Codeint pnpoly(int nvert, float *vertx, float *verty, float testx, float testy)
{int i, j, c = 0;for (i = 0, j = nvert-1; i < nvert; j = i++) {if ( ((verty[i]>testy) != (verty[j]>testy)) &&(testx < (vertx[j]-vertx[i]) * (testy-verty[i]) / (verty[j]-verty[i]) + vertx[i]) )c = !c;}return c;
}

Codepublic bool IsInside(PointLatLng p){int count = Points.Count;if(count < 3){return false;}bool result = false;for(int i = 0, j = count - 1; i < count; i++){var p1 = Points[i];var p2 = Points[j];if(p1.Lat < p.Lat && p2.Lat >= p.Lat || p2.Lat < p.Lat && p1.Lat >= p.Lat){if(p1.Lng + (p.Lat - p1.Lat) / (p2.Lat - p1.Lat) * (p2.Lng - p1.Lng) < p.Lng){result = !result;}}j = i;}return result;}

Codeprivate static double SignedPolygonArea(List<PointLatLng> points){// Add the first point to the end.int pointsCount = points.Count;PointLatLng[] pts = new PointLatLng[pointsCount + 1];points.CopyTo(pts, 0);pts[pointsCount] = points[0];for (int i = 0; i < pointsCount + 1; ++i){pts[i].Lat = pts[i].Lat * (System.Math.PI * 6378137 / 180);pts[i].Lng = pts[i].Lng * (System.Math.PI * 6378137 / 180);}// Get the areas.double area = 0;for (int i = 0; i < pointsCount; i++){area += (pts[i + 1].Lat - pts[i].Lat) * (pts[i + 1].Lng + pts[i].Lng) / 2;}// Return the result.return area;}/// <summary>/// Get the area of a polygon/// </summary>/// <param name="points"></param>/// <returns></returns>public static double GetPolygonArea(List<PointLatLng> points){// Return the absolute value of the signed area.// The signed area is negative if the polygon is oriented clockwise.return Math.Abs(SignedPolygonArea(points));}