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gif_lib.h - service library for decoding and encoding GIF images
#ifndef _GIF_LIB_H_
#define _GIF_LIB_H_ 1
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#define GIFLIB_MAJOR 5
#define GIFLIB_MINOR 1
#define GIF_ERROR 0
#define GIF_OK 1
#include <stddef.h>
#include <stdbool.h>
#define GIF_STAMP "GIFVER" /* First chars in file - GIF stamp. */
#define GIF_STAMP_LEN sizeof(GIF_STAMP) - 1
#define GIF_VERSION_POS 3 /* Version first character in stamp. */
#define GIF87_STAMP "GIF87a" /* First chars in file - GIF stamp. */
#define GIF89_STAMP "GIF89a" /* First chars in file - GIF stamp. */
typedef unsigned char GifPixelType;
typedef unsigned char *GifRowType;
typedef unsigned char GifByteType;
typedef unsigned int GifPrefixType;
typedef int GifWord;
typedef struct GifColorType {
GifByteType Red, Green, Blue;
} GifColorType;
typedef struct ColorMapObject {
int ColorCount;
int BitsPerPixel;
bool SortFlag;
GifColorType *Colors; /* on malloc(3) heap */
} ColorMapObject;
typedef struct GifImageDesc {
GifWord Left, Top, Width, Height; /* Current image dimensions. */
bool Interlace; /* Sequential/Interlaced lines. */
ColorMapObject *ColorMap; /* The local color map */
} GifImageDesc;
typedef struct ExtensionBlock {
int ByteCount;
GifByteType *Bytes; /* on malloc(3) heap */
int Function; /* The block function code */
#define CONTINUE_EXT_FUNC_CODE 0x00 /* continuation subblock */
#define COMMENT_EXT_FUNC_CODE 0xfe /* comment */
#define GRAPHICS_EXT_FUNC_CODE 0xf9 /* graphics control (GIF89) */
#define PLAINTEXT_EXT_FUNC_CODE 0x01 /* plaintext */
#define APPLICATION_EXT_FUNC_CODE 0xff /* application block */
} ExtensionBlock;
typedef struct SavedImage {
GifImageDesc ImageDesc;
GifByteType *RasterBits; /* on malloc(3) heap */
int ExtensionBlockCount; /* Count of extensions before image */
ExtensionBlock *ExtensionBlocks; /* Extensions before image */
} SavedImage;
typedef struct GifFileType {
GifWord SWidth, SHeight; /* Size of virtual canvas */
GifWord SColorResolution; /* How many colors can we generate? */
GifWord SBackGroundColor; /* Background color for virtual canvas */
GifByteType AspectByte; /* Used to compute pixel aspect ratio */
ColorMapObject *SColorMap; /* Global colormap, NULL if nonexistent. */
int ImageCount; /* Number of current image (both APIs) */
GifImageDesc Image; /* Current image (low-level API) */
SavedImage *SavedImages; /* Image sequence (high-level API) */
int ExtensionBlockCount; /* Count extensions past last image */
ExtensionBlock *ExtensionBlocks; /* Extensions past last image */
int Error; /* Last error condition reported */
void *UserData; /* hook to attach user data (TVT) */
void *Private; /* Don't mess with this! */
} GifFileType;
#define GIF_ASPECT_RATIO(n) ((n)+15.0/64.0)
typedef enum {
IMAGE_DESC_RECORD_TYPE, /* Begin with ',' */
EXTENSION_RECORD_TYPE, /* Begin with '!' */
TERMINATE_RECORD_TYPE /* Begin with ';' */
} GifRecordType;
/* func type to read gif data from arbitrary sources (TVT) */
typedef int (*InputFunc) (GifFileType *, GifByteType *, int);
/* func type to write gif data to arbitrary targets.
* Returns count of bytes written. (MRB)
typedef int (*OutputFunc) (GifFileType *, const GifByteType *, int);
GIF89 structures
typedef struct GraphicsControlBlock {
int DisposalMode;
#define DISPOSAL_UNSPECIFIED 0 /* No disposal specified. */
#define DISPOSE_DO_NOT 1 /* Leave image in place */
#define DISPOSE_BACKGROUND 2 /* Set area too background color */
#define DISPOSE_PREVIOUS 3 /* Restore to previous content */
bool UserInputFlag; /* User confirmation required before disposal */
int DelayTime; /* pre-display delay in 0.01sec units */
int TransparentColor; /* Palette index for transparency, -1 if none */
} GraphicsControlBlock;
GIF encoding routines
/* Main entry points */
GifFileType *EGifOpenFileName(const char *GifFileName,
const bool GifTestExistence, int *Error);
GifFileType *EGifOpenFileHandle(const int GifFileHandle, int *Error);
GifFileType *EGifOpen(void *userPtr, OutputFunc writeFunc, int *Error);
int EGifSpew(GifFileType * GifFile);
const char *EGifGetGifVersion(GifFileType *GifFile); /* new in 5.x */
int EGifCloseFile(GifFileType *GifFile, int *ErrorCode);
#define E_GIF_ERR_OPEN_FAILED 1 /* And EGif possible errors. */
/* These are legacy. You probably do not want to call them directly */
int EGifPutScreenDesc(GifFileType *GifFile,
const int GifWidth, const int GifHeight,
const int GifColorRes,
const int GifBackGround,
const ColorMapObject *GifColorMap);
int EGifPutImageDesc(GifFileType *GifFile,
const int GifLeft, const int GifTop,
const int GifWidth, const int GifHeight,
const bool GifInterlace,
const ColorMapObject *GifColorMap);
void EGifSetGifVersion(GifFileType *GifFile, const bool gif89);
int EGifPutLine(GifFileType *GifFile, GifPixelType *GifLine,
int GifLineLen);
int EGifPutPixel(GifFileType *GifFile, const GifPixelType GifPixel);
int EGifPutComment(GifFileType *GifFile, const char *GifComment);
int EGifPutExtensionLeader(GifFileType *GifFile, const int GifExtCode);
int EGifPutExtensionBlock(GifFileType *GifFile,
const int GifExtLen, const void *GifExtension);
int EGifPutExtensionTrailer(GifFileType *GifFile);
int EGifPutExtension(GifFileType *GifFile, const int GifExtCode,
const int GifExtLen,
const void *GifExtension);
int EGifPutCode(GifFileType *GifFile, int GifCodeSize,
const GifByteType *GifCodeBlock);
int EGifPutCodeNext(GifFileType *GifFile,
const GifByteType *GifCodeBlock);
GIF decoding routines
/* Main entry points */
GifFileType *DGifOpenFileName(const char *GifFileName, int *Error);
GifFileType *DGifOpenFileHandle(int GifFileHandle, int *Error);
int DGifSlurp(GifFileType * GifFile);
GifFileType *DGifOpen(void *userPtr, InputFunc readFunc, int *Error); /* new one (TVT) */
int DGifCloseFile(GifFileType * GifFile, int *ErrorCode);
#define D_GIF_ERR_OPEN_FAILED 101 /* And DGif possible errors. */
#define D_GIF_ERR_NOT_GIF_FILE 103
#define D_GIF_ERR_NO_SCRN_DSCR 104
#define D_GIF_ERR_NO_IMAG_DSCR 105
#define D_GIF_ERR_NO_COLOR_MAP 106
#define D_GIF_ERR_DATA_TOO_BIG 108
#define D_GIF_ERR_EOF_TOO_SOON 113
/* These are legacy. You probably do not want to call them directly */
int DGifGetScreenDesc(GifFileType *GifFile);
int DGifGetRecordType(GifFileType *GifFile, GifRecordType *GifType);
int DGifGetImageDesc(GifFileType *GifFile);
int DGifGetLine(GifFileType *GifFile, GifPixelType *GifLine, int GifLineLen);
int DGifGetPixel(GifFileType *GifFile, GifPixelType GifPixel);
int DGifGetComment(GifFileType *GifFile, char *GifComment);
int DGifGetExtension(GifFileType *GifFile, int *GifExtCode,
GifByteType **GifExtension);
int DGifGetExtensionNext(GifFileType *GifFile, GifByteType **GifExtension);
int DGifGetCode(GifFileType *GifFile, int *GifCodeSize,
GifByteType **GifCodeBlock);
int DGifGetCodeNext(GifFileType *GifFile, GifByteType **GifCodeBlock);
int DGifGetLZCodes(GifFileType *GifFile, int *GifCode);
Color table quantization (deprecated)
int GifQuantizeBuffer(unsigned int Width, unsigned int Height,
int *ColorMapSize, GifByteType * RedInput,
GifByteType * GreenInput, GifByteType * BlueInput,
GifByteType * OutputBuffer,
GifColorType * OutputColorMap);
Error handling and reporting.
extern const char *GifErrorString(int ErrorCode); /* new in 2012 - ESR */
Everything below this point is new after version 1.2, supporting `slurp
mode' for doing I/O in two big belts with all the image-bashing in core.
Color map handling from gif_alloc.c
extern ColorMapObject *GifMakeMapObject(int ColorCount,
const GifColorType *ColorMap);
extern void GifFreeMapObject(ColorMapObject *Object);
extern ColorMapObject *GifUnionColorMap(const ColorMapObject *ColorIn1,
const ColorMapObject *ColorIn2,
GifPixelType ColorTransIn2[]);
extern int GifBitSize(int n);
Support for the in-core structures allocation (slurp mode).
extern void GifApplyTranslation(SavedImage *Image, GifPixelType Translation[]);
extern int GifAddExtensionBlock(int *ExtensionBlock_Count,
ExtensionBlock **ExtensionBlocks,
int Function,
unsigned int Len, unsigned char ExtData[]);
extern void GifFreeExtensions(int *ExtensionBlock_Count,
ExtensionBlock **ExtensionBlocks);
extern SavedImage *GifMakeSavedImage(GifFileType *GifFile,
const SavedImage *CopyFrom);
extern void GifFreeSavedImages(GifFileType *GifFile);
5.x functions for GIF89 graphics control blocks
int DGifExtensionToGCB(const size_t GifExtensionLength,
const GifByteType *GifExtension,
GraphicsControlBlock *GCB);
size_t EGifGCBToExtension(const GraphicsControlBlock *GCB,
GifByteType *GifExtension);
int DGifSavedExtensionToGCB(GifFileType *GifFile,
int ImageIndex,
GraphicsControlBlock *GCB);
int EGifGCBToSavedExtension(const GraphicsControlBlock *GCB,
GifFileType *GifFile,
int ImageIndex);
The library's internal utility font
#define GIF_FONT_WIDTH 8
extern const unsigned char GifAsciiTable8x8[][GIF_FONT_WIDTH];
extern void GifDrawText8x8(SavedImage *Image,
const int x, const int y,
const char *legend, const int color);
extern void GifDrawBox(SavedImage *Image,
const int x, const int y,
const int w, const int d, const int color);
extern void GifDrawRectangle(SavedImage *Image,
const int x, const int y,
const int w, const int d, const int color);
extern void GifDrawBoxedText8x8(SavedImage *Image,
const int x, const int y,
const char *legend,
const int border, const int bg, const int fg);
#ifdef __cplusplus
#endif /* __cplusplus */
#endif /* _GIF_LIB_H */
/* end */