src/be/nikiroo/fanfix_swing/gui/utils/ListenerPanel.java

   1 package be.nikiroo.fanfix_swing.gui.utils;
   2
   3 import java.awt.event.ActionEvent;
   4 import java.awt.event.ActionListener;
   5 import java.util.LinkedList;
   6 import java.util.Queue;
   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.
  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 currently unique) listener will drain
  18  * the queue.
  19  *
  20  * @author niki
  21  */
  22 public class ListenerPanel extends JPanel {
  23         private static final long serialVersionUID = 1L;
  24
  25         /** Waiting queue until at least one listener is here to get the events. */
  26         private final Queue<ActionEvent> waitingQueue;
  27
  28         /**
  29          * Create a new {@link ListenerPanel}.
  30          */
  31         public ListenerPanel() {
  32                 waitingQueue = new LinkedList<ActionEvent>();
  33         }
  34
  35         /**
  36          * Check that this {@link ListenerPanel} currently has
  37          * {@link ActionListener}s that listen on it.
  38          *
  39          * @return TRUE if it has
  40          */
  41         public synchronized boolean hasListeners() {
  42                 return listenerList.getListenerList().length > 1;
  43         }
  44
  45         /**
  46          * Check how many events are currently waiting for an
  47          * {@link ActionListener}.
  48          *
  49          * @return the number of waiting events (can be 0)
  50          */
  51         public synchronized int getWaitingEventCount() {
  52                 return waitingQueue.size();
  53         }
  54
  55         /**
  56          * Adds the specified action listener to receive action events from this
  57          * {@link SearchBar}.
  58          *
  59          * @param listener
  60          *            the action listener to be added
  61          */
  62         public synchronized void addActionListener(ActionListener listener) {
  63                 if (!hasListeners()) {
  64                         while (!waitingQueue.isEmpty()) {
  65                                 listener.actionPerformed(waitingQueue.remove());
  66                         }
  67                 }
  68
  69                 listenerList.add(ActionListener.class, listener);
  70         }
  71
  72         /**
  73          * Removes the specified action listener so that it no longer receives
  74          * action events from this {@link SearchBar}.
  75          *
  76          * @param listener
  77          *            the action listener to be removed
  78          */
  79         public synchronized void removeActionListener(ActionListener listener) {
  80                 listenerList.remove(ActionListener.class, listener);
  81         }
  82
  83         /**
  84          * Notify the listeners of an action.
  85          *
  86          * @param listenerCommand
  87          *            A string that may specify a command (possibly one of several)
  88          *            associated with the event
  89          */
  90         protected synchronized void fireActionPerformed(String listenerCommand) {
  91                 ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED,
  92                                 listenerCommand);
  93                 if (hasListeners()) {
  94                         Object[] listeners = listenerList.getListenerList();
  95                         for (int i = listeners.length - 2; i >= 0; i -= 2) {
  96                                 if (listeners[i] == ActionListener.class) {
  97                                         ((ActionListener) listeners[i + 1]).actionPerformed(e);
  98                                 }
  99                         }
 100                 } else {
 101                         waitingQueue.add(e);
 102                 }
 103         }
 104 }