Pileus Git - ~andy/gtk/blob - gdk-pixbuf/io-gif.c

   1 /* GdkPixbuf library - GIF image loader
   2  *
   3  * Copyright (C) 1999 Mark Crichton
   4  * Copyright (C) 1999 The Free Software Foundation
   5  *
   6  * Authors: Mark Crichton <crichton@gimp.org>
   7  *          Federico Mena-Quintero <federico@gimp.org>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Library General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Library General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Library General Public
  20  * License along with this library; if not, write to the
  21  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22  * Boston, MA 02111-1307, USA.
  23  */
  24
  25 #include <config.h>
  26 #include <stdio.h>
  27 #include <glib.h>
  28 #include <gif_lib.h>
  29 #include "gdk-pixbuf.h"
  30
  31 \f
  32
  33 /* Destroy notification function for the libart pixbuf */
  34 static void
  35 free_buffer (gpointer user_data, gpointer data)
  36 {
  37         free (data);
  38 }
  39
  40 /* Shared library entry point */
  41 GdkPixbuf *
  42 image_load (FILE *f)
  43 {
  44         gint fn, is_trans = FALSE;
  45         gint done = 0;
  46         gint t_color = -1;
  47         gint w, h, i, j;
  48         guchar *pixels, *tmpptr;
  49         GifFileType *gif;
  50         GifRowType *rows;
  51         GifRecordType rec;
  52         ColorMapObject *cmap;
  53         int intoffset[] = { 0, 4, 2, 1 };
  54         int intjump[] = { 8, 8, 4, 2 };
  55
  56         fn = fileno (f);
  57         gif = DGifOpenFileHandle (fn);
  58
  59         if (!gif) {
  60                 g_warning ("DGifOpenFilehandle FAILED");
  61                 PrintGifError ();
  62                 return NULL;
  63         }
  64
  65         /* Now we do the ungodly mess of loading a GIF image I used to remember
  66          * when I liked this file format...  of course, I still coded in
  67          * assembler then.  This comes from gdk_imlib, with some cleanups.
  68          */
  69
  70         do {
  71                 if (DGifGetRecordType (gif, &rec) == GIF_ERROR) {
  72                         PrintGifError ();
  73                         DGifCloseFile (gif);
  74                         return NULL;
  75                 }
  76
  77                 if (rec == IMAGE_DESC_RECORD_TYPE && !done) {
  78                         if (DGifGetImageDesc (gif) == GIF_ERROR) {
  79                                 PrintGifError ();
  80                                 DGifCloseFile (gif);
  81                                 return NULL;
  82                         }
  83
  84                         /* Note the careful use of malloc/calloc vs. g_malloc;
  85                          * we want to fail gracefully if we run out of memory.
  86                          */
  87
  88                         w = gif->Image.Width;
  89                         h = gif->Image.Height;
  90                         rows = calloc (sizeof (GifRowType *), h);
  91                         if (!rows) {
  92                                 DGifCloseFile (gif);
  93                                 return NULL;
  94                         }
  95
  96                         for (i = 0; i < h; i++) {
  97                                 rows[i] = calloc (sizeof (GifPixelType), w);
  98                                 if (!rows[i]) {
  99                                         DGifCloseFile (gif);
 100                                         for (j = 0; j < h; j++)
 101                                                 if (rows[j])
 102                                                         free (rows[j]);
 103
 104                                         free (rows);
 105                                         return NULL;
 106                                 }
 107                         }
 108
 109                         if (gif->Image.Interlace)
 110                                 for (i = 0; i < 4; i++) {
 111                                         for (j = intoffset[i]; j < h; j += intjump[i])
 112                                                 DGifGetLine (gif, rows[j], w);
 113                                 }
 114                         else
 115                                 for (i = 0; i < h; i++)
 116                                         DGifGetLine (gif, rows[i], w);
 117
 118                         done = 1;
 119                 } else if (rec == EXTENSION_RECORD_TYPE) {
 120                         gint ext_code;
 121                         GifByteType *ext;
 122
 123                         DGifGetExtension (gif, &ext_code, &ext);
 124                         while (ext) {
 125                                 if ((ext_code == 0xf9) && (ext[1] & 1) && (t_color < 0)) {
 126                                         is_trans = TRUE;
 127                                         t_color = (gint) ext[4];
 128                                 }
 129
 130                                 ext = NULL;
 131                                 DGifGetExtensionNext (gif, &ext);
 132                         }
 133                 }
 134         } while (rec != TERMINATE_RECORD_TYPE);
 135
 136         /* Ok, we're loaded, now to convert from indexed -> RGB with alpha if necessary */
 137
 138         if (is_trans)
 139                 pixels = malloc (h * w * 4);
 140         else
 141                 pixels = malloc (h * w * 3);
 142
 143         tmpptr = pixels;
 144
 145         if (!pixels) {
 146                 DGifCloseFile (gif);
 147                 for (i = 0; i < h; i++)
 148                         if (rows[i])
 149                                 free (rows[i]);
 150
 151                 free (rows);
 152                 return NULL;
 153         }
 154
 155         cmap = (gif->Image.ColorMap ? gif->Image.ColorMap : gif->SColorMap);
 156
 157         /* Unindex the data, and pack it in RGB(A) order */
 158
 159         for (i = 0; i < h; i++) {
 160                 for (j = 0; j < w; j++) {
 161                         tmpptr[0] = cmap->Colors[rows[i][j]].Red;
 162                         tmpptr[1] = cmap->Colors[rows[i][j]].Green;
 163                         tmpptr[2] = cmap->Colors[rows[i][j]].Blue;
 164
 165                         if (is_trans) {
 166                                 if (rows[i][j] == t_color)
 167                                         tmpptr[3] = 0;
 168                                 else
 169                                         tmpptr[3] = 0xFF;
 170
 171                                 tmpptr += 4;
 172                         } else
 173                                 tmpptr += 3;
 174                 }
 175
 176                 free (rows[i]);
 177         }
 178
 179         free (rows);
 180         DGifCloseFile (gif);
 181
 182         return gdk_pixbuf_new_from_data (pixels, ART_PIX_RGB, is_trans,
 183                                          w, h, is_trans ? (w * 4) : (w * 3),
 184                                          free_buffer, NULL);
 185 }