Google Directions API 中路线编码解析

 1 public List<Location> GetGeoPoints(string encoded)

 2         {

 3             List<Location> poly = new List<Location>();

 4             int index = 0, len = encoded.Length;

 5             int lat = 0, lng = 0;

 6             while (index < len)

 7             {

 8                 int b, shift = 0, result = 0;

 9                 do

10                 {

11                     b = encoded.ToCharArray()[index++] - 63;

12                     result |= (b & 0x1f) << shift;

13                     shift += 5;

14                 } while (b >= 0x20);

15                 int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));

16                 lat += dlat;

17 

18                 shift = 0;

19                 result = 0;

20                 do

21                 {

22                     b = encoded.ToCharArray()[index++] - 63;

23                     result |= (b & 0x1f) << shift;

24                     shift += 5;

25                 } while (b >= 0x20);

26                 int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));

27                 lng += dlng;

28 

29                 double latResult = ((double)lat / 1E5) * 1E6 * Math.Pow(10, -6);

30                 double lngResult = ((double)lng / 1E5) * 1E6 * Math.Pow(10, -6);

31                 Location p = new Location(latResult, lngResult);

32                 poly.Add(p);

33             }

34             return poly;

35         }

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