/// <summary>
/// Calculates bearing between start and stop.
/// </summary>
/// <param name="start">Start coordinates.</param>
/// <param name="stop">Stop coordinates.</param>
/// <returns>The <see cref="System.Double" />.</returns>
public static double BearingFrom(this Position start, Position stop)
{
var deltaLon = stop.Longitude - start.Longitude;
var cosStop = Math.Cos(stop.Latitude);
return Math.Atan2(
(Math.Cos(start.Latitude) * Math.Sin(stop.Latitude)) -
(Math.Sin(start.Latitude) * cosStop * Math.Cos(deltaLon)),
Math.Sin(deltaLon) * cosStop);
}
/// <summary>
/// Initializes a new instance of the <see cref="Position" /> class.
/// </summary>
/// <param name="position">The position.</param>
/// <exception cref="System.ArgumentNullException">position</exception>
public Position(Position position)
{
if (position == null)
{
throw new ArgumentNullException("position");
}
Timestamp = position.Timestamp;
Latitude = position.Latitude;
Longitude = position.Longitude;
Altitude = position.Altitude;
AltitudeAccuracy = position.AltitudeAccuracy;
Accuracy = position.Accuracy;
Heading = position.Heading;
Speed = position.Speed;
}
/// <summary>
/// Calculates distance between two locations.
/// </summary>
/// <param name="a">Location a</param>
/// <param name="b">Location b</param>
/// <returns>The <see cref="System.Double" />The distance in meters</returns>
public static double DistanceFrom(this Position a, Position b)
{
/*
double distance = Math.Acos(
(Math.Sin(a.Latitude) * Math.Sin(b.Latitude)) +
(Math.Cos(a.Latitude) * Math.Cos(b.Latitude))
* Math.Cos(b.Longitude - a.Longitude));
* */
var dLat = b.Latitude.DegreesToRadians() - a.Latitude.DegreesToRadians();
var dLon = b.Longitude.DegreesToRadians() - a.Longitude.DegreesToRadians();
var a1 = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) + Math.Cos(a.Latitude.DegreesToRadians()) * Math.Cos(b.Latitude.DegreesToRadians()) * Math.Sin(dLon / 2) * Math.Sin(dLon / 2);
var distance = 2 * Math.Atan2(Math.Sqrt(a1), Math.Sqrt(1 - a1));
return EquatorRadius * distance;
}
/// <summary>
/// Handles the <see cref="E:ListenerPositionChanged" /> event.
/// </summary>
/// <param name="sender">The sender.</param>
/// <param name="e">The <see cref="PositionEventArgs" /> instance containing the event data.</param>
private void OnListenerPositionChanged(object sender, PositionEventArgs e)
{
if (!IsListening) // ignore anything that might come in afterwards
{
return;
}
lock (_positionSync)
{
_lastPosition = e.Position;
var changed = PositionChanged;
if (changed != null)
{
changed(this, e);
}
}
}
/// <summary>
/// Finishes the specified location.
/// </summary>
/// <param name="location">The location.</param>
private void Finish(Location location)
{
var p = new Position();
if (location.HasAccuracy)
{
p.Accuracy = location.Accuracy;
}
if (location.HasAltitude)
{
p.Altitude = location.Altitude;
}
if (location.HasBearing)
{
p.Heading = location.Bearing;
}
if (location.HasSpeed)
{
p.Speed = location.Speed;
}
p.Longitude = location.Longitude;
p.Latitude = location.Latitude;
p.Timestamp = Geolocator.GetTimestamp(location);
if (_finishedCallback != null)
{
_finishedCallback();
}
_completionSource.TrySetResult(p);
}
/// <summary>
/// Initializes a new instance of the <see cref="PositionEventArgs"/> class.
/// </summary>
/// <param name="position">The position.</param>
/// <exception cref="System.ArgumentNullException">position</exception>
public PositionEventArgs(Position position)
{
if (position == null)
{
throw new ArgumentNullException("position");
}
Position = position;
}
/// <summary>
/// Called when the location has changed.
/// </summary>
/// <param name="location">The new location, as a Location object.</param>
/// <since version="Added in API level 1" />
/// <remarks>
/// <para tool="javadoc-to-mdoc">
/// Called when the location has changed.
/// </para>
/// <para tool="javadoc-to-mdoc"> There are no restrictions on the use of the supplied Location object.</para>
/// <para tool="javadoc-to-mdoc">
/// <format type="text/html">
/// <a
/// href="http://developer.android.com/reference/android/location/LocationListener.html#onLocationChanged(android.location.Location)"
/// target="_blank">
/// [Android Documentation]
/// </a>
/// </format>
/// </para>
/// </remarks>
public void OnLocationChanged(Location location)
{
if (location.Provider != _activeProvider)
{
if (_activeProvider != null && _manager.IsProviderEnabled(_activeProvider))
{
var pr = _manager.GetProvider(location.Provider);
var lapsed = GetTimeSpan(location.Time) - GetTimeSpan(_lastLocation.Time);
if (pr.Accuracy > _manager.GetProvider(_activeProvider).Accuracy && lapsed < _timePeriod.Add(_timePeriod))
{
location.Dispose();
return;
}
}
_activeProvider = location.Provider;
}
var previous = Interlocked.Exchange(ref _lastLocation, location);
if (previous != null)
{
previous.Dispose();
}
var p = new Position();
if (location.HasAccuracy)
{
p.Accuracy = location.Accuracy;
}
if (location.HasAltitude)
{
p.Altitude = location.Altitude;
}
if (location.HasBearing)
{
p.Heading = location.Bearing;
}
if (location.HasSpeed)
{
p.Speed = location.Speed;
}
p.Longitude = location.Longitude;
p.Latitude = location.Latitude;
p.Timestamp = Geolocator.GetTimestamp(location);
var changed = PositionChanged;
if (changed != null)
{
changed(this, new PositionEventArgs(p));
}
}