/** 
  * Iterated Difference Equation Demonstrator Applet
  * @author Robert J Morton
  * @version 27 November 1997 modified 07 August 2009, 18 April 2012 */

/* <applet code=DifEqnAp.class width=545 height=365></applet>
   
   Iterates the two difference equations x = cx(1 - x) and x = x**2 + c 
   according to which one the user selects on the control panel. Provides 
   real-time Time Line and Bounce graphs so the user can see the equations 
   being iterated.

   This applet employs separate dedicated TimeGr and BounceGr classes to
   implement real-time graph plotting. Its control panel is provided by a 
   dedicated CtrlPanl class which is a container for separate dedicated 
   classes SelPer to select the iteration period, SelEqn to select the desired 
   equation to iterate, SelScan for selecting between single-scan mode 
   continuous scanning mode, SetCval to provide a text entry field for the 
   constant c in the equations, IncCval provides + - buttons to increment/
   decrement c by 0.1 per hit, and SetButt which contains Start/Stop and 
   Reset buttons. There is also a class SelPlot which allows you to select 
   between having the Time Graph plot by joining successive plots with straight
   lines or having it mark each spot value of x with a short horizontal line 
   equal in length to one time period. */

import java.awt.*;
import javax.swing.*;
import java.awt.image.BufferedImage;

public class difeqnap extends JPanel implements Runnable {

  private static final Color 
    bc = new Color(245,245,240),  // panel background colour
    BC = new Color(238,238,238);  // applet background colour

  private boolean 
    RunFlag=false,     // applet starts with no equation iterating
    INIT=true,         // in-loop initialisation not yet done
    AutoStart = true;  // auto-start required

  private int 
    XE,          // horizontal extent of window and JFrame.
    YE,          // vertical extent of window and JFrame.
    XM = 10,     // X-margin within frame
    YM = 12,     // Y-margin within frame
    delay = 20,  // initial three-second delay before autostart
    ls = 0;      // English/Portuguese switch: default English

  private long 
    P = 100,  // inter-plot time frame (milliseconds) 100ms
    t;        // system time at which a new plot is due to begin

  private BufferedImage
    TG = null,  // reference for a Time Graph image object
    BG = null;  // reference for a Bounce Graph image object

  private Graphics2D 
    ga,  // graphics reference for off-screen image
    gb;  // graphics reference for off-screen image

  private formula f;    // instance reference to the formula class
  private timegr tg;    // reference for a Time Graph object
  private bouncegr bg;  // reference for a Bounce Graph object
  private setbutt sb;   // instance reference to the setbutt class
  private Thread T;     // thread reference variable for this program
  private Font font = new Font("Sans",Font.BOLD,12);
  private FontMetrics fm;  // dimensions of the above font


  public difeqnap(int XE, int YE, int ls) {
    this.XE = XE;          // horizontal [X] dimension of the JPanel
    this.YE = YE;          // vertical [Y] dimension of the JPanel
    this.ls = ls;          // set the language swich position
    setBounds(0,0,XE,YE);  // the JPanel fills the whole of the JFrame area
    setLayout(null);       // JPanel has free-form layout [for graph]
    f = new formula(this); // create an instance of the formula class

    /* Create image object on which to draw Time
    Graph axes and get its graphics context.  */
    TG = new BufferedImage(545,180,BufferedImage.TYPE_INT_RGB);
    ga = TG.createGraphics();

    /* Create the Time Graph panel, add it to the applet's window, morph it 
    to bottom left corner of applet window and set its background colour. */
    tg = new timegr(this,bc,f,ga,font,TG);//CREATE TIME-GRAPH PANEL
    add(tg);
    tg.setBounds(XM,YM,545,180);
    tg.setBackground(bc);

   /* Create image object on which to draw Bounce Graph axes 
      and get its graphics context.  */
    BG = new BufferedImage(185,185,BufferedImage.TYPE_INT_RGB);
    gb = BG.createGraphics();

    /* Create Bounce Graph panel, add it into the applet's window, morph it
    to bottom left corner of applet window and set its background colour. */
    bg = new bouncegr(bc,f,gb,BG,font);
    add(bg);
    bg.setBounds(XM+360,YM+180,185,185);
    bg.setBackground(bc);

    f.setBG(bg);  // pass instance reference of bounce graph to formula class 

    /* Create the Control Panel, add it to the applet's window, morph it into
    bottom left corner of applet window, then set its background colour. */
    ctrlpanl CP = new ctrlpanl(this,tg,bg,f,ls);
    add(CP);
    CP.setBounds(XM,YM+180,360,185);
    CP.setBackground(bc);

    T=new Thread(this);  // Create a program thread 
    T.start();           // and start it running

    // Set the system time at which first plot's iteration period will end.
    t = System.currentTimeMillis() + P;
  }


  void setSB(setbutt sb){this.sb=sb;}  // instance reference to button panel
  void setPeriod(long p){P=p;}         // set the formula iteration period
  void setRF(boolean b){RunFlag=b;}    // set the Run() state


  public void run(){  // run the Track Recorder painting thread
    while(true){      // permanent loop
      runLoop();      // see below

      // get the time left in this plot's time-frame
      long s = t - System.currentTimeMillis();

      if(s < 5) s = 5;  // in case machine isn't fast enough

      try{Thread.currentThread().sleep(s);  // sleep for the time remaining
      } catch(InterruptedException e){ }    // catch interrupt from GUI

      // set system time at which next plot's time frame will end
      t = System.currentTimeMillis() + P;
    }
  }


  private void runLoop() {
    if(INIT){           // if in-loop initialisation has not yet been done
      if(delay-- < 0){  // if decremented delay has expired
        bg.reset();     // initialise the bounce-graph
        tg.reset();     // initialise the time-graph
        delay=20;       // reinitialise the delay
        INIT=false;     // signal that initialisation pass has been done
      }
      return;           // bail out
    }
    if(AutoStart){          // if not yet automatically started
      if(delay-- < 0){      // if decremented delay has expired
        sb.whichButton(0);  // hit the 'Start' button
        AutoStart=false;    // signal that auto start has occurred
      } 
      return;  // bail out
    }
    if(RunFlag) {   // if the iteration process is running
      f.iterate();  // update the value of x
      bg.Plot();    // paint next plot on the bounce graph
      tg.Plot();    // paint next plot on the time graph
    }
  }
}