#include <stdio.h>
#include <stdlib.h>
#include <cairo.h>
#include <cairo-quartz.h>

/* #undef CAIRO_HAS_QUARTZ_SURFACE */

cairo_surface_t *
create_surface (int width, int height, int channels)
{
#ifdef CAIRO_HAS_QUARTZ_SURFACE
  return cairo_quartz_surface_create (CAIRO_FORMAT_ARGB32, width, height);
#else
  /* create cairo-surface/context to act as Open_gL-texture source */
  unsigned char *buffer =
    calloc (channels * width * height, sizeof (unsigned char));

  return cairo_image_surface_create_for_data (buffer, CAIRO_FORMAT_ARGB32,
					      width, height, channels * width);
#endif
}

void
destroy_surface (cairo_surface_t *surface)
{
#ifndef CAIRO_HAS_QUARTZ_SURFACE
  free (cairo_image_surface_get_data (surface));
#endif
  cairo_surface_destroy (surface);
}

void
render (cairo_t *ctx, cairo_pattern_t *gradient)
{
  cairo_save (ctx);
  cairo_set_operator (ctx, CAIRO_OPERATOR_OVER);
  cairo_set_source (ctx, gradient);
  cairo_paint (ctx);
  cairo_restore (ctx);
  cairo_surface_flush (cairo_get_target (ctx));
}

#define WIDTH	256
#define HEIGHT	256

int
main ()
{
  cairo_surface_t *surface = create_surface (WIDTH, HEIGHT, 4);
  cairo_t *ctx = cairo_create (surface);
  cairo_pattern_t *gradient = cairo_pattern_create_linear (0, 1, 1, 0);

  cairo_pattern_add_color_stop_rgb (gradient, 0, 1, 0, 0);
  cairo_pattern_add_color_stop_rgb (gradient, 0.5, 0, 1, 0);
  cairo_pattern_add_color_stop_rgb (gradient, 1, 0, 0, 1);

  cairo_scale (ctx, WIDTH, HEIGHT);
  render (ctx, gradient);
  render (ctx, gradient);
  cairo_surface_write_to_png (surface, "frame.png");
  cairo_destroy (ctx);
  destroy_surface (surface);
}