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     GifFileType *gif = NULL;
  48     GifPixelType *buffer = NULL;
  49     int i, j, k, ofs = 0;
  50     int width, height;
  51     GifRecordType recType;
  52     ColorMapObject *colormap;
  53     unsigned char rmap[256];
  54     unsigned char gmap[256];
  55     unsigned char bmap[256];
  56
  57     if (index < 0)
  58         index = 0;
  59
  60     /* default error message */
  61     sprintf(RErrorString, "file does not contain image of index %i", index);
  62
  63     gif = DGifOpenFileName(file);
  64
  65     if (!gif) {
  66         sprintf(RErrorString, "could not load gif file");
  67         return NULL;
  68     }
  69
  70     colormap = gif->SColorMap;
  71
  72     i = 0;
  73
  74     do {
  75         int extCode;
  76         GifByteType *extension;
  77
  78         if (DGifGetRecordType(gif, &recType) == GIF_ERROR) {
  79             sprintf(RErrorString, "error while loading gif");
  80             goto bye;
  81         }
  82         switch (recType) {
  83          case IMAGE_DESC_RECORD_TYPE:
  84             if (i++ != index)
  85                 break;
  86
  87             if (DGifGetImageDesc(gif)==GIF_ERROR) {
  88                 sprintf(RErrorString, "error while loading gif");
  89                 goto bye;
  90             }
  91
  92             width = gif->Image.Width;
  93             height = gif->Image.Height;
  94
  95             if (gif->Image.ColorMap)
  96                 colormap = gif->Image.ColorMap;
  97
  98             /* the gif specs talk about a default colormap, but it
  99              * doesnt say what the heck is this default colormap */
 100             if (!colormap) {
 101                 /*
 102                  * Well, since the spec says the colormap can be anything,
 103                  * lets just render it with whatever garbage the stack
 104                  * has :)
 105                  *
 106                 sprintf(RErrorString, "bad gif file");
 107
 108                 goto bye;
 109                  */
 110             } else {
 111                 for (j = 0; j < colormap->ColorCount; j++) {
 112                     rmap[j] = colormap->Colors[j].Red;
 113                     gmap[j] = colormap->Colors[j].Green;
 114                     bmap[j] = colormap->Colors[j].Blue;
 115                 }
 116             }
 117
 118             buffer = malloc(width * sizeof(GifColorType));
 119             if (!buffer) {
 120                 sprintf(RErrorString, "out of memory while loading gif");
 121                 goto bye;
 122             }
 123
 124             image = RCreateImage(width, height, False);
 125             if (!image) {
 126                 sprintf(RErrorString, "out of memory while loading gif");
 127                 goto bye;
 128             }
 129
 130             if (gif->Image.Interlace) {
 131                 int l;
 132
 133                 for (j = 0; j < 4; j++) {
 134                     for (k = InterlacedOffset[j]; k < height;
 135                          k += InterlacedJumps[j]) {
 136                         if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 137                             sprintf(RErrorString, "error while loading gif");
 138                             goto bye;
 139                         }
 140                         ofs = k*width;
 141                         for (l = 0; l < width; l++, ofs++) {
 142                             int pixel = buffer[l];
 143                             image->data[0][ofs] = rmap[pixel];
 144                             image->data[1][ofs] = gmap[pixel];
 145                             image->data[2][ofs] = bmap[pixel];
 146                         }
 147                     }
 148                 }
 149             } else {
 150                 for (j = 0; j < height; j++) {
 151                     if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 152                         sprintf(RErrorString, "error while loading gif");
 153                         goto bye;
 154                     }
 155                     for (k = 0; k < width; k++, ofs++) {
 156                         int pixel = buffer[k];
 157                         image->data[0][ofs] = rmap[pixel];
 158                         image->data[1][ofs] = gmap[pixel];
 159                         image->data[2][ofs] = bmap[pixel];
 160                     }
 161                 }
 162             }
 163             break;
 164
 165          case EXTENSION_RECORD_TYPE:
 166             /* skip all extension blocks */
 167             if (DGifGetExtension(gif, &extCode, &extension)==GIF_ERROR) {
 168                 sprintf(RErrorString, "error while loading gif");
 169                 goto bye;
 170             }
 171             while (extension) {
 172                 if (DGifGetExtensionNext(gif, &extension)==GIF_ERROR) {
 173                     sprintf(RErrorString, "error while loading gif");
 174                     goto bye;
 175                 }
 176             }
 177             break;
 178
 179          default:
 180             break;
 181         }
 182     } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 183
 184     /* yuck! */
 185     goto did_not_get_any_errors;
 186 bye:
 187     if (image)
 188         RDestroyImage(image);
 189     image = NULL;
 190 did_not_get_any_errors:
 191
 192     if (buffer)
 193         free(buffer);
 194
 195     if (gif)
 196         DGifCloseFile(gif);
 197
 198     return image;
 199 }
 200
 201 #endif /* USE_GIF */