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