RealMagneticDeclinationCalculator.java

// Copyright 2009 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.android.stardroid.control;

import com.google.android.stardroid.units.LatLong;

import android.hardware.GeomagneticField;

/**
 * Encapsulates the calculation of magnetic declination for the user's location
 * and position.
 *
 * @author John Taylor
 */
public class RealMagneticDeclinationCalculator implements MagneticDeclinationCalculator {
  private GeomagneticField geomagneticField;

  /**
   * {@inheritDoc}
   * Silently returns zero if the time and location have not been set.
   */
  @Override
  public float getDeclination() {
    if (geomagneticField == null) {
      return 0;
    }
    return geomagneticField.getDeclination();
  }

  /**
   * Sets the user's current location and time.
   */
  @Override
  public void setLocationAndTime(LatLong location, long timeInMillis) {
    geomagneticField = new GeomagneticField(location.getLatitude(),
            location.getLongitude(),
                                            0,
                                            timeInMillis);
  }

  @Override
  public String toString() {
    return "Real Magnetic Correction";
  }
}