melitele / Leaflet.encoded

Plugin to support Google's polyline encoding in Leaflet.

Support encoded polylines in Leaflet

This Leaflet plugin extends the Leaflet API with functions to encode and decode Google maps polyline encoding. It is just a convenient way to use the Google polyline encoding algorithm in Leaflet.

The algorithm is described in the Google maps API Documentation.

Escaping backslashes

Make sure to always escape the backslashes in encoded strings! Not doing so will result in the backslash to be interpreted as an escape character, yielding wrong results.

API

Utility methods

• L.PolylineUtil.encode(latlngs [, precision])

  Encode an array of L.LatLng objects, or an array of arrays.

• L.PolylineUtil.decode(encoded [, precision])

  Decode the string encoded to an array of [lat, lng]-arrays.

Extensions for L.Polyline

• L.Polyline.fromEncoded(encoded [, options])

  Construct a new L.Polyline from a string, with optional options object. Backslashes in strings should be properly escaped.

• L.Polyline.encodePath()

  Return an encoded string for the current Polyline.

Extensions for L.Polygon

• L.Polygon.fromEncoded(encoded [, options])

  Construct a new L.Polygon from a string, with optional options object. Backslashes in strings should be properly escaped.

• L.Polygon.encodePath()

  Return an encoded string for the current Polygon.

Code examples

After loading leaflet.js, src/Polyline.encoded.js should be included.

Encoding

var latlngs = [
	[38.5, -120.5],
	[40.7, -120.95],
	[43.252, -126.453]
];
var polyline = L.polyline(latlngs);

//prints "_p~iF~cn~U_ulLn{vA_mqNvxq`@" to the console
console.log(polyline.encodePath());

Decoding

var encoded = "_p~iF~cn~U_ulLn{vA_mqNvxq`@";
var polyline = L.Polyline.fromEncoded(encoded);

// prints an array of 3 LatLng objects.
console.log(polyline.getLatLngs());

Use a decoding precision of 6 to decode OSRM Routing Engine geometries

var encoded = "_izlhA~pvydF_{geC~{mZ_kwzCn`{nI";
var polyline = new L.Polyline(L.PolylineUtil.decode(encoded, 6));

// prints an array of 3 LatLng objects.
console.log(polyline.getLatLngs());

Node package

You can use encode() and decode() in your Nodejs scripts:

npm install polyline-encoded

var polyUtil = require('polyline-encoded');

var encoded = "_p~iF~cn~U_ulLn{vA_mqNvxq`@";
var latlngs = polyUtil.decode(encoded);