/*
                Name:           Chris Johnson
                                        johnson@dcs.gla.ac.uk
 
                Last modified:  27/10/98
 
                Description:
		Declares three lights and places them in different positions
	 	on the canvas.

                From an idea originally suggested by: Quintin Blane
                qablane@surfaid.org

		
*/

import java.awt.*;
import java.applet.Applet;

public class Traffic_Lights extends Canvas {
	
	A_Light Red_Light = new A_Light("Red", 0, 0);
	A_Light Amber_Light = new A_Light("Amber", 0, 50);
	A_Light Green_Light = new A_Light("Green", 0, 100);
	
	private Lights parent;
	
	Traffic_Lights (Lights owner)
	{	
		super(); // make sure this is exactly like any other
			 // canvas - avoids us having to initialise
			 // lots of other variables - see Judy Bishop
			 // page 278-280.

		parent = owner;
	}
	
	public void set_lights(String the_color)
	{
		Red_Light.off();
		Green_Light.off();
		Amber_Light.off();
			
		if(the_color.equals("Amber"))
			Amber_Light.on();
		else if(the_color.equals("Green"))
			Green_Light.on();
		else
			Red_Light.on();
			
		update(getGraphics());			
		// update redraws the background of the canvas and then
		// calls paint() - see below.   We need to redraw the 
		// background of the canvas in order to get rid of the
		// previous lights that might have been on.
	}
		
	public void paint(Graphics g)
	{	
		Red_Light.paint(g);
		Green_Light.paint(g);
		Amber_Light.paint(g);
	}
}