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 curently 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         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
  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) {
  60                 if (!hasListeners()) {
  61                         while (!waitingQueue.isEmpty()) {
  62                                 listener.actionPerformed(waitingQueue.remove());
  63                         }
  64                 }
  65
  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          */
  85         protected synchronized void fireActionPerformed(String listenerCommand) {
  86                 ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, listenerCommand);
  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                                 }
  93                         }
  94                 } else {
  95                         waitingQueue.add(e);
  96                 }
  97         }
  98 }