wrlib/png.c

   1 /* png.c - load PNG image from file
   2  *
   3  *  Raster graphics library
   4  *
   5  *  Copyright (c) 1997 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 /* AIX requires this to be the first thing in the file.  */
  25 #ifdef __GNUC__
  26 # define alloca __builtin_alloca
  27 #else
  28 # if HAVE_ALLOCA_H
  29 #  include <alloca.h>
  30 # else
  31 #  ifdef _AIX
  32 #   pragma alloca
  33 #  else
  34 #   ifndef alloca /* predefined by HP cc +Olibcalls */
  35 char *alloca ();
  36 #   endif
  37 #  endif
  38 # endif
  39 #endif
  40
  41
  42 #ifdef USE_PNG
  43
  44 #include <stdlib.h>
  45 #include <stdio.h>
  46 #include <string.h>
  47
  48 #include <png.h>
  49
  50 #if PNG_LIBPNG_VER < 96
  51 #error libpng_must_be_more_at_least_0_96
  52 #endif
  53
  54 #include "wraster.h"
  55
  56
  57 RImage*
  58 RLoadPNG(RContext *context, char *file, int index)
  59 {
  60     char *tmp;
  61     RImage *image=NULL;
  62     FILE *f;
  63     png_structp png;
  64     png_infop pinfo, einfo;
  65     png_color_16p bkcolor;
  66     int alpha;
  67     int x, y, i;
  68     double gamma, sgamma;
  69     png_uint_32 width, height;
  70     int depth, junk, color_type;
  71     png_bytep *png_rows;
  72     unsigned char *r, *g, *b, *a;
  73
  74     f = fopen(file, "r");
  75     if (!f) {
  76         RErrorCode = RERR_OPEN;
  77         return NULL;
  78     }
  79     png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
  80                                  (png_error_ptr)NULL, (png_error_ptr)NULL);
  81     if (!png) {
  82         RErrorCode = RERR_NOMEMORY;
  83         fclose(f);
  84         return NULL;
  85     }
  86
  87     pinfo = png_create_info_struct(png);
  88     if (!pinfo) {
  89         RErrorCode = RERR_NOMEMORY;
  90         fclose(f);
  91         png_destroy_read_struct(&png, NULL, NULL);
  92         return NULL;
  93     }
  94
  95     einfo = png_create_info_struct(png);
  96     if (!einfo) {
  97         RErrorCode = RERR_NOMEMORY;
  98         fclose(f);
  99         png_destroy_read_struct(&png, &pinfo, NULL);
 100         return NULL;
 101     }
 102
 103     RErrorCode = RERR_INTERNAL;
 104     if (setjmp(png->jmpbuf)) {
 105         fclose(f);
 106         png_destroy_read_struct(&png, &pinfo, &einfo);
 107         if (image)
 108           RDestroyImage(image);
 109         return NULL;
 110     }
 111
 112     png_init_io(png, f);
 113
 114     png_read_info(png, pinfo);
 115
 116     png_get_IHDR(png, pinfo, &width, &height, &depth, &color_type,
 117                  &junk, &junk, &junk);
 118
 119
 120     /* check for an alpha channel */
 121     if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
 122       alpha = True;
 123     else
 124       alpha = (color_type & PNG_COLOR_MASK_ALPHA);
 125
 126     /* allocate RImage */
 127     image = RCreateImage(width, height, alpha);
 128     if (!image) {
 129         fclose(f);
 130         png_destroy_read_struct(&png, &pinfo, &einfo);
 131         return NULL;
 132     }
 133
 134     /* normalize to 8bpp with alpha channel */
 135     if (color_type == PNG_COLOR_TYPE_PALETTE && depth < 8)
 136         png_set_expand(png);
 137
 138     if (color_type == PNG_COLOR_TYPE_GRAY && depth < 8)
 139         png_set_expand(png);
 140
 141     if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
 142         png_set_expand(png);
 143
 144     if (depth == 16)
 145         png_set_strip_16(png);
 146
 147     if (color_type == PNG_COLOR_TYPE_GRAY ||
 148         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 149           png_set_gray_to_rgb(png);
 150
 151     /* set gamma correction */
 152     if ((context->attribs->flags & RC_GammaCorrection)
 153         && context->depth != 8) {
 154         sgamma = (context->attribs->rgamma + context->attribs->ggamma +
 155                   context->attribs->bgamma) / 3;
 156     } else if ((tmp = getenv("DISPLAY_GAMMA")) != NULL) {
 157         sgamma = atof(tmp);
 158         if (sgamma==0)
 159             sgamma = 1;
 160     } else {
 161         sgamma = 2.0;
 162     }
 163
 164     if (png_get_gAMA(png, pinfo, &gamma))
 165       png_set_gamma(png, sgamma, gamma);
 166     else
 167       png_set_gamma(png, sgamma, 0.45);
 168
 169     /* do the transforms */
 170     png_read_update_info(png, pinfo);
 171
 172     /* set background color */
 173     if (png_get_bKGD(png, pinfo, &bkcolor)) {
 174         image->background.red = bkcolor->red >> 8;
 175         image->background.green = bkcolor->green >> 8;
 176         image->background.blue = bkcolor->blue >> 8;
 177     }
 178
 179     png_rows = alloca(sizeof(char*)*height);
 180     if (!png_rows) {
 181         RErrorCode = RERR_NOMEMORY;
 182         fclose(f);
 183         RDestroyImage(image);
 184         png_destroy_read_struct(&png, &pinfo, &einfo);
 185 #ifdef C_ALLOCA
 186         alloca(0);
 187 #endif
 188         return NULL;
 189     }
 190     for (y=0; y<height; y++) {
 191         png_rows[y] = alloca(png_get_rowbytes(png, pinfo));
 192         if (!png_rows[y]) {
 193             RErrorCode = RERR_NOMEMORY;
 194             fclose(f);
 195             RDestroyImage(image);
 196             png_destroy_read_struct(&png, &pinfo, &einfo);
 197 #ifdef C_ALLOCA
 198             alloca(0);
 199 #endif
 200             return NULL;
 201         }
 202     }
 203     /* read data */
 204     png_read_image(png, png_rows);
 205
 206     png_read_end(png, einfo);
 207
 208     png_destroy_read_struct(&png, &pinfo, &einfo);
 209
 210     fclose(f);
 211
 212     r = image->data[0];
 213     g = image->data[1];
 214     b = image->data[2];
 215     a = image->data[3];
 216
 217     /* convert to RImage */
 218     if (alpha) {
 219         for (y=0; y<height; y++) {
 220             for (x=0, i=0; x<width; x++) {
 221                 *(r++) = *(png_rows[y]+i++);
 222                 *(g++) = *(png_rows[y]+i++);
 223                 *(b++) = *(png_rows[y]+i++);
 224                 *(a++) = *(png_rows[y]+i++);
 225             }
 226         }
 227     } else {
 228         for (y=0; y<height; y++) {
 229             for (x=0, i=0; x<width; x++) {
 230                 *(r++) = *(png_rows[y]+i++);
 231                 *(g++) = *(png_rows[y]+i++);
 232                 *(b++) = *(png_rows[y]+i++);
 233             }
 234         }
 235     }
 236 #ifdef C_ALLOCA
 237     alloca(0);
 238 #endif
 239     return image;
 240 }
 241
 242 #endif /* USE_PNG */