Handling for Google encoded polygons inside GeoJSON in Leaflet

leaflet-geojson-gpolydecode.js

// extend GeoJSON to handle google-encoded linestrings
// assumes that any array of coordinates that make up a linestring are replaced with the google encoded line string
L.extend(L.GeoJSON, {
    // This function is from Google's polyline utility.
    // Borrowed from: http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/decode.js
    // Changed to return lng/lats instead of lat/lngs
    decodeLine: function (encoded) {
        var len = encoded.length;
        var index = 0;
        var array = [];
        var lat = 0;
        var lng = 0;

        while (index < len) {
            var b;
            var shift = 0;
            var result = 0;
            do {
                b = encoded.charCodeAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            var dlat = ((result & 1) ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charCodeAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            var dlng = ((result & 1) ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            array.push([lng * 1e-5, lat * 1e-5]);
        }
        return array;
    },
    coordsToLatLngs: function (coords, levelsDeep, reverse) { // (Array, Number, Boolean) -> Array
        var latlng,
            latlngs = [],
            i, len;

        for (i = 0, len = coords.length; i < len; i++) {

            if (levelsDeep === 1 && typeof coords[i] === 'string') {
                coords[i] = this.decodeLine(coords[i]);
            }

            latlng = levelsDeep ?
                    this.coordsToLatLngs(coords[i], levelsDeep - 1, reverse) :
                    this.coordsToLatLng(coords[i], reverse);

            latlngs.push(latlng);
        }
        return latlngs;
    }
});