uk.ac.horizon.ubihelper.service.channel.SensorChannel.java Source code

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Here is the source code for uk.ac.horizon.ubihelper.service.channel.SensorChannel.java

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/**
 * Copyright (c) 2012 The University of Nottingham
 * 
 * This file is part of ubihelper
 *
 *  ubihelper is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  ubihelper 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with ubihelper. If not, see <http://www.gnu.org/licenses/>.
 *  
 *  @author Chris Greenhalgh (cmg@cs.nott.ac.uk), The University of Nottingham
 */
package uk.ac.horizon.ubihelper.service.channel;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import uk.ac.horizon.ubihelper.channel.NamedChannel;
import uk.ac.horizon.ubihelper.service.Service;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.util.Log;

/**
 * @author cmg
 *
 */
public class SensorChannel extends NamedChannel implements SensorEventListener {

    private static final String TAG = "ubihelper-sensor";
    private SensorManager mSensorManager;
    private Sensor mSensor;
    private long lastValueTime;
    private long minInterval;

    public SensorChannel(String name, Service service, Sensor sensor) {
        super(name);
        mSensorManager = (SensorManager) service.getSystemService(Context.SENSOR_SERVICE);
        mSensor = sensor;
    }

    public SensorChannel(String name, Service service, int sensorType) {
        super(name);
        mSensorManager = (SensorManager) service.getSystemService(Context.SENSOR_SERVICE);
        if (mSensorManager != null) {
            mSensor = mSensorManager.getDefaultSensor(sensorType);
            if (mSensor == null)
                Log.w(TAG, "No sensor found for " + name + " (type " + sensorType + ")");
        }
    }

    @Override
    protected void handleStart() {
        minInterval = (long) (1000 * period);
        lastValueTime = 0;
        if (mSensor != null) {
            mSensorManager.registerListener(this, mSensor, (int) (1000000 * period));
            Log.d(TAG, "Start sensor " + name);
        }
    }

    /* (non-Javadoc)
     * @see uk.ac.horizon.ubihelper.channel.NamedChannel#handleStop()
     */
    @Override
    protected void handleStop() {
        if (mSensor != null) {
            Log.d(TAG, "Stop sensor " + name);
            mSensorManager.unregisterListener(this);
        }
    }

    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // ? 
    }

    public void onSensorChanged(SensorEvent event) {
        long now = System.currentTimeMillis();
        long elapsed = now - lastValueTime;
        if (elapsed < minInterval) {
            Log.d(TAG, "Discard sensor value " + name + ", elapsed " + elapsed + "/" + minInterval);
            return;
        }
        lastValueTime = now;
        JSONObject value = new JSONObject();
        try {
            // event time is in nanoseconds
            value.put("timestamp", event.timestamp / 1000000);
            JSONArray values = new JSONArray();
            for (int i = 0; i < event.values.length; i++)
                values.put(event.values[i]);
            value.put("values", values);
            value.put("accuracy", event.accuracy);
            Log.d(TAG, "onSensorChanged(" + name + "): " + value);
        } catch (JSONException e) {
            /* ignore */
        }
        onNewValue(value);
    }
}