/** 
  * Bandscope Receiver Applet 1.0.0 ["LISTENING ON" PANEL]
  * @author Robert J Morton <robmorton@clara.net>
  * @version 13 March 2002, 20 March 2012
  * @copyright Robert J Morton (all rights reserved) */

import javax.swing.*;  // swing widgets
import java.awt.*;     // for graphics operations (GUI)

class listeningon extends JPanel {

  private static final long 
    serialVersionUID = 211L;  // what the hell this is for, I don't know!

  private int 
    W,      // width of the "listening on" panel
    H,      // Height of "listening on" frequency panel
    I = 5;  // text inset from beginning of text area

  private int
    J,   // end position for right-justified text
    tb,  // text base line for panel of height H
    rF,  // receiving frequency in integral half-kHz
    rX;  // x-coordinate of the "listening on" line on the scope graph

  private String rFs;      // receiving frequency rF in String form
  private Color bg;        // panel background colour
  private Font font;       // font used in this panel
  private FontMetrics fm;  // font metrics of the current font

  private scope sc;           // reference to the scope object
  private mousefreq mf;       // reference to mouse frequency panel object
  private ar86000 rx;         // reference to the receiver object
  private boolean receiving;  /* true when actually listening 
                                 on a specified frequency. */

  listeningon(Color bg, Font font, mousefreq mf, int W, int H) {
    this.bg = bg;  // set panel colour
    this.mf = mf;  // reference to mouse frequency panel class instance
    this.W = W;    // width of listening-on panel class instance
    this.H = H;    // width of listening-on panel class instance
    J = W - I;
    this.font = font;
    fm = getFontMetrics(font);  // get dimensions of current type face

    // y-coordinate for lettering within a field of depth H
    tb = fm.getAscent() + (H - fm.getHeight()) / 2;
  }


  // reference to scope panel class instance
  void setScope(scope sc) {this.sc = sc;}

  // reference to receiver class instance
  void setAR86000(ar86000 rx) {this.rx = rx;}


  void click(int x) {  // MOUSE CLICK EVENT HANDLER
    rX = x;            // x-coordinate of mouse within scope area
    atualizar();       // (0 = left edge of scope)
  }


  void inchFreq(int δx) {  // INCHING EVENT FROM THE UP/DOWN BUTTONS
    rX += δx;  // add +or- 1 to current x-coordinate of highlighted bar
    if(sc.withinScopeWidth(rX))  // provided inched x-coordinate is
      atualizar();               // still within scope area
  }


  private void atualizar() {
    rF = mf.pixTokHz(rX);  // convert x-coordinate to half-kHz
    int q = 3;             // use 3 decimal places of MHz, however,
    if(rF < 200000)        // if frequency less than 100MHz
      q = 4;               // use 4 decimal places of MHz

    // convert to string with 3 or 4 decimal places of MHz
    rFs = convert.toMHz(rF, q) + " MHz";
    // highlight the listening frequency in blue on the scope panel
    sc.highlightSignal(rX);
    // indicate that receiver is being tuned to the listening frequency
    setReceiving(true);
    repaint();  // shedule a repaint via the event-despatching thread
  }


  // DISPLAY FREQUENCY AT AT WHICH MOUSE WAS CLICKED
  public void paint(Graphics g) {
    g.setColor(bg);       // panel background colour
    g.fillRect(0,0,W,H);  // clear 'Listening on' area 

    // only if actually receiving on a clicked frequency
    if(receiving) {
      g.setFont(font);          // set the font for this panel
      g.setColor(Color.black);  // print colour

      // display the "Listening on" label
      g.drawString("Listening on:",I,tb);
      // display the string
      g.drawString(rFs,J-fm.stringWidth(rFs),tb);
    }
  }


  boolean getReceiving() {return receiving;}  // CALLED ONLY BY "SCOPE"


  // CALLED BY "BANDS", "CENTREFREQ" AND "FREQSPAN"
  void setReceiving(boolean b) {
      receiving = b;           // set the "receiving or not" state
      if(receiving)            // if currently receiving (listening-on)
         rx.tuneTo(rF * 500);  // send 'tune to' command to receiver
      else                     // otherwise
         rx.mute();            // mute the receiver
   }
}