triangle.cpp

教材例子

//程序TRIANGLE.CPP(8.6.4)	功能：三角形类TRIANGLE的类实现
#include "figstack.h"
TRIANGLE::TRIANGLE(int x, int y, int len):FIGURE(x, y)
{
	this->length=len;
}
void TRIANGLE::show()
{
	if(!is_visible()){
		this->visible=TRUE;
		line(x_pos, y_pos, x_pos+length, y_pos);
		line(x_pos, y_pos, x_pos+length/2, y_pos-length);
		line(x_pos+length/2, y_pos-length, x_pos+length, y_pos);
	}
}
void TRIANGLE::hide()
{
	int temp_color;
	if(is_visible()){
		temp_color=getcolor();
		setcolor(getbkcolor());
		visible=FALSE;
		line(x_pos, y_pos, x_pos+length, y_pos);
		line(x_pos, y_pos, x_pos+length/2, y_pos-length);
		line(x_pos+length/2, y_pos-length, x_pos+length, y_pos);
		setcolor(temp_color);
	}
}
void TRIANGLE::expand(int delta)
{
	this->hide();
	if(delta>0) length*=delta;
	else if(delta<0) length/=-delta;
	this->show();
}