wrlib/gif.c

   1 /* gif.c - load GIF image from file
   2  *
   3  * Raster graphics library
   4  *
   5  * Copyright (c) 1998-2003 Alfredo K. Kojima
   6  *
   7  *  This library is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU Library General Public
   9  *  License as published by the Free Software Foundation; either
  10  *  version 2 of the License, or (at your option) any later version.
  11  *
  12  *  This library is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  *  Library General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU Library General Public
  18  *  License along with this library; if not, write to the Free
  19  *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <config.h>
  23
  24 #ifdef USE_GIF
  25
  26 #include <stdlib.h>
  27 #include <stdio.h>
  28 #include <string.h>
  29
  30 #include <gif_lib.h>
  31
  32 #include "wraster.h"
  33
  34 static int InterlacedOffset[] = { 0, 4, 2, 1 };
  35 static int InterlacedJumps[] = { 8, 8, 4, 2 };
  36
  37 /*
  38  * Partially based on code in gif2rgb from giflib, by Gershon Elber.
  39  */
  40 RImage *RLoadGIF(RContext * context, char *file, int index)
  41 {
  42         RImage *image = NULL;
  43         unsigned char *cptr;
  44         GifFileType *gif = NULL;
  45         GifPixelType *buffer = NULL;
  46         int i, j, k;
  47         int width, height;
  48         GifRecordType recType;
  49         ColorMapObject *colormap;
  50         unsigned char rmap[256];
  51         unsigned char gmap[256];
  52         unsigned char bmap[256];
  53
  54         if (index < 0)
  55                 index = 0;
  56
  57         /* default error message */
  58         RErrorCode = RERR_BADINDEX;
  59
  60         gif = DGifOpenFileName(file);
  61
  62         if (!gif) {
  63                 switch (GifLastError()) {
  64                 case D_GIF_ERR_OPEN_FAILED:
  65                         RErrorCode = RERR_OPEN;
  66                         break;
  67                 case D_GIF_ERR_READ_FAILED:
  68                         RErrorCode = RERR_READ;
  69                         break;
  70                 default:
  71                         RErrorCode = RERR_BADIMAGEFILE;
  72                         break;
  73                 }
  74                 return NULL;
  75         }
  76
  77         if (gif->SWidth < 1 || gif->SHeight < 1) {
  78                 DGifCloseFile(gif);
  79                 RErrorCode = RERR_BADIMAGEFILE;
  80                 return NULL;
  81         }
  82
  83         colormap = gif->SColorMap;
  84
  85         i = 0;
  86
  87         do {
  88                 int extCode;
  89                 GifByteType *extension;
  90
  91                 if (DGifGetRecordType(gif, &recType) == GIF_ERROR) {
  92                         goto giferr;
  93                 }
  94                 switch (recType) {
  95                 case IMAGE_DESC_RECORD_TYPE:
  96                         if (i++ != index)
  97                                 break;
  98
  99                         if (DGifGetImageDesc(gif) == GIF_ERROR) {
 100                                 goto giferr;
 101                         }
 102
 103                         width = gif->Image.Width;
 104                         height = gif->Image.Height;
 105
 106                         if (gif->Image.ColorMap)
 107                                 colormap = gif->Image.ColorMap;
 108
 109                         /* the gif specs talk about a default colormap, but it
 110                          * doesnt say what the heck is this default colormap */
 111                         if (!colormap) {
 112                                 /*
 113                                  * Well, since the spec says the colormap can be anything,
 114                                  * lets just render it with whatever garbage the stack
 115                                  * has :)
 116                                  *
 117
 118                                  goto bye;
 119                                  */
 120                         } else {
 121                                 for (j = 0; j < colormap->ColorCount; j++) {
 122                                         rmap[j] = colormap->Colors[j].Red;
 123                                         gmap[j] = colormap->Colors[j].Green;
 124                                         bmap[j] = colormap->Colors[j].Blue;
 125                                 }
 126                         }
 127
 128                         buffer = malloc(width * sizeof(GifColorType));
 129                         if (!buffer) {
 130                                 RErrorCode = RERR_NOMEMORY;
 131                                 goto bye;
 132                         }
 133
 134                         image = RCreateImage(width, height, False);
 135                         if (!image) {
 136                                 goto bye;
 137                         }
 138
 139                         if (gif->Image.Interlace) {
 140                                 int l;
 141                                 int pelsPerLine;
 142
 143                                 if (RRGBAFormat == image->format)
 144                                         pelsPerLine = width * 4;
 145                                 else
 146                                         pelsPerLine = width * 3;
 147
 148                                 for (j = 0; j < 4; j++) {
 149                                         for (k = InterlacedOffset[j]; k < height; k += InterlacedJumps[j]) {
 150                                                 if (DGifGetLine(gif, buffer, width) == GIF_ERROR) {
 151                                                         goto giferr;
 152                                                 }
 153                                                 cptr = image->data + (k * pelsPerLine);
 154                                                 for (l = 0; l < width; l++) {
 155                                                         int pixel = buffer[l];
 156                                                         *cptr++ = rmap[pixel];
 157                                                         *cptr++ = gmap[pixel];
 158                                                         *cptr++ = bmap[pixel];
 159                                                 }
 160                                         }
 161                                 }
 162                         } else {
 163                                 cptr = image->data;
 164                                 for (j = 0; j < height; j++) {
 165                                         if (DGifGetLine(gif, buffer, width) == GIF_ERROR) {
 166                                                 goto giferr;
 167                                         }
 168                                         for (k = 0; k < width; k++) {
 169                                                 int pixel = buffer[k];
 170                                                 *cptr++ = rmap[pixel];
 171                                                 *cptr++ = gmap[pixel];
 172                                                 *cptr++ = bmap[pixel];
 173                                                 if (RRGBAFormat == image->format)
 174                                                         cptr++;
 175                                         }
 176                                 }
 177                         }
 178                         break;
 179
 180                 case EXTENSION_RECORD_TYPE:
 181                         /* skip all extension blocks */
 182                         if (DGifGetExtension(gif, &extCode, &extension) == GIF_ERROR) {
 183                                 goto giferr;
 184                         }
 185                         while (extension) {
 186                                 if (DGifGetExtensionNext(gif, &extension) == GIF_ERROR) {
 187                                         goto giferr;
 188                                 }
 189                         }
 190                         break;
 191
 192                 default:
 193                         break;
 194                 }
 195         } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 196
 197         /* yuck! */
 198         goto did_not_get_any_errors;
 199  giferr:
 200         switch (GifLastError()) {
 201         case D_GIF_ERR_OPEN_FAILED:
 202                 RErrorCode = RERR_OPEN;
 203                 break;
 204         case D_GIF_ERR_READ_FAILED:
 205                 RErrorCode = RERR_READ;
 206                 break;
 207         default:
 208                 RErrorCode = RERR_BADIMAGEFILE;
 209                 break;
 210         }
 211  bye:
 212         if (image)
 213                 RReleaseImage(image);
 214         image = NULL;
 215  did_not_get_any_errors:
 216
 217         if (buffer)
 218                 free(buffer);
 219
 220         if (gif)
 221                 DGifCloseFile(gif);
 222
 223         return image;
 224 }
 225
 226 #endif                          /* USE_GIF */