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     RErrorCode = RERR_BADINDEX;
  62
  63     gif = DGifOpenFileName(file);
  64
  65     if (!gif) {
  66         switch (GifLastError()) {
  67          case D_GIF_ERR_OPEN_FAILED:
  68             RErrorCode = RERR_OPEN;
  69             break;
  70          case D_GIF_ERR_READ_FAILED:
  71             RErrorCode = RERR_READ;
  72             break;
  73          default:
  74             RErrorCode = RERR_BADIMAGEFILE;
  75             break;
  76         }
  77         return NULL;
  78     }
  79
  80     colormap = gif->SColorMap;
  81
  82     i = 0;
  83
  84     do {
  85         int extCode;
  86         GifByteType *extension;
  87
  88         if (DGifGetRecordType(gif, &recType) == GIF_ERROR) {
  89             goto giferr;
  90         }
  91         switch (recType) {
  92          case IMAGE_DESC_RECORD_TYPE:
  93             if (i++ != index)
  94                 break;
  95
  96             if (DGifGetImageDesc(gif)==GIF_ERROR) {
  97                 goto giferr;
  98             }
  99
 100             width = gif->Image.Width;
 101             height = gif->Image.Height;
 102
 103             if (gif->Image.ColorMap)
 104                 colormap = gif->Image.ColorMap;
 105
 106             /* the gif specs talk about a default colormap, but it
 107              * doesnt say what the heck is this default colormap */
 108             if (!colormap) {
 109                 /*
 110                  * Well, since the spec says the colormap can be anything,
 111                  * lets just render it with whatever garbage the stack
 112                  * has :)
 113                  *
 114
 115                 goto bye;
 116                  */
 117             } else {
 118                 for (j = 0; j < colormap->ColorCount; j++) {
 119                     rmap[j] = colormap->Colors[j].Red;
 120                     gmap[j] = colormap->Colors[j].Green;
 121                     bmap[j] = colormap->Colors[j].Blue;
 122                 }
 123             }
 124
 125             buffer = malloc(width * sizeof(GifColorType));
 126             if (!buffer) {
 127                 RErrorCode = RERR_NOMEMORY;
 128                 goto bye;
 129             }
 130
 131             image = RCreateImage(width, height, False);
 132             if (!image) {
 133                 goto bye;
 134             }
 135
 136             if (gif->Image.Interlace) {
 137                 int l;
 138
 139                 for (j = 0; j < 4; j++) {
 140                     for (k = InterlacedOffset[j]; k < height;
 141                          k += InterlacedJumps[j]) {
 142                         if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 143                             goto giferr;
 144                         }
 145                         ofs = k*width;
 146                         for (l = 0; l < width; l++, ofs++) {
 147                             int pixel = buffer[l];
 148                             image->data[0][ofs] = rmap[pixel];
 149                             image->data[1][ofs] = gmap[pixel];
 150                             image->data[2][ofs] = bmap[pixel];
 151                         }
 152                     }
 153                 }
 154             } else {
 155                 for (j = 0; j < height; j++) {
 156                     if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 157                         goto giferr;
 158                     }
 159                     for (k = 0; k < width; k++, ofs++) {
 160                         int pixel = buffer[k];
 161                         image->data[0][ofs] = rmap[pixel];
 162                         image->data[1][ofs] = gmap[pixel];
 163                         image->data[2][ofs] = bmap[pixel];
 164                     }
 165                 }
 166             }
 167             break;
 168
 169          case EXTENSION_RECORD_TYPE:
 170             /* skip all extension blocks */
 171             if (DGifGetExtension(gif, &extCode, &extension)==GIF_ERROR) {
 172                 goto giferr;
 173             }
 174             while (extension) {
 175                 if (DGifGetExtensionNext(gif, &extension)==GIF_ERROR) {
 176                     goto giferr;
 177                 }
 178             }
 179             break;
 180
 181          default:
 182             break;
 183         }
 184     } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 185
 186     /* yuck! */
 187     goto did_not_get_any_errors;
 188 giferr:
 189     switch (GifLastError()) {
 190      case D_GIF_ERR_OPEN_FAILED:
 191         RErrorCode = RERR_OPEN;
 192         break;
 193      case D_GIF_ERR_READ_FAILED:
 194         RErrorCode = RERR_READ;
 195         break;
 196      default:
 197         RErrorCode = RERR_BADIMAGEFILE;
 198         break;
 199     }
 200 bye:
 201     if (image)
 202         RDestroyImage(image);
 203     image = NULL;
 204 did_not_get_any_errors:
 205
 206     if (buffer)
 207         free(buffer);
 208
 209     if (gif)
 210         DGifCloseFile(gif);
 211
 212     return image;
 213 }
 214
 215 #endif /* USE_GIF */