J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2005 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 | |
| 30 | /** |
| 31 | * An <code>UndoableEdit</code> represents an edit. The edit may |
| 32 | * be undone, or if already undone the edit may be redone. |
| 33 | * <p> |
| 34 | * <code>UndoableEdit</code> is designed to be used with the |
| 35 | * <code>UndoManager</code>. As <code>UndoableEdit</code>s are generated |
| 36 | * by an <code>UndoableEditListener</code> they are typically added to |
| 37 | * the <code>UndoManager</code>. When an <code>UndoableEdit</code> |
| 38 | * is added to an <code>UndoManager</code> the following occurs (assuming |
| 39 | * <code>end</code> has not been called on the <code>UndoManager</code>): |
| 40 | * <ol> |
| 41 | * <li>If the <code>UndoManager</code> contains edits it will call |
| 42 | * <code>addEdit</code> on the current edit passing in the new edit |
| 43 | * as the argument. If <code>addEdit</code> returns true the |
| 44 | * new edit is assumed to have been incorporated into the current edit and |
| 45 | * the new edit will not be added to the list of current edits. |
| 46 | * Edits can use <code>addEdit</code> as a way for smaller edits to |
| 47 | * be incorporated into a larger edit and treated as a single edit. |
| 48 | * <li>If <code>addEdit</code> returns false <code>replaceEdit</code> |
| 49 | * is called on the new edit with the current edit passed in as the |
| 50 | * argument. This is the inverse of <code>addEdit</code> — |
| 51 | * if the new edit returns true from <code>replaceEdit</code>, the new |
| 52 | * edit replaces the current edit. |
| 53 | * </ol> |
| 54 | * The <code>UndoManager</code> makes use of |
| 55 | * <code>isSignificant</code> to determine how many edits should be |
| 56 | * undone or redone. The <code>UndoManager</code> will undo or redo |
| 57 | * all insignificant edits (<code>isSignificant</code> returns false) |
| 58 | * between the current edit and the last or |
| 59 | * next significant edit. <code>addEdit</code> and |
| 60 | * <code>replaceEdit</code> can be used to treat multiple edits as |
| 61 | * a single edit, returning false from <code>isSignificant</code> |
| 62 | * allows for treating can be used to |
| 63 | * have many smaller edits undone or redone at once. Similar functionality |
| 64 | * can also be done using the <code>addEdit</code> method. |
| 65 | * |
| 66 | * @author Ray Ryan |
| 67 | */ |
| 68 | public interface UndoableEdit { |
| 69 | /** |
| 70 | * Undo the edit. |
| 71 | * |
| 72 | * @throws CannotUndoException if this edit can not be undone |
| 73 | */ |
| 74 | public void undo() throws CannotUndoException; |
| 75 | |
| 76 | /** |
| 77 | * Returns true if this edit may be undone. |
| 78 | * |
| 79 | * @return true if this edit may be undone |
| 80 | */ |
| 81 | public boolean canUndo(); |
| 82 | |
| 83 | /** |
| 84 | * Re-applies the edit. |
| 85 | * |
| 86 | * @throws CannotRedoException if this edit can not be redone |
| 87 | */ |
| 88 | public void redo() throws CannotRedoException; |
| 89 | |
| 90 | /** |
| 91 | * Returns true if this edit may be redone. |
| 92 | * |
| 93 | * @return true if this edit may be redone |
| 94 | */ |
| 95 | public boolean canRedo(); |
| 96 | |
| 97 | /** |
| 98 | * Informs the edit that it should no longer be used. Once an |
| 99 | * <code>UndoableEdit</code> has been marked as dead it can no longer |
| 100 | * be undone or redone. |
| 101 | * <p> |
| 102 | * This is a useful hook for cleaning up state no longer |
| 103 | * needed once undoing or redoing is impossible--for example, |
| 104 | * deleting file resources used by objects that can no longer be |
| 105 | * undeleted. <code>UndoManager</code> calls this before it dequeues edits. |
| 106 | * <p> |
| 107 | * Note that this is a one-way operation. There is no "un-die" |
| 108 | * method. |
| 109 | * |
| 110 | * @see CompoundEdit#die |
| 111 | */ |
| 112 | public void die(); |
| 113 | |
| 114 | /** |
| 115 | * Adds an <code>UndoableEdit</code> to this <code>UndoableEdit</code>. |
| 116 | * This method can be used to coalesce smaller edits into a larger |
| 117 | * compound edit. For example, text editors typically allow |
| 118 | * undo operations to apply to words or sentences. The text |
| 119 | * editor may choose to generate edits on each key event, but allow |
| 120 | * those edits to be coalesced into a more user-friendly unit, such as |
| 121 | * a word. In this case, the <code>UndoableEdit</code> would |
| 122 | * override <code>addEdit</code> to return true when the edits may |
| 123 | * be coalesced. |
| 124 | * <p> |
| 125 | * A return value of true indicates <code>anEdit</code> was incorporated |
| 126 | * into this edit. A return value of false indicates <code>anEdit</code> |
| 127 | * may not be incorporated into this edit. |
| 128 | * <p>Typically the receiver is already in the queue of a |
| 129 | * <code>UndoManager</code> (or other <code>UndoableEditListener</code>), |
| 130 | * and is being given a chance to incorporate <code>anEdit</code> |
| 131 | * rather than letting it be added to the queue in turn.</p> |
| 132 | * |
| 133 | * <p>If true is returned, from now on <code>anEdit</code> must return |
| 134 | * false from <code>canUndo</code> and <code>canRedo</code>, |
| 135 | * and must throw the appropriate exception on <code>undo</code> or |
| 136 | * <code>redo</code>.</p> |
| 137 | * |
| 138 | * @param anEdit the edit to be added |
| 139 | * @return true if <code>anEdit</code> may be incorporated into this |
| 140 | * edit |
| 141 | */ |
| 142 | public boolean addEdit(UndoableEdit anEdit); |
| 143 | |
| 144 | /** |
| 145 | * Returns true if this <code>UndoableEdit</code> should replace |
| 146 | * <code>anEdit</code>. This method is used by <code>CompoundEdit</code> |
| 147 | * and the <code>UndoManager</code>; it is called if |
| 148 | * <code>anEdit</code> could not be added to the current edit |
| 149 | * (<code>addEdit</code> returns false). |
| 150 | * <p> |
| 151 | * This method provides a way for an edit to replace an existing edit. |
| 152 | * <p>This message is the opposite of addEdit--anEdit has typically |
| 153 | * already been queued in an <code>UndoManager</code> (or other |
| 154 | * UndoableEditListener), and the receiver is being given a chance |
| 155 | * to take its place.</p> |
| 156 | * |
| 157 | * <p>If true is returned, from now on anEdit must return false from |
| 158 | * canUndo() and canRedo(), and must throw the appropriate |
| 159 | * exception on undo() or redo().</p> |
| 160 | * |
| 161 | * @param anEdit the edit that replaces the current edit |
| 162 | * @return true if this edit should replace <code>anEdit</code> |
| 163 | */ |
| 164 | public boolean replaceEdit(UndoableEdit anEdit); |
| 165 | |
| 166 | /** |
| 167 | * Returns true if this edit is considered significant. A significant |
| 168 | * edit is typically an edit that should be presented to the user, perhaps |
| 169 | * on a menu item or tooltip. The <code>UndoManager</code> will undo, |
| 170 | * or redo, all insignificant edits to the next significant edit. |
| 171 | * |
| 172 | * @return true if this edit is significant |
| 173 | */ |
| 174 | public boolean isSignificant(); |
| 175 | |
| 176 | /** |
| 177 | * Returns a localized, human-readable description of this edit, suitable |
| 178 | * for use in a change log, for example. |
| 179 | * |
| 180 | * @return description of this edit |
| 181 | */ |
| 182 | public String getPresentationName(); |
| 183 | |
| 184 | /** |
| 185 | * Returns a localized, human-readable description of the undoable form of |
| 186 | * this edit, suitable for use as an Undo menu item, for example. |
| 187 | * This is typically derived from <code>getPresentationName</code>. |
| 188 | * |
| 189 | * @return a description of the undoable form of this edit |
| 190 | */ |
| 191 | public String getUndoPresentationName(); |
| 192 | |
| 193 | /** |
| 194 | * Returns a localized, human-readable description of the redoable form of |
| 195 | * this edit, suitable for use as a Redo menu item, for example. This is |
| 196 | * typically derived from <code>getPresentationName</code>. |
| 197 | * |
| 198 | * @return a description of the redoable form of this edit |
| 199 | */ |
| 200 | public String getRedoPresentationName(); |
| 201 | } |