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., 51 Franklin St, Fifth Floor, Boston,
  20  *  MA 02110-1301, USA.
  21  */
  22
  23 #include <config.h>
  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 static int InterlacedOffset[] = { 0, 4, 2, 1 };
  36 static int InterlacedJumps[] = { 8, 8, 4, 2 };
  37
  38 /*
  39  * Partially based on code in gif2rgb from giflib, by Gershon Elber.
  40  */
  41 RImage *RLoadGIF(char *file, int index)
  42 {
  43         RImage *image = NULL;
  44         unsigned char *cptr;
  45         GifFileType *gif = NULL;
  46         GifPixelType *buffer = NULL;
  47         int i, j, k;
  48         int width, height;
  49         GifRecordType recType;
  50         ColorMapObject *colormap;
  51         unsigned char rmap[256];
  52         unsigned char gmap[256];
  53         unsigned char bmap[256];
  54
  55         if (index < 0)
  56                 index = 0;
  57
  58         /* default error message */
  59         RErrorCode = RERR_BADINDEX;
  60
  61         gif = DGifOpenFileName(file);
  62
  63         if (!gif) {
  64                 switch (GifLastError()) {
  65                 case D_GIF_ERR_OPEN_FAILED:
  66                         RErrorCode = RERR_OPEN;
  67                         break;
  68                 case D_GIF_ERR_READ_FAILED:
  69                         RErrorCode = RERR_READ;
  70                         break;
  71                 default:
  72                         RErrorCode = RERR_BADIMAGEFILE;
  73                         break;
  74                 }
  75                 return NULL;
  76         }
  77
  78         if (gif->SWidth < 1 || gif->SHeight < 1) {
  79                 DGifCloseFile(gif);
  80                 RErrorCode = RERR_BADIMAGEFILE;
  81                 return NULL;
  82         }
  83
  84         colormap = gif->SColorMap;
  85
  86         i = 0;
  87
  88         do {
  89                 int extCode;
  90                 GifByteType *extension;
  91
  92                 if (DGifGetRecordType(gif, &recType) == GIF_ERROR) {
  93                         goto giferr;
  94                 }
  95                 switch (recType) {
  96                 case IMAGE_DESC_RECORD_TYPE:
  97                         if (i++ != index)
  98                                 break;
  99
 100                         if (DGifGetImageDesc(gif) == GIF_ERROR) {
 101                                 goto giferr;
 102                         }
 103
 104                         width = gif->Image.Width;
 105                         height = gif->Image.Height;
 106
 107                         if (gif->Image.ColorMap)
 108                                 colormap = gif->Image.ColorMap;
 109
 110                         /* the gif specs talk about a default colormap, but it
 111                          * doesnt say what the heck is this default colormap */
 112                         if (!colormap) {
 113                                 /*
 114                                  * Well, since the spec says the colormap can be anything,
 115                                  * lets just render it with whatever garbage the stack
 116                                  * has :)
 117                                  *
 118
 119                                  goto bye;
 120                                  */
 121                         } else {
 122                                 for (j = 0; j < colormap->ColorCount; j++) {
 123                                         rmap[j] = colormap->Colors[j].Red;
 124                                         gmap[j] = colormap->Colors[j].Green;
 125                                         bmap[j] = colormap->Colors[j].Blue;
 126                                 }
 127                         }
 128
 129                         buffer = malloc(width * sizeof(GifColorType));
 130                         if (!buffer) {
 131                                 RErrorCode = RERR_NOMEMORY;
 132                                 goto bye;
 133                         }
 134
 135                         image = RCreateImage(width, height, False);
 136                         if (!image) {
 137                                 goto bye;
 138                         }
 139
 140                         if (gif->Image.Interlace) {
 141                                 int l;
 142                                 int pelsPerLine;
 143
 144                                 if (RRGBAFormat == image->format)
 145                                         pelsPerLine = width * 4;
 146                                 else
 147                                         pelsPerLine = width * 3;
 148
 149                                 for (j = 0; j < 4; j++) {
 150                                         for (k = InterlacedOffset[j]; k < height; k += InterlacedJumps[j]) {
 151                                                 if (DGifGetLine(gif, buffer, width) == GIF_ERROR) {
 152                                                         goto giferr;
 153                                                 }
 154                                                 cptr = image->data + (k * pelsPerLine);
 155                                                 for (l = 0; l < width; l++) {
 156                                                         int pixel = buffer[l];
 157                                                         *cptr++ = rmap[pixel];
 158                                                         *cptr++ = gmap[pixel];
 159                                                         *cptr++ = bmap[pixel];
 160                                                 }
 161                                         }
 162                                 }
 163                         } else {
 164                                 cptr = image->data;
 165                                 for (j = 0; j < height; j++) {
 166                                         if (DGifGetLine(gif, buffer, width) == GIF_ERROR) {
 167                                                 goto giferr;
 168                                         }
 169                                         for (k = 0; k < width; k++) {
 170                                                 int pixel = buffer[k];
 171                                                 *cptr++ = rmap[pixel];
 172                                                 *cptr++ = gmap[pixel];
 173                                                 *cptr++ = bmap[pixel];
 174                                                 if (RRGBAFormat == image->format)
 175                                                         cptr++;
 176                                         }
 177                                 }
 178                         }
 179                         break;
 180
 181                 case EXTENSION_RECORD_TYPE:
 182                         /* skip all extension blocks */
 183                         if (DGifGetExtension(gif, &extCode, &extension) == GIF_ERROR) {
 184                                 goto giferr;
 185                         }
 186                         while (extension) {
 187                                 if (DGifGetExtensionNext(gif, &extension) == GIF_ERROR) {
 188                                         goto giferr;
 189                                 }
 190                         }
 191                         break;
 192
 193                 default:
 194                         break;
 195                 }
 196         } while (recType != TERMINATE_RECORD_TYPE && i <= index);
 197
 198         /* yuck! */
 199         goto did_not_get_any_errors;
 200  giferr:
 201         switch (GifLastError()) {
 202         case D_GIF_ERR_OPEN_FAILED:
 203                 RErrorCode = RERR_OPEN;
 204                 break;
 205         case D_GIF_ERR_READ_FAILED:
 206                 RErrorCode = RERR_READ;
 207                 break;
 208         default:
 209                 RErrorCode = RERR_BADIMAGEFILE;
 210                 break;
 211         }
 212  bye:
 213         if (image)
 214                 RReleaseImage(image);
 215         image = NULL;
 216  did_not_get_any_errors:
 217
 218         if (buffer)
 219                 free(buffer);
 220
 221         if (gif)
 222                 DGifCloseFile(gif);
 223
 224         return image;
 225 }
 226
 227 #endif                          /* USE_GIF */