circle.cpp

教材例子

//程序CIRCLE.CPP(7.2.7)		功能：实现圆类CIRCLE的成员函数
#include "basgraph.h"
CIRCLE::CIRCLE(int x, int y, int r):POINT(x, y)
{
	radius=r;
}
void CIRCLE::show()
{
	if(!is_visible()){
		visible=TRUE;
		circle(x_pos, y_pos, radius);
	}
}
void CIRCLE::hide()
{
	unsigned int temp_color;
	if(is_visible()){
		temp_color=getcolor();
		setcolor(getbkcolor());
		visible=FALSE;
		circle(x_pos, y_pos, radius);
		setcolor(temp_color);
	}
}
void CIRCLE::move_to(int x, int y)
{
	hide();
	x_pos=x;
	y_pos=y;
	show();
}
void CIRCLE::expand(int delta)
{
	hide();
	radius+=delta;
	if(radius<0) radius=0;
	show();
}
void CIRCLE::contract(int delta)
{
	expand(-delta);
}