// Lissagous figures, Evgeny Demidov, 16 Jan 2003
import java.awt.*;

public class @file extends java.applet.Applet implements Runnable {
final int Max=10*360, M1=Max-1, lbSize=50;
int[] arrSin=new int[Max+1];
int height, width, iYo=0, parM=1, parN=2, delay=10;
Thread ScopeTrace;
Choice chDelay, chM, chN;
Label  lbDelay, lbM, lbN;
Image buffImage;
Graphics buffGraphics;

public void init() {
  height= Integer.parseInt(getParameter("height"));
  width = Integer.parseInt(getParameter("width"));
  int radius = width / 2;  int m2 = Max/2;
  double SiF=Math.sin(3.14159265/m2), CoF=Math.cos(3.14159265/m2);
  double Si=-SiF, Co=CoF;
  for (int i=0; i<=m2; i++) {
    Si=Si*CoF+Co*SiF; Co=Co*CoF-Si*SiF;
    int s= (int) (radius*Si);
    arrSin[i]=radius+s; arrSin[i+m2]=radius-s;
  }
  chM = new Choice();  chN = new Choice();
  for (int i=1; i<10; i++) {
    chM.addItem(Integer.toString(i));
    chN.addItem(Integer.toString(i));
  }
  chN.select(parN-1);
  lbM = new Label("M", Label.RIGHT);  add(lbM);  add(chM);
  lbN = new Label("N", Label.RIGHT);  add(lbN);  add(chN);
  lbDelay = new Label("Delay(ms)", Label.RIGHT); add(lbDelay);
  chDelay = new Choice();
  chDelay.addItem("0");    chDelay.addItem("10");
  chDelay.addItem("20");   chDelay.addItem("50");
  chDelay.addItem("100");  chDelay.addItem("200");
  chDelay.addItem("500");  chDelay.addItem("999");
  chDelay.select("10");     add(chDelay);
  buffImage = createImage(width, width);
  buffGraphics = buffImage.getGraphics();
}               

public void paint(Graphics g) {
  long cntTime = System.currentTimeMillis();
  int iX,iY, iXo=0, aX,aY, aXo=arrSin[0],aYo=arrSin[iYo];
  buffGraphics.clearRect(0, 0, width, width);
  for (int j=Max; j>0; j--) {
    iX=(iXo+parM) % Max;    iY=(iYo+parN) % M1;
    aX=arrSin[iX];  aY=arrSin[iY];
    buffGraphics.drawLine( aXo,aYo, aX,aY);
    iXo=iX; iYo=iY; aXo=aX; aYo=aY;
  }
  g.drawImage(buffImage, 0, lbSize, this);
//  showStatus( "time=" + (System.currentTimeMillis()-cntTime) );
}

public boolean action(Event evt, Object obj)  {
  if(evt.target instanceof Choice) {
    if(evt.target.equals(chDelay))
      delay=Integer.parseInt( chDelay.getSelectedItem() );
    else if(evt.target.equals(chM)) parM=chM.getSelectedIndex()+1;
    else if(evt.target.equals(chN)) parN=chN.getSelectedIndex()+1;
    else return false;
    return true;
  }
  return false;
}

public void update(Graphics g)   {  paint(g);  }

public void run() {
  while(true) {
    repaint();
    try {  Thread.sleep( delay );
    } catch (InterruptedException e) { }
  }
}

public void start() {
  ScopeTrace = new Thread(this);
  ScopeTrace.start();
}

public void stop() {  ScopeTrace.stop(); }

}