/*  Bresenham algorithm                */

import java.applet.*;
import java.awt.*;
//import java.awt.event.*; // for JDK1.2

/* **************************************************************: */
//public class Bresen extends Applet implements MouseListener{ // for JDK1.2
public class Bresen extends Applet {
	Point[] p = new Point[2];
	int n=0;

/* **************************************************************: */
    public void init() {
		setBackground(new Color( 160, 160,170)); // 背景の色
// for JDK1.0
		Dimension appsize = size();    // 画像サイズ for JDK1.0
		resize(appsize);
// for JDK1.2
/*		resize(getSize().width, getSize().height); // for JDK1.2
		this.addMouseListener(this); 
*/
    }
/* *************** 描画関数 *****************************: */
    public void paint(Graphics g) {
 		
		if(p[0]!=null){                
			g.setColor(Color.yellow); 
			for(int i = 0; i < n; i++)  // 2端点の表示
				g.fillOval(p[i].x-2, p[i].y-2, 5, 5);
			if(n>1) {                   
			g.setColor(Color.black);    // 線分の表示
            BresenDraw(p[0].x,p[0].y,p[1].x,p[1].y,g);
			}
		}
   }

/* ******************** event handling *****************************: */
// for JDK.1.
	public boolean mouseDown(Event evt, int x, int y) {
		if(n < 2){ 
			   p[n] = new Point(x,y);	n++;
		}else{	n=0; }
		repaint();
		return true;
    }
// for JDK 1.2
/*
  public void mousePressed(MouseEvent e) {
  } 
  public void mouseClicked(MouseEvent e) {
		if(n < 2){ 
			p[n] = new Point(e.getX(),e.getY()); n++;
		}else{	n=0; }
		repaint();
  }   
  public void mouseReleased(MouseEvent e) {
  }
  public void mouseEntered(MouseEvent e) {
  }
  public void mouseExited(MouseEvent e) {
  }   
  public void mouseMoved(MouseEvent e) { 
  }
*/
/* ------------------------------------------------ */
    public void BresenDraw(int x0, int y0, int x1, int y1, Graphics g) {

        int dx = x1 - x0; int dy = y1 - y0;
        int x = x0; int y = y0;
		int dx2 = 2*Math.abs(dx), dy2 = 2*Math.abs(dy); 

        if (Math.abs(dy) < Math.abs(dx)) 
			scanX(dx, dy, dx2, dy2, x, y, g);
        else							
			scanY(dx, dy, dx2, dy2, x, y, g);
	}
/*                   Scan X Direction      */
void scanX(int dx, int dy, int dx2, int dy2, int x, int y,Graphics g)
{
    int i, eps;

    eps = -Math.abs(dx);
    for (i=0; i<=Math.abs(dx); i++) {
		g.fillRect(x,y,1,1);
        x = x + addDir(dx); 
        eps = eps + dy2;
        if (eps >= 0) {
            y = y + addDir(dy);
            eps = eps - dx2;
        }
    }
}

/*                        Scan Y Direction           */
void scanY(int dx, int dy, int dx2, int dy2,int x, int y,Graphics g)
{
    int i, eps;

    eps = -Math.abs(dy);
    for (i=0; i<=Math.abs(dy); i++) {
		g.fillRect(x,y,1,1);
        y = y + addDir(dy);
        eps = eps + dx2;
        if (eps >= 0) {
            x = x + addDir(dx);
            eps = eps - dy2;
        }
    }
}

/*                  additional Direction      */
int addDir(int dxy)
{
    if (dxy < 0)       return -1;
    else if (dxy == 0) return  0;
    else               return  1;
}
}