/** 
  * Scan Mode Selector for CtrlPanl.class re DifEqnAp.class
  * @author Robert J Morton UK-YE572246C
  * @version 27 November 1997 modified 07 August 2009, 18 April 2012 */

/*  This class contains a pair of radio buttons for choosing whether the
    program should simply plot to the end of the time graph and then stop
    (single-scan mode); or whether, upon reaching the end of the time axis,
    it should fly back to the beginning again and continue plotting, wiping
    the old trace as it goes (continuous mode). */

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 selscan extends Panel {
  private timegr tg;          // instance reference of time-graph
  private setbutt sb;         // instance reference of setbutt panel
  private selplot st;         // instance reference of selplot panel
  private JLabel L;           // to hold reference to panel's 'heading'
  private ButtonGroup G;      // to hold reference to the checkbox group
  private JRadioButton a, b;  // and references to individual checkboxes

  private boolean 
    Flags[] = {false, true},  // the 2 options for the scan-mode flag
    ScanMode = true;          // start in continuous-scan mode


  selscan(timegr tg, setbutt sb, Color pc) {
    this.tg = tg;  // copy instance ref. of time-graph to local variable
    this.sb = sb;  // copy instance ref. of setbutt panel to local variable

    setBackground(pc);  // set panel colour

   // lay out items in a single column of 3
    setLayout(new GridLayout(3, 0));

    // create title label for selscan panel and add it to selscan panel
    L = new JLabel("Scan Mode:", Label.LEFT); add(L);

    G = new ButtonGroup();  // create a button group container

    /* Create the 'single-scan' radio button, add it to the button-
    group and to the selscan panel then create a istener for it. */

    a = new JRadioButton("Single-scan", false); G.add(a); add(a);
    a.addItemListener(new scanbut(0, this));

    /* Create the 'continuous' radio button, add it to the button-
    group and to the selscan panel then create a istener for it. */

    b = new JRadioButton("Continuous", true); G.add(b); add(b);
    b.addItemListener(new scanbut(1, this));
  }


  void setST(selplot st) {this.st = st;}  // set instance ref. of selplot


  void selectScanMode(int i){
    ScanMode = Flags[i];  // set the newly-selected scan mode
    tg.setSM(ScanMode);   // set scan mode flag in the time graph class
    st.resetPlotMode();   // sets plot mode to false = 'line-graph'
    sb.reset();           // stop iteration and clear (reset) the graphs
  }


  void setSM(boolean Flag) {  // used by selplot
    ScanMode = Flag;          // set the scan flag to its appropriate state
    if(ScanMode)              // if it has been set true
      b.setSelected(true);    // tick the 'continuous' button
    else                      // if it has been set false
      a.setSelected(true);    // tick the 'single-scan' button
    sb.reset();               // stop iteration and clear (reset) the graphs
  }
}


// LISTENS FOR EVENTS FROM SCAN MODE SELECTION BUTTONS
class scanbut implements ItemListener {
  int id;      // one of the above events
  selscan ss;  // the application that called: always the above class

  /* Constructor for a new checkbox event: sets 'id' number pertaining
  to this instance and the reference to the instance of the above class
  from which it came. (there will only be one instance). */

  public scanbut(int id, selscan ss) { this.id = id; this.ss = ss; }

  // a checkbox event has occurred from checkbox 'id'
  public void itemStateChanged(ItemEvent e) {
    switch(id) {
      case 0: ss.selectScanMode(0); break;  // continuous mode
      case 1: ss.selectScanMode(1); break;  // single-shot mode
    }
  }
}