+void xrchart_draw_scatterplot (const struct chart *, cairo_t *,
+ struct xrchart_geometry *);
+
+void xr_draw_chart (const struct chart *, cairo_t *,
+ double width, double height);
+
+cairo_surface_t *xr_draw_image_chart (const struct chart *,
+ const struct cell_color *fg,
+ const struct cell_color *bg);
+char *xr_write_png_image (cairo_surface_t *,
+ const char *file_name_template, int number);
+
+char *xr_draw_png_chart (const struct chart *,
+ const char *file_name_template, int number,
+ const struct cell_color *fg,
+ const struct cell_color *bg);