#include <stdio.h>
#include <stdlib.h>
#include <cairo.h>
#include <time.h>

#define N_INIT 100
#define N_STEP 100
#define N_MAX 1000
#define REPEATS 100

#define WIDTH 1000
#define HEIGHT 400

int main (int argc, char* argv[])
{
	double data[N_MAX];
	int i, j, n;

	for (i = 0; i < N_MAX; ++i)
	{
		data[i] = (double)rand() / RAND_MAX * HEIGHT;
	}

	printf("N_INIT=%d; N_STEP=%d; N_MAX=%d; REPEATS=%d\n", N_INIT, N_STEP, N_MAX, REPEATS);
	for (n = N_INIT; n <= N_MAX; n += N_STEP)
	{
		struct timespec begin, end;
		long long beginll, endll;
		cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, WIDTH, HEIGHT);
		cairo_t* cr = cairo_create(surface);

		clock_gettime(CLOCK_MONOTONIC, &begin);

		cairo_set_source_rgb(cr, 0.4, 0.8, 0.4);
		for (j = 0; j < REPEATS; ++j)
		{
			cairo_new_path(cr);
			cairo_move_to(cr, 0, data[0]);
			for (i = 0; i < n; ++i)
			{
				cairo_line_to(cr, (double)i / n * WIDTH, data[i]);
			}
			cairo_stroke(cr);
		}

		clock_gettime(CLOCK_MONOTONIC, &end);

		cairo_destroy(cr);
		cairo_surface_destroy(surface);

		beginll = (long long)begin.tv_sec * 1000000000 + begin.tv_nsec;
		endll = (long long)end.tv_sec * 1000000000 + end.tv_nsec;
		printf("%d dots: %.4lf ns\n", n, (double)(endll - beginll) / (n * REPEATS));
	}

	return 0;
}