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 #include "wraster.h"
  51
  52
  53 RImage*
  54 RLoadPNG(RContext *context, char *file, int index)
  55 {
  56     char *tmp;
  57     RImage *image=NULL;
  58     FILE *f;
  59     png_structp png;
  60     png_infop pinfo, einfo;
  61     png_color_16p bkcolor;
  62     int alpha;
  63     int x, y, i;
  64     double gamma, sgamma;
  65     png_uint_32 width, height;
  66     int depth, junk, color_type;
  67     png_bytep *png_rows;
  68     unsigned char *ptr;
  69
  70     f = fopen(file, "r");
  71     if (!f) {
  72         RErrorCode = RERR_OPEN;
  73         return NULL;
  74     }
  75     png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
  76                                  (png_error_ptr)NULL, (png_error_ptr)NULL);
  77     if (!png) {
  78         RErrorCode = RERR_NOMEMORY;
  79         fclose(f);
  80         return NULL;
  81     }
  82
  83     pinfo = png_create_info_struct(png);
  84     if (!pinfo) {
  85         RErrorCode = RERR_NOMEMORY;
  86         fclose(f);
  87         png_destroy_read_struct(&png, NULL, NULL);
  88         return NULL;
  89     }
  90
  91     einfo = png_create_info_struct(png);
  92     if (!einfo) {
  93         RErrorCode = RERR_NOMEMORY;
  94         fclose(f);
  95         png_destroy_read_struct(&png, &pinfo, NULL);
  96         return NULL;
  97     }
  98
  99     RErrorCode = RERR_INTERNAL;
 100     if (setjmp(png->jmpbuf)) {
 101         fclose(f);
 102         png_destroy_read_struct(&png, &pinfo, &einfo);
 103         if (image)
 104           RDestroyImage(image);
 105         return NULL;
 106     }
 107
 108     png_init_io(png, f);
 109
 110     png_read_info(png, pinfo);
 111
 112     png_get_IHDR(png, pinfo, &width, &height, &depth, &color_type,
 113                  &junk, &junk, &junk);
 114
 115
 116     /* check for an alpha channel */
 117     if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
 118       alpha = True;
 119     else
 120       alpha = (color_type & PNG_COLOR_MASK_ALPHA);
 121
 122     /* allocate RImage */
 123     image = RCreateImage(width, height, alpha);
 124     if (!image) {
 125         fclose(f);
 126         png_destroy_read_struct(&png, &pinfo, &einfo);
 127         return NULL;
 128     }
 129
 130     /* normalize to 8bpp with alpha channel */
 131     if (color_type == PNG_COLOR_TYPE_PALETTE && depth <= 8)
 132         png_set_expand(png);
 133
 134     if (color_type == PNG_COLOR_TYPE_GRAY && depth <= 8)
 135         png_set_expand(png);
 136
 137     if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
 138         png_set_expand(png);
 139
 140     if (depth == 16)
 141         png_set_strip_16(png);
 142
 143     if (color_type == PNG_COLOR_TYPE_GRAY ||
 144         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
 145           png_set_gray_to_rgb(png);
 146
 147     /* set gamma correction */
 148     if ((context->attribs->flags & RC_GammaCorrection)
 149         && context->depth != 8) {
 150         sgamma = (context->attribs->rgamma + context->attribs->ggamma +
 151                   context->attribs->bgamma) / 3;
 152     } else if ((tmp = getenv("DISPLAY_GAMMA")) != NULL) {
 153         sgamma = atof(tmp);
 154         if (sgamma==0)
 155             sgamma = 1;
 156     } else {
 157         /* blah */
 158         sgamma = 2.2;
 159     }
 160
 161     if (png_get_gAMA(png, pinfo, &gamma))
 162       png_set_gamma(png, sgamma, gamma);
 163     else
 164       png_set_gamma(png, sgamma, 0.45);
 165
 166     /* do the transforms */
 167     png_read_update_info(png, pinfo);
 168
 169     /* set background color */
 170     if (png_get_bKGD(png, pinfo, &bkcolor)) {
 171         image->background.red = bkcolor->red >> 8;
 172         image->background.green = bkcolor->green >> 8;
 173         image->background.blue = bkcolor->blue >> 8;
 174     }
 175
 176     png_rows = alloca(sizeof(char*)*height);
 177     if (!png_rows) {
 178         RErrorCode = RERR_NOMEMORY;
 179         fclose(f);
 180         RDestroyImage(image);
 181         png_destroy_read_struct(&png, &pinfo, &einfo);
 182 #ifdef C_ALLOCA
 183         alloca(0);
 184 #endif
 185         return NULL;
 186     }
 187     for (y=0; y<height; y++) {
 188         png_rows[y] = alloca(png_get_rowbytes(png, pinfo));
 189         if (!png_rows[y]) {
 190             RErrorCode = RERR_NOMEMORY;
 191             fclose(f);
 192             RDestroyImage(image);
 193             png_destroy_read_struct(&png, &pinfo, &einfo);
 194 #ifdef C_ALLOCA
 195             alloca(0);
 196 #endif
 197             return NULL;
 198         }
 199     }
 200     /* read data */
 201     png_read_image(png, png_rows);
 202
 203     png_read_end(png, einfo);
 204
 205     png_destroy_read_struct(&png, &pinfo, &einfo);
 206
 207     fclose(f);
 208
 209     ptr = image->data;
 210
 211     /* convert to RImage */
 212     if (alpha) {
 213         for (y=0; y<height; y++) {
 214             for (x=0, i=width*4; x<i; x++, ptr++) {
 215                 *ptr = *(png_rows[y]+x);
 216             }
 217         }
 218     } else {
 219         for (y=0; y<height; y++) {
 220             for (x=0, i=width*3; x<i; x++, ptr++) {
 221                 *ptr = *(png_rows[y]+x);
 222             }
 223         }
 224     }
 225 #ifdef C_ALLOCA
 226     alloca(0);
 227 #endif
 228     return image;
 229 }
 230
 231 #endif /* USE_PNG */