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 java.util.Enumeration; |
| 29 | import java.util.Hashtable; |
| 30 | import java.util.Vector; |
| 31 | |
| 32 | /** |
| 33 | * <P>StateEdit is a general edit for objects that change state. |
| 34 | * Objects being edited must conform to the StateEditable interface.</P> |
| 35 | * |
| 36 | * <P>This edit class works by asking an object to store it's state in |
| 37 | * Hashtables before and after editing occurs. Upon undo or redo the |
| 38 | * object is told to restore it's state from these Hashtables.</P> |
| 39 | * |
| 40 | * A state edit is used as follows: |
| 41 | * <PRE> |
| 42 | * // Create the edit during the "before" state of the object |
| 43 | * StateEdit newEdit = new StateEdit(myObject); |
| 44 | * // Modify the object |
| 45 | * myObject.someStateModifyingMethod(); |
| 46 | * // "end" the edit when you are done modifying the object |
| 47 | * newEdit.end(); |
| 48 | * </PRE> |
| 49 | * |
| 50 | * <P><EM>Note that when a StateEdit ends, it removes redundant state from |
| 51 | * the Hashtables - A state Hashtable is not guaranteed to contain all |
| 52 | * keys/values placed into it when the state is stored!</EM></P> |
| 53 | * |
| 54 | * @see StateEditable |
| 55 | * |
| 56 | * @author Ray Ryan |
| 57 | */ |
| 58 | |
| 59 | public class StateEdit |
| 60 | extends AbstractUndoableEdit { |
| 61 | |
| 62 | protected static final String RCSID = "$Id: StateEdit.java,v 1.6 1997/10/01 20:05:51 sandipc Exp $"; |
| 63 | |
| 64 | // |
| 65 | // Attributes |
| 66 | // |
| 67 | |
| 68 | /** |
| 69 | * The object being edited |
| 70 | */ |
| 71 | protected StateEditable object; |
| 72 | |
| 73 | /** |
| 74 | * The state information prior to the edit |
| 75 | */ |
| 76 | protected Hashtable<Object,Object> preState; |
| 77 | |
| 78 | /** |
| 79 | * The state information after the edit |
| 80 | */ |
| 81 | protected Hashtable<Object,Object> postState; |
| 82 | |
| 83 | /** |
| 84 | * The undo/redo presentation name |
| 85 | */ |
| 86 | protected String undoRedoName; |
| 87 | |
| 88 | // |
| 89 | // Constructors |
| 90 | // |
| 91 | |
| 92 | /** |
| 93 | * Create and return a new StateEdit. |
| 94 | * |
| 95 | * @param anObject The object to watch for changing state |
| 96 | * |
| 97 | * @see StateEdit |
| 98 | */ |
| 99 | public StateEdit(StateEditable anObject) { |
| 100 | super(); |
| 101 | init (anObject,null); |
| 102 | } |
| 103 | |
| 104 | /** |
| 105 | * Create and return a new StateEdit with a presentation name. |
| 106 | * |
| 107 | * @param anObject The object to watch for changing state |
| 108 | * @param name The presentation name to be used for this edit |
| 109 | * |
| 110 | * @see StateEdit |
| 111 | */ |
| 112 | public StateEdit(StateEditable anObject, String name) { |
| 113 | super(); |
| 114 | init (anObject,name); |
| 115 | } |
| 116 | |
| 117 | protected void init (StateEditable anObject, String name) { |
| 118 | this.object = anObject; |
| 119 | this.preState = new Hashtable(11); |
| 120 | this.object.storeState(this.preState); |
| 121 | this.postState = null; |
| 122 | this.undoRedoName = name; |
| 123 | } |
| 124 | |
| 125 | |
| 126 | // |
| 127 | // Operation |
| 128 | // |
| 129 | |
| 130 | |
| 131 | /** |
| 132 | * Gets the post-edit state of the StateEditable object and |
| 133 | * ends the edit. |
| 134 | */ |
| 135 | public void end() { |
| 136 | this.postState = new Hashtable(11); |
| 137 | this.object.storeState(this.postState); |
| 138 | this.removeRedundantState(); |
| 139 | } |
| 140 | |
| 141 | /** |
| 142 | * Tells the edited object to apply the state prior to the edit |
| 143 | */ |
| 144 | public void undo() { |
| 145 | super.undo(); |
| 146 | this.object.restoreState(preState); |
| 147 | } |
| 148 | |
| 149 | /** |
| 150 | * Tells the edited object to apply the state after the edit |
| 151 | */ |
| 152 | public void redo() { |
| 153 | super.redo(); |
| 154 | this.object.restoreState(postState); |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Gets the presentation name for this edit |
| 159 | */ |
| 160 | public String getPresentationName() { |
| 161 | return this.undoRedoName; |
| 162 | } |
| 163 | |
| 164 | |
| 165 | // |
| 166 | // Internal support |
| 167 | // |
| 168 | |
| 169 | /** |
| 170 | * Remove redundant key/values in state hashtables. |
| 171 | */ |
| 172 | protected void removeRedundantState() { |
| 173 | Vector uselessKeys = new Vector(); |
| 174 | Enumeration myKeys = preState.keys(); |
| 175 | |
| 176 | // Locate redundant state |
| 177 | while (myKeys.hasMoreElements()) { |
| 178 | Object myKey = myKeys.nextElement(); |
| 179 | if (postState.containsKey(myKey) && |
| 180 | postState.get(myKey).equals(preState.get(myKey))) { |
| 181 | uselessKeys.addElement(myKey); |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | // Remove redundant state |
| 186 | for (int i = uselessKeys.size()-1; i >= 0; i--) { |
| 187 | Object myKey = uselessKeys.elementAt(i); |
| 188 | preState.remove(myKey); |
| 189 | postState.remove(myKey); |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | } // End of class StateEdit |