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     unsigned char *cptr;
  48     GifFileType *gif = NULL;
  49     GifPixelType *buffer = NULL;
  50     int i, j, k;
  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                 int pelsPerLine;
 140
 141                 if (RRGBAFormat==image->format)
 142                     pelsPerLine = width * 4;
 143                 else
 144                     pelsPerLine = width * 3;
 145
 146                 for (j = 0; j < 4; j++) {
 147                     for (k = InterlacedOffset[j]; k < height;
 148                          k += InterlacedJumps[j]) {
 149                         if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 150                             goto giferr;
 151                         }
 152                         cptr = image->data + (k*pelsPerLine);
 153                         for (l = 0; l < width; l++) {
 154                             int pixel = buffer[l];
 155                             *cptr++ = rmap[pixel];
 156                             *cptr++ = gmap[pixel];
 157                             *cptr++ = bmap[pixel];
 158                         }
 159                     }
 160                 }
 161             } else {
 162                 cptr = image->data;
 163                 for (j = 0; j < height; j++) {
 164                     if (DGifGetLine(gif, buffer, width)==GIF_ERROR) {
 165                         goto giferr;
 166                     }
 167                     for (k = 0; k < width; k++) {
 168                         int pixel = buffer[k];
 169                         *cptr++ = rmap[pixel];
 170                         *cptr++ = gmap[pixel];
 171                         *cptr++ = bmap[pixel];
 172                         if (RRGBAFormat==image->format)
 173                             cptr++;
 174                     }
 175                 }
 176             }
 177             break;
 178
 179          case EXTENSION_RECORD_TYPE:
 180             /* skip all extension blocks */
 181             if (DGifGetExtension(gif, &extCode, &extension)==GIF_ERROR) {
 182                 goto giferr;
 183             }
 184             while (extension) {
 185                 if (DGifGetExtensionNext(gif, &extension)==GIF_ERROR) {
 186                     goto giferr;
 187                 }
 188             }
 189             break;
 190
 191          default:
 192             break;
 193         }
 194     } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 195
 196     /* yuck! */
 197     goto did_not_get_any_errors;
 198 giferr:
 199     switch (GifLastError()) {
 200      case D_GIF_ERR_OPEN_FAILED:
 201         RErrorCode = RERR_OPEN;
 202         break;
 203      case D_GIF_ERR_READ_FAILED:
 204         RErrorCode = RERR_READ;
 205         break;
 206      default:
 207         RErrorCode = RERR_BADIMAGEFILE;
 208         break;
 209     }
 210 bye:
 211     if (image)
 212         RReleaseImage(image);
 213     image = NULL;
 214 did_not_get_any_errors:
 215
 216     if (buffer)
 217         free(buffer);
 218
 219     if (gif)
 220         DGifCloseFile(gif);
 221
 222     return image;
 223 }
 224
 225 #endif /* USE_GIF */