/**
  * Text entry field and + - adjustment buttons for c for CtrlPanl.class re DifEqnAp.class
  * @author Robert John Morton
  * @version 27 November 1997 modified 07 August 2009, 18 April 2012 */

/*  This class contains a text entry field in which the user may enter a new 
    value for the constant c in the currently selected difference equation. 
    It also contains two buttons + and - for incrementing and decrementing 
    the current value of the constant c in the selected difference equation. */

import java.awt.*;        // for graphics operations (GUI)
import java.awt.event.*;  // for the new-fangled 1.1 event handling
import javax.swing.*;     // library for constructing Swing GUI


public class cval extends JPanel {
  private setbutt sb;       // instance reference to Start/Stop/Reset panel
  private formula F;        // instance reference to the formula class
  private JLabel L;         // label for the text field
  private JTextField t;     // text field to hold and set c
  private JButton a, b;     // 2 button id's and references
  private int ls = 0;       // language switch: 0=English 1=Portuguese
  private String s;         // for multi-language
  private double c = 3.68;  // value for access by main panel

  private static final double 
    D[] = {+0.1, -0.1};  // increment/decrement amounts

  private boolean EqnFlag = false;  // which equation is in force


  cval(setbutt sb, formula F, Color pc, int ls) {

    this.sb = sb;       // instance ref of setbutt panel to local variable
    this.F = F;         // instance ref of formula class to local variable
    this.ls = ls;       // language switch
    setLayout(null);    // NOTE: this panel is 100 by 50 pixels
    setBackground(pc);  // set panel colour

    s = "Adjust c";     // English/Portuguese
    if(ls != 0)
      s = "Ajustar c";

    L = new JLabel(s);       // create the panel's title label
    add(L);                  // add it to this panel
    L.setBounds(0,0,70,25);  // set its position & size within the panel

    a = new JButton();           // create the + button
    a.setText("+");              // annotate the button with a + symbol
    add(a);                      // add it to this panel
    a.setBounds(95, 0, 30, 24);  // set its position & size within the panel
    a.setMargin(
      new Insets(3,3,3,3)  // set button's annotation margins to minimum
    );
    a.addActionListener(
      new cbut(0, this)    // create a listener for it
    );
    b = new JButton();         // create the - button
    b.setText("-");            // annotate the button with a - symbol
    add(b);                    // add it to this panel 
    b.setBounds(95,27,30,24);  // set its position & size within the panel
    b.setMargin(
      new Insets(3,3,3,3)  // set button's annotation margins to minimum
    );
    b.addActionListener(
      new cbut(1, this)    // create a listener for it
    );
    t = new JTextField();     // create the text entry field
    add(t);                   // add it to this panel 
    t.setBounds(0,25,90,25);  // set its position & size within the panel
    t.setFont(                // set font for numbers in text field
      new Font("Sans",Font.BOLD,14)
    );
    t.addActionListener(
      new cbut(3,this)    // create a listener for it
    );
    t.setText(String.valueOf(c));  // display initial value of c in text field
  }


  void setEF(boolean b) {EqnFlag = b;}  // set which equation is to be used


  void initCval() {  // TO SET c DEFAULT VALUES [also called by seleqn]
    if(EqnFlag)      // if using x = x**2 + c
      c = -1.5;      // set appropriate default value for c
    else             // else x = cx(1 - x) is in use 
      c = +3.68;     // set appropriate default value for c
    ShowReset();     // see below
  }


  private void CheckLimits() {  // ENSURE c IS WITHIN GRAPH LIMITS
    if(EqnFlag) {               // if using x = x**2 + c
      if(c > +2.5) c = +2.5;    // set appropriate limits for c
      if(c < -2.5) c = -2.5;
    } else {                    // else if using x = cx(1 - x)
      if(c > 4.1) c =  4.1;     // set appropriate limits for c
      if(c < 0.1) c = .1;
    }
    ShowReset();                // see below
  }


  private void ShowReset() {       // for local code economy
    F.setC(c);                     // update the c-value in the formula class
    String s = String.valueOf(c);  // convert c to string
    if(s.length() > 9)             // if string is more than 9 characters
      s = s.substring(0,9);        // chop its end off after the 9th character
    t.setText(s);                  // display c in the text field
    sb.reset();                    // 'hit' the reset button
  }


  // EVENT HANDLERS ONLY CALLED BY THE LISTENER CLASS BELOW
  void incC(int i) {
    c += D[i];      // add the increment to current value of c
    CheckLimits();  // ensure it is still within graph limits
  }


  void setC() {
    double x = c;  // preserve the original value of c

    /* Try to parse a number from the entered text by creating
    a Double object of the numeric value of the string in the 
    text field then extracting its value as an ordinary double. */

    try {c = Double.valueOf(t.getText()).doubleValue();}

    /* If a valid number cannot be parsed from the text currently cont- 
    ained in the field put the original value of c back in text field. */

    catch(NumberFormatException f) {c = x;}

    CheckLimits();  // ensure entered value was within limits
  }
}



// LISTENS FOR THE + - BUTTONS & C/R FROM TEXT FIELD
class cbut implements ActionListener {
  int id;   // one of the above events
  cval cv;  // the application that called: always the above class

  //constructor for a new checkbox event
  public cbut(int id, cval cv) {
    this.id = id;  // set id number of the event type
    this.cv = cv;  // set the reference to the instance of the above class
  }                // from which it came. (there will only be one instance)

  //a checkbox event has occurred from checkbox 'id'
  public void actionPerformed(ActionEvent e) {
    switch(id) {
      case 0: cv.incC(0); break;  // + button pressed
      case 1: cv.incC(1); break;  // - button pressed
      case 2: cv.setC();          // C/R from text field
    }
  }
}