JASWizard.java

package jas.util;
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRootPane;
/**
 * The wizard is useful for getting user input on multiple pages.  The JASWizard supports a
 * tree structure of JASWizardPages, and the path down that tree is determined by each node
 * when the "Next" button is clicked.  At a leaf (or at any node), the "Finish" button can be
 * clicked and the wizard closes.  The "Next" button is enabled when a JASWizardPage that implements
 * the interface HasNextPages is showing, the "Finish" button is enabled when a page that implements
 * the interface Finishable is showing, and the "Help" button is enabled when a page that implements
 * HasHelpPages is showing.
 *  @author Jonas Gifford
 *  @see JASWizardPage
 *  @see HasNextPages
 *  @see Finishable
 *  @see HasHelpPage
 */
public class JASWizard extends JDialog implements ActionListener
{
	/**
	 * Creates a new wizard that shows itself automatically.
	 *  @param parent the parent JFrame
	 *  @param title the title for the wizard dialog
	 *  @firstPage the root of the tree structure and the page the wizard opens to
	 */
	public JASWizard(final JFrame parent, final String title, final JASWizardPage firstPage)
	{
		super(parent, title, true);
      m_frame = parent;
		m_contentPane = getContentPane();
		m_contentPane.setLayout(new BorderLayout());
		m_rootPane = getRootPane();
		m_wizardPagePanel = new JPanel(m_layout = new CardLayout());
		firstPage.addTo(m_wizardPagePanel, this, null); // recursive call
		final JPanel buttons = new JPanel(new FlowLayout());
		buttons.add(m_cancel = new JButton("Cancel"));		m_cancel.setMnemonic('C');
		buttons.add(m_help   = new JButton("Help"));        m_help.setMnemonic('H');
		buttons.add(m_prev   = new JButton("<< Previous")); m_prev.setMnemonic('P');
		buttons.add(m_next   = new JButton("Next >>"));		m_next.setMnemonic('N');
		buttons.add(m_finish = new JButton("Finish"));		m_finish.setMnemonic('F');
		m_wizardPagePanel.setBorder(new javax.swing.border.EtchedBorder());
		m_contentPane.add(BorderLayout.CENTER, m_wizardPagePanel);
		m_contentPane.add(BorderLayout.SOUTH, buttons);
		pack();
		final Dimension mySize = getSize();
		final Dimension parentSize = parent.getSize();
		final Point position = parent.getLocation();
		
		position.translate((parentSize.width-mySize.width)/2,
			               (parentSize.height-mySize.height)/2);

		setLocation(position);	
		m_layout.first(m_wizardPagePanel);
		(m_currentPage = m_firstPage = firstPage).doEnable();
		m_cancel.addActionListener(this);
		m_help.addActionListener(this);
		m_prev.addActionListener(this);
		m_next.addActionListener(this);
		m_finish.addActionListener(this);
		m_currentPageHasAmbiguousDefault = m_currentPage.isFinishable() && m_currentPage.hasNextPages();
	//	setDefaultButton();
		m_help.setEnabled(firstPage instanceof HasHelpPage);
		setResizable(false);
		enableEvents(java.awt.AWTEvent.WINDOW_EVENT_MASK);
		firstPage.beforeShowing();
      Application app = Application.getApplication();
		if (app != null) app.modalDialogOpening(this);
		show();
		if (app != null) app.modalDialogClosing(this);
	}
	void setNextEnabled(final boolean b)
	{
		m_next.setEnabled(b && m_currentPage.hasNextPages());
	}
	void setFinishEnabled(final boolean b)
	{
		m_finish.setEnabled(b && m_currentPage.isFinishable());
	}
	void doPrevEnabled()
	{
		m_prev.setEnabled(m_currentPage.getPrev() != null);
	}
	private void onHelp()
	{
		setToWaitCursor();
		HasHelpPage h = ((HasHelpPage) m_currentPage);
		Application.getApplication().showHelpTopic(h.getHelpTopic(),this);
		setToDefaultCursor();
	}
	private void setToCurrentPage(final JASWizardPage page)
	{
		m_currentPage = page;

		m_currentPageHasAmbiguousDefault = m_currentPage.isFinishable() && m_currentPage.hasNextPages();
		page.doEnable();
		if (! m_currentPageHasAmbiguousDefault) setDefaultButton();
		m_help.setEnabled(page instanceof HasHelpPage);
		page.beforeShowing();
		m_layout.show(m_wizardPagePanel, page.toString());
	}
	private void onPrev()
	{
		setToWaitCursor();
		try
		{
			setToCurrentPage(m_currentPage.getPrev());
		}
		catch (Throwable t)
		{
			handleError("Error during wizard processing",t);
		}
		finally
		{	
			setToDefaultCursor();
		}
	}
	private void onNext()
	{
		setToWaitCursor();
		try
		{
			final JASWizardPage newPage = ((HasNextPages) m_currentPage).getNext();

			if (newPage != null)
			{
				// Make sure this page was already added to the current (soon to be previous) page, 
				// if not add it now.

				if (!m_wizardPagePanel.isAncestorOf(newPage))
				{
					newPage.addTo(m_wizardPagePanel, this, m_currentPage);
					newPage.invalidate();
					validate();
				}

				setToCurrentPage(newPage);
			}
		}
		catch (Throwable t)
		{
			handleError("Error during wizard processing",t);
		}
		finally
		{	
			setToDefaultCursor();
		}
	}
	void setDefaultButton()
	{
		if (m_currentPageHasAmbiguousDefault && m_next.isEnabled())
			m_rootPane.setDefaultButton(m_next);
		else if (m_currentPageHasAmbiguousDefault && m_finish.isEnabled())
			m_rootPane.setDefaultButton(m_finish);
		else
			m_rootPane.setDefaultButton(m_currentPage.hasNextPages() ?  m_next : m_finish);
	}

	/**
	 * Closes the wizard.  Invoked by <code>dispose()</code> in JASWizardPage.
	 *  @see JASWizardPage
	 *  @see JASWizardPage#dispose()
	 */
	public void dispose()
	{
		m_firstPage.clear();
		/*
		 * References in it and all pages linked to
		 * it are set to null.
		 */
		JASWizardPage.pageNumber = 0;
		// next time the pages start at zero, so that the number doesn't get too big

		if (getCursor() == m_wait)
			m_frame.setCursor(m_wait);
		super.dispose();
	}
	private void onFinish()
	{
		setToWaitCursor();
		try
		{
			((Finishable) m_currentPage).onFinish();
		}
		catch (Throwable t)
		{
			handleError("Error during wizard processing",t);
		}
		finally
		{	
			setToDefaultCursor();
		}
	}
	private void onCancel()
	{
		setToWaitCursor();
		try
		{
			m_firstPage.doCancel();
			dispose();
		}
		catch (Throwable t)
		{
			handleError("Error during wizard processing",t);
		}
		finally
		{	
			setToDefaultCursor();
		}	
	}
	void setToWaitCursor()
	{
		// should set it on frame too, but doesn't work with modal dialog
		setCursor(m_wait);
	}
	void setToDefaultCursor()
	{
		setCursor(m_default);
		m_frame.setCursor(m_default);
	}
	/** Public as an implementation side effect; do not call. */
	public void actionPerformed(final ActionEvent e)
	{
		final Object source = e.getSource();
		     if (source == m_cancel) onCancel();
		else if (source == m_help)   onHelp();
		else if (source == m_prev)   onPrev();
		else if (source == m_next)   onNext();
		else if (source == m_finish) onFinish();
	}
	/** Public as an implementation side effect; do not call. */
	public void processWindowEvent(final WindowEvent e)
	{
//		super.processWindowEvent(e);
		final int id = e.getID();
		if (id == WindowEvent.WINDOW_CLOSING)
			onCancel();
		else if (id == WindowEvent.WINDOW_ACTIVATED)
			setDefaultButton();
	}
   protected void handleError(String message, Throwable t)
   {
      Application app = Application.getApplication();
      if (app != null) app.error("Error during wizard processing",t);
      else t.printStackTrace();
   }
	private final JFrame m_frame;
	private final Cursor m_default = Cursor.getDefaultCursor(), m_wait = new Cursor(Cursor.WAIT_CURSOR);
	private boolean m_currentPageHasAmbiguousDefault;
	final private JRootPane m_rootPane;
	final private java.awt.Container m_contentPane;
	final private JPanel m_wizardPagePanel;
	final private JASWizardPage m_firstPage;
	private JASWizardPage m_currentPage;
	final private JButton m_cancel, m_help, m_prev, m_next, m_finish;
	final private CardLayout m_layout;
}