import java.awt.*;
import java.awt.event.*;
import java.util.TooManyListenersException;

public class SignMe extends Panel implements ActionListener {

protected SigningSurface scribble;			// a fancy Canvas
protected Button eraseButton, acceptButton;

protected SignatureEventListener sigListener = null;

//-------------------------------------------------------------------
// SignMe constructor
// build GUI as a BorderLayout-managed Panel containing:
// - in its center slot: the SigningSurface
// - in its south  slot: a sub-Panel containing two sub-sub panels each holding:
//   - an Erase button
//   - an Accept button
// register us as event listener for the 2 buttons
//-------------------------------------------------------------------
public SignMe() {
Panel buttonsPanel, but1Panel, but2Panel;	// "Erase"  "Accept"


	setLayout(new BorderLayout());			// override default FlowLayout

	// instantiate individual GUI elements
	scribble	 = new SigningSurface();

	buttonsPanel = new Panel();
	but1Panel	 = new Panel();
	but2Panel	 = new Panel();

	eraseButton	 = new Button("Erase");
	acceptButton = new Button("Accept");

	// construct button panel
	but1Panel.add(eraseButton);
	but2Panel.add(acceptButton);
	buttonsPanel.add(but1Panel);
	buttonsPanel.add(but2Panel);

	add(scribble,	  "Center");
	add(buttonsPanel, "South");

	// register ourselves as interested click listener for both buttons
	 eraseButton.addActionListener(this);
	acceptButton.addActionListener(this);
}
//-------------------------------------------------------------------
// The ActionEvent listener method. The button clicks arrive here.
//-------------------------------------------------------------------
public void actionPerformed(ActionEvent buttonClick) {

	if ( buttonClick.getSource() == eraseButton ) {
		scribble.wipeSignature();
	}
	if ( buttonClick.getSource() == acceptButton ) {
		System.out.println("user accepted signature!");
		fireSignedEvent();
	}
}
//-------------------------------------------------------------------
// SignMe event listener (de)registration methods
//-------------------------------------------------------------------
public void addSignatureListener( SignatureEventListener listener)
							throws java.util.TooManyListenersException {
	if (sigListener != null) {
		throw new TooManyListenersException(
			"SignMe already has an event listener!");
	}
	sigListener = listener;
}
//-------------------------------------------------------------------
public void removeSignatureListener( SignatureEventListener listener) {

	if (sigListener == null) {
		throw new IllegalArgumentException(
			"Can't remove SignMe event listener because none currently set!");
	}

	if (sigListener != listener) {
		throw new IllegalArgumentException(
			"Can't remove SignMe event listener because different one from currently set!");
	}
	sigListener = null;
}
//-------------------------------------------------------------------
// Internal event raising method
//-------------------------------------------------------------------
protected void fireSignedEvent() {
SignatureEvent event;

	if ( sigListener != null ) {
		event = new SignatureEvent(this, scribble.getImage() );
		sigListener.userSigned( event );
	}
}
} // End of Class SignMe