void xr_rendering_measure (struct xr_rendering *, int *w, int *h);
void xr_rendering_draw (struct xr_rendering *, cairo_t *,
int x, int y, int w, int h);
void xr_rendering_measure (struct xr_rendering *, int *w, int *h);
void xr_rendering_draw (struct xr_rendering *, cairo_t *,
int x, int y, int w, int h);