// Simple applet illustrating use of add/removeChildren fields.

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import vrml.external.field.*;
import vrml.external.Node;
import vrml.external.Browser;
import vrml.external.exception.*;

public class AddRemoveTest extends Applet implements ActionListener {
    TextArea output = null;
    boolean error = false;

    // Browser we're using
    Browser browser;
    // Root of the scene graph (to which we add our nodes)
    Node root;
    // Shape group hierarchy
    Node[] shape;

    // EventIns of the root node
    EventInMFNode addChildren;
    EventInMFNode removeChildren;

    // Add and Remove Buttons
    Button addButton;
    Button removeButton;

    public void init() {
	add(addButton = new Button("Add Sphere"));
	add(removeButton =new Button("Remove Sphere"));
	addButton.addActionListener(this);
	removeButton.addActionListener(this);
      
	output = new TextArea(5, 40);
	add(output);
      
	browser = Browser.getBrowser(this);
      
	try {
	    // Get root node of the scene, and its EventIns
	    root = browser.getNode("ROOT");
	    addChildren = (EventInMFNode) root.getEventIn("addChildren");
	    removeChildren = (EventInMFNode) root.getEventIn("removeChildren");

	    // Instantiate our ubiquitous blue sphere hierarchy
	    shape = browser.createVrmlFromString("Shape {\n" +
						 "  appearance Appearance {\n" +
						 "    material Material {\n" +
						 "      diffuseColor 0.2 0.2 0.8\n" +
						 "    }\n" +
						 "  }\n" +
						 "  geometry Sphere {}\n" +
						 "}\n");
	}
	catch (InvalidNodeException e) {
	    output.append("PROBLEMS!: " + e + "\n");
	    error = true;
	}
	catch (InvalidEventInException e) {
	    output.append("PROBLEMS!: " + e + "\n");
	    error = true;
	}
	catch (InvalidVrmlException e) {
	    output.append("PROBLEMS!: " + e + "\n");
	    error = true;
	}
      
	if (error == false)
	    output.append("Ok...\n");
    }


    public void actionPerformed (ActionEvent event) {

	Object clickedButton = event.getSource();
	if (clickedButton == addButton) {	
	    addChildren.setValue(shape);
	}
	else if (clickedButton == removeButton) {
	    removeChildren.setValue(shape);
	}
    }
}