// This began from the book _Java in a Nutshell_ by David Flanagan.
// but I doubt they would claim it, now.
// Written by mf1i@virginia.edu and ajd2m@virginia.edu
//
// This applet shows two sine waves of different wavelengths interfering
// as they travel at different velocities.  There is a scrollbar and a
// textbox which change the velocity of the longer wavelength.

import java.applet.*;
import java.awt.*;
import java.lang.*;
import java.util.*;

public class NewtonianMountain extends Applet {
	// This is an animation derived from Canvas.  It shows the waves.
	EarthCanvas globe;
	Button bStop,bGo;
	TextSlide slideField;  // Shows the value of the velocity.
	GridBagLayout gbl = new GridBagLayout();
 	double minVal = -0.7, maxVal = 0.7;  // Min and max values for velocity from scrollbar.
	AudioClip	crash,fire,oops;

	// Initializtion called by the applet container.
	public void init() {
		Image earth;
		GridBagConstraints c = new GridBagConstraints();
		// We use a very simple layout manager.
		this.setLayout(gbl);
		earth=getImage(getDocumentBase(),"newtshrunk.gif");
		crash = getAudioClip(getDocumentBase(),"crash.au");		
		fire = getAudioClip(getDocumentBase(),"fire.au");		
		oops = getAudioClip(getDocumentBase(),"oops.au");		
		// This object is a homegrown class, but it can be added b/c it is also a canvas.
		globe = new EarthCanvas(earth,crash,fire,oops);
		c.fill = GridBagConstraints.BOTH;
		c.anchor = GridBagConstraints.NORTH;
		c.gridwidth = 3; c.gridheight = 1;
		c.gridx = 0; c.gridy = 0;
		c.weightx = 3; c.weighty = 40;
		gbl.setConstraints(globe,c);
		this.add(globe);

		bStop = new Button("Stop");
		bGo = new Button("Go");
		bStop.disable();
		bGo.disable();
		c.fill = GridBagConstraints.BOTH;
		c.anchor = GridBagConstraints.EAST;
		c.gridwidth = 1; c.gridheight = 1;
		c.gridx = 2; c.gridy = 1;
		c.weightx = 1; c.weighty = 1;
		gbl.setConstraints(bStop,c);
		this.add(bStop);
		c.fill = GridBagConstraints.BOTH;
		c.anchor = GridBagConstraints.EAST;
		c.gridwidth = 1; c.gridheight = 1;
		c.gridx = 1; c.gridy = 1;
		c.weightx = 1; c.weighty = 1;
		gbl.setConstraints(bGo,c);
		this.add(bGo);
		// Create a text field and add it to the layout.
		slideField = new TextSlide(this,"Projectile Velocity: ",minVal,maxVal);
		// Set the value of the slider and scrollbar.
		slideField.setValue(-0.2);
		c.fill = GridBagConstraints.HORIZONTAL;
		c.anchor = GridBagConstraints.SOUTH;
		c.gridwidth = 3; c.gridheight = 1;
		c.gridx = 0; c.gridy = 3;
		c.weightx = 3; c.weighty= 1;
		gbl.setConstraints(slideField,c);
		add(slideField);
		// You have to call validate to convince the canvas to adjust its layout.
		validate();
	}

	// Start the animation.  Called by applet's environment.  The applet calls the sines thread.
	public void start() { 
		globe.enable();
		bGo.enable();
		bStop.enable();
	}

	// Stop it.
	public void stop() { 
		globe.disable();
	}

	public void changeParam(TextSlide which) {
		if (which == slideField) {
			globe.setVelocity(slideField.getValue());
		}
	}

	public boolean action(Event e, Object arg) {
			if (e.target==bGo) {
					bGo.disable();
					bStop.enable();
					globe.fireButton();
			} else if (e.target==bStop) {
					bGo.enable();
					bStop.disable();
					globe.stopButton();
			}
			return true ;
	}

	// This method draws the background and  text at its current position.
	// There is nothing to do b/c each component draws itself.
	public void paint(Graphics g) {
		;
	}

	public void update(Graphics g) { ; }
}