| 1 | package be.nikiroo.utils.ui; |
| 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 | /** |
| 11 | * A {@link JPanel} with the default {@link ActionListener} add/remove/fire |
| 12 | * methods. |
| 13 | * <p> |
| 14 | * Note that it will queue all events until at least one listener comes (or |
| 15 | * comes back!); this first (or at least currently unique) listener will drain |
| 16 | * the queue. |
| 17 | * |
| 18 | * @author niki |
| 19 | */ |
| 20 | public class ListenerPanel extends JPanel implements ListenerItem { |
| 21 | private static final long serialVersionUID = 1L; |
| 22 | |
| 23 | /** Waiting queue until at least one listener is here to get the events. */ |
| 24 | private final Queue<ActionEvent> waitingQueue; |
| 25 | |
| 26 | /** |
| 27 | * Create a new {@link ListenerPanel}. |
| 28 | */ |
| 29 | public ListenerPanel() { |
| 30 | waitingQueue = new LinkedList<ActionEvent>(); |
| 31 | } |
| 32 | |
| 33 | @Override |
| 34 | public synchronized boolean hasListeners() { |
| 35 | return listenerList.getListenerList().length > 1; |
| 36 | } |
| 37 | |
| 38 | @Override |
| 39 | public synchronized int getWaitingEventCount() { |
| 40 | return waitingQueue.size(); |
| 41 | } |
| 42 | |
| 43 | @Override |
| 44 | public synchronized void addActionListener(ActionListener listener) { |
| 45 | if (!hasListeners()) { |
| 46 | while (!waitingQueue.isEmpty()) { |
| 47 | listener.actionPerformed(waitingQueue.remove()); |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | listenerList.add(ActionListener.class, listener); |
| 52 | } |
| 53 | |
| 54 | @Override |
| 55 | public synchronized void removeActionListener(ActionListener listener) { |
| 56 | listenerList.remove(ActionListener.class, listener); |
| 57 | } |
| 58 | |
| 59 | @Override |
| 60 | public synchronized void fireActionPerformed(String listenerCommand) { |
| 61 | ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, |
| 62 | listenerCommand); |
| 63 | |
| 64 | ActionListener[] listeners = getListeners(ActionListener.class); |
| 65 | if (listeners.length > 0) { |
| 66 | for (ActionListener action : listeners) { |
| 67 | action.actionPerformed(e); |
| 68 | } |
| 69 | } else { |
| 70 | waitingQueue.add(e); |
| 71 | } |
| 72 | } |
| 73 | } |