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dgif_lib.c File Reference
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include "gif_lib.h"
#include "gif_hash.h"

Go to the source code of this file.

Classes

struct  GifFilePrivateType

Defines

#define PROGRAM_NAME   "GIFLIB"
#define COMMENT_EXT_FUNC_CODE   0xfe /* Extension function code for comment. */
#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 LZ_MAX_CODE   4095 /* Biggest code possible in 12 bits. */
#define LZ_BITS   12
#define FILE_STATE_READ   0x01/* 1 write, 0 read - EGIF_LIB compatible.*/
#define FLUSH_OUTPUT   4096 /* Impossible code, to signal flush. */
#define FIRST_CODE   4097 /* Impossible code, to signal first. */
#define NO_SUCH_CODE   4098 /* Impossible code, to signal empty. */
#define IS_READABLE(Private)   (!(Private->FileState & FILE_STATE_READ))

Typedefs

typedef struct GifFilePrivateType GifFilePrivateType

Functions

static int DGifGetWord (FILE *File, int *Word)
static int DGifSetupDecompress (GifFileType *GifFile)
static int DGifDecompressLine (GifFileType *GifFile, GifPixelType *Line, int LineLen)
static int DGifGetPrefixChar (unsigned int *Prefix, int Code, int ClearCode)
static int DGifDecompressInput (GifFilePrivateType *Private, int *Code)
static int DGifBufferedInput (FILE *File, GifByteType *Buf, GifByteType *NextByte)
GifFileTypeDGifOpenFileName (const char *FileName)
GifFileTypeDGifOpenFileHandle (int FileHandle)
int DGifGetScreenDesc (GifFileType *GifFile)
int DGifGetRecordType (GifFileType *GifFile, GifRecordType *Type)
int DGifGetImageDesc (GifFileType *GifFile)
int DGifGetLine (GifFileType *GifFile, GifPixelType *Line, int LineLen)
int DGifGetPixel (GifFileType *GifFile, GifPixelType Pixel)
int DGifGetExtension (GifFileType *GifFile, int *ExtCode, GifByteType **Extension)
int DGifGetExtensionNext (GifFileType *GifFile, GifByteType **Extension)
int DGifCloseFile (GifFileType *GifFile)
int DGifGetCode (GifFileType *GifFile, int *CodeSize, GifByteType **CodeBlock)
int DGifGetCodeNext (GifFileType *GifFile, GifByteType **CodeBlock)
int DGifGetLZCodes (GifFileType *GifFile, int *Code)
int DGifSlurp (GifFileType *GifFile)

Variables

static char * VersionStr = "(C) Copyright 1989 Gershon Elber, Non commercial use only.\n"
int _GifError

Class Documentation

struct GifFilePrivateType

Definition at line 48 of file dgif_lib.c.

Class Members
int BitsPerPixel
GifByteType Buf
int ClearCode
int CrntCode
unsigned long CrntShiftDWord
int CrntShiftState
int EOFCode
FILE * File
int FileHandle
int FileState
int LastCode
int MaxCode1
unsigned long PixelCount
unsigned int Prefix
int RunningBits
int RunningCode
GifByteType Stack
int StackPtr
GifByteType Suffix

Define Documentation

#define COMMENT_EXT_FUNC_CODE   0xfe /* Extension function code for comment. */

Definition at line 32 of file dgif_lib.c.

#define FILE_STATE_READ   0x01/* 1 write, 0 read - EGIF_LIB compatible.*/

Definition at line 40 of file dgif_lib.c.

#define FIRST_CODE   4097 /* Impossible code, to signal first. */

Definition at line 43 of file dgif_lib.c.

#define FLUSH_OUTPUT   4096 /* Impossible code, to signal flush. */

Definition at line 42 of file dgif_lib.c.

#define GIF_STAMP   "GIFVER" /* First chars in file - GIF stamp. */

Definition at line 33 of file dgif_lib.c.

#define GIF_STAMP_LEN   sizeof(GIF_STAMP) - 1

Definition at line 34 of file dgif_lib.c.

#define GIF_VERSION_POS   3 /* Version first character in stamp. */

Definition at line 35 of file dgif_lib.c.

#define IS_READABLE (   Private)    (!(Private->FileState & FILE_STATE_READ))

Definition at line 46 of file dgif_lib.c.

#define LZ_BITS   12

Definition at line 38 of file dgif_lib.c.

#define LZ_MAX_CODE   4095 /* Biggest code possible in 12 bits. */

Definition at line 37 of file dgif_lib.c.

#define NO_SUCH_CODE   4098 /* Impossible code, to signal empty. */

Definition at line 44 of file dgif_lib.c.

#define PROGRAM_NAME   "GIFLIB"

Definition at line 30 of file dgif_lib.c.


Typedef Documentation


Function Documentation

static int DGifBufferedInput ( FILE *  File,
GifByteType Buf,
GifByteType NextByte 
) [static]

Definition at line 840 of file dgif_lib.c.

{
    if (Buf[0] == 0) {
       /* Needs to read the next buffer - this one is empty: */
       if (fread(Buf, 1, 1, File) != 1)
       {
           _GifError = D_GIF_ERR_READ_FAILED;
           return GIF_ERROR;
       }
       if (fread(&Buf[1], 1, Buf[0], File) != Buf[0])
       {
           _GifError = D_GIF_ERR_READ_FAILED;
           return GIF_ERROR;
       }
       *NextByte = Buf[1];
       Buf[1] = 2;      /* We use now the second place as last char read! */
       Buf[0]--;
    }
    else {
       *NextByte = Buf[Buf[1]++];
       Buf[0]--;
    }

    return GIF_OK;
}

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int DGifCloseFile ( GifFileType GifFile)

Definition at line 478 of file dgif_lib.c.

{
    GifFilePrivateType *Private;
    FILE *File;

    if (GifFile == NULL) return GIF_ERROR;

    Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    File = Private->File;

    if (GifFile->Image.ColorMap)
       FreeMapObject(GifFile->Image.ColorMap);
    if (GifFile->SColorMap)
       FreeMapObject(GifFile->SColorMap);
    if (Private)
       free((char *) Private);
    if (GifFile->SavedImages)
       FreeSavedImages(GifFile);
    free(GifFile);

    if (fclose(File) != 0) {
       _GifError = D_GIF_ERR_CLOSE_FAILED;
       return GIF_ERROR;
    }
    return GIF_OK;
}

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static int DGifDecompressInput ( GifFilePrivateType Private,
int *  Code 
) [static]

Definition at line 799 of file dgif_lib.c.

{
    GifByteType NextByte;
    static unsigned int CodeMasks[] = {
       0x0000, 0x0001, 0x0003, 0x0007,
       0x000f, 0x001f, 0x003f, 0x007f,
       0x00ff, 0x01ff, 0x03ff, 0x07ff,
       0x0fff
    };

    while (Private->CrntShiftState < Private->RunningBits) {
       /* Needs to get more bytes from input stream for next code: */
       if (DGifBufferedInput(Private->File, Private->Buf, &NextByte)
           == GIF_ERROR) {
           return GIF_ERROR;
       }
       Private->CrntShiftDWord |=
              ((unsigned long) NextByte) << Private->CrntShiftState;
       Private->CrntShiftState += 8;
    }
    *Code = Private->CrntShiftDWord & CodeMasks[Private->RunningBits];

    Private->CrntShiftDWord >>= Private->RunningBits;
    Private->CrntShiftState -= Private->RunningBits;

    /* If code cannt fit into RunningBits bits, must raise its size. Note */
    /* however that codes above 4095 are used for special signaling.      */
    if (++Private->RunningCode > Private->MaxCode1 &&
       Private->RunningBits < LZ_BITS) {
       Private->MaxCode1 <<= 1;
       Private->RunningBits++;
    }
    return GIF_OK;
}

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static int DGifDecompressLine ( GifFileType GifFile,
GifPixelType Line,
int  LineLen 
) [static]

Definition at line 619 of file dgif_lib.c.

{
    int i = 0, j, CrntCode, EOFCode, ClearCode, CrntPrefix, LastCode, StackPtr;
    GifByteType *Stack, *Suffix;
    unsigned int *Prefix;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    StackPtr = Private->StackPtr;
    Prefix = Private->Prefix;
    Suffix = Private->Suffix;
    Stack = Private->Stack;
    EOFCode = Private->EOFCode;
    ClearCode = Private->ClearCode;
    LastCode = Private->LastCode;

    if (StackPtr != 0) {
       /* Let pop the stack off before continueing to read the gif file: */
       while (StackPtr != 0 && i < LineLen) Line[i++] = Stack[--StackPtr];
    }

    while (i < LineLen) {                     /* Decode LineLen items. */
       if (DGifDecompressInput(Private, &CrntCode) == GIF_ERROR)
           return GIF_ERROR;

       if (CrntCode == EOFCode) {
           /* Note however that usually we will not be here as we will stop */
           /* decoding as soon as we got all the pixel, or EOF code will    */
           /* not be read at all, and DGifGetLine/Pixel clean everything.   */
           if (i != LineLen - 1 || Private->PixelCount != 0) {
              _GifError = D_GIF_ERR_EOF_TOO_SOON;
              return GIF_ERROR;
           }
           i++;
       }
       else if (CrntCode == ClearCode) {
           /* We need to start over again: */
           for (j = 0; j <= LZ_MAX_CODE; j++) Prefix[j] = NO_SUCH_CODE;
           Private->RunningCode = Private->EOFCode + 1;
           Private->RunningBits = Private->BitsPerPixel + 1;
           Private->MaxCode1 = 1 << Private->RunningBits;
           LastCode = Private->LastCode = NO_SUCH_CODE;
       }
       else {
           /* Its regular code - if in pixel range simply add it to output  */
           /* stream, otherwise trace to codes linked list until the prefix */
           /* is in pixel range:                                    */
           if (CrntCode < ClearCode) {
              /* This is simple - its pixel scalar, so add it to output:   */
              Line[i++] = CrntCode;
           }
           else {
              /* Its a code to needed to be traced: trace the linked list  */
              /* until the prefix is a pixel, while pushing the suffix     */
              /* pixels on our stack. If we done, pop the stack in reverse */
              /* (thats what stack is good for!) order to output.          */
              if (Prefix[CrntCode] == NO_SUCH_CODE) {
                  /* Only allowed if CrntCode is exactly the running code: */
                  /* In that case CrntCode = XXXCode, CrntCode or the      */
                  /* prefix code is last code and the suffix char is       */
                  /* exactly the prefix of last code!                      */
                  if (CrntCode == Private->RunningCode - 2) {
                     CrntPrefix = LastCode;
                     Suffix[Private->RunningCode - 2] =
                     Stack[StackPtr++] = DGifGetPrefixChar(Prefix,
                                                 LastCode, ClearCode);
                  }
                  else {
                     _GifError = D_GIF_ERR_IMAGE_DEFECT;
                     return GIF_ERROR;
                  }
              }
              else
                  CrntPrefix = CrntCode;

              /* Now (if image is O.K.) we should not get an NO_SUCH_CODE  */
              /* During the trace. As we might loop forever, in case of    */
              /* defective image, we count the number of loops we trace    */
              /* and stop if we got LZ_MAX_CODE. obviously we can not      */
              /* loop more than that.                                      */
              j = 0;
              while (j++ <= LZ_MAX_CODE &&
                     CrntPrefix > ClearCode &&
                     CrntPrefix <= LZ_MAX_CODE) {
                  Stack[StackPtr++] = Suffix[CrntPrefix];
                  CrntPrefix = Prefix[CrntPrefix];
              }
              if (j >= LZ_MAX_CODE || CrntPrefix > LZ_MAX_CODE) {
                  _GifError = D_GIF_ERR_IMAGE_DEFECT;
                  return GIF_ERROR;
              }
              /* Push the last character on stack: */
              Stack[StackPtr++] = CrntPrefix;

              /* Now lets pop all the stack into output: */
              while (StackPtr != 0 && i < LineLen)
                  Line[i++] = Stack[--StackPtr];
           }
           if (LastCode != NO_SUCH_CODE) {
              Prefix[Private->RunningCode - 2] = LastCode;

              if (CrntCode == Private->RunningCode - 2) {
                  /* Only allowed if CrntCode is exactly the running code: */
                  /* In that case CrntCode = XXXCode, CrntCode or the      */
                  /* prefix code is last code and the suffix char is       */
                  /* exactly the prefix of last code!                      */
                  Suffix[Private->RunningCode - 2] =
                     DGifGetPrefixChar(Prefix, LastCode, ClearCode);
              }
              else {
                  Suffix[Private->RunningCode - 2] =
                     DGifGetPrefixChar(Prefix, CrntCode, ClearCode);
              }
           }
           LastCode = CrntCode;
       }
    }

    Private->LastCode = LastCode;
    Private->StackPtr = StackPtr;

    return GIF_OK;
}

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int DGifGetCode ( GifFileType GifFile,
int *  CodeSize,
GifByteType **  CodeBlock 
)

Definition at line 535 of file dgif_lib.c.

{
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    *CodeSize = Private->BitsPerPixel;

    return DGifGetCodeNext(GifFile, CodeBlock);
}

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int DGifGetCodeNext ( GifFileType GifFile,
GifByteType **  CodeBlock 
)

Definition at line 555 of file dgif_lib.c.

{
    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (fread(&Buf, 1, 1, Private->File) != 1) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }

    if (Buf > 0) {
       *CodeBlock = Private->Buf;         /* Use private unused buffer. */
       (*CodeBlock)[0] = Buf;  /* Pascal strings notation (pos. 0 is len.). */
       if (fread(&((*CodeBlock)[1]), 1, Buf, Private->File) != Buf) {
           _GifError = D_GIF_ERR_READ_FAILED;
           return GIF_ERROR;
       }
    }
    else {
       *CodeBlock = NULL;
       Private->Buf[0] = 0;           /* Make sure the buffer is empty! */
       Private->PixelCount = 0;   /* And local info. indicate image read. */
    }

    return GIF_OK;
}

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int DGifGetExtension ( GifFileType GifFile,
int *  ExtCode,
GifByteType **  Extension 
)

Definition at line 426 of file dgif_lib.c.

{
    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    if (fread(&Buf, 1, 1, Private->File) != 1) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }
    *ExtCode = Buf;

    return DGifGetExtensionNext(GifFile, Extension);
}

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int DGifGetExtensionNext ( GifFileType GifFile,
GifByteType **  Extension 
)

Definition at line 452 of file dgif_lib.c.

{
    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (fread(&Buf, 1, 1, Private->File) != 1) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }
    if (Buf > 0) {
       *Extension = Private->Buf;           /* Use private unused buffer. */
       (*Extension)[0] = Buf;  /* Pascal strings notation (pos. 0 is len.). */
       if (fread(&((*Extension)[1]), 1, Buf, Private->File) != Buf) {
           _GifError = D_GIF_ERR_READ_FAILED;
           return GIF_ERROR;
       }
    }
    else
       *Extension = NULL;

    return GIF_OK;
}

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int DGifGetImageDesc ( GifFileType GifFile)

Definition at line 272 of file dgif_lib.c.

{
    int i, BitsPerPixel;
    GifByteType Buf[3];
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    if (DGifGetWord(Private->File, &GifFile->Image.Left) == GIF_ERROR ||
       DGifGetWord(Private->File, &GifFile->Image.Top) == GIF_ERROR ||
       DGifGetWord(Private->File, &GifFile->Image.Width) == GIF_ERROR ||
       DGifGetWord(Private->File, &GifFile->Image.Height) == GIF_ERROR)
       return GIF_ERROR;
    if (fread(Buf, 1, 1, Private->File) != 1) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }
    BitsPerPixel = (Buf[0] & 0x07) + 1;
    GifFile->Image.Interlace = (Buf[0] & 0x40);
    if (Buf[0] & 0x80) {        /* Does this image have local color map? */

       if (GifFile->Image.ColorMap && GifFile->SavedImages == NULL)
           FreeMapObject(GifFile->Image.ColorMap);

       GifFile->Image.ColorMap = MakeMapObject(1 << BitsPerPixel, NULL);
    
       /* Get the image local color map: */
       for (i = 0; i < GifFile->Image.ColorMap->ColorCount; i++) {
           if (fread(Buf, 1, 3, Private->File) != 3) {
              _GifError = D_GIF_ERR_READ_FAILED;
              return GIF_ERROR;
           }
           GifFile->Image.ColorMap->Colors[i].Red = Buf[0];
           GifFile->Image.ColorMap->Colors[i].Green = Buf[1];
           GifFile->Image.ColorMap->Colors[i].Blue = Buf[2];
       }
    }

    if (GifFile->SavedImages) {
       SavedImage    *sp;

       if ((GifFile->SavedImages = (SavedImage *)realloc(GifFile->SavedImages,
                  sizeof(SavedImage) * (GifFile->ImageCount + 1))) == NULL) {
           _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
           return GIF_ERROR;
       }

       sp = &GifFile->SavedImages[GifFile->ImageCount];
       memcpy(&sp->ImageDesc, &GifFile->Image, sizeof(GifImageDesc));
       sp->RasterBits = (char *)NULL;
       sp->ExtensionBlockCount = 0;
       sp->ExtensionBlocks = (ExtensionBlock *)NULL;
    }

    GifFile->ImageCount++;

    Private->PixelCount = (long) GifFile->Image.Width *
                         (long) GifFile->Image.Height;

    DGifSetupDecompress(GifFile);  /* Reset decompress algorithm parameters. */

    return GIF_OK;
}

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int DGifGetLine ( GifFileType GifFile,
GifPixelType Line,
int  LineLen 
)

Definition at line 343 of file dgif_lib.c.

{
    GifByteType *Dummy;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    if (!LineLen) LineLen = GifFile->Image.Width;

#if defined(__MSDOS__) || defined(__GNUC__)
    if ((Private->PixelCount -= LineLen) > 0xffff0000UL) {
#else
    if ((Private->PixelCount -= LineLen) > 0xffff0000) {
#endif /* __MSDOS__ */
       _GifError = D_GIF_ERR_DATA_TOO_BIG;
       return GIF_ERROR;
    }

    if (DGifDecompressLine(GifFile, Line, LineLen) == GIF_OK) {
       if (Private->PixelCount == 0) {
           /* We probably would not be called any more, so lets clean             */
           /* everything before we return: need to flush out all rest of    */
           /* image until empty block (size 0) detected. We use GetCodeNext.*/
           do if (DGifGetCodeNext(GifFile, &Dummy) == GIF_ERROR)
              return GIF_ERROR;
           while (Dummy != NULL);
       }
       return GIF_OK;
    }
    else
       return GIF_ERROR;
}

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int DGifGetLZCodes ( GifFileType GifFile,
int *  Code 
)

Definition at line 761 of file dgif_lib.c.

{
    GifByteType *CodeBlock;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    if (DGifDecompressInput(Private, Code) == GIF_ERROR)
       return GIF_ERROR;

    if (*Code == Private->EOFCode) {
       /* Skip rest of codes (hopefully only NULL terminating block): */
       do if (DGifGetCodeNext(GifFile, &CodeBlock) == GIF_ERROR)
           return GIF_ERROR;
       while (CodeBlock != NULL);

       *Code = -1;
    }
    else if (*Code == Private->ClearCode) {
       /* We need to start over again: */
       Private->RunningCode = Private->EOFCode + 1;
       Private->RunningBits = Private->BitsPerPixel + 1;
       Private->MaxCode1 = 1 << Private->RunningBits;
    }

    return GIF_OK;
}

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int DGifGetPixel ( GifFileType GifFile,
GifPixelType  Pixel 
)

Definition at line 383 of file dgif_lib.c.

{
    GifByteType *Dummy;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

#if defined(__MSDOS__) || defined(__GNUC__)
    if (--Private->PixelCount > 0xffff0000UL)
#else
    if (--Private->PixelCount > 0xffff0000)
#endif /* __MSDOS__ */
    {
       _GifError = D_GIF_ERR_DATA_TOO_BIG;
       return GIF_ERROR;
    }

    if (DGifDecompressLine(GifFile, &Pixel, 1) == GIF_OK) {
       if (Private->PixelCount == 0) {
           /* We probably would not be called any more, so lets clean             */
           /* everything before we return: need to flush out all rest of    */
           /* image until empty block (size 0) detected. We use GetCodeNext.*/
           do if (DGifGetCodeNext(GifFile, &Dummy) == GIF_ERROR)
              return GIF_ERROR;
           while (Dummy != NULL);
       }
       return GIF_OK;
    }
    else
       return GIF_ERROR;
}

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static int DGifGetPrefixChar ( unsigned int *  Prefix,
int  Code,
int  ClearCode 
) [static]

Definition at line 749 of file dgif_lib.c.

{
    int i = 0;

    while (Code > ClearCode && i++ <= LZ_MAX_CODE) Code = Prefix[Code];
    return Code;
}

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int DGifGetRecordType ( GifFileType GifFile,
GifRecordType Type 
)

Definition at line 233 of file dgif_lib.c.

{
    GifByteType Buf;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    if (fread(&Buf, 1, 1, Private->File) != 1) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }

    switch (Buf) {
       case ',':
           *Type = IMAGE_DESC_RECORD_TYPE;
           break;
       case '!':
           *Type = EXTENSION_RECORD_TYPE;
           break;
       case ';':
           *Type = TERMINATE_RECORD_TYPE;
           break;
       default:
           *Type = UNDEFINED_RECORD_TYPE;
           _GifError = D_GIF_ERR_WRONG_RECORD;
           return GIF_ERROR;
    }

    return GIF_OK;
}

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int DGifGetScreenDesc ( GifFileType GifFile)

Definition at line 187 of file dgif_lib.c.

{
    int i, BitsPerPixel;
    GifByteType Buf[3];
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    if (!IS_READABLE(Private)) {
       /* This file was NOT open for reading: */
       _GifError = D_GIF_ERR_NOT_READABLE;
       return GIF_ERROR;
    }

    /* Put the screen descriptor into the file: */
    if (DGifGetWord(Private->File, &GifFile->SWidth) == GIF_ERROR ||
       DGifGetWord(Private->File, &GifFile->SHeight) == GIF_ERROR)
       return GIF_ERROR;

    if (fread(Buf, 1, 3, Private->File) != 3) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }
    GifFile->SColorResolution = (((Buf[0] & 0x70) + 1) >> 4) + 1;
    BitsPerPixel = (Buf[0] & 0x07) + 1;
    GifFile->SBackGroundColor = Buf[1];
    if (Buf[0] & 0x80) {                /* Do we have global color map? */

       GifFile->SColorMap = MakeMapObject(1 << BitsPerPixel, NULL);

       /* Get the global color map: */
       for (i = 0; i < GifFile->SColorMap->ColorCount; i++) {
           if (fread(Buf, 1, 3, Private->File) != 3) {
              _GifError = D_GIF_ERR_READ_FAILED;
              return GIF_ERROR;
           }
           GifFile->SColorMap->Colors[i].Red = Buf[0];
           GifFile->SColorMap->Colors[i].Green = Buf[1];
           GifFile->SColorMap->Colors[i].Blue = Buf[2];
       }
    }

    return GIF_OK;
}

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static int DGifGetWord ( FILE *  File,
int *  Word 
) [static]

Definition at line 515 of file dgif_lib.c.

{
    unsigned char c[2];

    if (fread(c, 1, 2, File) != 2) {
       _GifError = D_GIF_ERR_READ_FAILED;
       return GIF_ERROR;
    }

    *Word = (((unsigned int) c[1]) << 8) + c[0];
    return GIF_OK;
}

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GifFileType* DGifOpenFileHandle ( int  FileHandle)

Definition at line 121 of file dgif_lib.c.

{
    char Buf[GIF_STAMP_LEN+1];
    GifFileType *GifFile;
    GifFilePrivateType *Private;
    FILE *f;

#ifdef __MSDOS__
    setmode(FileHandle, O_BINARY);   /* Make sure it is in binary mode. */
    f = fdopen(FileHandle, "rb");            /* Make it into a stream: */
    setvbuf(f, NULL, _IOFBF, GIF_FILE_BUFFER_SIZE);/* And inc. stream buffer.*/
#else
    f = fdopen(FileHandle, "r");             /* Make it into a stream: */
#endif /* __MSDOS__ */

    if ((GifFile = (GifFileType *) malloc(sizeof(GifFileType))) == NULL) {
       _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
       return NULL;
    }

    memset(GifFile, '\0', sizeof(GifFileType));

    if ((Private = (GifFilePrivateType *) malloc(sizeof(GifFilePrivateType)))
       == NULL) {
       _GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
       free((char *) GifFile);
       return NULL;
    }
    GifFile->Private = (VoidPtr) Private;
    Private->FileHandle = FileHandle;
    Private->File = f;
    Private->FileState = 0;   /* Make sure bit 0 = 0 (File open for read). */

    /* Lets see if this is a GIF file: */
    if (fread(Buf, 1, GIF_STAMP_LEN, Private->File) != GIF_STAMP_LEN) {
       _GifError = D_GIF_ERR_READ_FAILED;
       free((char *) Private);
       free((char *) GifFile);
       return NULL;
    }

    /* The GIF Version number is ignored at this time. Maybe we should do    */
    /* something more useful with it.                                      */
    Buf[GIF_STAMP_LEN] = 0;
    if (strncmp(GIF_STAMP, Buf, GIF_VERSION_POS) != 0) {
       _GifError = D_GIF_ERR_NOT_GIF_FILE;
       free((char *) Private);
       free((char *) GifFile);
       return NULL;
    }

    if (DGifGetScreenDesc(GifFile) == GIF_ERROR) {
       free((char *) Private);
       free((char *) GifFile);
       return NULL;
    }

    _GifError = 0;

    return GifFile;
}

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GifFileType* DGifOpenFileName ( const char *  FileName)

Definition at line 100 of file dgif_lib.c.

{
    int FileHandle;

    if ((FileHandle = open(FileName, O_RDONLY
#ifdef __MSDOS__
                                | O_BINARY
#endif /* __MSDOS__ */
                                          )) == -1) {
       _GifError = D_GIF_ERR_OPEN_FAILED;
       return NULL;
    }

    return DGifOpenFileHandle(FileHandle);
}

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static int DGifSetupDecompress ( GifFileType GifFile) [static]

Definition at line 585 of file dgif_lib.c.

{
    int i, BitsPerPixel;
    GifByteType CodeSize;
    unsigned int *Prefix;
    GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;

    fread(&CodeSize, 1, 1, Private->File);    /* Read Code size from file. */
    BitsPerPixel = CodeSize;

    Private->Buf[0] = 0;                        /* Input Buffer empty. */
    Private->BitsPerPixel = BitsPerPixel;
    Private->ClearCode = (1 << BitsPerPixel);
    Private->EOFCode = Private->ClearCode + 1;
    Private->RunningCode = Private->EOFCode + 1;
    Private->RunningBits = BitsPerPixel + 1;      /* Number of bits per code. */
    Private->MaxCode1 = 1 << Private->RunningBits;     /* Max. code + 1. */
    Private->StackPtr = 0;             /* No pixels on the pixel stack. */
    Private->LastCode = NO_SUCH_CODE;
    Private->CrntShiftState = 0;   /* No information in CrntShiftDWord. */
    Private->CrntShiftDWord = 0;

    Prefix = Private->Prefix;
    for (i = 0; i <= LZ_MAX_CODE; i++) Prefix[i] = NO_SUCH_CODE;

    return GIF_OK;
}

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int DGifSlurp ( GifFileType GifFile)

Definition at line 872 of file dgif_lib.c.

{
    int i, j, Error, ImageSize;
    GifRecordType RecordType;
    SavedImage *sp;
    ExtensionBlock *ep;
    GifByteType *ExtData;

    /* Some versions of malloc dislike 0-length requests */
    GifFile->SavedImages = (SavedImage *)malloc(sizeof(SavedImage));

    do {
       if (DGifGetRecordType(GifFile, &RecordType) == GIF_ERROR)
           return(GIF_ERROR);

       switch (RecordType) {
           case IMAGE_DESC_RECORD_TYPE:
              if (DGifGetImageDesc(GifFile) == GIF_ERROR)
                  return(GIF_ERROR);

              sp = &GifFile->SavedImages[GifFile->ImageCount-1];
              ImageSize = sp->ImageDesc.Width * sp->ImageDesc.Height;

              sp->RasterBits
                  = (GifPixelType*) malloc(ImageSize * sizeof(GifPixelType));

              if (DGifGetLine(GifFile, sp->RasterBits, ImageSize)
                  == GIF_ERROR)
                  return(GIF_ERROR);

              break;

           case EXTENSION_RECORD_TYPE:

              if (DGifGetExtension(GifFile,&sp->Function,&ExtData)==GIF_ERROR)
                  return(GIF_ERROR);
              else
              {
                  ep = &sp->ExtensionBlocks[sp->ExtensionBlockCount++];

                  ep->ByteCount = ExtData[0];
                  ep->Bytes = (GifByteType *)malloc(ep->ByteCount * sizeof(GifByteType));
                  memcpy(ep->Bytes, ExtData, ep->ByteCount * sizeof(char));
              }

              while (ExtData != NULL) {
                  if (DGifGetExtensionNext(GifFile, &ExtData) == GIF_ERROR)
                     return(GIF_ERROR);
                  else
                  {
                     ep = &sp->ExtensionBlocks[sp->ExtensionBlockCount++];

                     ep->ByteCount = ExtData[0];
                     ep->Bytes = (GifByteType *)malloc(ep->ByteCount * sizeof(GifByteType));
                     memcpy(ep->Bytes,ExtData,ep->ByteCount * sizeof(char));
                  }
              }
              break;

           case TERMINATE_RECORD_TYPE:
              break;

           default:  /* Should be trapped by DGifGetRecordType */
              break;
       }
    }
    while
       (RecordType != TERMINATE_RECORD_TYPE);

    return(GIF_OK);
}

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Variable Documentation

int _GifError

Definition at line 17 of file gif_err.c.

char* VersionStr = "(C) Copyright 1989 Gershon Elber, Non commercial use only.\n" [static]

Definition at line 75 of file dgif_lib.c.