-struct chart
- {
- const struct chart_class *class;
- int ref_cnt;
- };
-
-void chart_init (struct chart *, const struct chart_class *);
-
-void chart_geometry_init (cairo_t *, struct chart_geometry *,
- double width, double length);
-void chart_geometry_free (cairo_t *, struct chart_geometry *);
-
-void chart_draw (const struct chart *, cairo_t *, struct chart_geometry *);
-char *chart_draw_png (const struct chart *, const char *file_name_template,
- int number);