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Java > Open Source Codes > edu > rice > cs > util > swing > DelegatingAction


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33
34 package edu.rice.cs.util.swing;
35
36 import javax.swing.*;
37 import java.awt.event.*;
38 import java.beans.*;
39 import java.util.HashMap JavaDoc;
40 import java.util.ListIterator JavaDoc;
41 import java.util.LinkedList JavaDoc;
42
43 public class DelegatingAction implements Action {
44   /**
45    * These keys will be copied from the delegatee. All other keys are held in this action itself.
46    */
47   private static final String JavaDoc[] KEYS_TO_DELEGATE = {
48     //DEFAULT,
49 NAME,
50     //SHORT_DESCRIPTION,
51 //LONG_DESCRIPTION,
52 //SMALL_ICON,
53 //ACTION_COMMAND_KEY,
54 //ACCELERATOR_KEY,
55 //MNEMONIC_KEY,
56 };
57
58   /** Can't use a more specific type parameter because of Action interface. */
59   private HashMap JavaDoc<String JavaDoc, Object JavaDoc> _localProperties = new HashMap JavaDoc<String JavaDoc, Object JavaDoc>();
60
61   /** The action to delegate to. If it's null, this action is disabled and all method calls will result in
62    * IllegalStateExceptions.
63    */
64   private Action _delegatee;
65   private final LinkedList JavaDoc<PropertyChangeListener> _listenerList =
66     new LinkedList JavaDoc<PropertyChangeListener>();
67
68   /**
69    * Returns value of the key, from delegatee is it's in {@link #KEYS_TO_DELEGATE}
70    * or from this if not.
71    */
72   public Object JavaDoc getValue(String JavaDoc key) {
73     _checkState();
74
75     if (_isDelegatedKey(key)) {
76       return _delegatee.getValue(key);
77     }
78     else {
79       return _localProperties.get(key);
80     }
81   }
82
83   private boolean _isDelegatedKey(String JavaDoc key) {
84     for (int i = 0; i < KEYS_TO_DELEGATE.length; i++) {
85       if (KEYS_TO_DELEGATE[i].equals(key)) return true;
86     }
87     return false;
88   }
89
90   public void putValue(String JavaDoc key, Object JavaDoc value) {
91     _checkState();
92
93     if (_isDelegatedKey(key)) {
94       _delegatee.putValue(key, value);
95     }
96     else {
97       Object JavaDoc old = _localProperties.get(key);
98       _localProperties.put(key, value);
99       ListIterator JavaDoc itor = _listenerList.listIterator();
100
101       PropertyChangeEvent event = new PropertyChangeEvent(this, key, old, value);
102
103       while (itor.hasNext()) {
104         PropertyChangeListener listener = (PropertyChangeListener) itor.next();
105         listener.propertyChange(event);
106       }
107     }
108   }
109
110   public void setEnabled(boolean b) {
111     _checkState();
112     _delegatee.setEnabled(b);
113   }
114
115   public boolean isEnabled() {
116     _checkState();
117     return _delegatee.isEnabled();
118   }
119
120   public void addPropertyChangeListener(PropertyChangeListener listener) {
121     _checkState();
122     _delegatee.addPropertyChangeListener(listener);
123     _listenerList.add(listener);
124   }
125
126   public void removePropertyChangeListener(PropertyChangeListener listener) {
127     _checkState();
128     _delegatee.removePropertyChangeListener(listener);
129     _listenerList.remove(listener);
130   }
131
132   public void actionPerformed(ActionEvent ae) {
133     _checkState();
134     _delegatee.actionPerformed(ae);
135   }
136
137   public void setDelegatee(final Action newDelegatee) {
138     if (newDelegatee == null) {
139       throw new IllegalArgumentException JavaDoc("setDelegatee(null) is not allowed!");
140     }
141
142     // create property change notifications
143 Boolean JavaDoc isEnabled = newDelegatee.isEnabled() ? Boolean.TRUE : Boolean.FALSE;
144
145     PropertyChangeEvent enabledEvent
146       =new PropertyChangeEvent(newDelegatee, "enabled", Boolean.FALSE, isEnabled);
147
148     PropertyChangeEvent[] events = null;
149
150     if (_delegatee != null) {
151       events = new PropertyChangeEvent[KEYS_TO_DELEGATE.length];
152
153       for (int i = 0; i < KEYS_TO_DELEGATE.length; i++) {
154         Object JavaDoc oldValue = _delegatee.getValue(KEYS_TO_DELEGATE[i]);
155         Object JavaDoc newValue = newDelegatee.getValue(KEYS_TO_DELEGATE[i]);
156
157         events[i] = new PropertyChangeEvent(newDelegatee,
158                                             KEYS_TO_DELEGATE[i],
159                                             oldValue,
160                                             newValue);
161       }
162     }
163
164     // remove listeners from old and add to new
165 ListIterator JavaDoc itor = _listenerList.listIterator();
166     while (itor.hasNext()) {
167       PropertyChangeListener listener = (PropertyChangeListener) itor.next();
168
169       if (_delegatee != null) {
170         _delegatee.removePropertyChangeListener(listener);
171       }
172
173       newDelegatee.addPropertyChangeListener(listener);
174
175       // fire property change events for all properties
176
177       if (events != null) {
178         for (int i = 0; i < events.length; i++) {
179           listener.propertyChange(events[i]);
180         }
181       }
182
183       listener.propertyChange(enabledEvent);
184     }
185
186     _delegatee = newDelegatee;
187   }
188
189   private void _checkState() {
190     if (_delegatee == null) {
191       throw new IllegalStateException JavaDoc("delegatee is null!");
192     }
193   }
194 }
195
196
197
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