workbench/libs/png/contrib/gregbook/readppm.c

   1 /*---------------------------------------------------------------------------
   2
   3    rpng - simple PNG display program                              readppm.c
   4
   5   ---------------------------------------------------------------------------
   6
   7    This is a special-purpose replacement for readpng.c that allows binary
   8    PPM files to be used in place of PNG images.
   9
  10   ---------------------------------------------------------------------------
  11
  12       Copyright (c) 1998-2007 Greg Roelofs.  All rights reserved.
  13
  14       This software is provided "as is," without warranty of any kind,
  15       express or implied.  In no event shall the author or contributors
  16       be held liable for any damages arising in any way from the use of
  17       this software.
  18
  19       The contents of this file are DUAL-LICENSED.  You may modify and/or
  20       redistribute this software according to the terms of one of the
  21       following two licenses (at your option):
  22
  23
  24       LICENSE 1 ("BSD-like with advertising clause"):
  25
  26       Permission is granted to anyone to use this software for any purpose,
  27       including commercial applications, and to alter it and redistribute
  28       it freely, subject to the following restrictions:
  29
  30       1. Redistributions of source code must retain the above copyright
  31          notice, disclaimer, and this list of conditions.
  32       2. Redistributions in binary form must reproduce the above copyright
  33          notice, disclaimer, and this list of conditions in the documenta-
  34          tion and/or other materials provided with the distribution.
  35       3. All advertising materials mentioning features or use of this
  36          software must display the following acknowledgment:
  37
  38             This product includes software developed by Greg Roelofs
  39             and contributors for the book, "PNG: The Definitive Guide,"
  40             published by O'Reilly and Associates.
  41
  42
  43       LICENSE 2 (GNU GPL v2 or later):
  44
  45       This program is free software; you can redistribute it and/or modify
  46       it under the terms of the GNU General Public License as published by
  47       the Free Software Foundation; either version 2 of the License, or
  48       (at your option) any later version.
  49
  50       This program is distributed in the hope that it will be useful,
  51       but WITHOUT ANY WARRANTY; without even the implied warranty of
  52       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  53       GNU General Public License for more details.
  54
  55       You should have received a copy of the GNU General Public License
  56       along with this program; if not, write to the Free Software Foundation,
  57       Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  58
  59   ---------------------------------------------------------------------------*/
  60
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63
  64 #include "readpng.h"    /* typedefs, common macros, public prototypes */
  65
  66
  67 ulg  width, height;
  68 int  bit_depth, color_type, channels;
  69 uch  *image_data = NULL;
  70 FILE *saved_infile;
  71
  72
  73 void readpng_version_info()
  74 {
  75     fprintf(stderr, "   Compiled without libpng, zlib or PBMPLUS/NetPBM.\n");
  76 }
  77
  78
  79 /* return value = 0 for success, 1 for bad sig, 2 for bad IHDR, 4 for no mem */
  80
  81 int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight)
  82 {
  83     static uch ppmline[256];
  84     int maxval;
  85
  86
  87     saved_infile = infile;
  88
  89     fgets(ppmline, 256, infile);
  90     if (ppmline[0] != 'P' || ppmline[1] != '6') {
  91         fprintf(stderr, "ERROR:  not a PPM file\n");
  92         return 1;
  93     }
  94     /* possible color types:  P5 = grayscale (0), P6 = RGB (2), P8 = RGBA (6) */
  95     if (ppmline[1] == '6') {
  96         color_type = 2;
  97         channels = 3;
  98     } else if (ppmline[1] == '8') {
  99         color_type = 6;
 100         channels = 4;
 101     } else /* if (ppmline[1] == '5') */ {
 102         color_type = 0;
 103         channels = 1;
 104     }
 105
 106     do {
 107         fgets(ppmline, 256, infile);
 108     } while (ppmline[0] == '#');
 109     sscanf(ppmline, "%lu %lu", &width, &height);
 110
 111     do {
 112         fgets(ppmline, 256, infile);
 113     } while (ppmline[0] == '#');
 114     sscanf(ppmline, "%d", &maxval);
 115     if (maxval != 255) {
 116         fprintf(stderr, "ERROR:  maxval = %d\n", maxval);
 117         return 2;
 118     }
 119     bit_depth = 8;
 120
 121     *pWidth = width;
 122     *pHeight = height;
 123
 124     return 0;
 125 }
 126
 127
 128
 129
 130 /* returns 0 if succeeds, 1 if fails due to no bKGD chunk, 2 if libpng error;
 131  * scales values to 8-bit if necessary */
 132
 133 int readpng_get_bgcolor(uch *red, uch *green, uch *blue)
 134 {
 135     return 1;
 136 }
 137
 138
 139
 140
 141 /* display_exponent == LUT_exponent * CRT_exponent */
 142
 143 uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
 144 {
 145     ulg  rowbytes;
 146
 147
 148     /* expand palette images to RGB, low-bit-depth grayscale images to 8 bits,
 149      * transparency chunks to full alpha channel; strip 16-bit-per-sample
 150      * images to 8 bits per sample; and convert grayscale to RGB[A] */
 151
 152     /* GRR WARNING:  grayscale needs to be expanded and channels reset! */
 153
 154     *pRowbytes = rowbytes = channels*width;
 155     *pChannels = channels;
 156
 157     if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
 158         return NULL;
 159     }
 160
 161     Trace((stderr, "readpng_get_image:  rowbytes = %ld, height = %ld\n", rowbytes, height));
 162
 163
 164     /* now we can go ahead and just read the whole image */
 165
 166     fread(image_data, 1L, rowbytes*height, saved_infile);
 167
 168
 169     return image_data;
 170 }
 171
 172
 173 void readpng_cleanup(int free_image_data)
 174 {
 175     if (free_image_data && image_data) {
 176         free(image_data);
 177         image_data = NULL;
 178     }
 179 }