/* TreeUI.java --
   Copyright (C) 2002, 2003, 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package javax.swing.plaf;

import java.awt.Rectangle;

import javax.swing.JTree;
import javax.swing.tree.TreePath;

/**
 * An abstract base class for delegates that provide the user
 * interface for <code>JTree</code>.
 *
 * @see javax.swing.JTree
 *
 * @author Sascha Brawer (brawer@dandelis.ch)
 */
public abstract class TreeUI
  extends ComponentUI
{
  /**
   * Constructs a new <code>TreeUI</code>.
   */
  public TreeUI()
  {
  }


  /**
   * Determines the geometric extent of the label that is
   * drawn for a path.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @param path the path whose label extent is requested.
   *
   * @return a rectangle enclosing the label, or <code>null</code>
   *         if <code>path</code> contains invalid nodes.
   */
  public abstract Rectangle getPathBounds(JTree tree, TreePath path);


  /**
   * Creates a <code>TreePath</code> for the specified row.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @param row the index of the row, which should be a number
   *        in the range <code>[0, getRowCount(tree) - 1]</code>.
   *
   * @return a <code>TreePath</code> for the specified row, or
   *         <code>null</code> if <code>row</code> is outside
   *         the valid range.
   */
  public abstract TreePath getPathForRow(JTree tree, int row);


  /**
   * Determines in which row a <code>TreePath</code> is currently
   * being displayed.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @param path the path for which the caller wants to know
   *        in which row it is being displayed.
   *
   * @return a number in the range <code>[0, getRowCount(tree)
   *         - 1]</code> if the path is currently on display;
   *         <code>-1</code> if the path is not shown to the
   *        user.
   */
  public abstract int getRowForPath(JTree tree, TreePath path);


  /**
   * Counts how many rows are currently displayed.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @return the number of visible rows.
   */
  public abstract int getRowCount(JTree tree);


  /**
   * Finds the path that is closest to the specified position.
   *
   * <p><img src="doc-files/TreeUI-1.png" width="300" height="250"
   * alt="[A screen shot of a JTree]" />
   *
   * <p>As shown by the above illustration, the bounds of the
   * closest path do not necessarily need to contain the passed
   * location.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @param x the horizontal location, relative to the origin
   *        of <code>tree</code>.
   *
   * @param y the vertical location, relative to the origin
   *        of <code>tree</code>.
   *
   * @return the closest path, or <code>null</code> if the
   *         tree is currenlty not displaying any paths at all.
   */
  public abstract TreePath getClosestPathForLocation(JTree tree,
                                                     int x, int y);


  /**
   * Determines whether the user is currently editing a tree cell.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @see #getEditingPath
   */
  public abstract boolean isEditing(JTree tree);


  /**
   * Stops editing a tree cell, committing the entered value into the
   * tree&#x2019;s model. If no editing session is active, or if the
   * active editor does not agree to stopping, nothing happens.  In
   * some look and feels, this action happens when the user has
   * pressed the enter key.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @return <code>false</code> if the editing still goes on because
   *         the cell editor has objected to stopping the session;
   *         <code>true</code> if editing has been stopped.
   */
  public abstract boolean stopEditing(JTree tree);


  /**
   * Cancels editing a tree cell, discarding any entered value.
   * If no editing session is active, nothing happens. The cell
   * editor is not given an opportunity to veto the canceling.
   * In some look and feels, this action happens when the user has
   * pressed the escape key.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   */
  public abstract void cancelEditing(JTree tree);


  /**
   * Starts a session to edit a tree cell. If the cell editor
   * rejects editing the cell, it will just be selected.
   *
   * @param tree the <code>JTree</code> for which this delegate
   *        object provides the user interface.
   *
   * @param path the cell to edit.
   */
  public abstract void startEditingAtPath(JTree tree, TreePath path);


  /**
   * Retrieves the tree cell that is currently being edited.
   *
   * @return the currently edited path, or <code>null</code>
   *         if no editing session is currently active.
   */
  public abstract TreePath getEditingPath(JTree tree);
}