Java example source code file (dgif_lib.c)
The dgif_lib.c Java example source code
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/******************************************************************************
* "Gif-Lib" - Yet another gif library.
*
* Written by: Gershon Elber IBM PC Ver 1.1, Aug. 1990
******************************************************************************
* The kernel of the GIF Decoding process can be found here.
******************************************************************************
* History:
* 16 Jun 89 - Version 1.0 by Gershon Elber.
* 3 Sep 90 - Version 1.1 by Gershon Elber (Support for Gif89, Unique names).
*****************************************************************************/
/* !!!! */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#if defined (__MSDOS__) && !defined(__DJGPP__) && !defined(__GNUC__)
#include <io.h>
#include <alloc.h>
#include <sys\stat.h>
#else
#include <sys/types.h>
#include <sys/stat.h>
#endif /* __MSDOS__ */
#ifdef _WIN32
#include <io.h>
#define _OPEN_BINARY
#else
#include <unistd.h>
#endif
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include "gif_lib.h"
#include "gif_lib_private.h"
#define COMMENT_EXT_FUNC_CODE 0xfe /* Extension function code for
comment. */
/* avoid extra function call in case we use fread (TVT) */
#define READ(_gif,_buf,_len) \
(((GifFilePrivateType*)_gif->Private)->Read ? \
(size_t)((GifFilePrivateType*)_gif->Private)->Read(_gif,_buf,_len) : \
fread(_buf,1,_len,((GifFilePrivateType*)_gif->Private)->File))
static int DGifGetWord(GifFileType *GifFile, 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(GifFileType *GifFile, int *Code);
static int DGifBufferedInput(GifFileType *GifFile, GifByteType *Buf,
GifByteType *NextByte);
/******************************************************************************
* Open a new gif file for read, given by its name.
* Returns GifFileType pointer dynamically allocated which serves as the gif
* info record. _GifError is cleared if succesfull.
*****************************************************************************/
GifFileType *
DGifOpenFileName(const char *FileName) {
int FileHandle;
GifFileType *GifFile;
if ((FileHandle = open(FileName, O_RDONLY
#if defined(__MSDOS__) || defined(_OPEN_BINARY)
| O_BINARY
#endif /* __MSDOS__ || _OPEN_BINARY */
)) == -1) {
_GifError = D_GIF_ERR_OPEN_FAILED;
return NULL;
}
GifFile = DGifOpenFileHandle(FileHandle);
if (GifFile == (GifFileType *)NULL)
close(FileHandle);
return GifFile;
}
/******************************************************************************
* Update a new gif file, given its file handle.
* Returns GifFileType pointer dynamically allocated which serves as the gif
* info record. _GifError is cleared if succesfull.
*****************************************************************************/
GifFileType *
DGifOpenFileHandle(int FileHandle) {
unsigned char Buf[GIF_STAMP_LEN + 1];
GifFileType *GifFile;
GifFilePrivateType *Private;
FILE *f;
GifFile = (GifFileType *)malloc(sizeof(GifFileType));
if (GifFile == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return NULL;
}
memset(GifFile, '\0', sizeof(GifFileType));
Private = (GifFilePrivateType *)malloc(sizeof(GifFilePrivateType));
if (Private == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
free((char *)GifFile);
return NULL;
}
#ifdef __MSDOS__
setmode(FileHandle, O_BINARY); /* Make sure it is in binary mode. */
#endif /* __MSDOS__ */
f = fdopen(FileHandle, "rb"); /* Make it into a stream: */
#ifdef __MSDOS__
setvbuf(f, NULL, _IOFBF, GIF_FILE_BUFFER_SIZE); /* And inc. stream
buffer. */
#endif /* __MSDOS__ */
GifFile->Private = (VoidPtr)Private;
Private->FileHandle = FileHandle;
Private->File = f;
Private->FileState = FILE_STATE_READ;
Private->Read = 0; /* don't use alternate input method (TVT) */
GifFile->UserData = 0; /* TVT */
/* Lets see if this is a GIF file: */
if (READ(GifFile, Buf, GIF_STAMP_LEN) != GIF_STAMP_LEN) {
_GifError = D_GIF_ERR_READ_FAILED;
fclose(f);
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, (const char*)Buf, GIF_VERSION_POS) != 0) {
_GifError = D_GIF_ERR_NOT_GIF_FILE;
fclose(f);
free((char *)Private);
free((char *)GifFile);
return NULL;
}
if (DGifGetScreenDesc(GifFile) == GIF_ERROR) {
fclose(f);
free((char *)Private);
free((char *)GifFile);
return NULL;
}
_GifError = 0;
return GifFile;
}
/******************************************************************************
* GifFileType constructor with user supplied input function (TVT)
*****************************************************************************/
GifFileType *
DGifOpen(void *userData,
InputFunc readFunc) {
unsigned char Buf[GIF_STAMP_LEN + 1];
GifFileType *GifFile;
GifFilePrivateType *Private;
GifFile = (GifFileType *)malloc(sizeof(GifFileType));
if (GifFile == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return NULL;
}
memset(GifFile, '\0', sizeof(GifFileType));
Private = (GifFilePrivateType *)malloc(sizeof(GifFilePrivateType));
if (!Private) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
free((char *)GifFile);
return NULL;
}
GifFile->Private = (VoidPtr)Private;
Private->FileHandle = 0;
Private->File = 0;
Private->FileState = FILE_STATE_READ;
Private->Read = readFunc; /* TVT */
GifFile->UserData = userData; /* TVT */
/* Lets see if this is a GIF file: */
if (READ(GifFile, Buf, GIF_STAMP_LEN) != 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, (const char*)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;
}
/******************************************************************************
* This routine should be called before any other DGif calls. Note that
* this routine is called automatically from DGif file open routines.
*****************************************************************************/
int
DGifGetScreenDesc(GifFileType * GifFile) {
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(GifFile, &GifFile->SWidth) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->SHeight) == GIF_ERROR)
return GIF_ERROR;
if (READ(GifFile, Buf, 3) != 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);
if (GifFile->SColorMap == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
/* Get the global color map: */
for (i = 0; i < GifFile->SColorMap->ColorCount; i++) {
if (READ(GifFile, Buf, 3) != 3) {
FreeMapObject(GifFile->SColorMap);
_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];
}
} else {
GifFile->SColorMap = NULL;
}
return GIF_OK;
}
/******************************************************************************
* This routine should be called before any attempt to read an image.
*****************************************************************************/
int
DGifGetRecordType(GifFileType * GifFile,
GifRecordType * Type) {
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 (READ(GifFile, &Buf, 1) != 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;
}
/******************************************************************************
* This routine should be called before any attempt to read an image.
* Note it is assumed the Image desc. header (',') has been read.
*****************************************************************************/
int
DGifGetImageDesc(GifFileType * GifFile) {
int i, BitsPerPixel;
GifByteType Buf[3];
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
SavedImage *sp;
if (!IS_READABLE(Private)) {
/* This file was NOT open for reading: */
_GifError = D_GIF_ERR_NOT_READABLE;
return GIF_ERROR;
}
if (DGifGetWord(GifFile, &GifFile->Image.Left) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->Image.Top) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->Image.Width) == GIF_ERROR ||
DGifGetWord(GifFile, &GifFile->Image.Height) == GIF_ERROR)
return GIF_ERROR;
if (READ(GifFile, Buf, 1) != 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? */
/*** FIXME: Why do we check both of these in order to do this?
* Why do we have both Image and SavedImages? */
if (GifFile->Image.ColorMap && GifFile->SavedImages == NULL)
FreeMapObject(GifFile->Image.ColorMap);
GifFile->Image.ColorMap = MakeMapObject(1 << BitsPerPixel, NULL);
if (GifFile->Image.ColorMap == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
/* Get the image local color map: */
for (i = 0; i < GifFile->Image.ColorMap->ColorCount; i++) {
if (READ(GifFile, Buf, 3) != 3) {
FreeMapObject(GifFile->Image.ColorMap);
_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];
}
} else if (GifFile->Image.ColorMap) {
FreeMapObject(GifFile->Image.ColorMap);
GifFile->Image.ColorMap = NULL;
}
if (GifFile->SavedImages) {
if ((GifFile->SavedImages = (SavedImage *)realloc(GifFile->SavedImages,
sizeof(SavedImage) *
(GifFile->ImageCount + 1))) == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
} else {
if ((GifFile->SavedImages =
(SavedImage *) malloc(sizeof(SavedImage))) == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
}
sp = &GifFile->SavedImages[GifFile->ImageCount];
memcpy(&sp->ImageDesc, &GifFile->Image, sizeof(GifImageDesc));
if (GifFile->Image.ColorMap != NULL) {
sp->ImageDesc.ColorMap = MakeMapObject(
GifFile->Image.ColorMap->ColorCount,
GifFile->Image.ColorMap->Colors);
if (sp->ImageDesc.ColorMap == NULL) {
_GifError = D_GIF_ERR_NOT_ENOUGH_MEM;
return GIF_ERROR;
}
}
sp->RasterBits = (unsigned 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;
}
/******************************************************************************
* Get one full scanned line (Line) of length LineLen from GIF file.
*****************************************************************************/
int
DGifGetLine(GifFileType * GifFile,
GifPixelType * Line,
int LineLen) {
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;
}
/******************************************************************************
* Put one pixel (Pixel) into GIF file.
*****************************************************************************/
int
DGifGetPixel(GifFileType * GifFile,
GifPixelType Pixel) {
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;
}
/******************************************************************************
* Get an extension block (see GIF manual) from gif file. This routine only
* returns the first data block, and DGifGetExtensionNext should be called
* after this one until NULL extension is returned.
* The Extension should NOT be freed by the user (not dynamically allocated).
* Note it is assumed the Extension desc. header ('!') has been read.
*****************************************************************************/
int
DGifGetExtension(GifFileType * GifFile,
int *ExtCode,
GifByteType ** Extension) {
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 (READ(GifFile, &Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
*ExtCode = Buf;
return DGifGetExtensionNext(GifFile, Extension);
}
/******************************************************************************
* Get a following extension block (see GIF manual) from gif file. This
* routine should be called until NULL Extension is returned.
* The Extension should NOT be freed by the user (not dynamically allocated).
*****************************************************************************/
int
DGifGetExtensionNext(GifFileType * GifFile,
GifByteType ** Extension) {
GifByteType Buf;
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
if (READ(GifFile, &Buf, 1) != 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 (READ(GifFile, &((*Extension)[1]), Buf) != Buf) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
} else
*Extension = NULL;
return GIF_OK;
}
/******************************************************************************
* This routine should be called last, to close the GIF file.
*****************************************************************************/
int
DGifCloseFile(GifFileType * GifFile) {
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);
GifFile->Image.ColorMap = NULL;
}
if (GifFile->SColorMap) {
FreeMapObject(GifFile->SColorMap);
GifFile->SColorMap = NULL;
}
if (Private) {
free((char *)Private);
Private = NULL;
}
if (GifFile->SavedImages) {
FreeSavedImages(GifFile);
GifFile->SavedImages = NULL;
}
free(GifFile);
if (File && (fclose(File) != 0)) {
_GifError = D_GIF_ERR_CLOSE_FAILED;
return GIF_ERROR;
}
return GIF_OK;
}
/******************************************************************************
* Get 2 bytes (word) from the given file:
*****************************************************************************/
static int
DGifGetWord(GifFileType * GifFile,
int *Word) {
unsigned char c[2];
if (READ(GifFile, c, 2) != 2) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
*Word = (((unsigned int)c[1]) << 8) + c[0];
return GIF_OK;
}
/******************************************************************************
* Get the image code in compressed form. This routine can be called if the
* information needed to be piped out as is. Obviously this is much faster
* than decoding and encoding again. This routine should be followed by calls
* to DGifGetCodeNext, until NULL block is returned.
* The block should NOT be freed by the user (not dynamically allocated).
*****************************************************************************/
int
DGifGetCode(GifFileType * GifFile,
int *CodeSize,
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;
}
*CodeSize = Private->BitsPerPixel;
return DGifGetCodeNext(GifFile, CodeBlock);
}
/******************************************************************************
* Continue to get the image code in compressed form. This routine should be
* called until NULL block is returned.
* The block should NOT be freed by the user (not dynamically allocated).
*****************************************************************************/
int
DGifGetCodeNext(GifFileType * GifFile,
GifByteType ** CodeBlock) {
GifByteType Buf;
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
if (READ(GifFile, &Buf, 1) != 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 (READ(GifFile, &((*CodeBlock)[1]), Buf) != 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;
}
/******************************************************************************
* Setup the LZ decompression for this image:
*****************************************************************************/
static int
DGifSetupDecompress(GifFileType * GifFile) {
int i, BitsPerPixel;
GifByteType CodeSize;
unsigned int *Prefix;
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
READ(GifFile, &CodeSize, 1); /* Read Code size from file. */
if (CodeSize >= 12) {
/* Invalid initial code size: report failure */
return GIF_ERROR;
}
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;
}
/******************************************************************************
* The LZ decompression routine:
* This version decompress the given gif file into Line of length LineLen.
* This routine can be called few times (one per scan line, for example), in
* order the complete the whole image.
*****************************************************************************/
static int
DGifDecompressLine(GifFileType * GifFile,
GifPixelType * Line,
int LineLen) {
int i = 0;
int 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(GifFile, &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;
}
/******************************************************************************
* Routine to trace the Prefixes linked list until we get a prefix which is
* not code, but a pixel value (less than ClearCode). Returns that pixel value.
* If image is defective, we might loop here forever, so we limit the loops to
* the maximum possible if image O.k. - LZ_MAX_CODE times.
*****************************************************************************/
static int
DGifGetPrefixChar(unsigned int *Prefix,
int Code,
int ClearCode) {
int i = 0;
while (Code > ClearCode && i++ <= LZ_MAX_CODE)
Code = Prefix[Code];
return Code;
}
/******************************************************************************
* Interface for accessing the LZ codes directly. Set Code to the real code
* (12bits), or to -1 if EOF code is returned.
*****************************************************************************/
int
DGifGetLZCodes(GifFileType * GifFile,
int *Code) {
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(GifFile, 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;
}
/******************************************************************************
* The LZ decompression input routine:
* This routine is responsable for the decompression of the bit stream from
* 8 bits (bytes) packets, into the real codes.
* Returns GIF_OK if read succesfully.
*****************************************************************************/
static int
DGifDecompressInput(GifFileType * GifFile,
int *Code) {
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
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(GifFile, 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 cannot fit into RunningBits bits, must raise its size. Note
* however that codes above 4095 are used for special signaling. */
if (++Private->RunningCode > Private->MaxCode1) {
if (Private->RunningBits < LZ_BITS) {
Private->MaxCode1 <<= 1;
Private->RunningBits++;
} else {
Private->RunningCode = Private->MaxCode1;
}
}
return GIF_OK;
}
/******************************************************************************
* This routines read one gif data block at a time and buffers it internally
* so that the decompression routine could access it.
* The routine returns the next byte from its internal buffer (or read next
* block in if buffer empty) and returns GIF_OK if succesful.
*****************************************************************************/
static int
DGifBufferedInput(GifFileType * GifFile,
GifByteType * Buf,
GifByteType * NextByte) {
if (Buf[0] == 0) {
/* Needs to read the next buffer - this one is empty: */
if (READ(GifFile, Buf, 1) != 1) {
_GifError = D_GIF_ERR_READ_FAILED;
return GIF_ERROR;
}
if (READ(GifFile, &Buf[1], Buf[0]) != 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;
}
/******************************************************************************
* This routine reads an entire GIF into core, hanging all its state info off
* the GifFileType pointer. Call DGifOpenFileName() or DGifOpenFileHandle()
* first to initialize I/O. Its inverse is EGifSpew().
******************************************************************************/
int
DGifSlurp(GifFileType * GifFile) {
int ImageSize;
GifRecordType RecordType;
SavedImage *sp;
GifByteType *ExtData;
SavedImage temp_save;
temp_save.ExtensionBlocks = NULL;
temp_save.ExtensionBlockCount = 0;
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 = (unsigned char *)malloc(ImageSize *
sizeof(GifPixelType));
if (sp->RasterBits == NULL) {
return GIF_ERROR;
}
if (DGifGetLine(GifFile, sp->RasterBits, ImageSize) ==
GIF_ERROR)
return (GIF_ERROR);
if (temp_save.ExtensionBlocks) {
sp->ExtensionBlocks = temp_save.ExtensionBlocks;
sp->ExtensionBlockCount = temp_save.ExtensionBlockCount;
temp_save.ExtensionBlocks = NULL;
temp_save.ExtensionBlockCount = 0;
/* FIXME: The following is wrong. It is left in only for
* backwards compatibility. Someday it should go away. Use
* the sp->ExtensionBlocks->Function variable instead. */
sp->Function = sp->ExtensionBlocks[0].Function;
}
break;
case EXTENSION_RECORD_TYPE:
if (DGifGetExtension(GifFile, &temp_save.Function, &ExtData) ==
GIF_ERROR)
return (GIF_ERROR);
while (ExtData != NULL) {
/* Create an extension block with our data */
if (AddExtensionBlock(&temp_save, ExtData[0], &ExtData[1])
== GIF_ERROR)
return (GIF_ERROR);
if (DGifGetExtensionNext(GifFile, &ExtData) == GIF_ERROR)
return (GIF_ERROR);
temp_save.Function = 0;
}
break;
case TERMINATE_RECORD_TYPE:
break;
default: /* Should be trapped by DGifGetRecordType */
break;
}
} while (RecordType != TERMINATE_RECORD_TYPE);
/* Just in case the Gif has an extension block without an associated
* image... (Should we save this into a savefile structure with no image
* instead? Have to check if the present writing code can handle that as
* well.... */
if (temp_save.ExtensionBlocks)
FreeExtension(&temp_save);
return (GIF_OK);
}
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