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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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package sun.java2d.pipe.hw;

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.lang.annotation.Native;


This class is used to notify listeners about accelerated device's
events such as device reset or dispose that are about to occur.
/**
 * This class is used to notify listeners about accelerated device's
 * events such as device reset or dispose that are about to occur.
 */
public class AccelDeviceEventNotifier {

    private static AccelDeviceEventNotifier theInstance;

    
A device is about to be reset. The listeners have to release all
resources associated with the device which are required for the device
to be reset.
/**
     * A device is about to be reset. The listeners have to release all
     * resources associated with the device which are required for the device
     * to be reset.
     */
    @Native public static final int DEVICE_RESET = 0;

    
A device is about to be disposed. The listeners have to release all
resources associated with the device.
/**
     * A device is about to be disposed. The listeners have to release all
     * resources associated with the device.
     */
    @Native public static final int DEVICE_DISPOSED = 1;

    private final Map<AccelDeviceEventListener, Integer> listeners;

    private AccelDeviceEventNotifier() {
        listeners = Collections.synchronizedMap(
            new HashMap<AccelDeviceEventListener, Integer>(1));
    }

    
Returns a singleton of AccelDeviceEventNotifier if it exists. If the passed boolean is false and singleton doesn't exist yet, null is returned. If the passed boolean is true and singleton doesn't exist it will be created and returned. 
Params:
create – whether to create a singleton instance if doesn't yet
exist
Returns:
a singleton instance or null/**
     * Returns a singleton of AccelDeviceEventNotifier if it exists. If the
     * passed boolean is false and singleton doesn't exist yet, null is
     * returned. If the passed boolean is {@code true} and singleton doesn't
     * exist it will be created and returned.
     *
     * @param create whether to create a singleton instance if doesn't yet
     * exist
     * @return a singleton instance or null
     */
    private static synchronized
        AccelDeviceEventNotifier getInstance(boolean create)
    {
        if (theInstance == null && create) {
            theInstance = new AccelDeviceEventNotifier();
        }
        return theInstance;
    }

    
Called to indicate that a device event had occurred.
If a singleton exists, the listeners (those associated with
the device) will be notified.
Params:
screen – a screen number of the device which is a source of
the event
eventType – a type of the event
See Also:
DEVICE_DISPOSED
DEVICE_RESET/**
     * Called to indicate that a device event had occurred.
     * If a singleton exists, the listeners (those associated with
     * the device) will be notified.
     *
     * @param screen a screen number of the device which is a source of
     * the event
     * @param eventType a type of the event
     * @see #DEVICE_DISPOSED
     * @see #DEVICE_RESET
     */
    public static final void eventOccured(int screen, int eventType) {
        AccelDeviceEventNotifier notifier = getInstance(false);
        if (notifier != null) {
            notifier.notifyListeners(eventType, screen);
        }
    }

    
Adds the listener associated with a device on particular screen.
Note: the listener must be removed as otherwise it will forever
be referenced by the notifier.
Params:
l – the listener
screen – the screen number indicating which device the listener is
interested in./**
     * Adds the listener associated with a device on particular screen.
     *
     * Note: the listener must be removed as otherwise it will forever
     * be referenced by the notifier.
     *
     * @param l the listener
     * @param screen the screen number indicating which device the listener is
     * interested in.
     */
    public static final void addListener(AccelDeviceEventListener l,int screen){
        getInstance(true).add(l, screen);
    }

    
Removes the listener.
Params:
l – the listener/**
     * Removes the listener.
     *
     * @param l the listener
     */
    public static final void removeListener(AccelDeviceEventListener l) {
        getInstance(true).remove(l);
    }

    private final void add(AccelDeviceEventListener theListener, int screen) {
        listeners.put(theListener, screen);
    }
    private final void remove(AccelDeviceEventListener theListener) {
        listeners.remove(theListener);
    }

    
Notifies the listeners associated with the screen's device about the
event.
Implementation note: the current list of listeners is first duplicated
which allows the listeners to remove themselves during the iteration.
Params:
screen – a screen number with which the device which is a source of
the event is associated with
eventType – a type of the event
See Also:
DEVICE_DISPOSED
DEVICE_RESET/**
     * Notifies the listeners associated with the screen's device about the
     * event.
     *
     * Implementation note: the current list of listeners is first duplicated
     * which allows the listeners to remove themselves during the iteration.
     *
     * @param screen a screen number with which the device which is a source of
     * the event is associated with
     * @param eventType a type of the event
     * @see #DEVICE_DISPOSED
     * @see #DEVICE_RESET
     */
    private final void notifyListeners(int deviceEventType, int screen) {
        HashMap<AccelDeviceEventListener, Integer> listClone;
        Set<AccelDeviceEventListener> cloneSet;

        synchronized(listeners) {
            listClone =
                new HashMap<AccelDeviceEventListener, Integer>(listeners);
        }

        cloneSet = listClone.keySet();
        Iterator<AccelDeviceEventListener> itr = cloneSet.iterator();
        while (itr.hasNext()) {
            AccelDeviceEventListener current = itr.next();
            Integer i = listClone.get(current);
            // only notify listeners which are interested in this device
            if (i != null && i.intValue() != screen) {
                continue;
            }
            if (deviceEventType == DEVICE_RESET) {
                current.onDeviceReset();
            } else if (deviceEventType == DEVICE_DISPOSED) {
                current.onDeviceDispose();
            }
        }
    }
}