#include <cairo.h>
#include <stdio.h>
#include <math.h>


void drawGradient (cairo_t *cr, double scaleFactor){
	cairo_pattern_t *gradient;
	
	cairo_scale(cr, 1.0 / scaleFactor, 1.0 / scaleFactor);
	//scaling the gradient throug start and end
	gradient = cairo_pattern_create_linear (100.0 * scaleFactor, 100.0 * scaleFactor, 300.0 * scaleFactor, 300 * scaleFactor);

	cairo_pattern_add_color_stop_rgb(gradient, 0.0, 1.0, 0.0, 0.0);
	cairo_pattern_add_color_stop_rgb(gradient, 1.0, 0.0, 1.0, 1.0);
	cairo_set_source (cr, gradient);
	
	cairo_rectangle (cr, 0.0 * scaleFactor, 0.0 * scaleFactor, 400.0 * scaleFactor, 400.0 * scaleFactor);
	cairo_fill_preserve (cr);
	cairo_pattern_destroy(gradient);
	
	cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);
	cairo_set_line_width (cr, 2.0 * scaleFactor);
	cairo_stroke (cr);
}


int main (int argc, char *argv[]) {
	cairo_surface_t *surface;
	cairo_t *cr;
	int i;
	char fileString[128];
	double scaleFactor;

	//test drawing gradients with different scales
	for (i = 0; i <= 11; i++) {
		scaleFactor = pow(2.0,(double) i);
		
		surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 400, 400);
		cr = cairo_create (surface);
		drawGradient (cr, scaleFactor);
		cairo_destroy (cr);

		sprintf(fileString, "gradient_%d_%d.png", i, (int)scaleFactor);
		cairo_surface_write_to_png (surface, fileString);
		cairo_surface_destroy (surface);
	}

	return 0;
}