYTE *buf, int *len);
	void Done(void);

protected:
	bool m_done;

	int m_minCodeSize, m_clearCode, m_endCode, m_nextCode;

	int m_bpp, m_slack; //Compressor information

	int m_prefix; //Compressor state variable
	int m_codeSize, m_codeMask; //Compressor/Decompressor state variables
	int m_oldCode; //Decompressor state variable
	int m_partial, m_partialSize; //Compressor/Decompressor bit buffer

	int firstPixelPassed; // A specific flag that indicates if the first pixel
	                      // of the whole image had already been read

	std::string m_strings[MAX_LZW_CODE]; //This is what is really the "string table" data for the Decompressor
	int* m_strmap;

	//input buffer
	BYTE *m_buffer;
	int m_bufferSize, m_bufferRealSize, m_bufferPos, m_bufferShift;

	void ClearCompressorTable(void);
	void ClearDecompressorTable(void);
};

#define GIF_PACKED_LSD_HAVEGCT		0x80
#define GIF_PACKED_LSD_COLORRES		0x70
#define GIF_PACKED_LSD_GCTSORTED	0x08
#define GIF_PACKED_LSD_GCTSIZE		0x07
#define GIF_PACKED_ID_HAVELCT		0x80
#define GIF_PACKED_ID_INTERLACED	0x40
#define GIF_PACKED_ID_LCTSORTED		0x20
#define GIF_PACKED_ID_RESERVED		0x18
#define GIF_PACKED_ID_LCTSIZE		0x07
#define GIF_PACKED_GCE_RESERVED		0xE0
#define GIF_PACKED_GCE_DISPOSAL		0x1C
#define GIF_PACKED_GCE_WAITINPUT	0x02
#define GIF_PACKED_GCE_HAVETRANS	0x01

#define GIF_BLOCK_IMAGE_DESCRIPTOR	0x2C
#define GIF_BLOCK_EXTENSION			0x21
#define GIF_BLOCK_TRAILER			0x3B

#define GIF_EXT_PLAINTEXT			0x01
#define GIF_EXT_GRAPHIC_CONTROL		0xF9
#define GIF_EXT_COMMENT				0xFE
#define GIF_EXT_APPLICATION			0xFF

#define GIF_INTERLACE_PASSES		4