1 /************************************************************************* 2 * 3 * The Contents of this file are made available subject to the terms of 4 * the BSD license. 5 * 6 * Copyright 2000, 2010 Oracle and/or its affiliates. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of Sun Microsystems, Inc. nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 28 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 29 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR 30 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE 31 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 * 33 *************************************************************************/ 34 35 import com.sun.star.accessibility.XAccessible; 36 import com.sun.star.accessibility.XAccessibleEventListener; 37 import com.sun.star.accessibility.AccessibleEventObject; 38 import com.sun.star.lang.EventObject; 39 import com.sun.star.awt.XTopWindowListener; 40 import com.sun.star.uno.UnoRuntime; 41 42 import java.util.LinkedList; 43 44 /** This class acts as a proxy for the simple screen reader. It waits for 45 two types of events: 46 1. Accessibility events signal modifications concerning accessibility 47 objects. 48 2. Top window events inform the listener about new or removed windows. 49 50 This class exists because events had to be handled in a seperate thread 51 to avoid dead locks: The thread that receives an event must no call back 52 to the Office directly. 53 54 Soon this should not be necessary anymore. There is now a flag which 55 switches between synchronous and asynchronous callbacks. 56 57 All reveived events are eventually forwarded to the actual listener. In 58 this way it decouples the Office from the listener. 59 */ 60 class EventListenerProxy 61 implements Runnable, XAccessibleEventListener, XTopWindowListener 62 { 63 public EventListenerProxy (EventHandler aListener) 64 { 65 maListener = aListener; 66 mbAsynchron = true; 67 if (mbAsynchron) 68 { 69 maEventQueue = new LinkedList(); 70 new Thread (this, "EventListenerProxy").start(); 71 } 72 } 73 74 private void addEvent (Runnable aEventObject) 75 { 76 if (mbAsynchron) 77 synchronized (maEventQueue) 78 { 79 maEventQueue.addLast (aEventObject); 80 // Tell the queue that there is a new event in the queue. 81 maEventQueue.notify(); 82 } 83 else 84 { 85 System.out.println ("running " + aEventObject); 86 aEventObject.run(); 87 System.out.println (" done"); 88 } 89 } 90 91 92 93 94 /** In an infinite loop, check for events to deliver, then wait on lock 95 (which will be notified when new events arrive) 96 */ 97 public void run () 98 { 99 while (true) 100 { 101 // Process all events that are currently in the queue. 102 Runnable aEvent; 103 do 104 { 105 synchronized (maEventQueue) 106 { 107 if (maEventQueue.size() > 0) 108 aEvent = (Runnable)maEventQueue.removeFirst(); 109 else 110 aEvent = null; 111 } 112 113 if (aEvent != null) 114 { 115 try 116 { 117 aEvent.run(); 118 } 119 catch (Throwable aException) 120 { 121 MessageArea.println( 122 "Exception during event delivery: " + aException); 123 aException.printStackTrace(); 124 } 125 } 126 } 127 while (aEvent != null); 128 129 // Now that the queue is empty go to sleep again. 130 try 131 { 132 synchronized (maEventQueue) 133 { 134 maEventQueue.wait(); 135 } 136 } 137 catch (Exception aException) 138 { 139 // Ignore this exception since there is not much 140 // that we can do about it. 141 } 142 } 143 } 144 145 146 public void disposing( final EventObject aEvent) 147 { 148 addEvent (new Runnable() 149 { 150 public void run() 151 { 152 maListener.disposing (aEvent); 153 } 154 } ); 155 } 156 157 public void notifyEvent (final AccessibleEventObject aEvent) 158 { 159 addEvent ( 160 new Runnable() 161 { 162 public void run() 163 { 164 maListener.notifyEvent (aEvent); 165 } 166 } ); 167 } 168 169 public void windowOpened (final com.sun.star.lang.EventObject aEvent) 170 { 171 addEvent ( 172 new Runnable() 173 { 174 public void run() 175 { 176 maListener.windowOpened ( 177 (XAccessible) UnoRuntime.queryInterface( 178 XAccessible.class, 179 aEvent.Source)); 180 } 181 } ); 182 } 183 public void windowClosing (final com.sun.star.lang.EventObject aEvent) 184 { 185 // Ignored. 186 } 187 public void windowClosed (final com.sun.star.lang.EventObject aEvent) 188 { 189 addEvent ( 190 new Runnable() 191 { 192 public void run() 193 { 194 maListener.windowClosed ( 195 (XAccessible) UnoRuntime.queryInterface( 196 XAccessible.class, 197 aEvent.Source)); 198 } 199 } ); 200 } 201 public void windowMinimized (com.sun.star.lang.EventObject aEvent) 202 { 203 // Ignored. 204 } 205 public void windowNormalized (com.sun.star.lang.EventObject aEvent) 206 { 207 // Ignored. 208 } 209 public void windowActivated (com.sun.star.lang.EventObject aEvent) 210 { 211 // Ignored. 212 } 213 public void windowDeactivated (com.sun.star.lang.EventObject aEvent) 214 { 215 // Ignored. 216 } 217 218 /** The queue of event objects, LinkedList<Runnable>. 219 The queue object will also serve as lock for the consumer/producer type 220 syncronization. 221 */ 222 private LinkedList maEventQueue; 223 224 /** This is the actual listener that the events will eventually forwarded to. 225 */ 226 private EventHandler maListener; 227 228 /** This flag determines whether event forwarding is done asynchroniously 229 or synchroniously. 230 */ 231 private boolean mbAsynchron; 232 } 233