//mandel.java

import java.awt.*;
import java.util.*;

public class mandel extends java.applet.Applet implements Runnable{

	public double dx1=-2.0,dx2=2.0,dy1=-2.0,dy2=2.0;
	int x1,y1,x2,y2;
	Image offscreenImage;
	Graphics offscreenGfx;
	Thread t;

	public void init(){
		Dimension r = size();
		x1 = 0;
		y1 = 0;
		x2 = r.width;
		y2 = r.height;
		offscreenImage = createImage(r.width,r.height);
		offscreenGfx = offscreenImage.getGraphics();
	}
	
  public String getAppletInfo()  {
    String ainfo = "MandelZoom v.0.1 (19 May 1996), by Task";
    return ainfo;
  }
	
	public void start(){
		if(t==null){
			t=new Thread(this);
			t.start();
		}
	}

	public void stop (){
		if(t!=null){
			t.stop();
			t=null;
		}
	}

    public void update(Graphics g) {
		paint(g);
    }
	
	public void clear (Graphics g,int width,int height){
		Color saveC;
		saveC = g.getColor();
		g.setColor(Color.black);
		g.fillRect(0,0,width,height);
		g.setColor(saveC);
	}

	public void run(){
		int x,y,r=32,s;
		double xs,ys,x0,y0,zr,zi,zr0,zi0,mx1,my1,mx2,my2;
		Graphics g;
		Date now;
		long miliTime;
		
		mx1 = dx1;
		mx2 = dx2;
		my1 = dy1;
		my2 = dy2;
		xs=(mx2-mx1)/(x2-x1);
		ys=(my2-my1)/(y2-y1);
		g = offscreenGfx;
		clear(g,offscreenImage.getWidth(this),offscreenImage.getHeight(this));

		now = new Date();
		miliTime = now.getTime();
		
		for(y=y1;y<=y2;y++){
			y0 = my1+(y-y1)*ys;
			
			for(x=x1;x<=x2;x++){
				x0 = mx1+(x-x1)*xs;
				zr0 = x0;
				zi0 = y0;
				
				for(s=0;s<r;s++){
					zr=zr0*zr0-zi0*zi0+x0;
					zi=2*zr0*zi0+y0;
					if(zr*zr+zi*zi>=4.0)	break;
					zr0=zr;
					zi0=zi;
				}
				
				if(s<r) {
					g.setColor(new Color(255-s*10,0,0));
					g.drawLine(x,y,x,y);
				}else{
					g.setColor(Color.yellow);
					g.drawLine(x,y,x,y);
				}
				now = new Date();
				if (miliTime + 1000 < now.getTime()){
					miliTime = now.getTime();
					repaint();
					try{Thread.sleep(100);
					}
					catch(InterruptedException e){}
				}
			}
			/*
			repaint();
			try{Thread.sleep(100);
			}
			catch(InterruptedException e){}
			*/
		}
		repaint();
	}
	
	public void paint(Graphics g){
		g.drawImage(offscreenImage,0,0,this);
	}
	
	public boolean mouseUp(Event evt,int x,int y){
		double xs,ys,mx1,my1,mx2,my2;
		if(t!=null){
			t.stop();
			t=null;
		}
		xs=(dx2-dx1)/(x2-x1);
		ys=(dy2-dy1)/(y2-y1);
		mx1 = dx1 + x * xs - (dx2-dx1)/4;
		mx2 = dx1 + x * xs + (dx2-dx1)/4;
		my1 = dy1 + y * ys - (dy2-dy1)/4;
		my2 = dy1 + y * ys + (dy2-dy1)/4;
		dx1 = mx1;dy1 = my1;dx2 = mx2;dy2=my2;
		if(t==null){
			t=new Thread(this);
			t.start();
		}
		repaint();
		return true;
	}
}