/*
 * writepng.c:
 *
 * Copyright (c) 2006 UK Citizens Online Democracy. All rights reserved.
 * Email: chris@mysociety.org; WWW: http://www.mysociety.org/
 *
 */

static const char rcsid[] = "$Id: writepng.c,v 1.1 2006/01/19 01:57:32 chris Exp chris $";

#include <png.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

#include "postcodeine.h"

bool writepng(const char *filename, const struct image *img) {
    FILE *fp;
    png_structp png_ptr;
    png_infop info_ptr;
    png_color palette[2] = { {0, 0, 0}, {255, 0, 0} };
    png_byte transparency[2] = { 0, 255 };
    int Y;
    
    if (!(fp = fopen(filename, "w+")))
        return 0;
    
    if (!(png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL))) {
        unlink(filename);
        fclose(fp);
        return 0;
    }

    if (!(info_ptr = png_create_info_struct(png_ptr))
        || setjmp(png_ptr->jmpbuf)) {
        unlink(filename);
        fclose(fp);
        png_destroy_write_struct(&png_ptr, &info_ptr);
        return 0;
    }

    png_init_io(png_ptr, fp);
    png_set_filter(png_ptr, 0, PNG_ALL_FILTERS);
    png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);

    png_set_IHDR(png_ptr, info_ptr,
            img->w, img->h,
            8, PNG_COLOR_TYPE_PALETTE | PNG_COLOR_MASK_PALETTE,
            PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
            PNG_FILTER_TYPE_DEFAULT);

    png_set_PLTE(png_ptr, info_ptr, palette, 2);
    png_set_tRNS(png_ptr, info_ptr, transparency, 2, NULL);

    png_write_info(png_ptr, info_ptr);

    for (Y = 0; Y < img->h; ++Y)
        png_write_row(png_ptr, (png_bytep)img->data[Y]);

    png_write_end(png_ptr, NULL);
    png_destroy_write_struct(&png_ptr, &info_ptr);

    fclose(fp);

    return 1;
}