public void LatLng_DistanceTo_GivesSameResultAsDistance()
{
LatLng testLatLngA = new LatLng(RandomLat(), RandomLng());
LatLng testLatLngB = new LatLng(RandomLat(), RandomLng());
Assert.AreEqual(
LatLng.Distance(testLatLngA, testLatLngB),
testLatLngA.DistanceTo(testLatLngB),
"DistanceTo method should give the same result as static Distance method");
}
public void LatLng_ValidConstructor_PropertiesMatchThoseSupplied()
{
double lat = RandomLat();
double lng = RandomLng();
LatLng testLatLng = new LatLng(lat, lng);
Assert.AreEqual(lat, testLatLng.Latitude, "Latitude property should return the value initially supplied");
Assert.AreEqual(lng, testLatLng.Longitude, "Longtitude property should return the value initially supplied");
}
public void LatLng_EquivalantLatLng_AreEqual()
{
double lat = RandomLat();
double lng = RandomLng();
LatLng testLatLngA = new LatLng(lat, lng);
LatLng testLatLngB = new LatLng(lat, lng);
Assert.AreEqual(
testLatLngA,
testLatLngB,
"Two LatLng instances describing the same location should be equivalant");
}
/// <summary>
/// Calculates the midpoint between the current point and the <see cref="LatLng">point</see> specified.
/// </summary>
/// <param name="otherPoint">The other point to use in the calculation.</param>
/// <returns>
/// The midpoint between the current point and the <paramref name="otherPoint"/> specified.
/// </returns>
public LatLng MidpointTo(LatLng otherPoint)
{
return MidPoint(this, otherPoint);
}
/// <summary>
/// Calculates the distance (in km) between the current point and the <see cref="LatLng">point</see> specified.
/// By default this uses the Law of Cosines formula (http://en.wikipedia.org/wiki/Law_of_cosines).
/// </summary>
/// <param name="otherPoint">The point we want to calculate the distance to.</param>
/// <param name="calculation">
/// <para>The distance calculation to use.</para>
/// <para>By default this uses the Law of Cosines formula.</para>
/// </param>
/// <returns>
/// The distance (in km) between the current point and the <paramref name="otherPoint"/> specified.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// The specified <paramref name="calculation"/> is outside the allowable <see cref="DistanceCalculation">values</see>.
/// </exception>
public double DistanceTo(LatLng otherPoint, DistanceCalculation calculation = DistanceCalculation.LawOfCosines)
{
return Distance(this, otherPoint, calculation);
}
/// <summary>
/// Calculates the midpoint between two specified <see cref="LatLng">latlong points</see>.
/// </summary>
/// <param name="pointOne">The first point to use in the calculation.</param>
/// <param name="pointTwo">The second point to use in the calculation.</param>
/// <returns>
/// The midpoint between the two points specified.
/// </returns>
public static LatLng MidPoint(LatLng pointOne, LatLng pointTwo)
{
double dLon = (pointTwo.Longitude - pointTwo.Longitude).ToRadians();
double bx = Math.Cos(pointTwo.Latitude.ToRadians()) * Math.Cos(dLon);
double by = Math.Cos(pointTwo.Latitude.ToRadians()) * Math.Sin(dLon);
double latitude = (Math.Atan2(
Math.Sin(pointOne.Latitude.ToRadians()) + Math.Sin(pointTwo.Latitude.ToRadians()),
Math.Sqrt(
(Math.Cos(pointOne.Latitude.ToRadians()) + bx) *
(Math.Cos(pointOne.Latitude.ToRadians()) + bx) + by * by))).ToDegrees();
double longitude = pointOne.Longitude +
Math.Atan2(by, Math.Cos(pointOne.Latitude.ToRadians()) + bx).ToDegrees();
return new LatLng(latitude, longitude);
}
/// <summary>
/// Calculates the distance (in km) between two specified <see cref="LatLng">latlong points</see>.
/// By default this uses the Law of Cosines formula (http://en.wikipedia.org/wiki/Law_of_cosines).
/// </summary>
/// <param name="pointOne">The first point to use in the calculation.</param>
/// <param name="pointTwo">The second point to use in the calculation.</param>
/// <param name="calculation">
/// <para>The calculation to use.</para>
/// <para>By default this uses the Law of Cosines formula.</para>
/// </param>
/// <returns>
/// The distance (in km) between the two points specified.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// The specified <paramref name="calculation"/> is outside the allowable <see cref="DistanceCalculation">values</see>.
/// </exception>
public static double Distance(
LatLng pointOne,
LatLng pointTwo,
DistanceCalculation calculation = DistanceCalculation.LawOfCosines)
{
switch (calculation)
{
case DistanceCalculation.Haversine:
double pointOneLatitude = pointOne.Latitude.ToRadians();
double pointOneLongitude = pointOne.Longitude.ToRadians();
double pointTwoLatitude = pointTwo.Latitude.ToRadians();
double pointTwoLongitude = pointTwo.Longitude.ToRadians();
double longitude = pointTwoLongitude - pointOneLongitude;
double latitude = pointTwoLatitude - pointOneLatitude;
double intermediateResult = Math.Pow(Math.Sin(latitude / 2.0), 2.0) +
Math.Cos(pointOneLatitude) * Math.Cos(pointTwoLatitude) *
Math.Pow(Math.Sin(longitude / 2.0), 2.0);
// Intermediate result c (great circle distance in Radians).
double c = 2.0 * Math.Atan2(Math.Sqrt(intermediateResult), Math.Sqrt(1.0 - intermediateResult));
return EarthsRadiusInKilometers * c;
case DistanceCalculation.LawOfCosines:
return (Math.Acos(
Math.Sin(pointOne.Latitude) * Math.Sin(pointTwo.Latitude) +
Math.Cos(pointOne.Latitude) * Math.Cos(pointTwo.Latitude) *
Math.Cos(pointTwo.Longitude - pointOne.Longitude)
) * EarthsRadiusInKilometers).ToRadians();
default:
throw new ArgumentOutOfRangeException("calculation");
}
}
public void LatLng_MidpointTo_GivesSameResultAsMidpoint()
{
LatLng testLatLngA = new LatLng(RandomLat(), RandomLng());
LatLng testLatLngB = new LatLng(RandomLat(), RandomLng());
Assert.AreEqual(
LatLng.MidPoint(testLatLngA, testLatLngB),
testLatLngA.MidpointTo(testLatLngB),
"MidpointTo method should give the same result as static Midpoint method");
}
