X-Git-Url: http://git.nikiroo.be/?a=blobdiff_plain;f=src%2Fbe%2Fnikiroo%2Futils%2Fui%2FListenerPanel.java;fp=src%2Fbe%2Fnikiroo%2Futils%2Fui%2FListenerPanel.java;h=144cdd249a81be951a082618f2a9f4371adaf0a9;hb=60ee255638ef6e151a18ee1a93dd9a6c0e9ee1a7;hp=0000000000000000000000000000000000000000;hpb=727b9fb39d3386f14f66a33de80de04f1f58734c;p=nikiroo-utils.git

diff --git a/src/be/nikiroo/utils/ui/ListenerPanel.java b/src/be/nikiroo/utils/ui/ListenerPanel.java
new file mode 100644
index 0000000..144cdd2
--- /dev/null
+++ b/src/be/nikiroo/utils/ui/ListenerPanel.java
@@ -0,0 +1,101 @@
+package be.nikiroo.utils.ui;
+
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.util.LinkedList;
+import java.util.Queue;
+
+import javax.swing.JPanel;
+
+/**
+ * A {@link JPanel} with the default {@link ActionListener} add/remove/fire
+ * methods.
+ * <p>
+ * Note that it will queue all events until at least one listener comes (or
+ * comes back!); this first (or at least currently unique) listener will drain
+ * the queue.
+ * 
+ * @author niki
+ */
+public class ListenerPanel extends JPanel {
+	private static final long serialVersionUID = 1L;
+
+	/** Waiting queue until at least one listener is here to get the events. */
+	private final Queue<ActionEvent> waitingQueue;
+
+	/**
+	 * Create a new {@link ListenerPanel}.
+	 */
+	public ListenerPanel() {
+		waitingQueue = new LinkedList<ActionEvent>();
+	}
+
+	/**
+	 * Check that this {@link ListenerPanel} currently has
+	 * {@link ActionListener}s that listen on it.
+	 * 
+	 * @return TRUE if it has
+	 */
+	public synchronized boolean hasListeners() {
+		return listenerList.getListenerList().length > 1;
+	}
+
+	/**
+	 * Check how many events are currently waiting for an
+	 * {@link ActionListener}.
+	 * 
+	 * @return the number of waiting events (can be 0)
+	 */
+	public synchronized int getWaitingEventCount() {
+		return waitingQueue.size();
+	}
+
+	/**
+	 * Adds the specified action listener to receive action events from this
+	 * {@link ListenerPanel}.
+	 *
+	 * @param listener
+	 *            the action listener to be added
+	 */
+	public synchronized void addActionListener(ActionListener listener) {
+		if (!hasListeners()) {
+			while (!waitingQueue.isEmpty()) {
+				listener.actionPerformed(waitingQueue.remove());
+			}
+		}
+
+		listenerList.add(ActionListener.class, listener);
+	}
+
+	/**
+	 * Removes the specified action listener so that it no longer receives
+	 * action events from this {@link ListenerPanel}.
+	 *
+	 * @param listener
+	 *            the action listener to be removed
+	 */
+	public synchronized void removeActionListener(ActionListener listener) {
+		listenerList.remove(ActionListener.class, listener);
+	}
+
+	/**
+	 * Notify the listeners of an action.
+	 * 
+	 * @param listenerCommand
+	 *            A string that may specify a command (possibly one of several)
+	 *            associated with the event
+	 */
+	protected synchronized void fireActionPerformed(String listenerCommand) {
+		ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED,
+				listenerCommand);
+
+		ActionListener[] listeners = getListeners(ActionListener.class);
+		if (listeners.length > 0) {
+			for (ActionListener action : listeners) {
+				action.actionPerformed(e);
+			}
+		} else {
+			waitingQueue.add(e);
+		}
+	}
+}