/* LightBulb.java */

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.beans.*;

public class LightBulb
extends Canvas
implements Serializable
{
  //Instanzvariablen
  protected boolean lighton;
  transient protected Image offimage;
  transient protected Image onimage;

  //Methoden
  public LightBulb()
  {
    lighton = false;
    initTransientState();
  }

  //Getter/Setter Licht an/aus
  public void setLightOn(boolean on)
  {
    if (on != this.lighton) {
      this.lighton = on;
      repaint();
    }
  }

  public boolean getLightOn()
  {
    return this.lighton;
  }

  public void toggleLight()
  {
    setLightOn(!getLightOn());
  }

  //Implementierung der Oberfläche
  public void paint(Graphics g)
  {
    int width = getSize().width;
    int height = getSize().height;
    int xpos = 0;
    if (width > 40) {
      xpos = (width - 40) / 2;
    }
    int ypos = 0;
    if (height > 40) {
      ypos = (height - 40) / 2;
    }
    g.drawImage(
      (this.lighton ? onimage : offimage),
      xpos,
      ypos,
      this
    );
  }

  public Dimension getPreferredSize()
  {
    return new Dimension(40, 40);
  }

  public Dimension getMinimumSize()
  {
    return new Dimension(40, 40);
  }

  //Private Methoden
  private void initTransientState()
  {
    offimage = getImageResource("bulb1.gif");
    onimage  = getImageResource("bulb2.gif");
  }

  private void readObject(ObjectInputStream stream)
  throws IOException, ClassNotFoundException
  {
    stream.defaultReadObject();
    initTransientState();
  }

  private Image getImageResource(String name)
  {
    Image img = null;
    try {
      java.net.URL url = getClass().getResource(name);
      img = getToolkit().createImage(url);
    } catch (Exception e) {
      System.err.println(e.toString());
    }
    return img;
  }
}