source: trunk/gli/src/org/greenstone/gatherer/help/HelpFrame.java@ 7015

/**
 *#########################################################################
 *
 * A component of the Gatherer application, part of the Greenstone digital
 * library suite from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * <BR><BR>
 *
 * Principal Author: John Thompson, NZDL Project, University of Waikato
 *
 * <BR><BR>
 *
 * Copyright (C) 1999 New Zealand Digital Library Project
 *
 * <BR><BR>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * <BR><BR>
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * <BR><BR>
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *########################################################################
 */
package org.greenstone.gatherer.help;

import java.awt.*;
import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
import org.apache.xerces.parsers.DOMParser;
import org.greenstone.gatherer.Dictionary;
import org.greenstone.gatherer.Gatherer;
import org.greenstone.gatherer.util.StaticStrings;
import org.greenstone.gatherer.util.Utility;
import org.w3c.dom.*;

/**
 * This class provides a nice help facility. It is a separate frame that can be positioned
 * as the user wishes, and provides a contents page and the help information.
 * @author Michael Dewsnip, NZDL Project
 */
public class HelpFrame 
    extends JFrame {

    static private final String NULL_STRING = "<null>";
    /** The size of the frame */
    static private final Dimension SIZE = new Dimension(760, 560);

    /** The HTML rendering pane */
    private JEditorPane view = null;
    /** The contents tree model */
    private ContentsModel model = null;
    /** A contents tree for the top of the frame */
    private JTree contents = null;

    private JSplitPane split_pane = null;



    public HelpFrame()
    {
    setDefaultCloseOperation(HIDE_ON_CLOSE);
    setSize(SIZE);
    Dictionary.registerText(this, "Help.Title");

    view = new JEditorPane();
    view.setEditable(false);
    view.addHyperlinkListener(new ViewHyperlinkListener());

    HelpItem rootNode = new HelpItem(Dictionary.get("Help.Contents"), NULL_STRING);
    model = new ContentsModel(rootNode);
    contents = new JTree((DefaultTreeModel) model);
    contents.addTreeSelectionListener(new ContentsListener());
    contents.setExpandsSelectedPaths(true);

    // Creation
    JPanel content_pane = (JPanel) this.getContentPane();
    split_pane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
    JScrollPane index_scroll = new JScrollPane(contents);
    JScrollPane view_scroll = new JScrollPane(view);

    // Layout
    split_pane.add(index_scroll, JSplitPane.LEFT);
    split_pane.add(view_scroll, JSplitPane.RIGHT);
    content_pane.setLayout(new BorderLayout());
    content_pane.add(split_pane, BorderLayout.CENTER);

    // Center
    Dimension screen_size = Toolkit.getDefaultToolkit().getScreenSize();
    setLocation((screen_size.width - SIZE.width) / 2, (screen_size.height - SIZE.height) / 2);        
    }

    private class ViewHyperlinkListener
    implements HyperlinkListener {
    public void hyperlinkUpdate(HyperlinkEvent e) {
        if(e.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
        try {
            view.setPage(e.getURL());
        }
        catch(Exception exception) {
            Gatherer.printStackTrace(exception);
        }
        }
    }
    }

    public void destroy()
    {
    view = null;
    contents = null;
    }


    public void setView(String sectionName)
    {
    // Find the node in the tree with the specified sectionName
    HelpItem node = model.getHelpItemNamed(sectionName);

    // Ensure the node is selected and visible
    TreePath path = new TreePath(node.getPath());
    contents.setSelectionPath(path);
    contents.scrollPathToVisible(path);

    // Display the selected page
    URL url = node.getURL();
    if (url != null) {
        try {
        view.setPage(url);
        }
        catch (Exception exception) {
        Gatherer.printStackTrace(exception);
        }
    }

    // Make the help frame visible
    show();
    split_pane.setDividerLocation(0.2);
    }


    private class ContentsModel
    extends DefaultTreeModel {

    public ContentsModel(MutableTreeNode rootNode) {
        super(rootNode);

        // Load the XML help file and build the contents structure from it
        try {
        DOMParser parser = new DOMParser();
        parser.parse(Utility.getHelpFolder() + StaticStrings.HELP_INDEX_FILENAME);
        Document document = parser.getDocument();

        // Traverse the document hierarchy, building a tree representing its structure
        Node documentNode = document.getFirstChild();

        int sectionNum = 0;
        NodeList children = documentNode.getChildNodes();
        for (int i = 0; i < children.getLength(); i++) {
            Node child = children.item(i);
            if (child.getNodeName().equals(StaticStrings.SECTION_ELEMENT)) {
            sectionNum++;
            buildContentsHierarchy(rootNode, sectionNum + StaticStrings.EMPTY_STR, child);
            }
        }
        }
        catch (Exception ex) {
        ex.printStackTrace();
        }
    }


    public void buildContentsHierarchy(MutableTreeNode parent, String pos, Node node)
    {
        // Determine the section name
        String sectionName = ((Element) node).getAttribute(StaticStrings.NAME_ATTRIBUTE);

        // Determine the section title
        String sectionTitle = "";
        NodeList children = node.getChildNodes();
        for (int i = 0; i < children.getLength(); i++) {
        Node child = children.item(i);
        if (child.getNodeName().equals(StaticStrings.TITLE_ELEMENT)) {
            sectionTitle = pos + ": ";
            if (child.getFirstChild() != null) {
            sectionTitle = sectionTitle + child.getFirstChild().getNodeValue();
            }
        }
        }

        // Add the node into the tree
        HelpItem item = new HelpItem(sectionTitle, sectionName);
        insertNodeInto(item, parent, parent.getChildCount());

        // Apply recursively to the children of this node
        int sectionNum = 0;
        for (int i = 0; i < children.getLength(); i++) {
        Node child = children.item(i);
        if (child.getNodeName().equals(StaticStrings.SECTION_ELEMENT)) {
            sectionNum++;
            buildContentsHierarchy(item, pos + StaticStrings.STOP_CHARACTER + sectionNum, child);
        }
        }
    }


    public HelpItem getHelpItemNamed(String sectionName)
    {
        // Find the node with name matching sectionName, somewhere in the tree
        Enumeration descendants = ((DefaultMutableTreeNode) root).preorderEnumeration();
        while (descendants.hasMoreElements()) {
        HelpItem node = (HelpItem) descendants.nextElement();
        if (node.name.equals(sectionName)) {
            return node;
        }
        }

        // Couldn't be found, so just return the root (Contents) node
        return (HelpItem) root;
    }
    }


    /** This listener is used to listen for selection changes in the contents tree, and
     * to show the appropriate page as required.
     */
    private class ContentsListener
    implements TreeSelectionListener {

    /** Any implementation of <i>TreeSelectionListener</i> must include this method so we can be informed when the tree selection changes.
     * @param event A <strong>TreeSelectionEvent</strong> containing al the relevant information about the event itself.
     */
    public void valueChanged(TreeSelectionEvent event)
    {
        TreePath path = event.getPath();
        HelpItem node = (HelpItem) path.getLastPathComponent();
        URL url = node.getURL();
        if (url != null) {
        //view.showHTMLDocument(url);
        try {
            view.setPage(url);
        }
        catch (Exception exception) {
            Gatherer.printStackTrace(exception);
        }
        }
    }
    }


    /** This class provides a wrapper around a <strong>DefaultMutableTreeNode</strong> which
     * provides the ability to set an html page to be loaded when this node is selected.
     */
    private class HelpItem 
    extends DefaultMutableTreeNode {

    /** The unique name of the section (matches the HTML filename) */
    public String name = null;
    /** The title to be displayed for this tree node. */
    public String title = null;


    /** Constructor.
     * @param title The title to be shown for this node as a <strong>String</strong>.
     * @param name The name of the section as a <strong>String</strong>.
     */
    public HelpItem(String title, String name)
    {
        this.name = name;
        this.title = title;
    }


    /** Method to create a url from the file name.
     * @return A <strong>URL</strong> that points to the file's location.
     */
    public URL getURL()
    {
        if (name != null && !name.equals(NULL_STRING)) {
        try {
            File file = new File(Utility.getHelpFolder() + name + StaticStrings.HTM_FILE_EXTENSION);
            return file.toURL();
        }
        catch (Exception e) {
        }
        }

        return null;
    }


    public String toString()
    {
        return title;
    }
    }
}