gelcounter/counter.c/counter.c

#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <png.h>
#include "counter.h"
#include "powers_table.h"
#include "digits_data.h"

static int count_digits(unsigned long number) {
  for (int i = 1; i < POWERS_COUNT; i++)
    if (number < powers_table[i][0]) return powers_table[i][1];

  return powers_table[POWERS_COUNT-1][1];
}

static int nth_digit(unsigned long number, int n) {
  return (number / powers_table[n][0]) % 10;
}

void counter_create(unsigned long number, FILE *fd) {
  png_structp png;
  png_infop info;

  int digits_count;
  int width;

  int digits[POWERS_COUNT];

  png_byte **rows;

  png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  info = png_create_info_struct(png);

  digits_count = count_digits(number);
  width = digits_count * DIGIT_WIDTH;

  rows = malloc(sizeof(png_byte *) * DIGIT_HEIGHT);
 
  for (int i = 0; i < digits_count; i++)
    digits[i] = nth_digit(number, digits_count-1-i);

  for (int y = 0; y < DIGIT_HEIGHT; y++) {
    rows[y] = malloc(width * 4);

    for (int i = 0; i < digits_count; i++)
      memcpy(rows[y] + (i * DIGIT_WIDTH * 4), digits_data[digits[i]][y], DIGIT_WIDTH * 4);
  }

  png_init_io(png, fd);
  png_set_IHDR(
    png,
    info,
    width,
    DIGIT_HEIGHT,
    8,                 
    PNG_COLOR_TYPE_RGBA,
    PNG_INTERLACE_NONE,
    PNG_COMPRESSION_TYPE_BASE,
    PNG_FILTER_TYPE_BASE
  );
  png_write_info(png, info);
  png_write_image(png, rows);
  png_write_end(png, info);
  png_destroy_write_struct(&png, &info);

  for (int y = 0; y < DIGIT_HEIGHT; y++)
    free(rows[y]);

  free(rows);
}