#ifndef GRAPHIC_H_INCLUDED
#define GRAPHIC_H_INCLUDED

/* abstract class gobject 
*/
struct gobject;

/* non-virtual methods */
int gobject_get_id(const struct gobject *);

/* virtual methods */
void gobject_virtual_print(const struct gobject *); /* virtual call */
void gobject_print(const struct gobject *);	    /* concrete, non-virtual */

/* No concrete implementations of these virtual methods here. */
float gobject_virtual_area(const struct gobject *);
void gobject_virtual_translate(struct gobject *, float x, float y); 

/* virtual destructor */
void gobject_destroy(struct gobject *);
void gobject_virtual_destroy(struct gobject *); 

/* class point extends gobject */
struct point;

struct point * point_new(float x, float y);
void point_destroy(struct point *);

/* virtual methods */
void point_print(const struct gobject *);	    /* concrete */
float point_area(const struct gobject *);		    /* concrete */
void point_translate(struct gobject *, float x, float y); /* concrete */

/* class rectangle extends gobject 
*/
struct rectangle;

struct rectangle * rectangle_new(float x1, float y1, float x2, float y2);
void rectangle_destroy(struct rectangle *);

/* virtual methods */
void rectangle_print(const struct gobject *);	    /* concrete */
float rectangle_area(const struct gobject *);	    /* concrete */
void rectangle_translate(struct gobject *, float x, float y); /* concrete */

#endif