foregroundeventlistener.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 127 行

/*
 *  
 *
 * Copyright  1990-2007 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, as published by the Free Software Foundation.
 * 
 * This program 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 at /legal/license.txt).
 * 
 * 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
 * 
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions.
 */

package com.sun.midp.lcdui;

import com.sun.midp.configurator.Constants;

import com.sun.midp.events.Event;
import com.sun.midp.events.EventTypes;
import com.sun.midp.events.EventQueue;
import com.sun.midp.events.EventListener;
import com.sun.midp.events.NativeEvent;

import com.sun.midp.log.Logging;
import com.sun.midp.log.LogChannels;

/**
 * Listener for LCDUI events (user inputs, etc).
 */
public class ForegroundEventListener implements EventListener {

    /** Active displays. */
    private DisplayContainer displayContainer;
    
    /** Cached reference to the MIDP event queue. */
    private EventQueue eventQueue;

    /**
     * The constructor for the foreground event handler for LCDUI.
     *
     * @param theEventQueue the event queue
     * @param theDisplayContainer container for display objects
     */
    public ForegroundEventListener(
        EventQueue theEventQueue, 
        DisplayContainer theDisplayContainer) {
            
        eventQueue = theEventQueue;
        displayContainer = theDisplayContainer;

        /*
         * All events handled by this object are of NativeEventClass
         * and are instance specific events assosiated with some display Id.
         * So this listener is able to find an appropriate DisplayEventConsumer
         * associated with the displayId field of NativeEvent and 
         * to call methods of found consumer.
         */
        eventQueue.registerEventListener(EventTypes.FOREGROUND_NOTIFY_EVENT, 
					 this);
        eventQueue.registerEventListener(EventTypes.BACKGROUND_NOTIFY_EVENT, 
					 this);
    }

    /**
     * Preprocess an event that is being posted to the event queue.
     * 
     * @param event event being posted
     *
     * @param waitingEvent previous event of this type waiting in the
     *     queue to be processed
     * 
     * @return true to allow the post to continue, false to not post the
     *     event to the queue
     */
    public boolean preprocess(Event event, Event waitingEvent) {
        return true;
    }

    /**
     * Process an event.
     *
     * @param event event to process
     */
    public void process(Event event) {
        NativeEvent nativeEvent = (NativeEvent)event;

        /*
         * Find ForegroundEventConsumer instance by nativeEvent.intParam4
         * and (if not null) call ForegroundEventConsumer methods ...
         */
        ForegroundEventConsumer fc =
            displayContainer.findForegroundEventConsumer(
                nativeEvent.intParam4);

        if (fc != null) {
            switch (event.getType()) {
            case EventTypes.FOREGROUND_NOTIFY_EVENT:
                fc.handleDisplayForegroundNotifyEvent();
                return;

            case EventTypes.BACKGROUND_NOTIFY_EVENT:
                fc.handleDisplayBackgroundNotifyEvent();
                return;
            default:
                if (Logging.REPORT_LEVEL <= Logging.WARNING) {
                    Logging.report(Logging.WARNING, LogChannels.LC_CORE,
                                   "unknown system event (" +
                                   event.getType() + ")");
                }
            }
        }
    }
}