edu.mit.media.funf.probe.builtin.SimpleLocationProbe.java Source code

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Here is the source code for edu.mit.media.funf.probe.builtin.SimpleLocationProbe.java

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/**
 * 
 * Funf: Open Sensing Framework
 * Copyright (C) 2010-2011 Nadav Aharony, Wei Pan, Alex Pentland.
 * Acknowledgments: Alan Gardner
 * Contact: nadav@media.mit.edu
 * 
 * This file is part of Funf.
 * 
 * Funf is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 * 
 * Funf 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with Funf. If not, see <http://www.gnu.org/licenses/>.
 * 
 */
package edu.mit.media.funf.probe.builtin;

import java.math.BigDecimal;

import android.util.Log;

import com.google.gson.JsonElement;
import com.google.gson.JsonObject;

import edu.mit.media.funf.Schedule;
import edu.mit.media.funf.config.Configurable;
import edu.mit.media.funf.json.IJsonObject;
import edu.mit.media.funf.probe.Probe.Base;
import edu.mit.media.funf.probe.Probe.DisplayName;
import edu.mit.media.funf.probe.Probe.PassiveProbe;
import edu.mit.media.funf.probe.Probe.RequiredFeatures;
import edu.mit.media.funf.probe.Probe.RequiredPermissions;
import edu.mit.media.funf.probe.Probe.RequiredProbes;
import edu.mit.media.funf.probe.builtin.ProbeKeys.LocationKeys;
import edu.mit.media.funf.time.TimeUtil;
import edu.mit.media.funf.util.LogUtil;

/**
 * Filters the verbose location set for the most accurate location within a max wait time,
 * ending early if it finds a location that has at most the goodEnoughAccuracy.
 * Useful for sparse polling of location to limit battery usage.
 * @author alangardner
 *
 */
@DisplayName("Simple Location Probe")
@RequiredPermissions({ android.Manifest.permission.ACCESS_COARSE_LOCATION,
        android.Manifest.permission.ACCESS_FINE_LOCATION })
@RequiredFeatures("android.hardware.location")
@Schedule.DefaultSchedule(interval = 1800)
@RequiredProbes(LocationProbe.class)
public class SimpleLocationProbe extends Base implements PassiveProbe, LocationKeys {

    @Configurable
    private BigDecimal maxWaitTime = BigDecimal.valueOf(120);

    @Configurable
    private BigDecimal maxAge = BigDecimal.valueOf(120);

    @Configurable
    private BigDecimal goodEnoughAccuracy = BigDecimal.valueOf(80);

    @Configurable
    private boolean useGps = true;

    @Configurable
    private boolean useNetwork = true;

    private LocationProbe locationProbe;

    private BigDecimal startTime;
    private IJsonObject bestLocation;

    private Runnable sendLocationRunnable = new Runnable() {
        @Override
        public void run() {
            sendCurrentBestLocation();
        }
    };

    private DataListener listener = new DataListener() {

        @Override
        public void onDataReceived(IJsonObject completeProbeUri, IJsonObject data) {
            Log.d(LogUtil.TAG, "SimpleLocationProbe received data: " + data.toString());
            if (startTime == null) {
                startTime = TimeUtil.getTimestamp();
                getHandler().postDelayed(sendLocationRunnable, TimeUtil.secondsToMillis(maxWaitTime));
            }
            if (isBetterThanCurrent(data)) {
                Log.d(LogUtil.TAG, "SimpleLocationProbe evaluated better location.");
                bestLocation = data;
            }
            if (goodEnoughAccuracy != null
                    && bestLocation.get(ACCURACY).getAsDouble() < goodEnoughAccuracy.doubleValue()) {
                Log.d(LogUtil.TAG, "SimpleLocationProbe evaluated good enough location.");
                if (getState() == State.RUNNING) { // Actively Running
                    stop();
                } else if (getState() == State.ENABLED) { // Passive listening
                    // TODO: do we want to prematurely end this, or wait for the full duration
                    // Things to consider: 
                    // - the device falling to sleep before we send
                    // - too much unrequested data if we send all values within accuracy limits 
                    // (this will restart immediately if more passive data continues to come in)
                    getHandler().removeCallbacks(sendLocationRunnable);
                    sendCurrentBestLocation();
                }
            }
        }

        @Override
        public void onDataCompleted(IJsonObject completeProbeUri, JsonElement checkpoint) {
        }
    };

    private void sendCurrentBestLocation() {
        Log.d(LogUtil.TAG, "SimpleLocationProbe sending current best location.");
        if (bestLocation != null) {
            JsonObject data = bestLocation.getAsJsonObject();
            data.remove(PROBE); // Remove probe so that it fills with our probe name
            sendData(data);
        }
        startTime = null;
        bestLocation = null;
    }

    private boolean isBetterThanCurrent(IJsonObject newLocation) {
        BigDecimal age = startTime.subtract(newLocation.get(TIMESTAMP).getAsBigDecimal());
        return bestLocation == null || (age.doubleValue() < maxAge.doubleValue()
                && bestLocation.get(ACCURACY).getAsDouble() > newLocation.get(ACCURACY).getAsDouble());
    }

    @Override
    protected void onEnable() {
        super.onEnable();
        JsonObject config = new JsonObject();
        if (!useGps) {
            config.addProperty("useGps", false);
        }
        if (!useNetwork) {
            config.addProperty("useNetwork", false);
        }
        locationProbe = getGson().fromJson(config, LocationProbe.class);
        locationProbe.registerPassiveListener(listener);
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.d(LogUtil.TAG, "SimpleLocationProbe starting, registering listener");
        startTime = TimeUtil.getTimestamp();
        locationProbe.registerListener(listener);
        getHandler().sendMessageDelayed(getHandler().obtainMessage(STOP_MESSAGE),
                TimeUtil.secondsToMillis(maxWaitTime));
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.d(LogUtil.TAG, "SimpleLocationProbe stopping");
        getHandler().removeMessages(STOP_MESSAGE);
        locationProbe.unregisterListener(listener);
        sendCurrentBestLocation();
    }

    @Override
    protected void onDisable() {
        super.onDisable();
        locationProbe.unregisterPassiveListener(listener);
    }

}