/*
 * @(#)FixedHeightLayoutCache.java	1.11 01/11/29
 *
 * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.swing.tree;

import javax.swing.event.TreeModelEvent;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.NoSuchElementException;
import java.util.Stack;

/**
 * NOTE: This will become more open in a future release.
 * <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.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @version 1.11 11/29/01
 * @author Scott Violet
 */

public class FixedHeightLayoutCache extends AbstractLayoutCache {
    /** Root node. */
    private FHTreeStateNode    root;

    /** Number of rows currently visible. */
    private int                rowCount;

    /**
     * Used in getting sizes for nodes to avoid creating a new Rectangle
     * every time a size is needed.
     */
    private Rectangle          boundsBuffer;

    /**
     * Maps from TreePath to a FHTreeStateNode.
     */
    private Hashtable          treePathMapping;

    /**
     * Used for getting path/row information.
     */
    private SearchInfo         info;

    private Stack              tempStacks;


    public FixedHeightLayoutCache() {
	super();
	tempStacks = new Stack();
	boundsBuffer = new Rectangle();
	treePathMapping = new Hashtable();
	info = new SearchInfo();
    }

    /**
     * Sets the TreeModel that will provide the data.
     *
     * @param newModel the TreeModel that is to provide the data
     */
    public void setModel(TreeModel newModel) {
	super.setModel(newModel);
	rebuild();
    }

    /**
     * Determines whether or not the root node from
     * the TreeModel is visible.
     *
     * @param rootVisible true if the root node of the tree is to be displayed
     * @see #rootVisible
     */
    public void setRootVisible(boolean rootVisible) {
	if(isRootVisible() != rootVisible) {
	    super.setRootVisible(rootVisible);
	    if(root != null) {
		if(rootVisible) {
		    rowCount++;
		    root.adjustRowBy(1);
		}
		else {
		    rowCount--;
		    root.adjustRowBy(-1);
		}
		visibleNodesChanged();
	    }
	}
    }

    /**
     * Sets the height of each cell. If rowHeight is less than or equal to
     * 0 this will throw an IllegalArgumentException.
     *
     * @param rowHeight the height of each cell, in pixels
     */
    public void setRowHeight(int rowHeight) {
	if(rowHeight <= 0)
	    throw new IllegalArgumentException("FixedHeightLayoutCache only supports row heights greater than 0");
	if(getRowHeight() != rowHeight) {
	    super.setRowHeight(rowHeight);
	    visibleNodesChanged();
	}
    }

    /**
     * Returns the number of visible rows.
     */
    public int getRowCount() {
	return rowCount;
    }

    /**
     * Does nothing, FixedHeightLayoutCache doesn't cache width, and that
     * is all that could change.
     */
    public void invalidatePathBounds(TreePath path) {
    }


    /**
     * Informs the TreeState that it needs to recalculate all the sizes
     * it is referencing.
     */
    public void invalidateSizes() {
	// Nothing to do here, rowHeight still same, which is all
	// this is interested in, visible region may have changed though.
	visibleNodesChanged();
    }

    /**
      * Returns true if the value identified by row is currently expanded.
      */
    public boolean isExpanded(TreePath path) {
	if(path != null) {
	    FHTreeStateNode     lastNode = getNodeForPath(path, true, false);

	    return (lastNode != null && lastNode.isExpanded());
	}
	return false;
    }

    /**
     * Returns a rectangle giving the bounds needed to draw path.
     *
     * @param path     a TreePath specifying a node
     * @param placeIn  a Rectangle object giving the available space
     * @return a Rectangle object specifying the space to be used
     */
    public Rectangle getBounds(TreePath path, Rectangle placeIn) {
	if(path == null)
	    return null;

	FHTreeStateNode      node = getNodeForPath(path, true, false);

	if(node != null)
	    return getBounds(node, -1, placeIn);

	// node hasn't been created yet.
	TreePath       parentPath = path.getParentPath();

	node = getNodeForPath(parentPath, true, false);
	if(node != null) {
	    int              childIndex = treeModel.getIndexOfChild
		                 (parentPath.getLastPathComponent(),
				  path.getLastPathComponent());

	    if(childIndex != -1)
		return getBounds(node, childIndex, placeIn);
	}
	return null;
    }

    /**
      * Returns the path for passed in row.  If row is not visible
      * null is returned.
      */
    public TreePath getPathForRow(int row) {
	if(row >= 0 && row < getRowCount()) {
	    if(root.getPathForRow(row, getRowCount(), info)) {
		return info.getPath();
	    }
	}
	return null;
    }

    /**
      * Returns the row that the last item identified in path is visible
      * at.  Will return -1 if any of the elements in path are not
      * currently visible.
      */
    public int getRowForPath(TreePath path) {
	if(path == null || root == null)
	    return -1;

	FHTreeStateNode         node = getNodeForPath(path, true, false);

	if(node != null)
	    return node.getRow();

	TreePath       parentPath = path.getParentPath();

	node = getNodeForPath(parentPath, true, false);
	if(node != null) {
	    return node.getRowToModelIndex(treeModel.getIndexOfChild
					   (parentPath.getLastPathComponent(),
					    path.getLastPathComponent()));
	}
	return -1;
    }

    /**
      * Returns the path to the node that is closest to x,y.  If
      * there is nothing currently visible this will return null, otherwise
      * it'll always return a valid path.  If you need to test if the
      * returned object is exactly at x, y you should get the bounds for
      * the returned path and test x, y against that.
      */
    public TreePath getPathClosestTo(int x, int y) {
	if(getRowCount() == 0)
	    return null;

	int                row = getRowContainingYLocation(y);

	return getPathForRow(row);
    }

    /**
     * Returns the number of visible children for row.
     */
    public int getVisibleChildCount(TreePath path) {
	FHTreeStateNode         node = getNodeForPath(path, true, false);

	if(node == null)
	    return 0;
	return node.getTotalChildCount();
    }

    /**
     * Returns an Enumerator that increments over the visible paths
     * starting at the passed in location. The ordering of the enumeration
     * is based on how the paths are displayed.
     */
    public Enumeration getVisiblePathsFrom(TreePath path) {
	if(path == null)
	    return null;

	FHTreeStateNode         node = getNodeForPath(path, true, false);

	if(node != null) {
	    return new VisibleFHTreeStateNodeEnumeration(node);
	}
	TreePath            parentPath = path.getParentPath();

	node = getNodeForPath(parentPath, true, false);
	if(node != null && node.isExpanded()) {
	    return new VisibleFHTreeStateNodeEnumeration(node,
		  treeModel.getIndexOfChild(parentPath.getLastPathComponent(),
					    path.getLastPathComponent()));
	}
	return null;
    }

    /**
     * Marks the path <code>path</code> expanded state to
     * <code>isExpanded</code>.
     */
    public void setExpandedState(TreePath path, boolean isExpanded) {
	if(isExpanded)
	    ensurePathIsExpanded(path, true);
	else if(path != null) {
	    TreePath              parentPath = path.getParentPath();

	    // YECK! Make the parent expanded.
	    if(parentPath != null) {
		FHTreeStateNode     parentNode = getNodeForPath(parentPath,
								false, true);
		if(parentNode != null)
		    parentNode.makeVisible();
	    }
	    // And collapse the child.
	    FHTreeStateNode         childNode = getNodeForPath(path, true,
							       false);

	    if(childNode != null)
		childNode.collapse(true);
	}
    }

    /**
     * Returns true if the path is expanded, and visible.
     */
    public boolean getExpandedState(TreePath path) {
	FHTreeStateNode       node = getNodeForPath(path, true, false);

	return (node != null) ? (node.isVisible() && node.isExpanded()) :
	                         false;
    }

    //
    // TreeModelListener methods
    //

    /**
     * <p>Invoked after a node (or a set of siblings) has changed in some
     * way. The node(s) have not changed locations in the tree or
     * altered their children arrays, but other attributes have
     * changed and may affect presentation. Example: the name of a
     * file has changed, but it is in the same location in the file
     * system.</p>
     *
     * <p>e.path() returns the path the parent of the changed node(s).</p>
     *
     * <p>e.childIndices() returns the index(es) of the changed node(s).</p>
     */
    public void treeNodesChanged(TreeModelEvent e) {
	if(e != null) {
	    int                 changedIndexs[];
	    FHTreeStateNode     changedParent = getNodeForPath
		                  (e.getTreePath(), false, false);
	    int                 maxCounter;

	    changedIndexs = e.getChildIndices();
	    /* Only need to update the children if the node has been
	       expanded once. */
	    // PENDING(scott): make sure childIndexs is sorted!
	    if (changedParent != null) {
		if (changedIndexs != null &&
		    (maxCounter = changedIndexs.length) > 0) {
		    Object       parentValue = changedParent.getUserObject();

		    for(int counter = 0; counter < maxCounter; counter++) {
			FHTreeStateNode    child = changedParent.
			         getChildAtModelIndex(changedIndexs[counter]);

			if(child != null) {
			    child.setUserObject(treeModel.getChild(parentValue,
						     changedIndexs[counter]));
			}
		    }
		    if(changedParent.isVisible() && changedParent.isExpanded())
			visibleNodesChanged();
		}
		// Null for root indicates it changed.
		else if (changedParent == root && changedParent.isVisible() &&
			 changedParent.isExpanded()) {
		    visibleNodesChanged();
		}
	    }
	}
    }

    /**
     * <p>Invoked after nodes have been inserted into the tree.</p>
     *
     * <p>e.path() returns the parent of the new nodes
     * <p>e.childIndices() returns the indices of the new nodes in
     * ascending order.
     */
    public void treeNodesInserted(TreeModelEvent e) {
	if(e != null) {
	    int                 changedIndexs[];
	    FHTreeStateNode     changedParent = getNodeForPath
		                  (e.getTreePath(), false, false);
	    int                 maxCounter;

	    changedIndexs = e.getChildIndices();
	    /* Only need to update the children if the node has been
	       expanded once. */
	    // PENDING(scott): make sure childIndexs is sorted!
	    if(changedParent != null && changedIndexs != null &&
	       (maxCounter = changedIndexs.length) > 0) {
		boolean          isVisible =
		    (changedParent.isVisible() &&
		     changedParent.isExpanded());

		for(int counter = 0; counter < maxCounter; counter++) {
		    changedParent.childInsertedAtModelIndex
			(changedIndexs[counter], isVisible);
		}
		if(isVisible && treeSelectionModel != null)
		    treeSelectionModel.resetRowSelection();
		if(changedParent.isVisible())
		    this.visibleNodesChanged();
	    }
	}
    }

    /**
     * <p>Invoked after nodes have been removed from the tree.  Note that
     * if a subtree is removed from the tree, this method may only be
     * invoked once for the root of the removed subtree, not once for
     * each individual set of siblings removed.</p>
     *
     * <p>e.path() returns the former parent of the deleted nodes.</p>
     *
     * <p>e.childIndices() returns the indices the nodes had before they were deleted in ascending order.</p>
     */
    public void treeNodesRemoved(TreeModelEvent e) {
	if(e != null) {
	    int                  changedIndexs[];
	    int                  maxCounter;
	    TreePath             parentPath = e.getTreePath();
	    FHTreeStateNode      changedParentNode = getNodeForPath
		                       (parentPath, false, false);

	    changedIndexs = e.getChildIndices();
	    // PENDING(scott): make sure that changedIndexs are sorted in
	    // ascending order.
	    if(changedParentNode != null && changedIndexs != null &&
	       (maxCounter = changedIndexs.length) > 0) {
		Object[]           children = e.getChildren();
		boolean            isVisible =
		    (changedParentNode.isVisible() &&
		     changedParentNode.isExpanded());

		for(int counter = maxCounter - 1; counter >= 0; counter--) {
		    changedParentNode.removeChildAtModelIndex
			             (changedIndexs[counter], isVisible);

		    /* Clean up the selection. */
		    if(treeSelectionModel != null && children != null &&
			children[counter] != null) {
			treeSelectionModel.removeSelectionPath(parentPath.
				        pathByAddingChild(children[counter]));
		    }
		}
		if(isVisible) {
		    if(treeSelectionModel != null)
			treeSelectionModel.resetRowSelection();
		    visibleNodesChanged();
		}
		else if(changedParentNode.isVisible())
		    visibleNodesChanged();
	    }
	}
    }

    /**
     * <p>Invoked after the tree has drastically changed structure from a
     * given node down.  If the path returned by e.getPath() is of length
     * one and the first element does not identify the current root node
     * the first element should become the new root of the tree.<p>
     *
     * <p>e.path() holds the path to the node.</p>
     * <p>e.childIndices() returns null.</p>
     */
    public void treeStructureChanged(TreeModelEvent e) {
	if(e != null) {
	    TreePath          changedPath = e.getTreePath();

	    if(changedPath != null && changedPath.getPathCount() > 0) {
		if(changedPath.getPathCount() == 1)
		    rebuild();
		else {
		    FHTreeStateNode changedNode = getNodeForPath
			                        (changedPath, false, false);

		    if(changedNode != null) {
			boolean             wasExpanded, wasVisible;
			int                 newIndex;
			FHTreeStateNode     parent = (FHTreeStateNode)
			                       changedNode.getParent();
			int                 row = changedNode.getRow();


			wasExpanded = changedNode.isExpanded();
			wasVisible = changedNode.isVisible();
			if(wasVisible && wasExpanded) {
			    changedNode.collapse(true);
			    changedNode.removeFromParent();
			    changedNode = getNodeForPath(changedPath, false,
							 true);
			    changedNode.expand();
			}
			else
			    changedNode.removeFromParent();
			if(treeSelectionModel != null && wasVisible &&
			   wasExpanded)
			    treeSelectionModel.resetRowSelection();
			if(wasVisible)
			    this.visibleNodesChanged();
		    }
		}
	    }
	}
    }


    //
    // Local methods
    //

    private void visibleNodesChanged() {
    }

    /**
     * Returns the bounds for the given node. If <code>childIndex</code>
     * is -1, the bounds of <code>parent</code> are returned, otherwise
     * the bounds of the node at <code>childIndex</code> are returned.
     */
    private Rectangle getBounds(FHTreeStateNode parent, int childIndex,
				  Rectangle placeIn) {
	boolean              expanded;
	int                  level;
	int                  row;
	Object               value;

	if(childIndex == -1) {
	    // Getting bounds for parent
	    row = parent.getRow();
	    value = parent.getUserObject();
	    expanded = parent.isExpanded();
	    level = parent.getLevel();
	}
	else {
	    row = parent.getRowToModelIndex(childIndex);
	    value = treeModel.getChild(parent.getUserObject(), childIndex);
	    expanded = false;
	    level = parent.getLevel() + 1;
	}

	Rectangle      bounds = getNodeDimensions(value, row, level,
						  expanded, boundsBuffer);
	// No node dimensions, bail.
	if(bounds == null)
	    return null;

	if(placeIn == null)
	    placeIn = new Rectangle();

	placeIn.x = bounds.x;
	placeIn.height = getRowHeight();
	placeIn.y = row * placeIn.height;
	placeIn.width = boundsBuffer.width;
	return placeIn;
    }

    /**
     * Adjust the large row count of the AbstractTreeUI the receiver was
     * created with.
     */
    private void adjustRowCountBy(int changeAmount) {
	rowCount += changeAmount;
    }

    /**
     * Adds a mapping for node.
     */
    private void addMapping(FHTreeStateNode node) {
	treePathMapping.put(node.getTreePath(), node);
    }

    /**
     * Removes the mapping for a previously added node.
     */
    private void removeMapping(FHTreeStateNode node) {
	treePathMapping.remove(node.getTreePath());
    }

    /**
     * Returns the node previously added for <code>path</code>. This may
     * return null, if you to create a node use getNodeForPath.
     */
    private FHTreeStateNode getMapping(TreePath path) {
	return (FHTreeStateNode)treePathMapping.get(path);
    }

    /**
     * Sent to completely rebuild the visible tree. All nodes are collapsed.
     */
    private void rebuild() {
	treePathMapping.clear();
	if(treeModel != null) {
	    Object            rootUO = treeModel.getRoot();

	    root = createNodeForValue(rootUO, 0);
	    root.path = new TreePath(rootUO);
	    addMapping(root);
	    if(isRootVisible()) {
		rowCount = 1;
		root.row = 0;
	    }
	    else {
		rowCount = 0;
		root.row = -1;
	    }
	    root.expand();
	}
	else {
	    root = null;
	    rowCount = 0;
	}
	/* Clear out the selection model, might not always be the right
	   thing to do, but the tree is being rebuilt, soooo.... */
	if(treeSelectionModel != null) {
	    treeSelectionModel.clearSelection();
	}
	this.visibleNodesChanged();
    }

    /**
      * Returns the index of the row containing location.  If there
      * are no rows, -1 is returned.  If location is beyond the last
      * row index, the last row index is returned.
      */
    private int getRowContainingYLocation(int location) {
	if(getRowCount() == 0)
	    return -1;
	return Math.max(0, Math.min(getRowCount() - 1,
				    location / getRowHeight()));
    }

    /**
     * Ensures that all the path components in path are expanded, accept
     * for the last component which will only be expanded if expandLast
     * is true.
     * Returns true if succesful in finding the path.
     */
    private boolean ensurePathIsExpanded(TreePath aPath,
					   boolean expandLast) {
	if(aPath != null) {
	    // Make sure the last entry isn't a leaf.
	    if(treeModel.isLeaf(aPath.getLastPathComponent())) {
		aPath = aPath.getParentPath();
		expandLast = true;
	    }
	    if(aPath != null) {
		FHTreeStateNode     lastNode = getNodeForPath(aPath, false,
							      true);

		if(lastNode != null) {
		    lastNode.makeVisible();
		    if(expandLast)
			lastNode.expand();
		    return true;
		}
	    }
	}
	return false;
    }

    /**
     * Creates and returns an instance of FHTreeStateNode.
     */
    private FHTreeStateNode createNodeForValue(Object value,int childIndex) {
	return new FHTreeStateNode(value, childIndex, -1);
    }

    /**
     * Messages getTreeNodeForPage(path, onlyIfVisible, shouldCreate,
     * path.length) as long as path is non-null and the length is > 0.
     * Otherwise returns null.
     */
    private FHTreeStateNode getNodeForPath(TreePath path,
					     boolean onlyIfVisible,
					     boolean shouldCreate) {
	if(path != null) {
	    FHTreeStateNode      node;

	    node = getMapping(path);
	    if(node != null) {
		if(onlyIfVisible && !node.isVisible())
		    return null;
		return node;
	    }
	    if(onlyIfVisible)
		return null;

	    // Check all the parent paths, until a match is found.
	    Stack                paths;

	    if(tempStacks.size() == 0) {
		paths = new Stack();
	    }
	    else {
		paths = (Stack)tempStacks.pop();
	    }

	    try {
		paths.push(path);
		path = path.getParentPath();
		node = null;
		while(path != null) {
		    node = getMapping(path);
		    if(node != null) {
			// Found a match, create entries for all paths in
			// paths.
			while(node != null && paths.size() > 0) {
			    path = (TreePath)paths.pop();
			    node = node.createChildFor(path.
						       getLastPathComponent());
			}
			return node;
		    }
		    paths.push(path);
		    path = path.getParentPath();
		}
	    }
	    finally {
		paths.removeAllElements();
		tempStacks.push(paths);
	    }
	    // If we get here it means they share a different root!
	    return null;
	}
	return null;
    }

    /**
     * FHTreeStateNode is used to track what has been expanded.
     * FHTreeStateNode differs from VariableHeightTreeState.TreeStateNode
     * in that it is highly model intensive. That is almost all queries to a
     * FHTreeStateNode result in the TreeModel being queried. And it
     * obviously does not support variable sized row heights.
     */
    private class FHTreeStateNode extends DefaultMutableTreeNode {
	/** Is this node expanded? */
	protected boolean         isExpanded;

	/** Index of this node from the model. */
	protected int             childIndex;

	/** Row of the receiver. This is only valid if the row is expanded.
	 */
	protected int             row;

	/** Path of this node. */
	protected TreePath        path;


	public FHTreeStateNode(Object userObject, int childIndex, int row) {
	    super(userObject);
	    this.childIndex = childIndex;
	    this.row = row;
	}

	//
	// Overriden DefaultMutableTreeNode methods
	//

	/**
	 * Messaged when this node is added somewhere, resets the path
	 * and adds a mapping from path to this node.
	 */
	public void setParent(MutableTreeNode parent) {
	    super.setParent(parent);
	    if(parent != null) {
		path = ((FHTreeStateNode)parent).getTreePath().
		            pathByAddingChild(getUserObject());
		addMapping(this);
	    }
	}

	/**
	 * Messaged when this node is removed from its parent, this messages
	 * <code>removedFromMapping</code> to remove all the children.
	 */
	public void remove(int childIndex) {
	    FHTreeStateNode     node = (FHTreeStateNode)getChildAt(childIndex);

	    node.removeFromMapping();
	    super.remove(childIndex);
	}

	/**
	 * Messaged to set the user object. This resets the path.
	 */
	public void setUserObject(Object o) {
	    super.setUserObject(o);
	    if(path != null) {
		FHTreeStateNode      parent = (FHTreeStateNode)getParent();

		if(parent != null)
		    resetChildrenPaths(parent.getTreePath());
		else
		    resetChildrenPaths(null);
	    }
	}

	//
	//

	/**
	 * Returns the index of the reciever in the model.
	 */
	public int getChildIndex() {
	    return childIndex;
	}

	/**
	 * Returns the TreePath of the receiver.
	 */
	public TreePath getTreePath() {
	    return path;
	}

	/**
	 * Returns the child for the passed in model index, this will
	 * return null if the child for <code>index</code> has not yet
	 * been created (expanded).
	 */
	public FHTreeStateNode getChildAtModelIndex(int index) {
	    // PENDING: Make this a binary search!
	    for(int counter = getChildCount() - 1; counter >= 0; counter--)
		if(((FHTreeStateNode)getChildAt(counter)).childIndex == index)
		    return (FHTreeStateNode)getChildAt(counter);
	    return null;
	}

	/**
	 * Returns true if this node is visible. This is determined by
	 * asking all the parents if they are expanded.
	 */
	public boolean isVisible() {
	    FHTreeStateNode         parent = (FHTreeStateNode)getParent();

	    if(parent == null)
		return true;
	    return (parent.isExpanded() && parent.isVisible());
	}

	/**
	 * Returns the row of the receiver.
	 */
	public int getRow() {
	    return row;
	}

	/**
	 * Returns the row of the child with a model index of
	 * <code>index</code>.
	 */
	public int getRowToModelIndex(int index) {
	    FHTreeStateNode      child;
	    int                  lastRow = getRow() + 1;
	    int                  retValue = lastRow;

	    // This too could be a binary search!
	    for(int counter = 0, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		child = (FHTreeStateNode)getChildAt(counter);
		if(child.childIndex >= index) {
		    if(child.childIndex == index)
			return child.row;
		    if(counter == 0)
			return getRow() + 1 + index;
		    return child.row - (child.childIndex - index);
		}
	    }
	    // YECK!
	    return getRow() + 1 + getTotalChildCount() -
		             (treeModel.getChildCount(getUserObject()) -
			      index);
	}

	/**
	 * Returns the number of children in the receiver by descending all
	 * expanded nodes and messaging them with getTotalChildCount.
	 */
	public int getTotalChildCount() {
	    if(isExpanded()) {
		FHTreeStateNode      parent = (FHTreeStateNode)getParent();
		int                  pIndex;

		if(parent != null && (pIndex = parent.getIndex(this)) + 1 <
		   parent.getChildCount()) {
		    // This node has a created sibling, to calc total
		    // child count directly from that!
		    FHTreeStateNode  nextSibling = (FHTreeStateNode)parent.
			                   getChildAt(pIndex + 1);

		    return nextSibling.row - row -
			   (nextSibling.childIndex - childIndex);
		}
		else {
		    int   retCount = getModel().getChildCount(getUserObject());

		    for(int counter = getChildCount() - 1; counter >= 0;
			counter--) {
			retCount += ((FHTreeStateNode)getChildAt(counter))
			                          .getTotalChildCount();
		    }
		    return retCount;
		}
	    }
	    return 0;
	}

	/**
	 * Returns true if this node is expanded.
	 */
	public boolean isExpanded() {
	    return isExpanded;
	}

	/**
	 * The highest visible nodes have a depth of 0.
	 */
	public int getVisibleLevel() {
	    if (isRootVisible()) {
		return getLevel();
	    } else {
		return getLevel() - 1;
	    }
	}

	/**
	 * Recreates the receivers path, and all its childrens paths.
	 */
	protected void resetChildrenPaths(TreePath parentPath) {
	    removeMapping(this);
	    if(parentPath == null)
		path = new TreePath(getUserObject());
	    else
		path = parentPath.pathByAddingChild(getUserObject());
	    addMapping(this);
	    for(int counter = getChildCount() - 1; counter >= 0; counter--)
		((FHTreeStateNode)getChildAt(counter)).
		               resetChildrenPaths(path);
	}

	/**
	 * Removes the receiver, and all its children, from the mapping
	 * table.
	 */
	protected void removeFromMapping() {
	    if(path != null) {
		removeMapping(this);
		for(int counter = getChildCount() - 1; counter >= 0; counter--)
		    ((FHTreeStateNode)getChildAt(counter)).removeFromMapping();
	    }
	}

	/**
	 * Creates a new node to represent <code>userObject</code>.
	 * This does NOT check to ensure there isn't already a child node
	 * to manage <code>userObject</code>.
	 */
	protected FHTreeStateNode createChildFor(Object userObject) {
	    int      newChildIndex = treeModel.getIndexOfChild
		                     (getUserObject(), userObject);

	    if(newChildIndex < 0)
		return null;

	    FHTreeStateNode     aNode;
	    FHTreeStateNode     child = createNodeForValue(userObject,
							   newChildIndex);
	    int                 childRow;

	    if(isVisible()) {
		childRow = getRowToModelIndex(newChildIndex);
	    }
	    else {
		childRow = -1;
	    }
	    child.row = childRow;
	    for(int counter = 0, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		aNode = (FHTreeStateNode)getChildAt(counter);
		if(aNode.childIndex > newChildIndex) {
		    insert(child, counter);
		    return child;
		}
	    }
	    add(child);
	    return child;
	}

	/**
	 * Adjusts the receiver, and all its children rows by
	 * <code>amount</code>.
	 */
	protected void adjustRowBy(int amount) {
	    row += amount;
	    if(isExpanded) {
		for(int counter = getChildCount() - 1; counter >= 0;
		    counter--)
		    ((FHTreeStateNode)getChildAt(counter)).adjustRowBy(amount);
	    }
	}

	/**
	 * Adjusts this node, its child, and its parent starting at
	 * an index of <code>index</code> index is the index of the child
	 * to start adjusting from, which is not necessarily the model
	 * index.
	 */
	protected void adjustRowBy(int amount, int startIndex) {
	    // Could check isVisible, but probably isn't worth it.
	    if(isExpanded) {
		// children following startIndex.
		for(int counter = getChildCount() - 1; counter >= startIndex;
		    counter--)
		    ((FHTreeStateNode)getChildAt(counter)).adjustRowBy(amount);
	    }
	    // Parent
	    FHTreeStateNode        parent = (FHTreeStateNode)getParent();

	    if(parent != null) {
		parent.adjustRowBy(amount, parent.getIndex(this) + 1);
	    }
	}

	/**
	 * Messaged when the node has expanded. This updates all of
	 * the receivers children rows, as well as the total row count.
	 */
	protected void didExpand() {
	    int               nextRow = setRowAndChildren(row);
	    FHTreeStateNode   parent = (FHTreeStateNode)getParent();
	    int               childRowCount = nextRow - row - 1;

	    if(parent != null) {
		parent.adjustRowBy(childRowCount, parent.getIndex(this) + 1);
	    }
	    adjustRowCountBy(childRowCount);
	}

	/**
	 * Sets the receivers row to <code>nextRow</code> and recursively
	 * updates all the children of the receivers rows. The index the
	 * next row is to be placed as is returned.
	 */
	protected int setRowAndChildren(int nextRow) {
	    row = nextRow;

	    if(!isExpanded())
		return row + 1;

	    int              lastRow = row + 1;
	    int              lastModelIndex = 0;
	    FHTreeStateNode  child;
	    int              maxCounter = getChildCount();

	    for(int counter = 0; counter < maxCounter; counter++) {
		child = (FHTreeStateNode)getChildAt(counter);
		lastRow += (child.childIndex - lastModelIndex);
		lastModelIndex = child.childIndex + 1;
		if(child.isExpanded) {
		    lastRow = child.setRowAndChildren(lastRow);
		}
		else {
		    child.row = lastRow++;
		}
	    }
	    return lastRow + treeModel.getChildCount(getUserObject()) -
		             lastModelIndex;
	}

	/**
	 * Resets the receivers childrens rows. Starting with the child
	 * at <code>childIndex</code> (and <code>modelIndex</code>) to
	 * <code>newRow</code>. This uses <code>setRowAndChildren</code>
	 * to recursively descend children, and uses
	 * <code>resetRowSelection</code> to ascend parents.
	 */
	// This can be rather expensive, but is needed for the collapse
	// case this is resulting from a remove (although I could fix
	// that by having instances of FHTreeStateNode hold a ref to
	// the number of children). I prefer this though, making determing
	// the row of a particular node fast is very nice!
	protected void resetChildrenRowsFrom(int newRow, int childIndex,
					    int modelIndex) {
	    int              lastRow = newRow;
	    int              lastModelIndex = modelIndex;
	    FHTreeStateNode  node;
	    int              maxCounter = getChildCount();

	    for(int counter = childIndex; counter < maxCounter; counter++) {
		node = (FHTreeStateNode)getChildAt(counter);
		lastRow += (node.childIndex - lastModelIndex);
		lastModelIndex = node.childIndex + 1;
		if(node.isExpanded) {
		    lastRow = node.setRowAndChildren(lastRow);
		}
		else {
		    node.row = lastRow++;
		}
	    }
	    lastRow += treeModel.getChildCount(getUserObject()) -
		                 lastModelIndex;
	    node = (FHTreeStateNode)getParent();
	    if(node != null) {
		node.resetChildrenRowsFrom(lastRow, node.getIndex(this) + 1,
					   this.childIndex + 1);
	    }
	    else { // This is the root, reset total ROWCOUNT!
		rowCount = lastRow;
	    }
	}

	/**
	 * Makes the receiver visible, but invoking
	 * <code>expandParentAndReceiver</code> on the superclass.
	 */
	protected void makeVisible() {
	    FHTreeStateNode       parent = (FHTreeStateNode)getParent();

	    if(parent != null)
		parent.expandParentAndReceiver();
	}

	/**
	 * Invokes <code>expandParentAndReceiver</code> on the parent,
	 * and expands the receiver.
	 */
	protected void expandParentAndReceiver() {
	    FHTreeStateNode       parent = (FHTreeStateNode)getParent();

	    if(parent != null)
		parent.expandParentAndReceiver();
	    expand();
	}

	/**
	 * Expands the receiver.
	 */
	protected void expand() {
	    if(!isExpanded) {
		boolean            visible = isVisible();

		isExpanded = true;
		if(visible) {
		    didExpand();
		}

		// Update the selection model.
		if(visible && treeSelectionModel != null) {
		    treeSelectionModel.resetRowSelection();
		}
	    }
	}

	/**
	 * Collapses the receiver. If <code>adjustRows</code> is true,
	 * the rows of nodes after the receiver are adjusted.
	 */
	protected void collapse(boolean adjustRows) {
	    if(isExpanded) {
		TreePath[]                selPaths;

		if(treeSelectionModel != null)
		    selPaths = treeSelectionModel.getSelectionPaths();
		else
		    selPaths = null;

		if(isVisible() && adjustRows) {
		    int              childCount = getTotalChildCount();

		    isExpanded = false;
		    adjustRowCountBy(-childCount);
		    // We can do this because adjustRowBy won't descend
		    // the children.
		    adjustRowBy(-childCount, 0);
		}
		else
		    isExpanded = false;

		/* update the selection */
		if(selPaths != null) {
		    boolean        shouldRemove = false;
		    TreePath       ourPath = getTreePath();

		    for(int counter = selPaths.length - 1; counter >= 0;
			counter--) {
			if(selPaths[counter] != null &&
			   ourPath.isDescendant(selPaths[counter]) &&
			   !ourPath.equals(selPaths[counter]))
			    shouldRemove = true;
			else
			    selPaths[counter] = null;
		    }
		    if(shouldRemove)
			treeSelectionModel.removeSelectionPaths(selPaths);
		}
		if(adjustRows && isVisible() && treeSelectionModel != null)
		    treeSelectionModel.resetRowSelection();
	    }
	}

	/**
	 * Adds newChild to this nodes children at the appropriate location.
	 * The location is determined from the childIndex of newChild.
	 */
	protected void addNode(FHTreeStateNode newChild) {
	    boolean         added = false;
	    int             childIndex = newChild.getChildIndex();

	    for(int counter = 0, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		if(((FHTreeStateNode)getChildAt(counter)).getChildIndex() >
		   childIndex) {
		    added = true;
		    insert(newChild, counter);
		    counter = maxCounter;
		}
	    }
	    if(!added)
		add(newChild);
	}

	/**
	 * Removes the child at <code>modelIndex</code>.
	 * <code>isChildVisible</code> should be true if the receiver
	 * is visible and expanded.
	 */
	protected void removeChildAtModelIndex(int modelIndex,
					       boolean isChildVisible) {
	    FHTreeStateNode     childNode = getChildAtModelIndex(modelIndex);

	    if(childNode != null) {
		int          row = childNode.getRow();
		int          index = getIndex(childNode);

		childNode.collapse(false);
		remove(index);
		adjustChildIndexs(index, -1);
		if(isChildVisible) {
		    // Adjust the rows.
		    resetChildrenRowsFrom(row, index, modelIndex);
		}
	    }
	    else {
		int                  maxCounter = getChildCount();
		FHTreeStateNode      aChild;

		for(int counter = 0; counter < maxCounter; counter++) {
		    aChild = (FHTreeStateNode)getChildAt(counter);
		    if(aChild.childIndex >= modelIndex) {
			if(isChildVisible) {
			    adjustRowBy(-1, counter);
			    adjustRowCountBy(-1);
			}
			// Since matched and children are always sorted by
			// index, no need to continue testing with the
			// above.
			for(; counter < maxCounter; counter++)
			    ((FHTreeStateNode)getChildAt(counter)).
				              childIndex--;
			return;
		    }
		}
		// No children to adjust, but it was a child, so we still need
		// to adjust nodes after this one.
		if(isChildVisible) {
		    adjustRowBy(-1, maxCounter);
		    adjustRowCountBy(-1);
		}
	    }
	}

	/**
	 * Adjusts the child indexs of the receivers children by
	 * <code>amount</code>, starting at <code>index</code>.
	 */
	protected void adjustChildIndexs(int index, int amount) {
	    for(int counter = index, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		((FHTreeStateNode)getChildAt(counter)).childIndex += amount;
	    }
	}

	/**
	 * Messaged when a child has been inserted at index. For all the
	 * children that have a childIndex >= index their index is incremented
	 * by one.
	 */
	protected void childInsertedAtModelIndex(int index,
					       boolean isExpandedAndVisible) {
	    FHTreeStateNode                aChild;
	    int                            maxCounter = getChildCount();

	    for(int counter = 0; counter < maxCounter; counter++) {
		aChild = (FHTreeStateNode)getChildAt(counter);
		if(aChild.childIndex >= index) {
		    if(isExpandedAndVisible) {
			adjustRowBy(1, counter);
			adjustRowCountBy(1);
		    }
		    /* Since matched and children are always sorted by
		       index, no need to continue testing with the above. */
		    for(; counter < maxCounter; counter++)
			((FHTreeStateNode)getChildAt(counter)).childIndex++;
		    return;
		}
	    }
	    // No children to adjust, but it was a child, so we still need
	    // to adjust nodes after this one.
	    if(isExpandedAndVisible) {
		adjustRowBy(1, maxCounter);
		adjustRowCountBy(1);
	    }
	}

	/**
	 * Returns true if there is a row for <code>row</code>.
	 * <code>nextRow</code> gives the bounds of the receiver.
	 * Information about the found row is returned in <code>info</code>.
	 * This should be invoked on root with <code>nextRow</code> set
	 * to <code>getRowCount</code>().
	 */
	protected boolean getPathForRow(int row, int nextRow,
					SearchInfo info) {
	    if(this.row == row) {
		info.node = this;
		info.isNodeParentNode = false;
		info.childIndex = childIndex;
		return true;
	    }

	    FHTreeStateNode            child;
	    FHTreeStateNode            lastChild = null;

	    for(int counter = 0, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		child = (FHTreeStateNode)getChildAt(counter);
		if(child.row > row) {
		    if(counter == 0) {
			// No node exists for it, and is first.
			info.node = this;
			info.isNodeParentNode = true;
			info.childIndex = row - this.row - 1;
			return true;
		    }
		    else {
			// May have been in last childs bounds.
			int          lastChildEndRow = 1 + child.row -
			             (child.childIndex - lastChild.childIndex);

			if(row < lastChildEndRow) {
			    return lastChild.getPathForRow(row,
						       lastChildEndRow, info);
			}
			// Between last child and child, but not in last child
			info.node = this;
			info.isNodeParentNode = true;
			info.childIndex = row - lastChildEndRow +
			                        lastChild.childIndex + 1;
			return true;
		    }
		}
		lastChild = child;
	    }

	    int      childCount = treeModel.getChildCount(getUserObject());

	    // Not in children, but we should have it, offset from
	    // nextRow.
	    if(lastChild != null) {
		int        lastChildEndRow = nextRow -
		                  (childCount - lastChild.childIndex) + 1;

		if(row < lastChildEndRow) {
		    return lastChild.getPathForRow(row, lastChildEndRow, info);
		}
		// Between last child and child, but not in last child
		info.node = this;
		info.isNodeParentNode = true;
		info.childIndex = row - lastChildEndRow +
		                             lastChild.childIndex + 1;
		return true;
	    }
	    else {
		// No children.
		int         retChildIndex = row - this.row - 1;

		if(retChildIndex >= childCount) {
		    return false;
		}
		info.node = this;
		info.isNodeParentNode = true;
		info.childIndex = retChildIndex;
		return true;
	    }
	}

	/**
	 * Asks all the children of the receiver for their totalChildCount
	 * and returns this value (plus stopIndex).
	 */
	protected int getCountTo(int stopIndex) {
	    FHTreeStateNode    aChild;
	    int                retCount = stopIndex + 1;

	    for(int counter = 0, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		aChild = (FHTreeStateNode)getChildAt(counter);
		if(aChild.childIndex >= stopIndex)
		    counter = maxCounter;
		else
		    retCount += aChild.getTotalChildCount();
	    }
	    if(parent != null)
		return retCount + ((FHTreeStateNode)getParent())
		                   .getCountTo(childIndex);
	    if(!isRootVisible())
		return (retCount - 1);
	    return retCount;
	}

	/**
	 * Returns the number of children that are expanded to
	 * <code>stopIndex</code>. This does not include the number
	 * of children that the child at <code>stopIndex</code> might
	 * have.
	 */
	protected int getNumExpandedChildrenTo(int stopIndex) {
	    FHTreeStateNode    aChild;
	    int                retCount = stopIndex;

	    for(int counter = 0, maxCounter = getChildCount();
		counter < maxCounter; counter++) {
		aChild = (FHTreeStateNode)getChildAt(counter);
		if(aChild.childIndex >= stopIndex)
		    return retCount;
		else {
		    retCount += aChild.getTotalChildCount();
		}
	    }
	    return retCount;
	}

	/**
	 * Messaged when this node either expands or collapses.
	 */
	protected void didAdjustTree() {
	}

    } // FixedHeightLayoutCache.FHTreeStateNode


    /**
     * Used as a placeholder when getting the path in FHTreeStateNodes.
     */
    private class SearchInfo {
	protected FHTreeStateNode   node;
	protected boolean           isNodeParentNode;
	protected int               childIndex;

	protected TreePath getPath() {
	    if(node == null)
		return null;

	    if(isNodeParentNode)
		return node.getTreePath().pathByAddingChild(treeModel.getChild
					    (node.getUserObject(),
					     childIndex));
	    return node.path;
	}
    } // FixedHeightLayoutCache.SearchInfo


    /**
     * An enumerator to iterate through visible nodes.
     */
    // This is very similiar to
    // VariableHeightTreeState.VisibleTreeStateNodeEnumeration
    private class VisibleFHTreeStateNodeEnumeration implements Enumeration {
	/** Parent thats children are being enumerated. */
	protected FHTreeStateNode     parent;
	/** Index of next child. An index of -1 signifies parent should be
	 * visibled next. */
	protected int                 nextIndex;
	/** Number of children in parent. */
	protected int                 childCount;

	protected VisibleFHTreeStateNodeEnumeration(FHTreeStateNode node) {
	    this(node, -1);
	}

	protected VisibleFHTreeStateNodeEnumeration(FHTreeStateNode parent,
						    int startIndex) {
	    this.parent = parent;
	    this.nextIndex = startIndex;
	    this.childCount = treeModel.getChildCount(this.parent.
						      getUserObject());
	}

	/**
	 * @return true if more visible nodes.
	 */
	public boolean hasMoreElements() {
	    return (parent != null);
	}

	/**
	 * @return next visible TreePath.
	 */
	public Object nextElement() {
	    if(!hasMoreElements())
		throw new NoSuchElementException("No more visible paths");

	    Object                retObject;

	    if(nextIndex == -1)
		retObject = parent.getTreePath();
	    else {
		FHTreeStateNode  node = parent.getChildAtModelIndex(nextIndex);

		if(node == null)
		    retObject = parent.getTreePath().pathByAddingChild
			          (treeModel.getChild(parent.getUserObject(),
						      nextIndex));
		else
		    retObject = node.getTreePath();
	    }
	    updateNextObject();
	    return retObject;
	}

	/**
	 * Determines the next object by invoking <code>updateNextIndex</code>
	 * and if not succesful <code>findNextValidParent</code>.
	 */
	protected void updateNextObject() {
	    if(!updateNextIndex()) {
		findNextValidParent();
	    }
	}

	/**
	 * Finds the next valid parent, this should be called when nextIndex
	 * is beyond the number of children of the current parent.
	 */
	protected boolean findNextValidParent() {
	    if(parent == root) {
		// mark as invalid!
		parent = null;
		return false;
	    }
	    while(parent != null) {
		FHTreeStateNode      newParent = (FHTreeStateNode)parent.
		                                  getParent();

		if(newParent != null) {
		    nextIndex = parent.childIndex;
		    parent = newParent;
		    childCount = treeModel.getChildCount
			                    (parent.getUserObject());
		    if(updateNextIndex())
			return true;
		}
		else
		    parent = null;
	    }
	    return false;
	}

	/**
	 * Updates <code>nextIndex</code> returning false if it is beyond
	 * the number of children of parent.
	 */
	protected boolean updateNextIndex() {
	    // nextIndex == -1 identifies receiver, make sure is expanded
	    // before descend.
	    if(nextIndex == -1 && !parent.isExpanded()) {
		return false;
	    }

	    // Check that it can have kids
	    if(childCount == 0) {
		return false;
	    }
	    // Make sure next index not beyond child count.
	    else if(++nextIndex >= childCount) {
		return false;
	    }

	    FHTreeStateNode    child = parent.getChildAtModelIndex(nextIndex);

	    if(child != null && child.isExpanded()) {
		parent = child;
		nextIndex = -1;
		childCount = treeModel.getChildCount(child.getUserObject());
	    }
	    return true;
	}
    } // FixedHeightLayoutCache.VisibleFHTreeStateNodeEnumeration
}