// Standard map,   Evgeny Demidov,  26 Aug 2003
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.StringTokenizer;
public class @file extends java.applet.Applet implements MouseListener,
  KeyListener, ActionListener {
  int w,h,w2,h2, it=3000, rand=50;
  double Xo=3, Po=-4, K=.3,  Pi2 = Math.PI*2,
    Xc=Math.PI, Yc=0, dX=Pi2, Mx, My;
  Image buffImage; Graphics buffGraphics;
  boolean   bClear = true;
  Label     lbK;
  TextField tfK, tfXY;
  Button    btClear, btRand;

public void init() {
  double  dx = Pi2,  dy = 4.;
  w = getSize().width;   h = getSize().height;
  w2 = w/2;  h2 = h/2;
  buffImage = createImage(w, h);
  buffGraphics = buffImage.getGraphics();
  String s=getParameter("K");
  if (s != null) K = Double.valueOf(s).doubleValue();
  s=getParameter("it");  if (s != null) it = Integer.parseInt(s);
  s=getParameter("rand"); if (s != null) rand = Integer.parseInt(s);
  s=getParameter("coord");  if (s != null){
    StringTokenizer st = new StringTokenizer(s);
    Xc = Double.valueOf(st.nextToken()).doubleValue();
    Yc = Double.valueOf(st.nextToken()).doubleValue();
    dx = Double.valueOf(st.nextToken()).doubleValue();
    dy = Double.valueOf(st.nextToken()).doubleValue();}
  Mx = dx/w;  My = dy/h;
  this.setLayout( new FlowLayout(FlowLayout.LEFT, 0, 0) );
  tfXY = new TextField( ""+(float)Xc+" "+(float)Yc+"; "+(float)dx+
    " "+(float)dy, 30);   add(tfXY);
  lbK = new Label("K", Label.RIGHT); add(lbK);
  tfK = new TextField( "" + K, 5);   add(tfK);
  tfK.addKeyListener(this);
  btClear = new Button("Clear"); btClear.addActionListener(this); add(btClear);
  btRand = new Button("Rand");   btRand.addActionListener(this);  add(btRand);
  addMouseListener(this);
  clear();
  random();
}
public void destroy() {
  removeMouseListener(this);
}

public void random(){
  buffGraphics.setColor(Color.black);
  for(int i = 0; i < rand; i++){
    Xo = Xc + Mx*w*(Math.random() - .5);
    Po = Yc + My*h*(Math.random() - .5);
    iterate();}
}

public void iterate() {
  double X=Xo, P=Po;
  for(int i = 0; i < it; i++){
    P = P + K*Math.sin(X);
    X = X + P;
    while(X < 0.) X += Pi2;
    while(X > Pi2) X -= Pi2;
    int ix  = w2 + (int)((X-Xc)/Mx), iy  = h2 - (int)((P-Yc)/My);
    buffGraphics.drawLine( ix,iy, ix,iy);
  }
  repaint();
}

public void mouseClicked(MouseEvent e){}       // event handling
public void mousePressed(MouseEvent e) {
  int mx0 = e.getX() - w2,  my0 = h2 - e.getY();
  Xo = mx0*Mx + Xc;  Po = my0*My + Yc;
  if ( e.isAltDown() ){
    Xc = Xo;  Yc = Po;
    My /= 2.;  if ( !e.isShiftDown() ) Mx /= 2.;
    tfXY.setText(""+(float)Xc+" "+(float)Yc+"; "+(float)(w*Mx)+
      " "+(float)(h*My) );
    clear(); random();
    return;}
  if ( e.isControlDown() ){
    Xc = Xo;  Yc = Po;
    My *= 2.;  if ( !e.isShiftDown() ) Mx *= 2.;
    tfXY.setText(""+(float)Xc+" "+(float)Yc+"; "+(float)(w*Mx)+
      " "+(float)(h*My) );
    clear(); random();
    return;}
  buffGraphics.setColor(Color.red);
  iterate();
}
public void mouseReleased(MouseEvent e){}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e)  {}
public void actionPerformed(ActionEvent e){
  if ( e.getActionCommand().equals("Clear") ){
    clear(); repaint();}
  else random();
}
public void keyTyped(KeyEvent e) {}
public void keyPressed(KeyEvent e) {}
public void keyReleased(KeyEvent e) {
  final int keyEnter = 10;
  if (e.getKeyCode() == keyEnter) {
    try{
      K = Double.valueOf(tfK.getText()).doubleValue();
      clear(); random();
    }catch ( NumberFormatException ne) {}
  }
  e.consume();
}

public void clear(){
  buffGraphics.setColor(Color.white);
  buffGraphics.fillRect(0, 0, w, h);
}

public void paint(Graphics g) {
  g.drawImage(buffImage, 0, 0, this);
  showStatus("X=" + (float)Xo + "  P=" + (float)Po );
}
public void update(Graphics g){ paint(g); }

}