J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2004 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.swing.undo; |
| 27 | |
| 28 | import javax.swing.event.*; |
| 29 | import java.util.*; |
| 30 | |
| 31 | /** |
| 32 | * A support class used for managing <code>UndoableEdit</code> listeners. |
| 33 | * |
| 34 | * @author Ray Ryan |
| 35 | */ |
| 36 | public class UndoableEditSupport { |
| 37 | protected int updateLevel; |
| 38 | protected CompoundEdit compoundEdit; |
| 39 | protected Vector<UndoableEditListener> listeners; |
| 40 | protected Object realSource; |
| 41 | |
| 42 | /** |
| 43 | * Constructs an <code>UndoableEditSupport</code> object. |
| 44 | */ |
| 45 | public UndoableEditSupport() { |
| 46 | this(null); |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * Constructs an <code>UndoableEditSupport</code> object. |
| 51 | * |
| 52 | * @param r an <code>Object</code> |
| 53 | */ |
| 54 | public UndoableEditSupport(Object r) { |
| 55 | realSource = r == null ? this : r; |
| 56 | updateLevel = 0; |
| 57 | compoundEdit = null; |
| 58 | listeners = new Vector<UndoableEditListener>(); |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Registers an <code>UndoableEditListener</code>. |
| 63 | * The listener is notified whenever an edit occurs which can be undone. |
| 64 | * |
| 65 | * @param l an <code>UndoableEditListener</code> object |
| 66 | * @see #removeUndoableEditListener |
| 67 | */ |
| 68 | public synchronized void addUndoableEditListener(UndoableEditListener l) { |
| 69 | listeners.addElement(l); |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Removes an <code>UndoableEditListener</code>. |
| 74 | * |
| 75 | * @param l the <code>UndoableEditListener</code> object to be removed |
| 76 | * @see #addUndoableEditListener |
| 77 | */ |
| 78 | public synchronized void removeUndoableEditListener(UndoableEditListener l) |
| 79 | { |
| 80 | listeners.removeElement(l); |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * Returns an array of all the <code>UndoableEditListener</code>s added |
| 85 | * to this UndoableEditSupport with addUndoableEditListener(). |
| 86 | * |
| 87 | * @return all of the <code>UndoableEditListener</code>s added or an empty |
| 88 | * array if no listeners have been added |
| 89 | * @since 1.4 |
| 90 | */ |
| 91 | public synchronized UndoableEditListener[] getUndoableEditListeners() { |
| 92 | return (UndoableEditListener[])(listeners.toArray( |
| 93 | new UndoableEditListener[0])); |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Called only from <code>postEdit</code> and <code>endUpdate</code>. Calls |
| 98 | * <code>undoableEditHappened</code> in all listeners. No synchronization |
| 99 | * is performed here, since the two calling methods are synchronized. |
| 100 | */ |
| 101 | protected void _postEdit(UndoableEdit e) { |
| 102 | UndoableEditEvent ev = new UndoableEditEvent(realSource, e); |
| 103 | Enumeration cursor = ((Vector)listeners.clone()).elements(); |
| 104 | while (cursor.hasMoreElements()) { |
| 105 | ((UndoableEditListener)cursor.nextElement()). |
| 106 | undoableEditHappened(ev); |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * DEADLOCK WARNING: Calling this method may call |
| 112 | * <code>undoableEditHappened</code> in all listeners. |
| 113 | * It is unwise to call this method from one of its listeners. |
| 114 | */ |
| 115 | public synchronized void postEdit(UndoableEdit e) { |
| 116 | if (updateLevel == 0) { |
| 117 | _postEdit(e); |
| 118 | } else { |
| 119 | // PENDING(rjrjr) Throw an exception if this fails? |
| 120 | compoundEdit.addEdit(e); |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | /** |
| 125 | * Returns the update level value. |
| 126 | * |
| 127 | * @return an integer representing the update level |
| 128 | */ |
| 129 | public int getUpdateLevel() { |
| 130 | return updateLevel; |
| 131 | } |
| 132 | |
| 133 | /** |
| 134 | * |
| 135 | */ |
| 136 | public synchronized void beginUpdate() { |
| 137 | if (updateLevel == 0) { |
| 138 | compoundEdit = createCompoundEdit(); |
| 139 | } |
| 140 | updateLevel++; |
| 141 | } |
| 142 | |
| 143 | /** |
| 144 | * Called only from <code>beginUpdate</code>. |
| 145 | * Exposed here for subclasses' use. |
| 146 | */ |
| 147 | protected CompoundEdit createCompoundEdit() { |
| 148 | return new CompoundEdit(); |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * DEADLOCK WARNING: Calling this method may call |
| 153 | * <code>undoableEditHappened</code> in all listeners. |
| 154 | * It is unwise to call this method from one of its listeners. |
| 155 | */ |
| 156 | public synchronized void endUpdate() { |
| 157 | updateLevel--; |
| 158 | if (updateLevel == 0) { |
| 159 | compoundEdit.end(); |
| 160 | _postEdit(compoundEdit); |
| 161 | compoundEdit = null; |
| 162 | } |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Returns a string that displays and identifies this |
| 167 | * object's properties. |
| 168 | * |
| 169 | * @return a <code>String</code> representation of this object |
| 170 | */ |
| 171 | public String toString() { |
| 172 | return super.toString() + |
| 173 | " updateLevel: " + updateLevel + |
| 174 | " listeners: " + listeners + |
| 175 | " compoundEdit: " + compoundEdit; |
| 176 | } |
| 177 | } |