Google Directions API 中路线编码解析

 public List<Location> GetGeoPoints(string encoded)
         {
             List<Location> poly = new List<Location>();
             int index = , len = encoded.Length;
             int lat = , lng = ;
             while (index < len)
             {
                 int b, shift = , result = ;
                 do
                 {
                     b = encoded.ToCharArray()[index++] - ;
                     result |= (b & 0x1f) << shift;
                     shift += ;
                 } while (b >= 0x20);
                 int dlat = ((result & ) !=  ? ~(result >> ) : (result >> ));
                 lat += dlat;

                 shift = ;
                 result = ;
                 do
                 {
                     b = encoded.ToCharArray()[index++] - ;
                     result |= (b & 0x1f) << shift;
                     shift += ;
                 } while (b >= 0x20);
                 int dlng = ((result & ) !=  ? ~(result >> ) : (result >> ));
                 lng += dlng;

                 double latResult = ((double)lat / 1E5) * 1E6 * Math.Pow(, -);
                 double lngResult = ((double)lng / 1E5) * 1E6 * Math.Pow(, -);
                 Location p = new Location(latResult, lngResult);
                 poly.Add(p);
             }
             return poly;
         }