public async Task <bool> SubscribeToTargetPositionEventsAsync(ITargetPositionObserver observer,
TargetPositionObserverOptions options)
{
// TODO: Add thread safety
if (TargetPositionObservers.ContainsKey(observer))
{
TargetPositionObservers[observer] = options;
return(true);
}
Task <bool>[] tasks = { StartGeolocatorAsync(), StartCompassAsync() };
bool[] results = await Task.WhenAll(tasks);
if (!results.All(x => x))
{
#pragma warning disable 4014
StopCompassIfUnusedAsync();
StopGeolocatorIfUnusedAsync();
#pragma warning restore 4014
return(false);
}
TargetPositionObservers.Add(observer, options);
return(true);
}
protected void NotifyTargetPositionObserver(ITargetPositionObserver observer, TargetPositionObserverOptions options)
{
IPosition targetPosition = options.TargetPosition;
double distance = Location.CalculateDistance(new Location(CurrentPosition.Latitude, CurrentPosition.Longitude),
new Location(targetPosition.Latitude, targetPosition.Longitude), DistanceUnits.Kilometers);
double direction = (CurrentPosition.GetBearing(targetPosition) - CurrentHeading.Value + 360) % 360;
observer.OnDistanceChanged(distance);
observer.OnDirectionChanged(direction);
}
