libreoffice/odk/examples/DevelopersGuide/Accessibility/RegistrationThread.java

/*************************************************************************
 *
 *  The Contents of this file are made available subject to the terms of
 *  the BSD license.
 *
 *  Copyright 2000, 2010 Oracle and/or its affiliates.
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of Sun Microsystems, Inc. nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 *  COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 *  OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 *  TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 *  USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *************************************************************************/

import com.sun.star.uno.UnoRuntime;
import com.sun.star.accessibility.*;

/** This class is used as a thread and registers or unregsiters a listener
    given the constructor at all nodes of a tree of accessibility objects.
*/
public class RegistrationThread
    implements Runnable
{
    /** Start a new thread that adds or removes the given listener at all
        accessible objects in the sub-tree rooted in the given accessible
        object.
        @param aListener
            The listener that is added or removed.
        @param xRoot
            The root of the sub-tree of accessibility objects.
        @param bRegister
            This flag decides whether to add or remove the listener.
    */
    public RegistrationThread (
        EventListenerProxy aListener,
        XAccessibleContext xRoot,
        boolean bRegister,
        boolean bShowMessages)
    {
        maListener = aListener;
        mxRoot = xRoot;
        mbRegister = bRegister;
        mbShowMessages = bShowMessages;

        if (mxRoot != null)
        {
            if (mbShowMessages)
                MessageArea.println ("starting to register at " + mxRoot.getAccessibleName());
            new Thread (this, "RegistrationThread").start();
        }
    }



    public void run ()
    {
        System.out.println ("starting registration");
        long nNodeCount = traverseTree (mxRoot);
        System.out.println ("ending registration");
        if (mbShowMessages)
        {
            if ( ! mbRegister)
                MessageArea.print ("un");
            MessageArea.println ("registered at " + nNodeCount
                + " objects in accessibility tree of " + mxRoot.getAccessibleName());
        }
    }




    /** Register this object as listener for accessibility events at all nodes
        of the given tree.
        @param xRoot
            The root node of the tree at which to register.
    */
    public long traverseTree (XAccessibleContext xRoot)
    {
        long nNodeCount = 0;
        if (xRoot != null)
        {
            // Register the root node.
            XAccessibleEventBroadcaster xBroadcaster =
                (XAccessibleEventBroadcaster) UnoRuntime.queryInterface (
                    XAccessibleEventBroadcaster.class,
                    xRoot);
            if (xBroadcaster != null)
            {
                if (mbRegister)
                    xBroadcaster.addAccessibleEventListener (maListener);
                else
                    xBroadcaster.removeAccessibleEventListener (maListener);
                nNodeCount += 1;
            }

            // Call this method recursively to register all sub-trees.
            try
            {
                int nChildCount = xRoot.getAccessibleChildCount();
                for (int i=0; i<nChildCount; i++)
                {
                    XAccessible xChild = xRoot.getAccessibleChild (i);
                    if (xChild != null)
                        nNodeCount += traverseTree (xChild.getAccessibleContext());
                }
            }
            catch (com.sun.star.lang.IndexOutOfBoundsException aException)
            {
                // The set of children has changed since our last call to
                // getAccesibleChildCount().  Don't try any further on this
                // sub-tree.
            }
            catch (com.sun.star.lang.DisposedException aException)
            {
                // The child has been destroyed since our last call to
                // getAccesibleChildCount().  That is OK. Don't try any
                // further on this sub-tree.
            }
        }
        return nNodeCount;
    }

    private EventListenerProxy maListener;
    private XAccessibleContext mxRoot;
    private boolean mbRegister;
    private boolean mbShowMessages;
}