/** Lissajou's Figures Generator by Robert John Morton 
  * Originated as an applet  
  * Finished 01 October 1997
  * Converted to a JFramed application Wed 15 Feb 2017 */

/* Open a terminal and change directory to where this file is loacated.
   To compile this program, enter the terminal command: javac lissajou.java
   To run this program, enter the terminal command: java lissajou */

import javax.swing.*;
import java.awt.Dimension;  // to be able to set the preferred JFrame size
import java.awt.Color;

public class lissajou extends JFrame {

  private int
    XE = 240,  // Horizontal extent of window and JFrame.
    YE = 260;  // Vertical extent of window and JFrame.

  /* Declare a reference to an instance of the child class. Beware: 
  an instance of the child class cannot be created here because this 
  must be done within the invokeAndWait environment. */
  private lgraph LG; 


  public lissajou() {  // construct an instance of this extended JFrame

    super("Lissajou's Figures");  // set the window frame title on title bar

    /* Set up the window listener to listen for the window close command which
    occurs when the user clicks on the X control in the window's title bar.*/
    setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

    /* Set the initial size of the extended JFrame. This is the area INSIDE 
    the frame. It does not include the border or the title bar areas. */
    setPreferredSize(new Dimension(XE, YE));

    setBounds(0,0,XE,YE);        // of area inside window frame
    setBackground(Color.black);  // default background colour of JFrame

    LG = new trackrec(XE,YE);  // Create new instance of lissajou class
    getContentPane().add(LG);  // add it to the extended JFrame's pane.

    pack();            // it should automatically pack to fill JFrame
    setVisible(true);  // make this extended JFrame visible
  }


  public static void main(final String[] args) {

   /* Initiate the creation of a new instance of this extended JFrame and
      then wait until the building process has completely finished before
      giving the new instance of the child class permission to commence
      running. */

    try {
      javax.swing.SwingUtilities.invokeAndWait(
        new Runnable() {
          public void run() { 
            new lissajou();
          }
        }
      );
    } catch(Exception e) {
      System.out.println("Couldn't create Swing GUI. You have probably");
      System.out.println("made a mistake in the constructor code of one");
      System.out.println("of this class's child classes.");
    }
  }

   /* The above try-catch sequence is necessary for the following reason. 
   The statement "LG = new lissajou();" is a request to Swing to create
   a GUI instance of this application. It includes, in effect, all the
   statements in the constructor methods of all this class's child classes.
   All these requests are made on this, the main() program thread. 

   However, these requests are carried out [ie the actual constructing is 
   done] by the underlying Swing system on the Event Despatching Thread. 
   The constructing process necessarily takes longer to do than the mere
   task of REQUESTING that the constructing be done. This means that the
   main() thread will set the run() thread in motion before the GUI has 
   finished being constructed. Hence trouble.

   The solution is to force the main() thread to withhold permission for 
   the run() thread to start its job until the Event Despatching Thread 
   has completely finished constructing the GUI. */

   /* NOTE: This class inherits a paint() method from the JFrame class that 
   it extends. This method automatically calls the paint() method of the
   child [extended JPanel] class when necessary. */
}