public static bool LocationIsInDistance(Wgs84Location pointForCheck, Wgs84Location center, double radius)
{
if (GetDistanceBetweenTwoPoints(pointForCheck, center) <= radius)
return true;
else
return false;
}
public static Wgs84Location CalculateDerivedPosition(Wgs84Location point, double range, double bearing)
{
const double EarthRadius = 6371000; // m
double latA = DegreeToRadian(point.Latitude);
double lonA = DegreeToRadian(point.Longitude);
double angularDistance = range / EarthRadius;
double trueCourse = DegreeToRadian(bearing);
double lat = Math.Asin(
Math.Sin(latA) * Math.Cos(angularDistance) +
Math.Cos(latA) * Math.Sin(angularDistance)
* Math.Cos(trueCourse));
double dlon = Math.Atan2(
Math.Sin(trueCourse) * Math.Sin(angularDistance)
* Math.Cos(latA),
Math.Cos(angularDistance) - Math.Sin(latA) * Math.Sin(lat));
double lon = ((lonA + dlon + Math.PI) % (Math.PI * 2)) - Math.PI;
lat = RadianToDegree(lat);
lon = RadianToDegree(lon);
var newPoint = new Wgs84Location((float) lon, (float) lat);
return newPoint;
}
protected async void ContinueNearestSearchOnUiThread()
{
Haltestellen = null;
NotifyOfPropertyChange(() => Haltestellen);
var posResult = await _locationService.GetCurrentPosition();
if (posResult.Succeeded)
{
var pos = posResult.Position;
InfoMessage = String.Format("{0}: {1:F2} {2:F2}", AppResources.PositionMessage_YourPosition, pos.Coordinate.Point.Position.Longitude, pos.Coordinate.Point.Position.Latitude);
MyLocation = new Wgs84Location(pos.Coordinate);
var haltestellen = await _dataService.GetNearestHaltestellenAsync(MyLocation);
if (!haltestellen.Any())
{
InfoMessage = String.Format("{0}: {1:F2} {2:F2}", AppResources.PositionMessage_NoStopsFoundNear,
pos.Coordinate.Point.Position.Longitude, pos.Coordinate.Point.Position.Latitude);
}
else
{
Haltestellen = new BindableCollection<Haltestelle>(haltestellen.OrderBy(h => h.Distanz));
NotifyOfPropertyChange(() => Haltestellen);
}
}
else
{
InfoMessage = posResult.ErrorMessage;
}
}
public static double GetDistanceBetweenTwoPoints(Wgs84Location p1, Wgs84Location p2)
{
const double R = 6371000; // m
double dLat = DegreeToRadian(p2.Latitude - p1.Latitude);
double dLon = DegreeToRadian(p2.Longitude - p1.Longitude);
double lat1 = DegreeToRadian(p1.Latitude);
double lat2 = DegreeToRadian(p2.Latitude);
double a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) + Math.Sin(dLon / 2)
* Math.Sin(dLon / 2) * Math.Cos(lat1) * Math.Cos(lat2);
double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
double d = R * c;
return d;
}
public static double GetDistanceBetweenTwoPoints(Wgs84Location p1, double p2Lon, double p2Lat)
{
return GetDistanceBetweenTwoPoints(p1, new Wgs84Location(p2Lon, p2Lat));
}
//
// http://stackoverflow.com/questions/3695224/android-sqlite-getting-nearest-locations-with-latitude-and-longitude/12997900#12997900
//
public async Task<List<Haltestelle>> GetNearestHaltestellenAsync(Wgs84Location center, double radius = 500.0)
{
try
{
double mult = 1; // mult = 1.1; is more reliable
var p1 = NearestLocationHelpers.CalculateDerivedPosition(center, mult * radius, 0);
var p2 = NearestLocationHelpers.CalculateDerivedPosition(center, mult * radius, 90);
var p3 = NearestLocationHelpers.CalculateDerivedPosition(center, mult * radius, 180);
var p4 = NearestLocationHelpers.CalculateDerivedPosition(center, mult * radius, 270);
var db = GetReferenceDataContext();
var haltestellen = await db.GetNearestHaltestellenAsync(p3.Latitude, p1.Latitude, p2.Longitude, p4.Longitude).ConfigureAwait(false);
foreach (var h in haltestellen)
{
h.Distanz = NearestLocationHelpers.GetDistanceBetweenTwoPoints(center, h.Longitude, h.Latitude);
}
return haltestellen;
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
return new List<Haltestelle>();
}