001/* TreeUI.java --
002   Copyright (C) 2002, 2003, 2004  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.swing.plaf;
040
041import java.awt.Rectangle;
042
043import javax.swing.JTree;
044import javax.swing.tree.TreePath;
045
046/**
047 * An abstract base class for delegates that provide the user
048 * interface for <code>JTree</code>.
049 *
050 * @see javax.swing.JTree
051 *
052 * @author Sascha Brawer (brawer@dandelis.ch)
053 */
054public abstract class TreeUI extends ComponentUI
055{
056  /**
057   * Constructs a new <code>TreeUI</code>.
058   */
059  public TreeUI()
060  {
061    // Nothing to do here.
062  }
063
064
065  /**
066   * Determines the geometric extent of the label that is
067   * drawn for a path.
068   *
069   * @param tree the <code>JTree</code> for which this delegate
070   *        object provides the user interface.
071   *
072   * @param path the path whose label extent is requested.
073   *
074   * @return a rectangle enclosing the label, or <code>null</code>
075   *         if <code>path</code> contains invalid nodes.
076   */
077  public abstract Rectangle getPathBounds(JTree tree, TreePath path);
078
079
080  /**
081   * Creates a <code>TreePath</code> for the specified row.
082   *
083   * @param tree the <code>JTree</code> for which this delegate
084   *        object provides the user interface.
085   *
086   * @param row the index of the row, which should be a number
087   *        in the range <code>[0, getRowCount(tree) - 1]</code>.
088   *
089   * @return a <code>TreePath</code> for the specified row, or
090   *         <code>null</code> if <code>row</code> is outside
091   *         the valid range.
092   */
093  public abstract TreePath getPathForRow(JTree tree, int row);
094
095
096  /**
097   * Determines in which row a <code>TreePath</code> is currently
098   * being displayed.
099   *
100   * @param tree the <code>JTree</code> for which this delegate
101   *        object provides the user interface.
102   *
103   * @param path the path for which the caller wants to know
104   *        in which row it is being displayed.
105   *
106   * @return a number in the range <code>[0, getRowCount(tree)
107   *         - 1]</code> if the path is currently on display;
108   *         <code>-1</code> if the path is not shown to the
109   *        user.
110   */
111  public abstract int getRowForPath(JTree tree, TreePath path);
112
113
114  /**
115   * Counts how many rows are currently displayed.
116   *
117   * @param tree the <code>JTree</code> for which this delegate
118   *        object provides the user interface.
119   *
120   * @return the number of visible rows.
121   */
122  public abstract int getRowCount(JTree tree);
123
124
125  /**
126   * Finds the path that is closest to the specified position.
127   *
128   * <p><img src="doc-files/TreeUI-1.png" width="300" height="250"
129   * alt="[A screen shot of a JTree]" />
130   *
131   * <p>As shown by the above illustration, the bounds of the
132   * closest path do not necessarily need to contain the passed
133   * location.
134   *
135   * @param tree the <code>JTree</code> for which this delegate
136   *        object provides the user interface.
137   *
138   * @param x the horizontal location, relative to the origin
139   *        of <code>tree</code>.
140   *
141   * @param y the vertical location, relative to the origin
142   *        of <code>tree</code>.
143   *
144   * @return the closest path, or <code>null</code> if the
145   *         tree is currenlty not displaying any paths at all.
146   */
147  public abstract TreePath getClosestPathForLocation(JTree tree,
148                                                     int x, int y);
149
150
151  /**
152   * Determines whether the user is currently editing a tree cell.
153   *
154   * @param tree the <code>JTree</code> for which this delegate
155   *        object provides the user interface.
156   *
157   * @see #getEditingPath
158   */
159  public abstract boolean isEditing(JTree tree);
160
161
162  /**
163   * Stops editing a tree cell, committing the entered value into the
164   * tree&#x2019;s model. If no editing session is active, or if the
165   * active editor does not agree to stopping, nothing happens.  In
166   * some look and feels, this action happens when the user has
167   * pressed the enter key.
168   *
169   * @param tree the <code>JTree</code> for which this delegate
170   *        object provides the user interface.
171   *
172   * @return <code>false</code> if the editing still goes on because
173   *         the cell editor has objected to stopping the session;
174   *         <code>true</code> if editing has been stopped.
175   */
176  public abstract boolean stopEditing(JTree tree);
177
178
179  /**
180   * Cancels editing a tree cell, discarding any entered value.
181   * If no editing session is active, nothing happens. The cell
182   * editor is not given an opportunity to veto the canceling.
183   * In some look and feels, this action happens when the user has
184   * pressed the escape key.
185   *
186   * @param tree the <code>JTree</code> for which this delegate
187   *        object provides the user interface.
188   */
189  public abstract void cancelEditing(JTree tree);
190
191
192  /**
193   * Starts a session to edit a tree cell. If the cell editor
194   * rejects editing the cell, it will just be selected.
195   *
196   * @param tree the <code>JTree</code> for which this delegate
197   *        object provides the user interface.
198   *
199   * @param path the cell to edit.
200   */
201  public abstract void startEditingAtPath(JTree tree, TreePath path);
202
203
204  /**
205   * Retrieves the tree cell that is currently being edited.
206   *
207   * @return the currently edited path, or <code>null</code>
208   *         if no editing session is currently active.
209   */
210  public abstract TreePath getEditingPath(JTree tree);
211}