void
draw_buffer (GnomeScanPreviewArea *area)
{
  GnomeScanPreviewAreaPrivate *priv = GET_PRIVATE (area);
  GdkRectangle *r, *i, *a;
  GtkWidget *da = priv->da;
  GdkPixbuf *pb;
  gint hpos;
  cairo_t *cr;
  cairo_surface_t *cs;

  if (!GDK_IS_PIXBUF (priv->pixbuf))
    return;

  pb = priv->pixbuf;

  /* area rectangle */
  r = priv->roi;

  a = g_new0 (GdkRectangle, 1);
  a->x = r->x - 1;
  a->y = r->y - 1;
  a->width = r->width + 2;
  a->height = r->height + 2;

  i = g_new0 (GdkRectangle, 1);
  i->x = 0;
  i->y = 0;
  i->width = gdk_pixbuf_get_width (pb);
  i->height = gdk_pixbuf_get_height (pb);

  /* DRAW */
  cr = gdk_cairo_create (da->window);
  cs = cairo_get_target (cr);
  priv->cs = cairo_surface_create_similar (cs,
					   CAIRO_CONTENT_COLOR,
					   gdk_pixbuf_get_width (pb),
					   gdk_pixbuf_get_height (pb));

  cairo_set_source_surface (cr, priv->cs, 0, 0);
  cairo_paint (cr);

  /* draw pixbuf */
  gdk_cairo_set_source_pixbuf (cr, pb, 0, 0);
  cairo_paint (cr);

  /* draw shaded white */
  cairo_set_source_rgba (cr, 0xff, 0xff, 0xff, 0.5);
  cairo_new_path (cr);
  gdk_cairo_rectangle (cr, i);
  cairo_close_path (cr);
  cairo_paint (cr);

  /* draw border */
  cairo_set_source_rgba (cr, 0, 0, 0, 1);
  cairo_new_path (cr);
  gdk_cairo_rectangle (cr, a);
  cairo_close_path (cr);
  cairo_clip (cr);
  cairo_paint (cr);

  /* draw area pixbuf */
  gdk_cairo_set_source_pixbuf (cr, pb, 0, 0);
  cairo_new_path (cr);

  gdk_cairo_rectangle (cr, r);
  cairo_close_path (cr);
  cairo_clip (cr);
  cairo_paint (cr);

  for (hpos = 0; hpos < N_ANCHOR; hpos++) {
    draw_handle (da, cr, r, hpos);
  }

  g_debug ("writing %p to png", priv->cs);
  cairo_surface_write_to_png (priv->cs, "/home/bersace/test.png");
  cairo_destroy (cr);
}

gboolean
expose_drawing_area (GtkWidget *da,
		     GdkEventExpose *event,
		     GnomeScanPreviewArea *area)
{
  GnomeScanPreviewAreaPrivate *priv = GET_PRIVATE (area);
  g_debug ("%s %p", __FUNCTION__, priv->cs);

  cairo_t *cr;
  cairo_surface_t *cs;

  if (!priv->cs) {
    return TRUE;
  }

  cr = gdk_cairo_create (da->window);
  cairo_set_source_surface (cr, priv->cs, 0, 0);
  gdk_cairo_rectangle (cr, priv->area);
  cairo_clip (cr);
  cairo_paint (cr);
  cairo_destroy (cr);

  return TRUE;
}