/*
 * Compile with:
 *      cc `pkg-config --cflags --libs gtk+-3.0` bug.c -o bug
 */
#include <stdlib.h>
#include <gtk/gtk.h>

void
dump (cairo_surface_t *surface,
      char            *path)
{
  if (cairo_surface_write_to_png (surface, path) == CAIRO_STATUS_WRITE_ERROR)
    printf ("error writing to %s\n", path);
}

void
draw_checkerboard (cairo_surface_t *surface)
{
  cairo_t *cr;
  int i, j;

  cr = cairo_create (surface);

  cairo_set_source_rgb (cr, 0, 0, 0);
  cairo_rectangle (cr, 0, 0, 10, 10);
  cairo_fill (cr);

  cairo_set_source_rgb (cr, 1, 1, 1);

  for (i = 0; i < 10; ++i)
    for (j = 0; j < 10; ++j)
      if ((i % 2) == (j % 2))
        {
          cairo_rectangle (cr, i, j, 1, 1);
          cairo_fill (cr);
        }

  cairo_destroy (cr);
}

void
draw (cairo_t *cr)
{
  cairo_surface_t *surface, *pat_surface;
  cairo_pattern_t *pattern;
  cairo_matrix_t _matrix;
  cairo_matrix_t *matrix = &_matrix;

  surface = cairo_get_target (cr);
  surface = cairo_surface_create_similar (surface, CAIRO_CONTENT_COLOR, 10, 10);

  draw_checkerboard (surface);

  pat_surface = cairo_surface_create_for_rectangle (surface, 0, 0, 2, 2);

  cairo_matrix_init_identity (matrix);
  cairo_matrix_scale (matrix, 1 / 50., 1 / 50.);

  pattern = cairo_pattern_create_for_surface (pat_surface);
  cairo_pattern_set_extend (pattern, CAIRO_EXTEND_PAD);
  cairo_pattern_set_matrix (pattern, matrix);

  cairo_set_source (cr, pattern);
  cairo_rectangle (cr, 0, 0, 100, 100);
  cairo_fill (cr);

  cairo_pattern_destroy (pattern);
  cairo_surface_destroy (pat_surface);
  cairo_surface_destroy (surface);
}

void
image (char *path)
{
  cairo_surface_t *surface = NULL;
  cairo_t *cr = NULL;

  surface = cairo_image_surface_create (CAIRO_FORMAT_RGB24, 100, 100);
  cr = cairo_create (surface);

  draw (cr);
  dump (surface, path);

  cairo_destroy (cr);
  cairo_surface_destroy (surface);
}

gboolean
window_draw (GtkWidget *widget,
             cairo_t   *cr,
             gpointer   path)
{
  draw (cr);
  dump (cairo_get_target (cr), (char *)path);

  g_idle_add ((GSourceFunc)gtk_main_quit, NULL);

  return FALSE;
}

void
xlib (char *path)
{
  GtkWidget *window = NULL;

  gtk_init (NULL, NULL);
  window = gtk_window_new (GTK_WINDOW_POPUP);
  gtk_widget_set_size_request (window, 100, 100);

  g_signal_connect (G_OBJECT (window), "draw",
                    G_CALLBACK (window_draw), path);

  gtk_widget_show (window);

  gtk_main ();

  gtk_widget_destroy (window);
}

void
usage (char *s)
{
  printf ("usage: %s <image|xlib> <output_path>\n", s);
  exit (1);
}

int
main (int argc, char **argv)
{
  if (argc != 3)
    usage (argv[0]);

  if (g_str_equal (argv[1], "image"))
    image (argv[2]);
  else if (g_str_equal (argv[1], "xlib"))
    xlib (argv[2]);
  else
    usage (argv[0]);

  return 0;
}