/* SnellDemo.java

* Jan. 10, 1998

* by Douglas Beeson

*/

import java.awt.*;

import java.applet.*;



/** An applet to demonstrate Snell's Law of refraction. It uses a

* data model (SnellModel.java) and a separate subclass of Panel (Display.java)

* to do the work of calculating theta values and displaying the light rays.

* This class is the one directly called by the browser. It also handles all

* mouse events and places all GUI objects on the screen.

*/

public class SnellDemo extends java.applet.Applet {



	Checkbox air1, water1, glass1, diamond1, other1;

	Checkbox air2, water2, glass2, diamond2, other2;

	Scrollbar tb, custom1, custom2;

	Panel controls, angleP;



	SnellModel model = new SnellModel();	//the data model

	Display display;					//the drawing engine



	final String theta = "\u03b8";   //a Unicode character for the Greek theta symbol (not supported on all platforms)





public SnellDemo() {

	super();

} //constructor



/** The first method called when the applet is started. It is called

* only once. If the applet is restarted (upon the browser coming back to

* the page), only the start() method will be called.

*

* This class is responsible for instantiating and laying out

* all the GUI components, and for linking the data model and display

* classes together using the Observer/Observable pattern.

*/

public void init() {



//Use a BorderLayout layout manager as the top-level GUI component arrangement

	  setLayout(new BorderLayout());

	  setBackground(Color.white);



//Instantiate the display class and connect it to the model

	  display = new Display();

	  model.addObserver(display);

//put the display in the middle of the GUI

	  add("Center",display);



//this sub panel holds the left-side scrollbar and theta symbol

	  angleP = new Panel();

//Ouch! The Gridbag is a hard layout manager for beginners to learn, but it is useful...

	  GridBagLayout gbl = new GridBagLayout();

	  angleP.setLayout(gbl);

	  //angleP.setLayout(new BorderLayout());



//	  GridBagConstraints gbc1 = new GridBagConstraints();	  //constrains the label

	  GridBagConstraints gbc2 = new GridBagConstraints();	  //constrins the scrollbar



/*	  gbc1.gridx = 0;

*	  gbc1.gridy = 0;

*	  gbc1.anchor = GridBagConstraints.NORTH;

*	  gbc1.fill = GridBagConstraints.NONE;

*	  gbc1.weighty = 1;

*	  gbc1.weightx = 1;

*/

	  gbc2.gridx = 0;

	  gbc2.gridy = 0;

	  gbc2.anchor = GridBagConstraints.CENTER;

	  gbc2.fill = GridBagConstraints.VERTICAL;

	  gbc2.weightx = 1;

	  gbc2.weighty = 1;

/*

*	  Label angleL = new Label(theta, Label.CENTER);

*	  gbl.setConstraints(angleL,gbc1);

*	  angleP.add(angleL);

*/

	  tb = new Scrollbar(Scrollbar.VERTICAL,45,5,0,90);

	  tb.setBackground(Color.white);

	  gbl.setConstraints(tb,gbc2);

	  angleP.add(tb);



//Put the scrollbar and theta symbol on the left side

	  add("West",angleP);



//the controls subpanel holds the radio buttons and custom n scrollbars

	  controls = new Panel();

//the grid layout is simple (only one column here)

	  controls.setLayout(new GridLayout(0,1));

	  controls.setBackground(Color.white);



	  Label l1 = new Label(" Material 1", Label.LEFT);

/* all the top radio buttons are linked logically to a checkbox group that

* ensures that only one of them is "true" at any given time.

*/

	  CheckboxGroup cb1 = new CheckboxGroup();

	  air1 = new Checkbox("Air", cb1, true);

	  water1 = new Checkbox("Water", cb1, false);

	  glass1 = new Checkbox("Glass", cb1, false);

	  diamond1 = new Checkbox("Diamond", cb1, false);

	  other1 = new Checkbox("Other", cb1, false);

	  custom1 = new Scrollbar(Scrollbar.HORIZONTAL,125,10,100,250);



	  Label space = new Label("____________", Label.LEFT);



	  Label l2 = new Label(" Material 2", Label.LEFT);



//Same with the bottom radio buttons

	  CheckboxGroup cb2 = new CheckboxGroup();

	  air2 = new Checkbox("Air", cb2, false);

	  water2 = new Checkbox("Water", cb2, true);

	  glass2 = new Checkbox("Glass", cb2, false);

	  diamond2 = new Checkbox("Diamond", cb2, false);

	  other2 = new Checkbox("Other", cb2, false);

	  custom2 = new Scrollbar(Scrollbar.HORIZONTAL,125,10,100,250);



	  controls.add(l1);

	  controls.add(air1);

	  controls.add(water1);

	  controls.add(glass1);

	  controls.add(diamond1);

	  controls.add(other1);

	  controls.add(custom1);



	  controls.add(space);



	  controls.add(l2);

	  controls.add(air2);

	  controls.add(water2);

	  controls.add(glass2);

	  controls.add(diamond2);

	  controls.add(other2);

	  controls.add(custom2);

	  

// Force all Checkboxes in the "controls" subpanel to be white.

	Component c;

	for (int i=0;i<controls.countComponents();i++) {

       	c = controls.getComponent(i);

		if (c instanceof Checkbox) {

			c.setBackground(Color.white);

		}//if

    	}//for



//put the controls subpanel on the right side

	  add("East", controls);

}//init





/** Handles all events generated by the GUI.

* Anything the mouse does generates an event (the Java runtime handles this)

* which is passed as an argument to this method. It's up to you to do something

* or not with the event. After trapping an event you want (by testing whether

* the event's target is a certain component, you must return true. If the event does not

* interest you, return whetever value the superclasse's handleEvent method returns.

*/

public boolean handleEvent(Event e) {

	if (e.target==tb) { //tb is the left scrollbar

		model.setTheta1(SnellModel.deg2rad((double)tb.getValue()));

		return true;

	}

	else if (e.target instanceof Scrollbar) {

//		System.out.println("Clicked?");

        switch (e.id) { //figure out which event was sent

            case Event.SCROLL_LINE_UP :

            case Event.SCROLL_LINE_DOWN :

            case Event.SCROLL_PAGE_UP : //all of these are okay

            case Event.SCROLL_PAGE_DOWN :

            case Event.SCROLL_ABSOLUTE :

		    if (e.target==custom1) {//the top custom n scrollbar

    			other1.setState(true);

	    		model.setIndex1((double)(custom1.getValue())/100);

	    		break;

//		    	System.out.println("Clicked1?");

		    } else if (e.target==custom2) {//the bottom custom n scrollbar

			    other2.setState(true);

    			model.setIndex2((double)(custom2.getValue())/100);

    			break;

//	    		System.out.println("Clicked2?");

            }

		    default : //any other events are ignored

		} //switch

    	return true;

	}

    //here we only want Checkbox events where the mouse is clicked (ACTION_EVENT)

	else if (e.target instanceof Checkbox && e.id==Event.ACTION_EVENT) {

		if (e.target==air1) {

			model.setIndex1(SnellModel.IR_AIR);

		} else if (e.target==water1) {

			model.setIndex1(SnellModel.IR_WATER);

		} else if (e.target==glass1) {

			model.setIndex1(SnellModel.IR_GLASS);

		} else if (e.target==diamond1) {

			model.setIndex1(SnellModel.IR_DIAMOND);

		} else if (e.target==other1) {

			model.setIndex1((double)(custom1.getValue())/100);

		} else if (e.target==air2) {

			model.setIndex2(SnellModel.IR_AIR);

		} else if (e.target==water2) {

			model.setIndex2(SnellModel.IR_WATER);

		} else if (e.target==glass2) {

			model.setIndex2(SnellModel.IR_GLASS);

		}else if (e.target==diamond2) {

			model.setIndex2(SnellModel.IR_DIAMOND);

		}else if (e.target==other2) {

			model.setIndex2((double)(custom2.getValue())/100);

		}

		return true;

	}

	else {	// we don't want the Event; given to our super class to deal with

		return super.handleEvent(e);

	}//else

}



/**This method is called each time the applet comes into view on the web page.

*/

public void start() {

	model.setTheta1(SnellModel.deg2rad(tb.getValue()));	//get the left scrollbar value and calculate theta

	model.setIndex1(SnellModel.IR_AIR);

	model.setIndex2(SnellModel.IR_WATER);

	air1.setState(true);

	water2.setState(true);

	repaint();

}//start



/**This method is called each time the applet goes out of view from the web page.

*/

public void stop() {

}//stop



/** Standard trick to reduce flicker.

*/

public void update(Graphics g) {

	paint(g);

}



/** We don't have to paint standard AWT components like Checkboxes and Scrollbars.

* They already have their own paint() methods that are automatically called by the

* Java runtime (the browser, actually) whenever needed.

* The only thing we do here is display a little reminder on the applet status line.

*/

public void paint(Graphics g) {

	showStatus("Snell's Law: n1 x sin(theta1) = n2 x sin(theta2)");

}//paint





} //class