static cairo_format_t
compat_gdk_cairo_format_for_content (cairo_content_t content)
{
  switch (content)
    {
    case CAIRO_CONTENT_COLOR:
      return CAIRO_FORMAT_RGB24;
    case CAIRO_CONTENT_ALPHA:
      return CAIRO_FORMAT_A8;
    case CAIRO_CONTENT_COLOR_ALPHA:
    default:
      return CAIRO_FORMAT_ARGB32;
    }
}

static cairo_surface_t *
compat_gdk_cairo_surface_coerce_to_image (cairo_surface_t *surface,
                                   cairo_content_t  content,
                                   int              src_x,
                                   int              src_y,
                                   int              width,
                                   int              height)
{
  cairo_surface_t *copy;
  cairo_t *cr;

  copy = cairo_image_surface_create (compat_gdk_cairo_format_for_content (content),
                                     width,
                                     height);

  cr = cairo_create (copy);
  cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
  cairo_set_source_surface (cr, surface, -src_x, -src_y);
  cairo_paint (cr);
  cairo_destroy (cr);

  return copy;
}

static void
compat_convert_alpha (guchar *dest_data,
               int     dest_stride,
               guchar *src_data,
               int     src_stride,
               int     src_x,
               int     src_y,
               int     width,
               int     height)
{
  int x, y;

  src_data += src_stride * src_y + src_x * 4;

  for (y = 0; y < height; y++) {
    guint32 *src = (guint32 *) src_data;

    for (x = 0; x < width; x++) {
      guint alpha = src[x] >> 24;

      if (alpha == 0)
        {
          dest_data[x * 4 + 0] = 0;
          dest_data[x * 4 + 1] = 0;
          dest_data[x * 4 + 2] = 0;
        }
      else
        {
          dest_data[x * 4 + 0] = (((src[x] & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
          dest_data[x * 4 + 1] = (((src[x] & 0x00ff00) >>  8) * 255 + alpha / 2) / alpha;
          dest_data[x * 4 + 2] = (((src[x] & 0x0000ff) >>  0) * 255 + alpha / 2) / alpha;
        }
      dest_data[x * 4 + 3] = alpha;
    }

    src_data += src_stride;
    dest_data += dest_stride;
  }
}

static void
compat_convert_no_alpha (guchar *dest_data,
                  int     dest_stride,
                  guchar *src_data,
                  int     src_stride,
                  int     src_x,
                  int     src_y,
                  int     width,
                  int     height)
{
  int x, y;

  src_data += src_stride * src_y + src_x * 4;

  for (y = 0; y < height; y++) {
    guint32 *src = (guint32 *) src_data;

    for (x = 0; x < width; x++) {
      dest_data[x * 3 + 0] = src[x] >> 16;
      dest_data[x * 3 + 1] = src[x] >>  8;
      dest_data[x * 3 + 2] = src[x];
    }

    src_data += src_stride;
    dest_data += dest_stride;
  }
}

GdkPixbuf *
compat_gdk_pixbuf_get_from_surface  (cairo_surface_t *surface,
                              gint             src_x,
                              gint             src_y,
                              gint             width,
                              gint             height)
{
  cairo_content_t content;
  GdkPixbuf *dest;

  /* General sanity checks */
  g_return_val_if_fail (surface != NULL, NULL);
  g_return_val_if_fail (width > 0 && height > 0, NULL);

  content = cairo_surface_get_content (surface) | CAIRO_CONTENT_COLOR;
  dest = gdk_pixbuf_new (GDK_COLORSPACE_RGB,
                         !!(content & CAIRO_CONTENT_ALPHA),
                         8,
                         width, height);

  surface = compat_gdk_cairo_surface_coerce_to_image (surface, content,
                                               src_x, src_y,
                                               width, height);
  cairo_surface_flush (surface);
  if (cairo_surface_status (surface) || dest == NULL)
    {
      cairo_surface_destroy (surface);
      return NULL;
    }

  if (gdk_pixbuf_get_has_alpha (dest))
    compat_convert_alpha (gdk_pixbuf_get_pixels (dest),
                   gdk_pixbuf_get_rowstride (dest),
                   cairo_image_surface_get_data (surface),
                   cairo_image_surface_get_stride (surface),
                   0, 0,
                   width, height);
  else
    compat_convert_no_alpha (gdk_pixbuf_get_pixels (dest),
                      gdk_pixbuf_get_rowstride (dest),
                      cairo_image_surface_get_data (surface),
                      cairo_image_surface_get_stride (surface),
                      0, 0,
                      width, height);

  cairo_surface_destroy (surface);
  return dest;
}
