/** Alternative Relativity: Doppler Effect Demonstrator 
    by Robert John Morton (Belo Horizonte-MG 27 September 2006, 02 May 2012) 

    Produced (concept to full release) in 5 afternoons. 
    + 2 more afternoons to convert it to Swing. */

import javax.swing.*;     // library of swing widgets
import java.awt.*;        // for graphics operations (GUI)
import java.lang.System;  // to deal with foreign language options
import java.awt.event.*;  // for the new-fangled 1.1 event handling
import java.awt.image.BufferedImage;

public class doppler extends JPanel implements Runnable {
  private int  // Integer values which are private to this class
    XE,        // Horizontal extent of window and JFrame. 500 +  4
    YE,        // Vertical extent of window and JFrame.   230 + 25
    ds = 0;    // default mode selection

  private long 
    p = 15,    // applet's prescribed cycle period (milliseconds)
    t = 0,     // System Time at end of last cycle
    dt = 0;    // change in System Time between last cycle and this cycle

  private BufferedImage H;    // off-screen image
  private Graphics2D h;       // graphics reference for off-screen image
  private volatile Thread T;  // declare a thread reference variable
  private wpanel wp;          // instance for the wave display panel


  doppler(int XE, int YE, int ls) {
    this.XE = XE;
    this.YE = YE;
    String SA[][] = {  // localized annotations for app's mode selector buttons
      {"Mode Selector:","Selecione Modo:"}, 
      {"Classical Relativity","Rel. Clássica"},
      {"Alternative Relativity","Rel. Alternativa"} 
    };
    String S[] = new String[3];  // array for localized annotations

    /* Get language selection from applet's HTML parameter to
       display the annotations in the appropriate language. */

    for(int i = 0; i < 3; i++) S[i] = SA[i][ls];
    ds = 0;  // get applet's default mode from HTML parameter

    boolean DS[] = {false,false};  // boolean array to represent button states
    DS[ds] = true;  // default mode received from HTML call parameter

    setLayout(null);  // to allow the control panels to be laid out manually

    JLabel L = new JLabel(S[0],Label.LEFT);  // mode selector label
    add(L);  L.setBounds(0,0,130,39);        // add title label to JPanel

    // checkbox group to contain the two mode buttons
    ButtonGroup G = new ButtonGroup(); 

    // create the first and second mode buttons
    JRadioButton A = new JRadioButton(S[1], DS[0]);
    JRadioButton B = new JRadioButton(S[2], DS[1]);

    // add them to the button group and JPanel, set their positions and sizes
    G.add(A); add(A); A.setBounds(130,0,170,39);
    G.add(B); add(B); B.setBounds(300,0,180,39);

    // creat and add a listener to know when either is pressed
    A.addItemListener(new modebut(0,this));
    B.addItemListener(new modebut(1,this));

    // Create image in which to animate off screen
    H = new BufferedImage(1200,191,BufferedImage.TYPE_INT_RGB);
    h = H.createGraphics();      // capture its graphics context

    wp = new wpanel(H,h,ds);     // create an instance of wave display panel
    add(wp);                     // add image to JPanel
    wp.setBounds(0,40,500,190);  // set its position and size

    T = new Thread(this);        // creating the thread object
    T.start();                   // and starting it running

    // System time at which first cycle period will finish
    t = System.currentTimeMillis() + p;
  }


  public void run() {
    while (T != null) {  // while the run() thread remains alive...

      // The time remaining in the current cycle period
      dt = t - System.currentTimeMillis();

      if(dt < 10) dt = 10;  // in case machine is too slow
 
      try {
        Thread.sleep(dt);               // sleep for remainder of cycle period
      } catch(InterruptedException e){  // catch interrupt from GUI
        wp.setCF(true);                 // re-start traverse of light-source
      }
      // Set the System Time at which the following cycle will end
      t = System.currentTimeMillis() + p; 

      wp.atualizar();  // update the waves
      repaint();       // repaint the entire applet (necessary for Swing)
    }
  }


  void selectMode(int ds) {
    wave.setMode(ds);  // re-initialize the static mode variable in wave.class
    wp.setCF(true);    // set the change flag to re-start the waves
    wp.setDS(ds);      // set new mode: 'classical' or 'alternative'
    wp.atualizar();    // re-initialize the display - sets up call to update()
  }                    // (CALLED BY EVENT LISTENER CLASS BELOW)
}



// LISTENS FOR EVENTS FROM THE MODE SELECTOR BUTTONS
class modebut implements ItemListener {
  int id;      // one of the above events
  doppler ap;  // application that called: always the above applet!

  public modebut(int id, doppler ap){  // constructor for a new checkbox event
    this.id = id;  // set id number of this instance of 'modebut'
    this.ap = ap;  // set the reference to this instance of the applet
  }                // from which it came. (only one instance anyway).

  // a checkbox event has occurred from checkbox 'id'
  public void itemStateChanged(ItemEvent e){
    switch(id) {  // communicate the selection to the above applet.

      // "classical relativity" mode has been selected
      case 0: ap.selectMode(0); break;

      // "alternative relativity" mode has been selected
      case 1: ap.selectMode(1); break;
    }
  }
}