/*****************************************
write by tjm
用來展示畫圖的功能
*************************************************/
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class demo26 extends JFrame //畫圖物件是JFrame的擴充
{
    Container c;
    public demo26()   //建構元
    {
	super("Mydraw:畫函式圖");
        c=getContentPane();
	setSize(640,480);
	setVisible(true);
    }
    public void paint(Graphics g)  //真正的畫圖設定
    {
	double y,x;
	int DY,DX;
	Color blue=Color.blue; //設定紅色
	g.setColor(blue);
	g.drawLine(320,0,320,479);
	g.drawLine(0,240,639,240);//座標軸
	g.drawString("函數圖形",10,100);
	Color red=Color.red; //設定紅色
	g.setColor(red);
	/**算 y=x**/
	for (DX=0;DX<=639;DX=DX+1)
	{
		x=(double)(DX-320)/50.0;
		y=Math.cos(x);
		DY=(int)(y*100.0+240);
		DY=479-DY;
		g.drawLine(DX,DY,DX,DY);
		//System.out.println(DX+"  "+DY+"  "+x+"  "+y);
	}
    }
    public static void main(String args[]) //程式起點
    {
	demo26 app=new demo26(); //畫圖
	app.addWindowListener(new WindowAdapter(){ //匿名內部類別
		public void windowClosing(WindowEvent e)
		{
			System.exit(0);
		}
	}); //處理視窗關閉要求
    }
}