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1 | package be.nikiroo.fanfix_swing.gui.utils; |
2 | ||
3 | import java.awt.event.ActionEvent; | |
4 | import java.awt.event.ActionListener; | |
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5 | import java.util.LinkedList; |
6 | import java.util.Queue; | |
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7 | |
8 | import javax.swing.JPanel; | |
9 | ||
10 | import be.nikiroo.fanfix_swing.gui.SearchBar; | |
11 | ||
12 | /** | |
13 | * A {@link JPanel} with the default {@link ActionListener} add/remove/fire | |
14 | * methods. | |
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15 | * <p> |
16 | * Note that it will queue all events until at least one listener comes (or | |
17 | * comes back!); this first (or at least curently unique) listener will drain | |
18 | * the queue. | |
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19 | * |
20 | * @author niki | |
21 | */ | |
22 | public class ListenerPanel extends JPanel { | |
23 | private static final long serialVersionUID = 1L; | |
24 | ||
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25 | private final Queue<ActionEvent> waitingQueue; |
26 | ||
27 | /** | |
28 | * Create a new {@link ListenerPanel}. | |
29 | */ | |
30 | public ListenerPanel() { | |
31 | waitingQueue = new LinkedList<ActionEvent>(); | |
32 | } | |
33 | ||
34 | /** | |
35 | * Check that this {@link ListenerPanel} currently has {@link ActionListener}s | |
36 | * that listen on it. | |
37 | * | |
38 | * @return TRUE if it has | |
39 | */ | |
40 | public synchronized boolean hasListeners() { | |
41 | return listenerList.getListenerList().length > 1; | |
42 | } | |
43 | ||
44 | /** | |
45 | * Check how many events are currently waiting for an {@link ActionListener}. | |
46 | * | |
47 | * @return the number of waiting events (can be 0) | |
48 | */ | |
49 | public synchronized int getWaitingEventCount() { | |
50 | return waitingQueue.size(); | |
51 | } | |
52 | ||
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53 | /** |
54 | * Adds the specified action listener to receive action events from this | |
55 | * {@link SearchBar}. | |
56 | * | |
57 | * @param listener the action listener to be added | |
58 | */ | |
59 | public synchronized void addActionListener(ActionListener listener) { | |
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60 | if (!hasListeners()) { |
61 | while (!waitingQueue.isEmpty()) { | |
62 | listener.actionPerformed(waitingQueue.remove()); | |
63 | } | |
64 | } | |
65 | ||
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66 | listenerList.add(ActionListener.class, listener); |
67 | } | |
68 | ||
69 | /** | |
70 | * Removes the specified action listener so that it no longer receives action | |
71 | * events from this {@link SearchBar}. | |
72 | * | |
73 | * @param listener the action listener to be removed | |
74 | */ | |
75 | public synchronized void removeActionListener(ActionListener listener) { | |
76 | listenerList.remove(ActionListener.class, listener); | |
77 | } | |
78 | ||
79 | /** | |
80 | * Notify the listeners of an action. | |
81 | * | |
82 | * @param listenerCommand A string that may specify a command (possibly one of | |
83 | * several) associated with the event | |
84 | */ | |
d6c8579c | 85 | protected synchronized void fireActionPerformed(String listenerCommand) { |
2a03ecc0 | 86 | ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, listenerCommand); |
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87 | if (hasListeners()) { |
88 | Object[] listeners = listenerList.getListenerList(); | |
89 | for (int i = listeners.length - 2; i >= 0; i -= 2) { | |
90 | if (listeners[i] == ActionListener.class) { | |
91 | ((ActionListener) listeners[i + 1]).actionPerformed(e); | |
92 | } | |
2a03ecc0 | 93 | } |
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94 | } else { |
95 | waitingQueue.add(e); | |
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96 | } |
97 | } | |
98 | } |