wrlib/gif.c

   1 /* gif.c - load GIF image from file
   2  *
   3  *  Raster graphics library
   4  *
   5  *  Copyright (c) 1998 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
  25 #ifdef USE_GIF
  26
  27 #include <stdlib.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30
  31 #include <gif_lib.h>
  32
  33 #include "wraster.h"
  34
  35
  36 static int InterlacedOffset[] = { 0, 4, 2, 1 };
  37 static int InterlacedJumps[] = { 8, 8, 4, 2 };
  38
  39
  40 /*
  41  * Partially based on code in gif2rgb from giflib, by Gershon Elber.
  42  */
  43 RImage*
  44 RLoadGIF(RContext *context, char *file, int index)
  45 {
  46     RImage *image = NULL;
  47 #if 0
  48     GifFileType *gif = NULL;
  49     GifPixelType *buffer = NULL;
  50     int i, j, k, ofs = 0;
  51     int width, height;
  52     GifRecordType recType;
  53     ColorMapObject *colormap;
  54     unsigned char rmap[256];
  55     unsigned char gmap[256];
  56     unsigned char bmap[256];
  57
  58     if (index < 0)
  59         index = 0;
  60
  61     /* default error message */
  62     RErrorCode = RERR_BADINDEX;
  63
  64     gif = DGifOpenFileName(file);
  65
  66     if (!gif) {
  67         switch (GifLastError()) {
  68          case D_GIF_ERR_OPEN_FAILED:
  69             RErrorCode = RERR_OPEN;
  70             break;
  71          case D_GIF_ERR_READ_FAILED:
  72             RErrorCode = RERR_READ;
  73             break;
  74          default:
  75             RErrorCode = RERR_BADIMAGEFILE;
  76             break;
  77         }
  78         return NULL;
  79     }
  80
  81     colormap = gif->SColorMap;
  82
  83     i = 0;
  84
  85     do {
  86         int extCode;
  87         GifByteType *extension;
  88
  89         if (DGifGetRecordType(gif, &recType) == GIF_ERROR) {
  90             goto giferr;
  91         }
  92         switch (recType) {
  93          case IMAGE_DESC_RECORD_TYPE:
  94             if (i++ != index)
  95                 break;
  96
  97             if (DGifGetImageDesc(gif)==GIF_ERROR) {
  98                 goto giferr;
  99             }
 100
 101             width = gif->Image.Width;
 102             height = gif->Image.Height;
 103
 104             if (gif->Image.ColorMap)
 105                 colormap = gif->Image.ColorMap;
 106
 107             /* the gif specs talk about a default colormap, but it
 108              * doesnt say what the heck is this default colormap */
 109             if (!colormap) {
 110                 /*
 111                  * Well, since the spec says the colormap can be anything,
 112                  * lets just render it with whatever garbage the stack
 113                  * has :)
 114                  *
 115
 116                 goto bye;
 117                  */
 118             } else {
 119                 for (j = 0; j < colormap->ColorCount; j++) {
 120                     rmap[j] = colormap->Colors[j].Red;
 121                     gmap[j] = colormap->Colors[j].Green;
 122                     bmap[j] = colormap->Colors[j].Blue;
 123                 }
 124             }
 125
 126             buffer = malloc(width * sizeof(GifColorType));
 127             if (!buffer) {
 128                 RErrorCode = RERR_NOMEMORY;
 129                 goto bye;
 130             }
 131
 132             image = RCreateImage(width, height, False);
 133             if (!image) {
 134                 goto bye;
 135             }
 136
 137             if (gif->Image.Interlace) {
 138                 int l;
 139
 140                 for (j = 0; j < 4; j++) {
 141                     for (k = InterlacedOffset[j]; k < height;
 142                          k += InterlacedJumps[j]) {
 143                         if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 144                             goto giferr;
 145                         }
 146                         ofs = k*width;
 147                         for (l = 0; l < width; l++, ofs++) {
 148                             int pixel = buffer[l];
 149                             image->data[0][ofs] = rmap[pixel];
 150                             image->data[1][ofs] = gmap[pixel];
 151                             image->data[2][ofs] = bmap[pixel];
 152                         }
 153                     }
 154                 }
 155             } else {
 156                 for (j = 0; j < height; j++) {
 157                     if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 158                         goto giferr;
 159                     }
 160                     for (k = 0; k < width; k++, ofs++) {
 161                         int pixel = buffer[k];
 162                         image->data[0][ofs] = rmap[pixel];
 163                         image->data[1][ofs] = gmap[pixel];
 164                         image->data[2][ofs] = bmap[pixel];
 165                     }
 166                 }
 167             }
 168             break;
 169
 170          case EXTENSION_RECORD_TYPE:
 171             /* skip all extension blocks */
 172             if (DGifGetExtension(gif, &extCode, &extension)==GIF_ERROR) {
 173                 goto giferr;
 174             }
 175             while (extension) {
 176                 if (DGifGetExtensionNext(gif, &extension)==GIF_ERROR) {
 177                     goto giferr;
 178                 }
 179             }
 180             break;
 181
 182          default:
 183             break;
 184         }
 185     } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 186
 187     /* yuck! */
 188     goto did_not_get_any_errors;
 189 giferr:
 190     switch (GifLastError()) {
 191      case D_GIF_ERR_OPEN_FAILED:
 192         RErrorCode = RERR_OPEN;
 193         break;
 194      case D_GIF_ERR_READ_FAILED:
 195         RErrorCode = RERR_READ;
 196         break;
 197      default:
 198         RErrorCode = RERR_BADIMAGEFILE;
 199         break;
 200     }
 201 bye:
 202     if (image)
 203         RDestroyImage(image);
 204     image = NULL;
 205 did_not_get_any_errors:
 206
 207     if (buffer)
 208         free(buffer);
 209
 210     if (gif)
 211         DGifCloseFile(gif);
 212 #endif
 213     return image;
 214 }
 215
 216 #endif /* USE_GIF */