MotionSubject.java

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 *    - Redistributions of source code must retain the above copyright notice,
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package com.buglabs.bug.module.motion;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Timer;
import java.util.TimerTask;

import org.osgi.service.log.LogService;

import com.buglabs.bug.dragonfly.module.IModuleLEDController;
import com.buglabs.bug.jni.motion.Motion;
import com.buglabs.bug.module.motion.pub.IMotionObserver;
import com.buglabs.bug.module.motion.pub.IMotionSubject;

/**
 * 
 * @author kgilmer
 *
 */
public class MotionSubject extends Thread implements IMotionSubject {

	/**
	 * Default value for sleep interval between motion detector reads.
	 */
	private static final int DEFAULT_SLEEP_INTERVAL = 500;
	/**
	 * System property to define sleep between motion detector reads.
	 */
	public static final String SLEEP_INTERVAL_PROPERTY_KEY = "bug.motion.sleep_interval";
	InputStream motionIs;
	ArrayList observers;
	private final IModuleLEDController ledController;
	private final Timer timer = new Timer();
	private final LogService log;
	private volatile boolean flashing;
	private final int sleepInterval;

	MotionSubject(InputStream gpsIs, IModuleLEDController ledController, LogService log) {
		this.motionIs = gpsIs;
		this.ledController = ledController;
		this.log = log;
		observers = new ArrayList();
		sleepInterval = getSleepInterval();
	}

	private int getSleepInterval() {
		String is = System.getProperty(SLEEP_INTERVAL_PROPERTY_KEY);
		if (is != null) {
			return Integer.parseInt(is);
		}
		
		return DEFAULT_SLEEP_INTERVAL;
	}

	public void run() {
		byte read = 0;
		byte expected = Motion.BMI_MOTION_DETECT_ENABLED | Motion.BMI_MOTION_DETECT_DELTA | Motion.BMI_MOTION_DETECT_LATCHED_STATUS | Motion.BMI_MOTION_DETECT_STATUS;
		try {
			while (motionIs != null && !isInterrupted() && (read = (byte) motionIs.read()) != -1) {
				if (read == expected) {
					notifyObservers();
					flashLed();
				}
				Thread.sleep(sleepInterval);
			}
		} catch (IOException e) {
			log.log(LogService.LOG_ERROR, "An IOException occured while reading from Motion module.", e);
		} catch (InterruptedException e) {
			// Shutdown
		} finally {
			if (motionIs != null) {
				try {
					motionIs.close();
				} catch (IOException e) {
					// Ignore exception
				}
			}
		}
	}

	private void flashLed() {
		if (!flashing) {
			try {
				flashing = true;
				ledController.setLEDGreen(true);
				TimerTask tt = new TimerTask() {

					public void run() {
						try {
							ledController.setLEDGreen(false);
							flashing = false;
						} catch (IOException e) {
						}
					}

				};
				timer.schedule(tt, 400);

			} catch (IOException e) {
				//Ignore exception
			}
		}
	}

	public void notifyObservers() {
		synchronized (observers) {
			Iterator iter = observers.iterator();
			while (iter.hasNext()) {
				IMotionObserver obs = (IMotionObserver) iter.next();
				obs.motionDetected();
			}
		}
	}

	public void register(IMotionObserver obs) {
		synchronized (observers) {
			observers.add(obs);
		}
	}

	public void unregister(IMotionObserver obs) {
		synchronized (observers) {
			observers.remove(obs);
		}
	}
}