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) 1998-2007,2017 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
 67ulg  width, height;
 68int  bit_depth, color_type, channels;
 69uch  *image_data = NULL;
 70FILE *saved_infile;
 71
 72
 73void 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
 81int 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
133int 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
143uch *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    Trace((stderr, "readpng_get_image:  rowbytes = %ld, height = %ld\n", rowbytes, height));
158
159    /* Guard against integer overflow */
160    if (height > ((size_t)(-1))/rowbytes) {
161        fprintf(stderr, PROGNAME ":  image_data buffer would be too large\n",
162        return NULL;
163    }
164
165    if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
166        return NULL;
167    }
168
169    /* now we can go ahead and just read the whole image */
170
171    if (fread(image_data, 1L, rowbytes*height, saved_infile) <
172       rowbytes*height) {
173        free (image_data);
174        image_data = NULL;
175        return NULL;
176    }
177
178    return image_data;
179}
180
181
182void readpng_cleanup(int free_image_data)
183{
184    if (free_image_data && image_data) {
185        free(image_data);
186        image_data = NULL;
187    }
188}