001 /*
002 * LAPIS lightweight structured text processing system
003 *
004 * Copyright (C) 1998-2002 Carnegie Mellon University,
005 * Copyright (C) 2003 Massachusetts Institute of Technology.
006 * All rights reserved.
007 *
008 * This library is free software; you can redistribute it
009 * and/or modify it under the terms of the GNU General
010 * Public License as published by the Free Software
011 * Foundation, version 2.
012 *
013 * LAPIS homepage: http://graphics.lcs.mit.edu/lapis/
014 */
015
016 package lapisx.swing;
017
018 import java.awt.*;
019 import java.awt.event.*;
020 import javax.swing.*;
021
022 /**
023 * A popup menu that appears only after the mouse is held down for
024 * a certain period of time.
025 */
026 public class DelayedPopupMenu {
027 Component frame;
028 Component trigger;
029 Timer timer;
030 JPopupMenu menu;
031
032
033 /**
034 * Make a delayed popup menu.
035 * @param frame Component in which the popup menu will appear (see
036 * {@link javax.swing.JPopupMenu#show}. This is often a JFrame.
037 * @param trigger Component which should trigger the menu.
038 * @param delay Delay before showing menu, in milliseconds.
039 * @effects Creates a DelayedPopupMenu and attaches a mouse listener
040 * to <i>trigger</i> so that when the mouse is pressed down <i>trigger</i>
041 * and held for more than <i>delay</i> msec, the menu appears.
042 */
043 public DelayedPopupMenu (Component frame, Component trigger, int delay) {
044 this.frame = frame;
045 this.trigger = trigger;
046
047 trigger.addMouseListener (new MouseAdapter () {
048 public void mousePressed (MouseEvent event) {
049 timer.restart ();
050 }
051 public void mouseReleased (MouseEvent event) {
052 timer.stop ();
053
054 if (menu != null
055 && menu.isVisible ()
056 && !menu.contains
057 (SwingUtilities.convertPoint ((Component) event.getSource (),
058 event.getPoint (),
059 menu)))
060 menu.setVisible (false);
061 }
062 });
063
064 timer = new Timer (delay, new ActionListener () {
065 public void actionPerformed (ActionEvent event) {
066 menu = makeMenu ();
067 showMenu (menu);
068 }
069 });
070 timer.setRepeats (false);
071 }
072
073 /**
074 * Test whether menu is popped up.
075 * @return true iff menu is showing
076 */
077 public boolean isVisible () {
078 return menu != null && menu.isVisible ();
079 }
080
081 /**
082 * Callback that constructs the menu just before showing it.
083 * Default implementation just creates an empty JPopupMenu.
084 * A subclass should override this to populate the menu.
085 * @return menu, or null to prevent popping up the menu
086 */
087 protected JPopupMenu makeMenu () {
088 return new JPopupMenu ();
089 }
090
091 /**
092 * Callback that shows the menu.
093 * Default implementation positions the menu just below the trigger
094 * that triggered it in the frame passed to the constructor.
095 * A subclass can override this for different placement.
096 * @param menu Menu about to be shown
097 */
098 protected void showMenu (JPopupMenu menu) {
099 Point triggerLocation =
100 SwingUtilities.convertPoint (trigger.getParent (),
101 trigger.getLocation (),
102 frame);
103 Dimension triggerSize = trigger.getSize ();
104
105 int x = triggerLocation.x;
106 int y = triggerLocation.y + triggerSize.height;
107
108 menu.show (frame, x, y);
109 }
110
111 /**
112 * Get the component that triggers this menu.
113 * @return trigger component
114 */
115 public Component getTrigger () {
116 return trigger;
117 }
118
119 /**
120 * Get the frame in which this menu will popup.
121 * @return frame component
122 */
123 public Component getFrame () {
124 return frame;
125 }
126 }