source: trunk/gli/src/org/greenstone/gatherer/util/TreeSynchronizer.java@ 8650

/**
 *#########################################################################
 *
 * 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.
 *
 * Author: John Thompson, Greenstone Digital Library, University of Waikato
 *
 * Copyright (C) 1999 New Zealand Digital Library Project
 *
 * 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.
 *
 * 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.
 *
 * 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.util;

import java.util.Vector;
import javax.swing.JTree;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
import org.greenstone.gatherer.gui.tree.DragTree;
/** My latest diabolical class synchronizes the expansion state of two or more JTrees. Muh-hahahaha. Note that these tree should be based on the same model. If they aren't it won't work. So there.
 * @author John Thompson, Greenstone Digital Library, University of Waikato
 * @version 2.1
 */
final public class TreeSynchronizer 
    extends Vector 
    implements TreeExpansionListener, TreeSelectionListener {
    /** <i>true</i> if we should temporarily ignore further events, most likely because we know our actions are causing them. */ 
    private boolean ignore;
    /** A list of tree selection listeners. */
    private Vector selection_listeners = new Vector();
    /** Add a new tree to the synchronization list of trees to be synchronized.
     * @param tree The lastest victim, a <strong>JTree</strong>.
     */
    public void add(JTree tree) {
    super.add(tree);
    tree.addTreeExpansionListener(this);
    tree.addTreeSelectionListener(this);
    }

    /** We allow the Gatherer to add tree listeners to this class, as it persists between collection changes transparently. Thus there is no need to reattach listeners everytime the collection changes. */
    public void addTreeSelectionListener(TreeSelectionListener listener) {
    if(!selection_listeners.contains(listener)) {
        selection_listeners.add(listener);
    }
    }

    /** Called whenever an item in the tree has been collapsed.
     * @param event A <strong>TreeExpansionEvent</strong> containing information about the event.
     */
    public void treeCollapsed(TreeExpansionEvent event) {
    if(!ignore) {
        ignore = true;
        // Collapse that path in all registered trees.
        JTree tree = (JTree)event.getSource();
        TreePath path = event.getPath();
        for(int i = size(); i != 0; i--) {
        JTree sibling = (JTree) get(i - 1);
        if(!sibling.equals(tree)) {
            sibling.collapsePath(path);
        }
        }
        ignore = false;
    }
    }
    /** Called whenever an item in the tree has been expanded.
     * @param event A <strong>TreeExpansionEvent</strong> containing information about the event.
     */
    public void treeExpanded(TreeExpansionEvent event) {
    if(!ignore) {
        ignore = true;
        // Expand that path in all registered trees.
        JTree tree = (JTree)event.getSource();
        TreePath path = event.getPath();
        for(int i = size(); i != 0; i--) {
        JTree sibling = (JTree) get(i - 1);
        if(!sibling.equals(tree)) {
            sibling.expandPath(path);
        }
        }
        ignore = false;
    }
    }
    /** Called whenever the one of the trees selection changes.
     * @param event A <strong>TreeSelectionEvent</strong> containing information about the event.
     */
    public void valueChanged(TreeSelectionEvent event) {
    if(!ignore) {
        ignore = true;
        // Recover the tree that is the source.
        JTree tree = (JTree) event.getSource();
        // Brute Force approach.
        // Extract the currently selected paths.
        TreePath paths[] = tree.getSelectionPaths();
        // Then for every registered tree, that isn't this one, ensure those paths are selected.
        /*
        for(int i = size(); paths != null && i != 0; i--) {
        JTree sibling = (JTree) get(i - 1);
        if(!sibling.equals(tree)) {
            // One last thing to do. If this is actually a DragTree we are dealing with we have to tell it to set the selection values immediately, not wait for the clear until it is sure it is no the pre-cursor to a drag.
            if(sibling instanceof DragTree) {
            DragTree gtree = (DragTree)sibling;
            gtree.setImmediate(true);
            gtree.setSelectionPaths(paths);
            // I'm going to ensure that the last selected path is visible.
            gtree.scrollPathToVisible(paths[paths.length - 1]);
            gtree.setImmediate(false);
            }
            else {
            sibling.setSelectionPaths(paths);
            sibling.scrollPathToVisible(paths[paths.length - 1]);
            }
        }
        }
        */
        // Pass on message to all listeners.
        for(int i = 0; i < selection_listeners.size(); i++) {
        ((TreeSelectionListener) selection_listeners.get(i)).valueChanged(event);
        }
        ignore = false;
    }
    }
}