public Task<Position> GetPositionAsync(int timeout, CancellationToken cancelToken, bool includeHeading)
{
if (timeout <= 0 && timeout != Timeout.Infinite)
throw new ArgumentOutOfRangeException("timeout", "Timeout must be positive or Timeout.Infinite");
TaskCompletionSource<Position> tcs;
if (!IsListening)
{
var m = GetManager();
tcs = new TaskCompletionSource<Position>(m);
var singleListener = new GeolocationSingleUpdateDelegate(m, DesiredAccuracy, includeHeading, timeout, cancelToken);
m.Delegate = singleListener;
m.StartUpdatingLocation();
if (includeHeading && SupportsHeading)
m.StartUpdatingHeading();
return singleListener.Task;
}
else
{
tcs = new TaskCompletionSource<Position>();
if (this.position == null)
{
EventHandler<PositionErrorEventArgs> gotError = null;
gotError = (s, e) =>
{
tcs.TrySetException(new GeolocationException(e.Error));
PositionError -= gotError;
};
PositionError += gotError;
EventHandler<PositionEventArgs> gotPosition = null;
gotPosition = (s, e) =>
{
tcs.TrySetResult(e.Position);
PositionChanged -= gotPosition;
};
PositionChanged += gotPosition;
}
else
tcs.SetResult(this.position);
}
return tcs.Task;
}