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/*
* MODULE: g.ppmtopng
* AUTHOR(S): Glynn Clements
* PURPOSE: g.ppmtopng isn't meant for end users. It's an internal tool for use by
* the script to generate thumbnails for the r.colors manual page.
* COPYRIGHT: (C) 2009 by Glynn Clements and the GRASS Development Team
*
* This program is free software under the GNU General Public
* License (>=v2). Read the file COPYING that comes with GRASS
* for details.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <png.h>
#include <grass/gis.h>
#include <grass/glocale.h>
static int width, height;
static unsigned char *buf;
static void read_ppm(const char *filename)
{
FILE *input;
int x, y;
int maxval;
unsigned char *p;
input = fopen(filename, "rb");
if (!input)
G_fatal_error(_("Unable to open input file %s"), filename);
if (fscanf(input, "P6 %d %d %d", &width, &height, &maxval) != 3)
G_fatal_error(_("Invalid input file %s"), filename);
fgetc(input);
buf = G_malloc(width * height * 3);
p = buf;
for (y = 0; y < height; y++) {
for (x = 0; x < width; x++) {
int r = fgetc(input);
int g = fgetc(input);
int b = fgetc(input);
*p++ = (unsigned char) (r * 255 / maxval);
*p++ = (unsigned char) (g * 255 / maxval);
*p++ = (unsigned char) (b * 255 / maxval);
}
}
fclose(input);
}
static void write_png(const char *filename)
{
static jmp_buf jbuf;
static png_struct *png_ptr;
static png_info *info_ptr;
FILE *output;
int y;
unsigned char *p;
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, &jbuf, NULL, NULL);
if (!png_ptr)
G_fatal_error(_("Unable to allocate PNG structure"));
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
G_fatal_error(_("Unable to allocate PNG structure"));
if (setjmp(png_jmpbuf(png_ptr)))
G_fatal_error(_("Error writing PNG file"));
output = fopen(filename, "wb");
if (!output)
G_fatal_error(_("Unable to open output file %s"), filename);
png_init_io(png_ptr, output);
png_set_IHDR(png_ptr, info_ptr,
width, height,
8, PNG_COLOR_TYPE_RGB,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
png_set_invert_alpha(png_ptr);
png_write_info(png_ptr, info_ptr);
for (y = 0, p = buf; y < height; y++, p += 3 * width)
png_write_row(png_ptr, p);
png_write_end(png_ptr, info_ptr);
png_destroy_write_struct(&png_ptr, &info_ptr);
fclose(output);
}
int main(int argc, char *argv[])
{
struct GModule *module;
struct
{
struct Option *in, *out;
} opt;
G_gisinit(argv[0]);
module = G_define_module();
G_add_keyword(_("general"));
G_add_keyword(_("display"));
module->description = _("Converts between PPM/PGM and PNG image formats.");
opt.in = G_define_standard_option(G_OPT_F_INPUT);
opt.out = G_define_standard_option(G_OPT_F_OUTPUT);
if (G_parser(argc, argv))
exit(EXIT_FAILURE);
read_ppm(opt.in->answer);
write_png(opt.out->answer);
return 0;
}
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