pngdriver/write_ppm.c

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/*!
   \file lib/pngdriver/write_ppm.c
 
   \brief GRASS png display driver - write PPM image (lower level functions)
 
   SPDX-FileCopyrightText: 2007-2014 Glynn Clements
   SPDX-FileCopyrightText: GRASS Development Team
   SPDX-License-Identifier: GPL-2.0-or-later
 
   \author Glynn Clements
 */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <grass/gis.h>
#include "pngdriver.h"
 
void write_ppm(void)
{
    FILE *output;
    int x, y;
    unsigned int *p;
 
    output = fopen(png.file_name, "wb");
    if (!output)
        G_fatal_error("PNG: couldn't open output file %s", png.file_name);
 
    fprintf(output, "P6\n%d %d\n255\n", png.width, png.height);
 
    for (y = 0, p = png.grid; y < png.height; y++) {
        for (x = 0; x < png.width; x++, p++) {
            unsigned int c = *p;
            int r, g, b, a;
 
            png_get_pixel(c, &r, &g, &b, &a);
 
            fputc((unsigned char)r, output);
            fputc((unsigned char)g, output);
            fputc((unsigned char)b, output);
        }
    }
 
    fclose(output);
}
 
void write_pgm(void)
{
    char *mask_name = G_store(png.file_name);
    FILE *output;
    int x, y;
    unsigned int *p;
 
    mask_name[strlen(mask_name) - 2] = 'g';
 
    output = fopen(mask_name, "wb");
    if (!output)
        G_fatal_error("PNG: couldn't open mask file %s", mask_name);
 
    G_free(mask_name);
 
    fprintf(output, "P5\n%d %d\n255\n", png.width, png.height);
 
    for (y = 0, p = png.grid; y < png.height; y++) {
        for (x = 0; x < png.width; x++, p++) {
            unsigned int c = *p;
            int r, g, b, a;
 
            png_get_pixel(c, &r, &g, &b, &a);
 
            fputc((unsigned char)(255 - a), output);
        }
    }
 
    fclose(output);
}