Java/Swing JFC/Help

Simple Help Frame based on JFC JEditorPane

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Cursor;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.BorderFactory;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;
import javax.swing.text.Document;
/**
 * Simple Help Frame based on JFC JEditorPane.
 * <p>
 * May someday rewrite using JavaHelp API.
 * 
 * @version $Id: SimpleHelp.java,v 1.10 2003/05/30 13:16:07 ian Exp $
 */
public class SimpleHelp extends JFrame implements HyperlinkListener {
  /** The contentpane */
  protected Container cp;
  /** The editorpane */
  JEditorPane help;
  /*
   * Construct a Help object. Just construct a JEditorPane with a URL, and it
   * does all the help from there.
   */
  public SimpleHelp(String windowName, String helpIndexFileName) {
    super(windowName + " Help Window");
    cp = getContentPane();
    getAccessibleContext().setAccessibleName(windowName + " Help Window");
    getAccessibleContext().setAccessibleDescription(
        "A window for viewing the help for " + windowName
            + ", which is somewhat hyperlinked.");
    try {
      URL url = new File(helpIndexFileName).toURL();
      // Only create the window once.
      if (help == null) {
        // System.out.println("Creat-ing help window for " + url);
        help = new JEditorPane(url);
        // System.out.println("Done!");
        help.setEditable(false);
        help.addHyperlinkListener(this);
        JScrollPane scroller = new JScrollPane();
        scroller.setBorder(BorderFactory.createTitledBorder(windowName
            + " Help"));
        scroller.getViewport().add(help);
        cp.add(BorderLayout.CENTER, scroller);
        addWindowListener(new WindowAdapter() {
          public void windowClosing(WindowEvent e) {
            SimpleHelp.this.setVisible(false);
            SimpleHelp.this.dispose();
          }
        });
        setSize(500, 400);
      } else {
        System.out.println("Re-using help window!");
      }
    } catch (MalformedURLException e) {
      System.out.println("Malformed URL: " + e);
    } catch (IOException e) {
      System.out.println("IOException: " + e);
    }
  }
  /**
   * Notification of a change relative to a hyperlink. From:
   * java.swing.event.HyperlinkListener
   */
  public void hyperlinkUpdate(HyperlinkEvent e) {
    if (e.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
      URL target = e.getURL();
      // System.out.println("linkto: " + target);
      // Get the help panel"s cursor and the wait cursor
      Cursor oldCursor = help.getCursor();
      Cursor waitCursor = Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR);
      help.setCursor(waitCursor);
      // Now arrange for the page to get loaded asynchronously,
      // and the cursor to be set back to what it was.
      SwingUtilities.invokeLater(new PageLoader(target, oldCursor));
    }
  }
  /**
   * Inner class that loads a URL synchronously into the help panel. Loads it
   * later than the request so that a cursor change can be done at the very
   * end.
   * 
   * @author BORROWED FROM SUN"S SWING DEMO, UNTIL JAVAHELP AVAILABLE
   */
  class PageLoader implements Runnable {
    URL url;
    Cursor cursor;
    PageLoader(URL u, Cursor c) {
      url = u;
      cursor = c;
    }
    public void run() {
      // System.out.println("PageLoader: u=" + url);
      if (url == null) {
        // restore the original cursor
        help.setCursor(cursor);
        // PENDING(prinz) remove this hack when
        // automatic validation is activated.
        Container parent = help.getParent();
        parent.repaint();
      } else {
        Document doc = help.getDocument();
        try {
          help.setPage(url);
        } catch (Exception ioe) {
          help.setDocument(doc);
          getToolkit().beep();
        } finally {
          // schedule the cursor to revert after
          // the paint has happended.
          url = null;
          SwingUtilities.invokeLater(this);
        }
      }
    }
  }
}