Class PolylineCodec

java.lang.Object
com.codename1.maps.PolylineCodec
public final class PolylineCodec extends Object

Reads and writes the encoded polyline format -- the compact ASCII representation of a coordinate sequence that virtually every directions and routing service uses for route geometry (Google Directions, OSRM, Mapbox Directions, GraphHopper, Valhalla, OpenRouteService).

Use it to turn a route geometry straight into something drawable:

map.addPolyline(Polyline.fromEncoded(geometryFromMyDirectionsApi));

The encoding stores each coordinate as a zig-zag, base-64-ish delta from the previous one at a fixed decimal precision. Precision 5 is the original Google format and the OSRM/Google/GraphHopper default; precision 6 (polyline6) is what Valhalla and OSRM's geometries=polyline6 emit. Decoding with the wrong precision yields coordinates off by a factor of ten, so pass the precision your service documents.

  • Method Details

    • decode

      public static List decode(String encoded)

      Decodes an encoded polyline at the default precision of 5.

      Parameters
      • encoded: the encoded geometry, may be null
      Returns

      the decoded LatLng vertices, empty when encoded is null or blank

    • decode

      public static List decode(String encoded, int precision)

      Decodes an encoded polyline at an explicit decimal precision (5 for the classic format, 6 for polyline6).

      Trailing bytes that do not form a complete coordinate pair -- the usual symptom of a truncated response -- are dropped rather than throwing, so a partial geometry still draws the coordinates it did carry. A value cut in half is discarded too: half a delta is not a coordinate, and emitting it would put a spurious vertex on the map and skew the route bounds. Decoding likewise stops at the first character outside the encoding's alphabet instead of folding it into a coordinate.

      Parameters

      • encoded: the encoded geometry, may be null

      • precision: the number of decimal digits the encoder scaled by, between 1 and 10

      Returns

      the decoded LatLng vertices, never null

      Throws
      • IllegalArgumentException: when precision is outside 1 to 10, which would scale every coordinate into nonsense rather than fail

    • encode

      public static String encode(List points)

      Encodes LatLng vertices at the default precision of 5.

      Parameters
      • points: the vertices to encode, may be null
      Returns

      the encoded geometry, empty for a null or empty list

    • encode

      public static String encode(List points, int precision)

      Encodes LatLng vertices at an explicit decimal precision.

      Parameters

      • points: the vertices to encode, may be null

      • precision: the number of decimal digits to scale by, between 1 and 10

      Returns

      the encoded geometry, never null

      Throws
      • IllegalArgumentException: when precision is outside 1 to 10