979 lines
34 KiB
C
979 lines
34 KiB
C
/*
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* Gif extracting routines - derived from libungif
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*
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* Portions Copyright 2006 Mike McCormack
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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/*
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* Original copyright notice:
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*
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* The GIFLIB distribution is Copyright (c) 1997 Eric S. Raymond
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*/
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/******************************************************************************
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* "Gif-Lib" - Yet another gif library.
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*
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* Written by: Gershon Elber IBM PC Ver 1.1, Aug. 1990
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******************************************************************************
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* The kernel of the GIF Decoding process can be found here.
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******************************************************************************
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* History:
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* 16 Jun 89 - Version 1.0 by Gershon Elber.
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* 3 Sep 90 - Version 1.1 by Gershon Elber (Support for Gif89, Unique names).
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*****************************************************************************/
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#include <stdlib.h>
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#include <string.h>
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#include "ungif.h"
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#define LZ_MAX_CODE 4095 /* Biggest code possible in 12 bits. */
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#define LZ_BITS 12
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#define NO_SUCH_CODE 4098 /* Impossible code, to signal empty. */
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typedef struct GifFilePrivateType {
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GifWord BitsPerPixel, /* Bits per pixel (Codes uses at least this + 1). */
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ClearCode, /* The CLEAR LZ code. */
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EOFCode, /* The EOF LZ code. */
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RunningCode, /* The next code algorithm can generate. */
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RunningBits, /* The number of bits required to represent RunningCode. */
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MaxCode1, /* 1 bigger than max. possible code, in RunningBits bits. */
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LastCode, /* The code before the current code. */
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CrntCode, /* Current algorithm code. */
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StackPtr, /* For character stack (see below). */
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CrntShiftState; /* Number of bits in CrntShiftDWord. */
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unsigned long CrntShiftDWord; /* For bytes decomposition into codes. */
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unsigned long PixelCount; /* Number of pixels in image. */
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InputFunc Read; /* function to read gif input (TVT) */
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GifByteType Buf[256]; /* Compressed input is buffered here. */
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GifByteType Stack[LZ_MAX_CODE]; /* Decoded pixels are stacked here. */
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GifByteType Suffix[LZ_MAX_CODE + 1]; /* So we can trace the codes. */
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GifPrefixType Prefix[LZ_MAX_CODE + 1];
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} GifFilePrivateType;
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/* avoid extra function call in case we use fread (TVT) */
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#define READ(_gif,_buf,_len) \
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((GifFilePrivateType*)_gif->Private)->Read(_gif,_buf,_len)
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static int DGifGetWord(GifFileType *GifFile, GifWord *Word);
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static int DGifSetupDecompress(GifFileType *GifFile);
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static int DGifDecompressLine(GifFileType *GifFile, GifPixelType *Line, int LineLen);
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static int DGifGetPrefixChar(GifPrefixType *Prefix, int Code, int ClearCode);
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static int DGifDecompressInput(GifFileType *GifFile, int *Code);
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static int DGifBufferedInput(GifFileType *GifFile, GifByteType *Buf,
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GifByteType *NextByte);
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static int DGifGetExtensionNext(GifFileType * GifFile, GifByteType ** GifExtension);
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static int DGifGetCodeNext(GifFileType * GifFile, GifByteType ** GifCodeBlock);
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/******************************************************************************
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* Miscellaneous utility functions
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*****************************************************************************/
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/* return smallest bitfield size n will fit in */
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static int
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BitSize(int n) {
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register int i;
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for (i = 1; i <= 8; i++)
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if ((1 << i) >= n)
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break;
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return (i);
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}
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/******************************************************************************
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* Color map object functions
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*****************************************************************************/
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/*
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* Allocate a color map of given size; initialize with contents of
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* ColorMap if that pointer is non-NULL.
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*/
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static ColorMapObject *
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MakeMapObject(int ColorCount,
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const GifColorType * ColorMap) {
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ColorMapObject *Object;
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/*** FIXME: Our ColorCount has to be a power of two. Is it necessary to
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* make the user know that or should we automatically round up instead? */
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if (ColorCount != (1 << BitSize(ColorCount))) {
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return ((ColorMapObject *) NULL);
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}
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Object = malloc(sizeof(ColorMapObject));
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if (Object == (ColorMapObject *) NULL) {
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return ((ColorMapObject *) NULL);
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}
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Object->Colors = (GifColorType *)calloc(ColorCount, sizeof(GifColorType));
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if (Object->Colors == (GifColorType *) NULL) {
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return ((ColorMapObject *) NULL);
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}
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Object->ColorCount = ColorCount;
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Object->BitsPerPixel = BitSize(ColorCount);
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if (ColorMap) {
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memcpy(Object->Colors, ColorMap, ColorCount * sizeof(GifColorType));
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}
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return (Object);
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}
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/*
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* Free a color map object
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*/
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static void
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FreeMapObject(ColorMapObject * Object) {
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if (Object != NULL) {
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free(Object->Colors);
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free(Object);
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/*** FIXME:
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* When we are willing to break API we need to make this function
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* FreeMapObject(ColorMapObject **Object)
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* and do this assignment to NULL here:
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* *Object = NULL;
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*/
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}
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}
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static int
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AddExtensionBlock(SavedImage * New,
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int Len,
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unsigned char ExtData[]) {
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ExtensionBlock *ep;
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if (New->ExtensionBlocks == NULL)
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New->ExtensionBlocks = malloc(sizeof(ExtensionBlock));
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else
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New->ExtensionBlocks = realloc(New->ExtensionBlocks,
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sizeof(ExtensionBlock) *
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(New->ExtensionBlockCount + 1));
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if (New->ExtensionBlocks == NULL)
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return (GIF_ERROR);
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ep = &New->ExtensionBlocks[New->ExtensionBlockCount++];
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ep->ByteCount=Len;
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ep->Bytes = malloc(ep->ByteCount);
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if (ep->Bytes == NULL)
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return (GIF_ERROR);
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if (ExtData) {
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memcpy(ep->Bytes, ExtData, Len);
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ep->Function = New->Function;
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}
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return (GIF_OK);
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}
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static void
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FreeExtension(SavedImage * Image)
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{
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ExtensionBlock *ep;
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if ((Image == NULL) || (Image->ExtensionBlocks == NULL)) {
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return;
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}
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for (ep = Image->ExtensionBlocks;
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ep < (Image->ExtensionBlocks + Image->ExtensionBlockCount); ep++)
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free(ep->Bytes);
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free(Image->ExtensionBlocks);
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Image->ExtensionBlocks = NULL;
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}
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/******************************************************************************
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* Image block allocation functions
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******************************************************************************/
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static void
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FreeSavedImages(GifFileType * GifFile) {
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SavedImage *sp;
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if ((GifFile == NULL) || (GifFile->SavedImages == NULL)) {
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return;
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}
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for (sp = GifFile->SavedImages;
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sp < GifFile->SavedImages + GifFile->ImageCount; sp++) {
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if (sp->ImageDesc.ColorMap) {
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FreeMapObject(sp->ImageDesc.ColorMap);
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sp->ImageDesc.ColorMap = NULL;
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}
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if (sp->RasterBits)
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free(sp->RasterBits);
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if (sp->ExtensionBlocks)
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FreeExtension(sp);
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}
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free(GifFile->SavedImages);
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GifFile->SavedImages=NULL;
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}
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/******************************************************************************
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* This routine should be called before any other DGif calls. Note that
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* this routine is called automatically from DGif file open routines.
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*****************************************************************************/
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static int
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DGifGetScreenDesc(GifFileType * GifFile) {
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int i, BitsPerPixel;
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GifByteType Buf[3];
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/* Put the screen descriptor into the file: */
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if (DGifGetWord(GifFile, &GifFile->SWidth) == GIF_ERROR ||
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DGifGetWord(GifFile, &GifFile->SHeight) == GIF_ERROR)
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return GIF_ERROR;
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if (READ(GifFile, Buf, 3) != 3) {
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return GIF_ERROR;
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}
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GifFile->SColorResolution = (((Buf[0] & 0x70) + 1) >> 4) + 1;
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BitsPerPixel = (Buf[0] & 0x07) + 1;
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GifFile->SBackGroundColor = Buf[1];
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if (Buf[0] & 0x80) { /* Do we have global color map? */
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GifFile->SColorMap = MakeMapObject(1 << BitsPerPixel, NULL);
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if (GifFile->SColorMap == NULL) {
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return GIF_ERROR;
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}
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/* Get the global color map: */
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for (i = 0; i < GifFile->SColorMap->ColorCount; i++) {
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if (READ(GifFile, Buf, 3) != 3) {
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FreeMapObject(GifFile->SColorMap);
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GifFile->SColorMap = NULL;
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return GIF_ERROR;
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}
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GifFile->SColorMap->Colors[i].Red = Buf[0];
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GifFile->SColorMap->Colors[i].Green = Buf[1];
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GifFile->SColorMap->Colors[i].Blue = Buf[2];
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}
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} else {
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GifFile->SColorMap = NULL;
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}
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return GIF_OK;
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}
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/******************************************************************************
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* This routine should be called before any attempt to read an image.
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*****************************************************************************/
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static int
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DGifGetRecordType(GifFileType * GifFile,
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GifRecordType * Type) {
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GifByteType Buf;
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if (READ(GifFile, &Buf, 1) != 1) {
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return GIF_ERROR;
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}
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switch (Buf) {
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case ',':
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*Type = IMAGE_DESC_RECORD_TYPE;
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break;
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case '!':
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*Type = EXTENSION_RECORD_TYPE;
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break;
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case ';':
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*Type = TERMINATE_RECORD_TYPE;
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break;
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default:
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*Type = UNDEFINED_RECORD_TYPE;
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return GIF_ERROR;
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}
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return GIF_OK;
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}
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/******************************************************************************
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* This routine should be called before any attempt to read an image.
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* Note it is assumed the Image desc. header (',') has been read.
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*****************************************************************************/
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static int
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DGifGetImageDesc(GifFileType * GifFile) {
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int i, BitsPerPixel;
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GifByteType Buf[3];
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GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
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SavedImage *sp;
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if (DGifGetWord(GifFile, &GifFile->Image.Left) == GIF_ERROR ||
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DGifGetWord(GifFile, &GifFile->Image.Top) == GIF_ERROR ||
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DGifGetWord(GifFile, &GifFile->Image.Width) == GIF_ERROR ||
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DGifGetWord(GifFile, &GifFile->Image.Height) == GIF_ERROR)
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return GIF_ERROR;
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if (READ(GifFile, Buf, 1) != 1) {
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return GIF_ERROR;
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}
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BitsPerPixel = (Buf[0] & 0x07) + 1;
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GifFile->Image.Interlace = (Buf[0] & 0x40);
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if (Buf[0] & 0x80) { /* Does this image have local color map? */
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/*** FIXME: Why do we check both of these in order to do this?
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* Why do we have both Image and SavedImages? */
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if (GifFile->Image.ColorMap && GifFile->SavedImages == NULL)
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FreeMapObject(GifFile->Image.ColorMap);
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GifFile->Image.ColorMap = MakeMapObject(1 << BitsPerPixel, NULL);
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if (GifFile->Image.ColorMap == NULL) {
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return GIF_ERROR;
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}
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/* Get the image local color map: */
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for (i = 0; i < GifFile->Image.ColorMap->ColorCount; i++) {
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if (READ(GifFile, Buf, 3) != 3) {
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FreeMapObject(GifFile->Image.ColorMap);
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GifFile->Image.ColorMap = NULL;
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return GIF_ERROR;
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}
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GifFile->Image.ColorMap->Colors[i].Red = Buf[0];
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GifFile->Image.ColorMap->Colors[i].Green = Buf[1];
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GifFile->Image.ColorMap->Colors[i].Blue = Buf[2];
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}
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} else if (GifFile->Image.ColorMap) {
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FreeMapObject(GifFile->Image.ColorMap);
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GifFile->Image.ColorMap = NULL;
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}
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if (GifFile->SavedImages) {
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if ((GifFile->SavedImages = realloc(GifFile->SavedImages,
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sizeof(SavedImage) *
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(GifFile->ImageCount + 1))) == NULL) {
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return GIF_ERROR;
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}
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} else {
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if ((GifFile->SavedImages = malloc(sizeof(SavedImage))) == NULL) {
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return GIF_ERROR;
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}
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}
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sp = &GifFile->SavedImages[GifFile->ImageCount];
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memcpy(&sp->ImageDesc, &GifFile->Image, sizeof(GifImageDesc));
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if (GifFile->Image.ColorMap != NULL) {
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sp->ImageDesc.ColorMap = MakeMapObject(
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GifFile->Image.ColorMap->ColorCount,
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GifFile->Image.ColorMap->Colors);
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if (sp->ImageDesc.ColorMap == NULL) {
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return GIF_ERROR;
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}
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}
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sp->RasterBits = (unsigned char *)NULL;
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sp->ExtensionBlockCount = 0;
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sp->ExtensionBlocks = (ExtensionBlock *) NULL;
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GifFile->ImageCount++;
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Private->PixelCount = (long)GifFile->Image.Width *
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(long)GifFile->Image.Height;
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DGifSetupDecompress(GifFile); /* Reset decompress algorithm parameters. */
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return GIF_OK;
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}
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/******************************************************************************
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* Get one full scanned line (Line) of length LineLen from GIF file.
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*****************************************************************************/
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static int
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DGifGetLine(GifFileType * GifFile,
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GifPixelType * Line,
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int LineLen) {
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GifByteType *Dummy;
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GifFilePrivateType *Private = (GifFilePrivateType *) GifFile->Private;
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if (!LineLen)
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LineLen = GifFile->Image.Width;
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if ((Private->PixelCount -= LineLen) > 0xffff0000UL) {
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return GIF_ERROR;
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}
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if (DGifDecompressLine(GifFile, Line, LineLen) == GIF_OK) {
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if (Private->PixelCount == 0) {
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/* We probably would not be called any more, so lets clean
|
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* everything before we return: need to flush out all rest of
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* image until empty block (size 0) detected. We use GetCodeNext. */
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do
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if (DGifGetCodeNext(GifFile, &Dummy) == GIF_ERROR)
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return GIF_ERROR;
|
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while (Dummy != NULL) ;
|
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}
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return GIF_OK;
|
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} else
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return GIF_ERROR;
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}
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|
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/******************************************************************************
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|
* Get an extension block (see GIF manual) from gif file. This routine only
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* returns the first data block, and DGifGetExtensionNext should be called
|
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* after this one until NULL extension is returned.
|
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* The Extension should NOT be freed by the user (not dynamically allocated).
|
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* Note it is assumed the Extension desc. header ('!') has been read.
|
|
*****************************************************************************/
|
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static int
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DGifGetExtension(GifFileType * GifFile,
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int *ExtCode,
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GifByteType ** Extension) {
|
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|
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GifByteType Buf;
|
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|
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if (READ(GifFile, &Buf, 1) != 1) {
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return GIF_ERROR;
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}
|
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*ExtCode = Buf;
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|
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return DGifGetExtensionNext(GifFile, Extension);
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}
|
|
|
|
/******************************************************************************
|
|
* Get a following extension block (see GIF manual) from gif file. This
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* routine should be called until NULL Extension is returned.
|
|
* The Extension should NOT be freed by the user (not dynamically allocated).
|
|
*****************************************************************************/
|
|
static int
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DGifGetExtensionNext(GifFileType * GifFile,
|
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GifByteType ** Extension) {
|
|
|
|
GifByteType Buf;
|
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GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
|
|
|
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if (READ(GifFile, &Buf, 1) != 1) {
|
|
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) {
|
|
return GIF_ERROR;
|
|
}
|
|
} else
|
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*Extension = NULL;
|
|
|
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return GIF_OK;
|
|
}
|
|
|
|
/******************************************************************************
|
|
* Get 2 bytes (word) from the given file:
|
|
*****************************************************************************/
|
|
static int
|
|
DGifGetWord(GifFileType * GifFile,
|
|
GifWord *Word) {
|
|
|
|
unsigned char c[2];
|
|
|
|
if (READ(GifFile, c, 2) != 2) {
|
|
return GIF_ERROR;
|
|
}
|
|
|
|
*Word = (((unsigned int)c[1]) << 8) + c[0];
|
|
return GIF_OK;
|
|
}
|
|
|
|
/******************************************************************************
|
|
* 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).
|
|
*****************************************************************************/
|
|
static int
|
|
DGifGetCodeNext(GifFileType * GifFile,
|
|
GifByteType ** CodeBlock) {
|
|
|
|
GifByteType Buf;
|
|
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
|
|
|
|
if (READ(GifFile, &Buf, 1) != 1) {
|
|
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) {
|
|
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;
|
|
GifPrefixType *Prefix;
|
|
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
|
|
|
|
READ(GifFile, &CodeSize, 1); /* 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;
|
|
}
|
|
|
|
/******************************************************************************
|
|
* 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;
|
|
GifPrefixType *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) {
|
|
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 {
|
|
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) {
|
|
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(GifPrefixType *Prefix,
|
|
int Code,
|
|
int ClearCode) {
|
|
|
|
int i = 0;
|
|
|
|
while (Code > ClearCode && i++ <= LZ_MAX_CODE)
|
|
Code = Prefix[Code];
|
|
return Code;
|
|
}
|
|
|
|
/******************************************************************************
|
|
* The LZ decompression input routine:
|
|
* This routine is responsible for the decompression of the bit stream from
|
|
* 8 bits (bytes) packets, into the real codes.
|
|
* Returns GIF_OK if read successfully.
|
|
*****************************************************************************/
|
|
static int
|
|
DGifDecompressInput(GifFileType * GifFile,
|
|
int *Code) {
|
|
|
|
GifFilePrivateType *Private = (GifFilePrivateType *)GifFile->Private;
|
|
|
|
GifByteType NextByte;
|
|
static unsigned short CodeMasks[] = {
|
|
0x0000, 0x0001, 0x0003, 0x0007,
|
|
0x000f, 0x001f, 0x003f, 0x007f,
|
|
0x00ff, 0x01ff, 0x03ff, 0x07ff,
|
|
0x0fff
|
|
};
|
|
/* The image can't contain more than LZ_BITS per code. */
|
|
if (Private->RunningBits > LZ_BITS) {
|
|
return GIF_ERROR;
|
|
}
|
|
|
|
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 we're using LZ_BITS bits already and we're at the max code, just
|
|
* keep using the table as it is, don't increment Private->RunningCode.
|
|
*/
|
|
if (Private->RunningCode < LZ_MAX_CODE + 2 &&
|
|
++Private->RunningCode > Private->MaxCode1 &&
|
|
Private->RunningBits < LZ_BITS) {
|
|
Private->MaxCode1 <<= 1;
|
|
Private->RunningBits++;
|
|
}
|
|
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 successful.
|
|
*****************************************************************************/
|
|
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) {
|
|
return GIF_ERROR;
|
|
}
|
|
/* There shouldn't be any empty data blocks here as the LZW spec
|
|
* says the LZW termination code should come first. Therefore we
|
|
* shouldn't be inside this routine at that point.
|
|
*/
|
|
if (Buf[0] == 0) {
|
|
return GIF_ERROR;
|
|
}
|
|
if (READ(GifFile, &Buf[1], Buf[0]) != Buf[0]) {
|
|
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 = 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);
|
|
}
|
|
|
|
/******************************************************************************
|
|
* 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 = malloc(sizeof(GifFileType));
|
|
if (GifFile == NULL) {
|
|
return NULL;
|
|
}
|
|
|
|
memset(GifFile, '\0', sizeof(GifFileType));
|
|
|
|
Private = malloc(sizeof(GifFilePrivateType));
|
|
if (!Private) {
|
|
free(GifFile);
|
|
return NULL;
|
|
}
|
|
|
|
GifFile->Private = (void*)Private;
|
|
|
|
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) {
|
|
free(Private);
|
|
free(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 (memcmp(GIF_STAMP, Buf, GIF_VERSION_POS) != 0) {
|
|
free(Private);
|
|
free(GifFile);
|
|
return NULL;
|
|
}
|
|
|
|
if (DGifGetScreenDesc(GifFile) == GIF_ERROR) {
|
|
free(Private);
|
|
free(GifFile);
|
|
return NULL;
|
|
}
|
|
|
|
return GifFile;
|
|
}
|
|
|
|
/******************************************************************************
|
|
* This routine should be called last, to close the GIF file.
|
|
*****************************************************************************/
|
|
int
|
|
DGifCloseFile(GifFileType * GifFile) {
|
|
|
|
GifFilePrivateType *Private;
|
|
|
|
if (GifFile == NULL)
|
|
return GIF_ERROR;
|
|
|
|
Private = (GifFilePrivateType *) GifFile->Private;
|
|
|
|
if (GifFile->Image.ColorMap) {
|
|
FreeMapObject(GifFile->Image.ColorMap);
|
|
GifFile->Image.ColorMap = NULL;
|
|
}
|
|
|
|
if (GifFile->SColorMap) {
|
|
FreeMapObject(GifFile->SColorMap);
|
|
GifFile->SColorMap = NULL;
|
|
}
|
|
|
|
if (Private) {
|
|
free(Private);
|
|
Private = NULL;
|
|
}
|
|
|
|
if (GifFile->SavedImages) {
|
|
FreeSavedImages(GifFile);
|
|
GifFile->SavedImages = NULL;
|
|
}
|
|
|
|
free(GifFile);
|
|
|
|
return GIF_OK;
|
|
}
|