/*
 * @(#)JTree.java	1.165 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.swing;

import java.awt.*;
import java.awt.event.*;
import java.beans.*;
import java.io.*;
import java.util.*;
import javax.swing.event.*;
import javax.swing.plaf.TreeUI;
import javax.swing.tree.*;
import javax.swing.text.Position;
import javax.accessibility.*;


/**
 * <a name="jtree_description">
 * A control that displays a set of hierarchical data as an outline.
 * You can find task-oriented documentation and examples of using trees in
 * <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/tree.html">How to Use Trees</a>,
 * a section in <em>The Java Tutorial.</em>
 * <p>
 * A specific node in a tree can be identified either by a
 * <code>TreePath</code> (an object
 * that encapsulates a node and all of its ancestors), or by its
 * display row, where each row in the display area displays one node.
 * An <i>expanded</i> node is a non-leaf node (as identified by
 * <code>TreeModel.isLeaf(node)</code> returning false) that will displays
 * its children when all its ancestors are <i>expanded</i>.
 * A <i>collapsed</i>
 * node is one which hides them. A <i>hidden</i> node is one which is
 * under a collapsed ancestor. All of a <i>viewable</i> nodes parents
 * are expanded, but may or may not be displayed. A <i>displayed</i> node
 * is both viewable and in the display area, where it can be seen.
 * <p>
 * The following <code>JTree</code> methods use "visible" to mean "displayed":
 * <ul>
 * <li><code>isRootVisible()</code>
 * <li><code>setRootVisible()</code>
 * <li><code>scrollPathToVisible()</code>
 * <li><code>scrollRowToVisible()</code>
 * <li><code>getVisibleRowCount()</code>
 * <li><code>setVisibleRowCount()</code>
 * </ul>
 * <p>
 * The next group of <code>JTree</code> methods use "visible" to mean
 * "viewable" (under an expanded parent):
 * <ul>
 * <li><code>isVisible()</code>
 * <li><code>makeVisible()</code>
 * </ul>
 * <p>
 * If you are interested in knowing when the selection changes implement
 * the <code>TreeSelectionListener</code> interface and add the instance
 * using the method <code>addTreeSelectionListener</code>.
 * <code>valueChanged</code> will be invoked when the
 * selection changes, that is if the user clicks twice on the same
 * node <code>valueChanged</code> will only be invoked once.
 * <p>
 * If you are interested in detecting either double-click events or when
 * a user clicks on a node, regardless of whether or not it was selected,
 * we recommend you do the following:
 * <pre>
 * final JTree tree = ...;
 *
 * MouseListener ml = new MouseAdapter() {
 *     public void <b>mousePressed</b>(MouseEvent e) {
 *         int selRow = tree.getRowForLocation(e.getX(), e.getY());
 *         TreePath selPath = tree.getPathForLocation(e.getX(), e.getY());
 *         if(selRow != -1) {
 *             if(e.getClickCount() == 1) {
 *                 mySingleClick(selRow, selPath);
 *             }
 *             else if(e.getClickCount() == 2) {
 *                 myDoubleClick(selRow, selPath);
 *             }
 *         }
 *     }
 * };
 * tree.addMouseListener(ml);
 * </pre>
 * NOTE: This example obtains both the path and row, but you only need to
 * get the one you're interested in.
 * <p>
 * To use <code>JTree</code> to display compound nodes
 * (for example, nodes containing both
 * a graphic icon and text), subclass {@link TreeCellRenderer} and use 
 * {@link #setCellRenderer} to tell the tree to use it. To edit such nodes,
 * subclass {@link TreeCellEditor} and use {@link #setCellEditor}.
 * <p>
 * Like all <code>JComponent</code> classes, you can use {@link InputMap} and
 * {@link ActionMap}
 * to associate an {@link Action} object with a {@link KeyStroke}
 * and execute the action under specified conditions.
 * <p>
 * For the keyboard keys used by this component in the standard Look and
 * Feel (L&F) renditions, see the
 * <a href="doc-files/Key-Index.html#JTree"><code>JTree</code> key assignments</a>.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans<sup><font size="-2">TM</font></sup>
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @beaninfo
 *   attribute: isContainer false
 * description: A component that displays a set of hierarchical data as an outline.
 *
 * @version 1.165, 01/23/03
 * @author Rob Davis
 * @author Ray Ryan
 * @author Scott Violet
 */
public class JTree extends JComponent implements Scrollable, Accessible
{
    /**
     * @see #getUIClassID
     * @see #readObject
     */
    private static final String uiClassID = "TreeUI";

    /**
     * The model that defines the tree displayed by this object.
     */
    transient protected TreeModel        treeModel;

    /**
     * Models the set of selected nodes in this tree.
     */
    transient protected TreeSelectionModel selectionModel;

    /**
     * True if the root node is displayed, false if its children are
     * the highest visible nodes.
     */
    protected boolean                    rootVisible;

    /**
     * The cell used to draw nodes. If <code>null</code>, the UI uses a default
     * <code>cellRenderer</code>.
     */
    transient protected TreeCellRenderer  cellRenderer;

    /**
     * Height to use for each display row. If this is <= 0 the renderer 
     * determines the height for each row.
     */
    protected int                         rowHeight;

    /**
     * Maps from <code>TreePath</code> to <code>Boolean</code>
     * indicating whether or not the
     * particular path is expanded. This ONLY indicates whether a 
     * given path is expanded, and NOT if it is visible or not. That
     * information must be determined by visiting all the parent
     * paths and seeing if they are visible.
     */
    transient private Hashtable           expandedState;


    /**
     * True if handles are displayed at the topmost level of the tree.
     * <p>
     * A handle is a small icon that displays adjacent to the node which 
     * allows the user to click once to expand or collapse the node. A
     * common interface shows a plus sign (+) for a node which can be
     * expanded and a minus sign (-) for a node which can be collapsed.
     * Handles are always shown for nodes below the topmost level.
     * <p>
     * If the <code>rootVisible</code> setting specifies that the root 
     * node is to be displayed, then that is the only node at the topmost
     * level. If the root node is not displayed, then all of its 
     * children are at the topmost level of the tree. Handles are 
     * always displayed for nodes other than the topmost.
     * <p> 
     * If the root node isn't visible, it is generally a good to make 
     * this value true. Otherwise, the tree looks exactly like a list,
     * and users may not know that the "list entries" are actually
     * tree nodes.
     *
     * @see #rootVisible
     */
    protected boolean           showsRootHandles;

    /**
     * Creates a new event and passed it off the
     * <code>selectionListeners</code>.
     */
    protected transient TreeSelectionRedirector selectionRedirector;

    /**
     * Editor for the entries.  Default is <code>null</code>
     * (tree is not editable).
     */
    transient protected TreeCellEditor          cellEditor;

    /**
     * Is the tree editable? Default is false.
     */
    protected boolean                 editable;

    /**
     * Is this tree a large model? This is a code-optimization setting.
     * A large model can be used when the cell height is the same for all
     * nodes. The UI will then cache very little information and instead
     * continually message the model. Without a large model the UI caches 
     * most of the information, resulting in fewer method calls to the model.
     * <p>
     * This value is only a suggestion to the UI. Not all UIs will
     * take advantage of it. Default value is false.
     */
    protected boolean                 largeModel;

    /**
     * Number of rows to make visible at one time. This value is used for
     * the <code>Scrollable</code> interface. It determines the preferred
     * size of the display area.
     */
    protected int                     visibleRowCount;

    /**
     * If true, when editing is to be stopped by way of selection changing,
     * data in tree changing or other means <code>stopCellEditing</code>
     * is invoked, and changes are saved. If false,
     * <code>cancelCellEditing</code> is invoked, and changes
     * are discarded. Default is false.
     */
    protected boolean                 invokesStopCellEditing;

    /**
     * If true, when a node is expanded, as many of the descendants are 
     * scrolled to be visible.
     */
    protected boolean                 scrollsOnExpand;

    /**
     * Number of mouse clicks before a node is expanded.
     */
    protected int                     toggleClickCount;

    /**
     * Updates the <code>expandedState</code>.
     */
    transient protected TreeModelListener       treeModelListener;

    /**
     * Used when <code>setExpandedState</code> is invoked,
     * will be a <code>Stack</code> of <code>Stack</code>s.
     */
    transient private Stack           expandedStack;

    /**
     * Lead selection path, may not be <code>null</code>.
     */
    private TreePath                  leadPath;

    /**
     * Anchor path.
     */
    private TreePath                  anchorPath;

    /**
     * True if paths in the selection should be expanded.
     */
    private boolean                   expandsSelectedPaths;

    /**
     * This is set to true for the life of the <code>setUI</code> call.
     */
    private boolean                   settingUI;

    /** If true, mouse presses on selections initiate a drag operation. */
    private boolean dragEnabled;

    /**
     * When <code>addTreeExpansionListener</code> is invoked,
     * and <code>settingUI</code> is true, this ivar gets set to the passed in
     * <code>Listener</code>. This listener is then notified first in
     * <code>fireTreeCollapsed</code> and <code>fireTreeExpanded</code>.
     * <p>This is an ugly workaround for a way to have the UI listener
     * get notified before other listeners.
     */
    private transient TreeExpansionListener     uiTreeExpansionListener;

    /**
     * Max number of stacks to keep around.
     */
    private static int                TEMP_STACK_SIZE = 11;

    //
    // Bound property names
    //
    /** Bound property name for <code>cellRenderer</code>. */
    public final static String        CELL_RENDERER_PROPERTY = "cellRenderer";
    /** Bound property name for <code>treeModel</code>. */
    public final static String        TREE_MODEL_PROPERTY = "model";
    /** Bound property name for <code>rootVisible</code>. */
    public final static String        ROOT_VISIBLE_PROPERTY = "rootVisible";
    /** Bound property name for <code>showsRootHandles</code>. */
    public final static String        SHOWS_ROOT_HANDLES_PROPERTY = "showsRootHandles";
    /** Bound property name for <code>rowHeight</code>. */
    public final static String        ROW_HEIGHT_PROPERTY = "rowHeight";
    /** Bound property name for <code>cellEditor</code>. */
    public final static String        CELL_EDITOR_PROPERTY = "cellEditor";
    /** Bound property name for <code>editable</code>. */
    public final static String        EDITABLE_PROPERTY = "editable";
    /** Bound property name for <code>largeModel</code>. */
    public final static String        LARGE_MODEL_PROPERTY = "largeModel";
    /** Bound property name for selectionModel. */
    public final static String        SELECTION_MODEL_PROPERTY = "selectionModel";
    /** Bound property name for <code>visibleRowCount</code>. */
    public final static String        VISIBLE_ROW_COUNT_PROPERTY = "visibleRowCount";
    /** Bound property name for <code>messagesStopCellEditing</code>. */
    public final static String        INVOKES_STOP_CELL_EDITING_PROPERTY = "invokesStopCellEditing";
    /** Bound property name for <code>scrollsOnExpand</code>. */
    public final static String        SCROLLS_ON_EXPAND_PROPERTY = "scrollsOnExpand";
    /** Bound property name for <code>toggleClickCount</code>. */
    public final static String        TOGGLE_CLICK_COUNT_PROPERTY = "toggleClickCount";
    /** Bound property name for <code>leadSelectionPath</code>.
     * @since 1.3 */
    public final static String        LEAD_SELECTION_PATH_PROPERTY = "leadSelectionPath";
    /** Bound property name for anchor selection path.
     * @since 1.3 */
    public final static String        ANCHOR_SELECTION_PATH_PROPERTY = "anchorSelectionPath";
    /** Bound property name for expands selected paths property
     * @since 1.3 */
    public final static String        EXPANDS_SELECTED_PATHS_PROPERTY = "expandsSelectedPaths";


    /**
     * Creates and returns a sample <code>TreeModel</code>.
     * Used primarily for beanbuilders to show something interesting.
     *
     * @return the default <code>TreeModel</code>
     */
    protected static TreeModel getDefaultTreeModel() {
        DefaultMutableTreeNode      root = new DefaultMutableTreeNode("JTree");
	DefaultMutableTreeNode      parent;

	parent = new DefaultMutableTreeNode("colors");
	root.add(parent);
	parent.add(new DefaultMutableTreeNode("blue"));
	parent.add(new DefaultMutableTreeNode("violet"));
	parent.add(new DefaultMutableTreeNode("red"));
	parent.add(new DefaultMutableTreeNode("yellow"));

	parent = new DefaultMutableTreeNode("sports");
	root.add(parent);
	parent.add(new DefaultMutableTreeNode("basketball"));
	parent.add(new DefaultMutableTreeNode("soccer"));
	parent.add(new DefaultMutableTreeNode("football"));
	parent.add(new DefaultMutableTreeNode("hockey"));

	parent = new DefaultMutableTreeNode("food");
	root.add(parent);
	parent.add(new DefaultMutableTreeNode("hot dogs"));
	parent.add(new DefaultMutableTreeNode("pizza"));
	parent.add(new DefaultMutableTreeNode("ravioli"));
	parent.add(new DefaultMutableTreeNode("bananas"));
        return new DefaultTreeModel(root);
    }

    /**
     * Returns a <code>TreeModel</code> wrapping the specified object.
     * If the object is:<ul>
     * <li>an array of <code>Object</code>s,
     * <li>a <code>Hashtable</code>, or
     * <li>a <code>Vector</code>
     * </ul>then a new root node is created with each of the incoming 
     * objects as children. Otherwise, a new root is created with the 
     * specified object as its value.
     *
     * @param value  the <code>Object</code> used as the foundation for
     *		the <code>TreeModel</code>
     * @return a <code>TreeModel</code> wrapping the specified object
     */
    protected static TreeModel createTreeModel(Object value) {
        DefaultMutableTreeNode           root;

        if((value instanceof Object[]) || (value instanceof Hashtable) ||
           (value instanceof Vector)) {
            root = new DefaultMutableTreeNode("root");
            DynamicUtilTreeNode.createChildren(root, value);
        }
        else {
            root = new DynamicUtilTreeNode("root", value);
        }
        return new DefaultTreeModel(root, false);
    }

    /**
     * Returns a <code>JTree</code> with a sample model.
     * The default model used by the tree defines a leaf node as any node
     * without children.
     *
     * @see DefaultTreeModel#asksAllowsChildren
     */
    public JTree() {
        this(getDefaultTreeModel());
    }

    /**
     * Returns a <code>JTree</code> with each element of the
     * specified array as the
     * child of a new root node which is not displayed.
     * By default, the tree defines a leaf node as any node without
     * children.
     *
     * @param value  an array of <code>Object</code>s
     * @see DefaultTreeModel#asksAllowsChildren
     */
    public JTree(Object[] value) {
        this(createTreeModel(value));
        this.setRootVisible(false);
        this.setShowsRootHandles(true);
        expandRoot();
    }

    /**
     * Returns a <code>JTree</code> with each element of the specified
     * <code>Vector</code> as the
     * child of a new root node which is not displayed. By default, the
     * tree defines a leaf node as any node without children.
     *
     * @param value  a <code>Vector</code>
     * @see DefaultTreeModel#asksAllowsChildren
     */
    public JTree(Vector value) {
        this(createTreeModel(value));
        this.setRootVisible(false);
        this.setShowsRootHandles(true);
        expandRoot();
    }

    /**
     * Returns a <code>JTree</code> created from a <code>Hashtable</code>
     * which does not display with root.
     * Each value-half of the key/value pairs in the <code>HashTable</code>
     * becomes a child of the new root node. By default, the tree defines
     * a leaf node as any node without children.
     *
     * @param value  a <code>Hashtable</code>
     * @see DefaultTreeModel#asksAllowsChildren
     */
    public JTree(Hashtable value) {
        this(createTreeModel(value));
        this.setRootVisible(false);
        this.setShowsRootHandles(true);
        expandRoot();
    }

    /**
     * Returns a <code>JTree</code> with the specified
     * <code>TreeNode</code> as its root,
     * which displays the root node.
     * By default, the tree defines a leaf node as any node without children.
     *
     * @param root  a <code>TreeNode</code> object
     * @see DefaultTreeModel#asksAllowsChildren
     */
    public JTree(TreeNode root) {
        this(root, false);
    }

    /**
     * Returns a <code>JTree</code> with the specified <code>TreeNode</code>
     * as its root, which 
     * displays the root node and which decides whether a node is a 
     * leaf node in the specified manner.
     *
     * @param root  a <code>TreeNode</code> object
     * @param asksAllowsChildren  if false, any node without children is a 
     *              leaf node; if true, only nodes that do not allow 
     *              children are leaf nodes
     * @see DefaultTreeModel#asksAllowsChildren
     */
    public JTree(TreeNode root, boolean asksAllowsChildren) {
        this(new DefaultTreeModel(root, asksAllowsChildren));
    }

    /**
     * Returns an instance of <code>JTree</code> which displays the root node 
     * -- the tree is created using the specified data model.
     *
     * @param newModel  the <code>TreeModel</code> to use as the data model
     */
    public JTree(TreeModel newModel) {
        super();
	expandedStack = new Stack();
	toggleClickCount = 2;
	expandedState = new Hashtable();
        setLayout(null);
        rowHeight = 16;
        visibleRowCount = 20;
        rootVisible = true;
        selectionModel = new DefaultTreeSelectionModel();
        cellRenderer = null;
	scrollsOnExpand = true;
        setOpaque(true);
	expandsSelectedPaths = true;
        updateUI();
        setModel(newModel);
    }

    /**
     * Returns the L&F object that renders this component.
     *
     * @return the <code>TreeUI</code> object that renders this component
     */
    public TreeUI getUI() {
        return (TreeUI)ui;
    }

    /**
     * Sets the L&F object that renders this component.
     *
     * @param ui  the <code>TreeUI</code> L&F object
     * @see UIDefaults#getUI
     * @beaninfo
     *        bound: true
     *       hidden: true
     *    attribute: visualUpdate true
     *  description: The UI object that implements the Component's LookAndFeel. 
     */
    public void setUI(TreeUI ui) {
        if ((TreeUI)this.ui != ui) {
	    settingUI = true;
	    uiTreeExpansionListener = null;
	    try {
		super.setUI(ui);
	    }
	    finally {
		settingUI = false;
	    }
        }
    }

    /**
     * Notification from the <code>UIManager</code> that the L&F has changed. 
     * Replaces the current UI object with the latest version from the 
     * <code>UIManager</code>.
     *
     * @see JComponent#updateUI
     */
    public void updateUI() {
        setUI((TreeUI)UIManager.getUI(this));
        invalidate();
    }


    /**
     * Returns the name of the L&F class that renders this component.
     *
     * @return the string "TreeUI"
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }


    /**
     * Returns the current <code>TreeCellRenderer</code>
     *  that is rendering each cell.
     *
     * @return the <code>TreeCellRenderer</code> that is rendering each cell
     */
    public TreeCellRenderer getCellRenderer() {
        return cellRenderer;
    }

    /**
     * Sets the <code>TreeCellRenderer</code> that will be used to
     * draw each cell.
     *
     * @param x  the <code>TreeCellRenderer</code> that is to render each cell
     * @beaninfo
     *        bound: true
     *  description: The TreeCellRenderer that will be used to draw
     *               each cell.
     */
    public void setCellRenderer(TreeCellRenderer x) {
        TreeCellRenderer oldValue = cellRenderer;

        cellRenderer = x;
        firePropertyChange(CELL_RENDERER_PROPERTY, oldValue, cellRenderer);
        invalidate();
    }

    /**
      * Determines whether the tree is editable. Fires a property
      * change event if the new setting is different from the existing
      * setting.
      *
      * @param flag  a boolean value, true if the tree is editable
      * @beaninfo
      *        bound: true
      *  description: Whether the tree is editable.
      */
    public void setEditable(boolean flag) {
        boolean                 oldValue = this.editable;

        this.editable = flag;
        firePropertyChange(EDITABLE_PROPERTY, oldValue, flag);
        if (accessibleContext != null) {
            accessibleContext.firePropertyChange(
                AccessibleContext.ACCESSIBLE_STATE_PROPERTY, 
                (oldValue ? AccessibleState.EDITABLE : null),
                (flag ? AccessibleState.EDITABLE : null));
        }
    }

    /**
     * Returns true if the tree is editable.
     *
     * @return true if the tree is editable
     */
    public boolean isEditable() {
        return editable;
    }

    /**
     * Sets the cell editor.  A <code>null</code> value implies that the
     * tree cannot be edited.  If this represents a change in the
     * <code>cellEditor</code>, the <code>propertyChange</code>
     * method is invoked on all listeners.
     *
     * @param cellEditor the <code>TreeCellEditor</code> to use
     * @beaninfo
     *        bound: true
     *  description: The cell editor. A null value implies the tree
     *               cannot be edited.
     */
    public void setCellEditor(TreeCellEditor cellEditor) {
        TreeCellEditor        oldEditor = this.cellEditor;

        this.cellEditor = cellEditor;
        firePropertyChange(CELL_EDITOR_PROPERTY, oldEditor, cellEditor);
        invalidate();
    }

    /**
     * Returns the editor used to edit entries in the tree.
     *
     * @return the <code>TreeCellEditor</code> in use,
     *		or <code>null</code> if the tree cannot be edited
     */
    public TreeCellEditor getCellEditor() {
        return cellEditor;
    }

    /**
     * Returns the <code>TreeModel</code> that is providing the data.
     *
     * @return the <code>TreeModel</code> that is providing the data
     */
    public TreeModel getModel() {
        return treeModel;
    }

    /**
     * Sets the <code>TreeModel</code> that will provide the data.
     *
     * @param newModel the <code>TreeModel</code> that is to provide the data
     * @beaninfo
     *        bound: true
     *  description: The TreeModel that will provide the data.
     */
    public void setModel(TreeModel newModel) {
        TreeModel oldModel = treeModel;

	if(treeModel != null && treeModelListener != null)
	    treeModel.removeTreeModelListener(treeModelListener);

        if (accessibleContext != null) {
	    if (treeModel != null) {
                treeModel.removeTreeModelListener((TreeModelListener)accessibleContext);
	    }
            if (newModel != null) {
	        newModel.addTreeModelListener((TreeModelListener)accessibleContext);
	    }
        }

        treeModel = newModel;
	clearToggledPaths();
	if(treeModel != null) {
	    if(treeModelListener == null)
		treeModelListener = createTreeModelListener();
	    if(treeModelListener != null)
		treeModel.addTreeModelListener(treeModelListener);
	    // Mark the root as expanded, if it isn't a leaf.
	    if(treeModel.getRoot() != null &&
               !treeModel.isLeaf(treeModel.getRoot())) {
		expandedState.put(new TreePath(treeModel.getRoot()),
				  Boolean.TRUE);
            }
	}
        firePropertyChange(TREE_MODEL_PROPERTY, oldModel, treeModel);
        invalidate();

        clearSelection();
    }

    /**
     * Returns true if the root node of the tree is displayed.
     *
     * @return true if the root node of the tree is displayed
     * @see #rootVisible
     */
    public boolean isRootVisible() {
        return rootVisible;
    }

    /**
     * Determines whether or not the root node from
     * the <code>TreeModel</code> is visible.
     *
     * @param rootVisible true if the root node of the tree is to be displayed
     * @see #rootVisible
     * @beaninfo
     *        bound: true
     *  description: Whether or not the root node 
     *               from the TreeModel is visible.
     */
    public void setRootVisible(boolean rootVisible) {
        boolean                oldValue = this.rootVisible;

        this.rootVisible = rootVisible;
        firePropertyChange(ROOT_VISIBLE_PROPERTY, oldValue, this.rootVisible);
        if (accessibleContext != null) {
            ((AccessibleJTree)accessibleContext).fireVisibleDataPropertyChange();
        }
    }

    /**
     * Sets the value of the <code>showsRootHandles</code> property,
     * which specifies whether the node handles should be displayed.
     * The default value of this property depends on the constructor
     * used to create the <code>JTree</code>.
     * Some look and feels might not support handles;
     * they will ignore this property.
     *
     * @param newValue <code>true</code> if root handles should be displayed;
     *                 otherwise, <code>false</code>
     * @see #showsRootHandles
     * @see #getShowsRootHandles
     * @beaninfo
     *        bound: true
     *  description: Whether the node handles are to be
     *               displayed.
     */
    public void setShowsRootHandles(boolean newValue) {
        boolean                oldValue = showsRootHandles;
	TreeModel              model = getModel();

        showsRootHandles = newValue;
        firePropertyChange(SHOWS_ROOT_HANDLES_PROPERTY, oldValue,
                           showsRootHandles);
        if (accessibleContext != null) {
            ((AccessibleJTree)accessibleContext).fireVisibleDataPropertyChange();
        }
        invalidate();
    }

    /**
     * Returns the value of the <code>showsRootHandles</code> property.
     * 
     * @return the value of the <code>showsRootHandles</code> property
     * @see #showsRootHandles
     */
    public boolean getShowsRootHandles()
    {
        return showsRootHandles;
    }

    /**
     * Sets the height of each cell, in pixels.  If the specified value
     * is less than or equal to zero the current cell renderer is
     * queried for each row's height.
     *
     * @param rowHeight the height of each cell, in pixels
     * @beaninfo
     *        bound: true
     *  description: The height of each cell.
     */
    public void setRowHeight(int rowHeight)
    {
        int                oldValue = this.rowHeight;

        this.rowHeight = rowHeight;
        firePropertyChange(ROW_HEIGHT_PROPERTY, oldValue, this.rowHeight);
        invalidate();
    }

    /**
     * Returns the height of each row.  If the returned value is less than
     * or equal to 0 the height for each row is determined by the
     * renderer.
     *
     */
    public int getRowHeight()
    {
        return rowHeight;
    }

    /**
     * Returns true if the height of each display row is a fixed size.
     *
     * @return true if the height of each row is a fixed size
     */
    public boolean isFixedRowHeight()
    {
        return (rowHeight > 0);
    }

    /**
     * Specifies whether the UI should use a large model.
     * (Not all UIs will implement this.) Fires a property change
     * for the LARGE_MODEL_PROPERTY.
     * 
     * @param newValue true to suggest a large model to the UI
     * @see #largeModel
     * @beaninfo
     *        bound: true
     *  description: Whether the UI should use a 
     *               large model.
     */
    public void setLargeModel(boolean newValue) {
        boolean                oldValue = largeModel;

        largeModel = newValue;
        firePropertyChange(LARGE_MODEL_PROPERTY, oldValue, newValue);
    }

    /**
     * Returns true if the tree is configured for a large model.
     * 
     * @return true if a large model is suggested
     * @see #largeModel
     */
    public boolean isLargeModel() {
        return largeModel;
    }

    /**
     * Determines what happens when editing is interrupted by selecting
     * another node in the tree, a change in the tree's data, or by some
     * other means. Setting this property to <code>true</code> causes the
     * changes to be automatically saved when editing is interrupted.
     * <p>
     * Fires a property change for the INVOKES_STOP_CELL_EDITING_PROPERTY.
     *
     * @param newValue true means that <code>stopCellEditing</code> is invoked 
     *        when editing is interrupted, and data is saved; false means that
     *        <code>cancelCellEditing</code> is invoked, and changes are lost
     * @beaninfo
     *        bound: true
     *  description: Determines what happens when editing is interrupted,
     *               selecting another node in the tree, a change in the
     *               tree's data, or some other means.
     */
    public void setInvokesStopCellEditing(boolean newValue) {
        boolean                  oldValue = invokesStopCellEditing;

        invokesStopCellEditing = newValue;
        firePropertyChange(INVOKES_STOP_CELL_EDITING_PROPERTY, oldValue,
                           newValue);
    }

    /**
     * Returns the indicator that tells what happens when editing is 
     * interrupted.
     *
     * @return the indicator that tells what happens when editing is 
     *         interrupted
     * @see #setInvokesStopCellEditing
     */
    public boolean getInvokesStopCellEditing() {
        return invokesStopCellEditing;
    }

    /**
     * Sets the <code>scrollsOnExpand</code> property,
     * which determines whether the 
     * tree might scroll to show previously hidden children.
     * If this property is <code>true</code> (the default), 
     * when a node expands
     * the tree can use scrolling to make
     * the maximum possible number of the node's descendants visible.
     * In some look and feels, trees might not need to scroll when expanded;
     * those look and feels will ignore this property.
     *
     * @param newValue <code>false</code> to disable scrolling on expansion;
     *                 <code>true</code> to enable it
     * @see #getScrollsOnExpand
     *
     * @beaninfo
     *        bound: true
     *  description: Indicates if a node descendant should be scrolled when expanded.
     */
    public void setScrollsOnExpand(boolean newValue) {
	boolean           oldValue = scrollsOnExpand;

	scrollsOnExpand = newValue;
        firePropertyChange(SCROLLS_ON_EXPAND_PROPERTY, oldValue,
                           newValue);
    }

    /**
     * Returns the value of the <code>scrollsOnExpand</code> property.
     *
     * @return the value of the <code>scrollsOnExpand</code> property
     */
    public boolean getScrollsOnExpand() {
	return scrollsOnExpand;
    }

    /**
     * Sets the number of mouse clicks before a node will expand or close.
     * The default is two. 
     *
     * @since 1.3
     * @beaninfo
     *        bound: true
     *  description: Number of clicks before a node will expand/collapse.
     */
    public void setToggleClickCount(int clickCount) {
	int         oldCount = toggleClickCount;

	toggleClickCount = clickCount;
	firePropertyChange(TOGGLE_CLICK_COUNT_PROPERTY, oldCount,
			   clickCount);
    }

    /**
     * Returns the number of mouse clicks needed to expand or close a node.
     *
     * @return number of mouse clicks before node is expanded
     * @since 1.3
     */
    public int getToggleClickCount() {
	return toggleClickCount;
    }

    /**
     * Configures the <code>expandsSelectedPaths</code> property. If
     * true, any time the selection is changed, either via the
     * <code>TreeSelectionModel</code>, or the cover methods provided by 
     * <code>JTree</code>, the <code>TreePath</code>s parents will be
     * expanded to make them visible (visible meaning the parent path is
     * expanded, not necessarily in the visible rectangle of the
     * <code>JTree</code>). If false, when the selection
     * changes the nodes parent is not made visible (all its parents expanded).
     * This is useful if you wish to have your selection model maintain paths
     * that are not always visible (all parents expanded).
     *
     * @param newValue the new value for <code>expandsSelectedPaths</code>
     *
     * @since 1.3
     * @beaninfo
     *        bound: true
     *  description: Indicates whether changes to the selection should make
     *               the parent of the path visible.
     */
    public void setExpandsSelectedPaths(boolean newValue) {
	boolean         oldValue = expandsSelectedPaths;

	expandsSelectedPaths = newValue;
	firePropertyChange(EXPANDS_SELECTED_PATHS_PROPERTY, oldValue,
			   newValue);
    }

    /**
     * Returns the <code>expandsSelectedPaths</code> property.
     * @return true if selection changes result in the parent path being
     *         expanded
     * @since 1.3
     * @see #setExpandsSelectedPaths
     */
    public boolean getExpandsSelectedPaths() {
	return expandsSelectedPaths;
    }

    /**
     * Sets the <code>dragEnabled</code> property,
     * which must be <code>true</code> to enable
     * automatic drag handling (the first part of drag and drop)
     * on this component.
     * The <code>transferHandler</code> property needs to be set
     * to a non-<code>null</code> value for the drag to do
     * anything.  The default value of the <code>dragEnabled</code>
     * property
     * is <code>false</code>.
     *
     * <p>
     *
     * When automatic drag handling is enabled,
     * most look and feels begin a drag-and-drop operation
     * whenever the user presses the mouse button over a selection
     * and then moves the mouse a few pixels.
     * Setting this property to <code>true</code>
     * can therefore have a subtle effect on
     * how selections behave.
     *
     * <p>
     *
     * Some look and feels might not support automatic drag and drop;
     * they will ignore this property.  You can work around such
     * look and feels by modifying the component
     * to directly call the <code>exportAsDrag</code> method of a
     * <code>TransferHandler</code>.
     *
     * @param b the value to set the <code>dragEnabled</code> property to
     * @exception HeadlessException if
     *            <code>b</code> is <code>true</code> and
     *            <code>GraphicsEnvironment.isHeadless()</code>
     *            returns <code>true</code>
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @see #getDragEnabled
     * @see #setTransferHandler
     * @see TransferHandler
     * @since 1.4
     *
     * @beaninfo
     *  description: determines whether automatic drag handling is enabled
     *        bound: false
     */
    public void setDragEnabled(boolean b) {
        if (b && GraphicsEnvironment.isHeadless()) {
            throw new HeadlessException();
        }
	dragEnabled = b;
    }

    /**
     * Gets the value of the <code>dragEnabled</code> property.
     *
     * @return  the value of the <code>dragEnabled</code> property
     * @see #setDragEnabled
     * @since 1.4
     */
    public boolean getDragEnabled() {
	return dragEnabled;
    }

    /**
     * Returns <code>isEditable</code>. This is invoked from the UI before
     * editing begins to insure that the given path can be edited. This
     * is provided as an entry point for subclassers to add filtered
     * editing without having to resort to creating a new editor.
     *
     * @return true if every parent node and the node itself is editable
     * @see #isEditable
     */
    public boolean isPathEditable(TreePath path) {
        return isEditable();
    }

    /**
     * Overrides <code>JComponent</code>'s <code>getToolTipText</code>
     * method in order to allow 
     * renderer's tips to be used if it has text set.
     * <p>
     * NOTE: For <code>JTree</code> to properly display tooltips of its
     * renderers, <code>JTree</code> must be a registered component with the
     * <code>ToolTipManager</code>.  This can be done by invoking
     * <code>ToolTipManager.sharedInstance().registerComponent(tree)</code>.
     * This is not done automatically!
     *
     * @param event the <code>MouseEvent</code> that initiated the 
     *		<code>ToolTip</code> display
     * @return a string containing the  tooltip or <code>null</code>
     *		if <code>event</code> is null
     */
    public String getToolTipText(MouseEvent event) {
        if(event != null) {
            Point p = event.getPoint();
            int selRow = getRowForLocation(p.x, p.y);
            TreeCellRenderer       r = getCellRenderer();

            if(selRow != -1 && r != null) {
                TreePath     path = getPathForRow(selRow);
                Object       lastPath = path.getLastPathComponent();
                Component    rComponent = r.getTreeCellRendererComponent
                    (this, lastPath, isRowSelected(selRow),
                     isExpanded(selRow), getModel().isLeaf(lastPath), selRow,
                     true);

                if(rComponent instanceof JComponent) {
                    MouseEvent      newEvent;
                    Rectangle       pathBounds = getPathBounds(path);

                    p.translate(-pathBounds.x, -pathBounds.y);
                    newEvent = new MouseEvent(rComponent, event.getID(),
                                          event.getWhen(),
                                              event.getModifiers(),
                                              p.x, p.y, event.getClickCount(),
                                              event.isPopupTrigger());
                    
                    return ((JComponent)rComponent).getToolTipText(newEvent);
                }
            }
        }
        return null;
    }
    
    /**
     * Called by the renderers to convert the specified value to
     * text. This implementation returns <code>value.toString</code>, ignoring
     * all other arguments. To control the conversion, subclass this 
     * method and use any of the arguments you need.
     * 
     * @param value the <code>Object</code> to convert to text
     * @param selected true if the node is selected
     * @param expanded true if the node is expanded
     * @param leaf  true if the node is a leaf node
     * @param row  an integer specifying the node's display row, where 0 is 
     *             the first row in the display
     * @param hasFocus true if the node has the focus
     * @return the <code>String</code> representation of the node's value
     */
    public String convertValueToText(Object value, boolean selected,
                                     boolean expanded, boolean leaf, int row,
                                     boolean hasFocus) {
        if(value != null)
            return value.toString();
        return "";
    }

    //
    // The following are convenience methods that get forwarded to the
    // current TreeUI.
    //

    /**
     * Returns the number of rows that are currently being displayed.
     *
     * @return the number of rows that are being displayed
     */
    public int getRowCount() {
        TreeUI            tree = getUI();

        if(tree != null)
            return tree.getRowCount(this);
        return 0;
    }

    /** 
     * Selects the node identified by the specified path. If any
     * component of the path is hidden (under a collapsed node), and
     * <code>getExpandsSelectedPaths</code> is true it is 
     * exposed (made viewable).
     *
     * @param path the <code>TreePath</code> specifying the node to select
     */
    public void setSelectionPath(TreePath path) {
        getSelectionModel().setSelectionPath(path);
    }

    /** 
     * Selects the nodes identified by the specified array of paths.
     * If any component in any of the paths is hidden (under a collapsed
     * node), and <code>getExpandsSelectedPaths</code> is true
     * it is exposed (made viewable).
     *
     * @param paths an array of <code>TreePath</code> objects that specifies
     *		the nodes to select
     */
    public void setSelectionPaths(TreePath[] paths) {
        getSelectionModel().setSelectionPaths(paths);
    }

    /**
     * Sets the path identifies as the lead. The lead may not be selected.
     * The lead is not maintained by <code>JTree</code>,
     * rather the UI will update it.
     *
     * @param newPath  the new lead path
     * @since 1.3
     * @beaninfo
     *        bound: true
     *  description: Lead selection path
     */
    public void setLeadSelectionPath(TreePath newPath) {
	TreePath          oldValue = leadPath;

	leadPath = newPath;
	firePropertyChange(LEAD_SELECTION_PATH_PROPERTY, oldValue, newPath);
    }

    /**
     * Sets the path identified as the anchor.
     * The anchor is not maintained by <code>JTree</code>, rather the UI will 
     * update it.
     *
     * @param newPath  the new anchor path
     * @since 1.3
     * @beaninfo
     *        bound: true
     *  description: Anchor selection path
     */
    public void setAnchorSelectionPath(TreePath newPath) {
	TreePath          oldValue = anchorPath;

	anchorPath = newPath;
	firePropertyChange(ANCHOR_SELECTION_PATH_PROPERTY, oldValue, newPath);
    }

    /**
     * Selects the node at the specified row in the display.
     *
     * @param row  the row to select, where 0 is the first row in
     *             the display
     */
    public void setSelectionRow(int row) {
        int[]             rows = { row };

        setSelectionRows(rows);
    }

    /**
     * Selects the nodes corresponding to each of the specified rows
     * in the display. If a particular element of <code>rows</code> is
     * < 0 or >= <code>getRowCount</code>, it will be ignored.
     * If none of the elements
     * in <code>rows</code> are valid rows, the selection will
     * be cleared. That is it will be as if <code>clearSelection</code>
     * was invoked.
     * 
     * @param rows  an array of ints specifying the rows to select,
     *              where 0 indicates the first row in the display
     */
    public void setSelectionRows(int[] rows) {
        TreeUI               ui = getUI();

        if(ui != null && rows != null) {
            int                  numRows = rows.length;
            TreePath[]           paths = new TreePath[numRows];

            for(int counter = 0; counter < numRows; counter++) {
                paths[counter] = ui.getPathForRow(this, rows[counter]);
	    }
            setSelectionPaths(paths);
        }
    }

    /**
     * Adds the node identified by the specified <code>TreePath</code>
     * to the current selection. If any component of the path isn't
     * viewable, and <code>getExpandsSelectedPaths</code> is true it is 
     * made viewable.
     * <p>
     * Note that <code>JTree</code> does not allow duplicate nodes to
     * exist as children under the same parent -- each sibling must be
     * a unique object.
     *
     * @param path the <code>TreePath</code> to add
     */
    public void addSelectionPath(TreePath path) {
        getSelectionModel().addSelectionPath(path);
    }

    /**
     * Adds each path in the array of paths to the current selection. If
     * any component of any of the paths isn't viewable and
     * <code>getExpandsSelectedPaths</code> is true, it is
     * made viewable.
     * <p>
     * Note that <code>JTree</code> does not allow duplicate nodes to
     * exist as children under the same parent -- each sibling must be
     * a unique object.
     *
     * @param paths an array of <code>TreePath</code> objects that specifies
     *		the nodes to add
     */
    public void addSelectionPaths(TreePath[] paths) {
	getSelectionModel().addSelectionPaths(paths);
    }

    /**
     * Adds the path at the specified row to the current selection.
     *
     * @param row  an integer specifying the row of the node to add,
     *             where 0 is the first row in the display
     */
    public void addSelectionRow(int row) {
        int[]      rows = { row };

        addSelectionRows(rows);
    }

    /**
     * Adds the paths at each of the specified rows to the current selection.
     * 
     * @param rows  an array of ints specifying the rows to add,
     *              where 0 indicates the first row in the display
     */
    public void addSelectionRows(int[] rows) {
        TreeUI             ui = getUI();

        if(ui != null && rows != null) {
            int                  numRows = rows.length;
            TreePath[]           paths = new TreePath[numRows];

            for(int counter = 0; counter < numRows; counter++)
                paths[counter] = ui.getPathForRow(this, rows[counter]);
            addSelectionPaths(paths);
        }
    }

    /**
     * Returns the last path component in the first node of the current 
     * selection.
     *
     * @return the last <code>Object</code> in the first selected node's
     *		<code>TreePath</code>,
     *		or <code>null</code> if nothing is selected
     * @see TreePath#getLastPathComponent
     */
    public Object getLastSelectedPathComponent() {
        TreePath     selPath = getSelectionModel().getSelectionPath();

        if(selPath != null)
            return selPath.getLastPathComponent();
        return null;
    }

    /**
     * Returns the path identified as the lead.
     * @return path identified as the lead
     */
    public TreePath getLeadSelectionPath() {
	return leadPath;
    }

    /**
     * Returns the path identified as the anchor.
     * @return path identified as the anchor
     * @since 1.3
     */
    public TreePath getAnchorSelectionPath() {
	return anchorPath;
    }

    /**
     * Returns the path to the first selected node.
     *
     * @return the <code>TreePath</code> for the first selected node,
     *		or <code>null</code> if nothing is currently selected
     */
    public TreePath getSelectionPath() {
        return getSelectionModel().getSelectionPath();
    }

    /**
     * Returns the paths of all selected values.
     *
     * @return an array of <code>TreePath</code> objects indicating the selected
     *         nodes, or <code>null</code> if nothing is currently selected
     */
    public TreePath[] getSelectionPaths() {
        return getSelectionModel().getSelectionPaths();
    }

    /**
     * Returns all of the currently selected rows. This method is simply
     * forwarded to the <code>TreeSelectionModel</code>.
     * If nothing is selected <code>null</code> or an empty array will
     * be returned, based on the <code>TreeSelectionModel</code>
     * implementation.
     *
     * @return an array of integers that identifies all currently selected rows
     *         where 0 is the first row in the display
     */
    public int[] getSelectionRows() {
        return getSelectionModel().getSelectionRows();
    }

    /**
     * Returns the number of nodes selected.
     *
     * @return the number of nodes selected
     */
    public int getSelectionCount() {
        return selectionModel.getSelectionCount();
    }

    /**
     * Gets the first selected row.
     *
     * @return an integer designating the first selected row, where 0 is the 
     *         first row in the display
     */
    public int getMinSelectionRow() {
        return getSelectionModel().getMinSelectionRow();
    }

    /**
     * Returns the last selected row.
     *
     * @return an integer designating the last selected row, where 0 is the 
     *         first row in the display
     */
    public int getMaxSelectionRow() {
        return getSelectionModel().getMaxSelectionRow();
    }

    /**
     * Returns the row index corresponding to the lead path.
     *
     * @return an integer giving the row index of the lead path,
     *		where 0 is the first row in the display; or -1
     *		if <code>leadPath</code> is <code>null</code>
     */
    public int getLeadSelectionRow() {
	TreePath leadPath = getLeadSelectionPath();

	if (leadPath != null) {
	    return getRowForPath(leadPath);
	}
        return -1;
    }

    /**
     * Returns true if the item identified by the path is currently selected.
     *
     * @param path a <code>TreePath</code> identifying a node
     * @return true if the node is selected
     */
    public boolean isPathSelected(TreePath path) {
        return getSelectionModel().isPathSelected(path);
    }

    /**
     * Returns true if the node identified by row is selected.
     *
     * @param row  an integer specifying a display row, where 0 is the first
     *             row in the display
     * @return true if the node is selected
     */
    public boolean isRowSelected(int row) {
        return getSelectionModel().isRowSelected(row);
    }

    /**
     * Returns an <code>Enumeration</code> of the descendants of the
     * path <code>parent</code> that
     * are currently expanded. If <code>parent</code> is not currently
     * expanded, this will return <code>null</code>.
     * If you expand/collapse nodes while
     * iterating over the returned <code>Enumeration</code>
     * this may not return all
     * the expanded paths, or may return paths that are no longer expanded.
     *
     * @param parent  the path which is to be examined
     * @return an <code>Enumeration</code> of the descendents of 
     *		<code>parent</code>, or <code>null</code> if
     *		<code>parent</code> is not currently expanded
     */
    public Enumeration getExpandedDescendants(TreePath parent) {
	if(!isExpanded(parent))
	    return null;

	Enumeration       toggledPaths = expandedState.keys();
	Vector            elements = null;
	TreePath          path;
	Object            value;

	if(toggledPaths != null) {
	    while(toggledPaths.hasMoreElements()) {
		path = (TreePath)toggledPaths.nextElement();
		value = expandedState.get(path);
		// Add the path if it is expanded, a descendant of parent,
		// and it is visible (all parents expanded). This is rather
		// expensive!
		if(path != parent && value != null &&
		   ((Boolean)value).booleanValue() &&
		   parent.isDescendant(path) && isVisible(path)) {
		    if (elements == null) {
			elements = new Vector();
		    }
		    elements.addElement(path);
		}
	    }
	}
	if (elements == null) {
	    return DefaultMutableTreeNode.EMPTY_ENUMERATION;
	}
	return elements.elements();
    }

    /**
     * Returns true if the node identified by the path has ever been
     * expanded.
     * @return true if the <code>path</code> has ever been expanded
     */
    public boolean hasBeenExpanded(TreePath path) {
	return (path != null && expandedState.get(path) != null);
    }

    /**
     * Returns true if the node identified by the path is currently expanded,
     * 
     * @param path  the <code>TreePath</code> specifying the node to check
     * @return false if any of the nodes in the node's path are collapsed, 
     *               true if all nodes in the path are expanded
     */
    public boolean isExpanded(TreePath path) {
	if(path == null)
	    return false;

	// Is this node expanded?
	Object          value = expandedState.get(path);

	if(value == null || !((Boolean)value).booleanValue())
	    return false;

	// It is, make sure its parent is also expanded.
	TreePath        parentPath = path.getParentPath();

	if(parentPath != null)
	    return isExpanded(parentPath);
        return true;
    }

    /**
     * Returns true if the node at the specified display row is currently
     * expanded.
     * 
     * @param row  the row to check, where 0 is the first row in the 
     *             display
     * @return true if the node is currently expanded, otherwise false
     */
    public boolean isExpanded(int row) {
        TreeUI                  tree = getUI();

        if(tree != null) {
	    TreePath         path = tree.getPathForRow(this, row);

	    if(path != null) {
                Boolean value = (Boolean)expandedState.get(path);

                return (value != null && value.booleanValue());
            }
	}