bikeinparis/Polyline.encoded.js

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2013-07-24 12:52:41 +02:00
/*
* L.PolylineUtil contains utilify functions for polylines, two methods
* are added to the L.Polyline object to support creation of polylines
* from an encoded string and converting existing polylines to an
* encoded string.
*
* - L.Polyline.fromEncoded(encoded [, options]) returns a L.Polyline
* - L.Polyline.encodePath() returns a string
*
* Actual code from:
* http://facstaff.unca.edu/mcmcclur/GoogleMaps/EncodePolyline/\
*/
/*jshint browser:true, debug: true, strict:false, globalstrict:false, indent:4, white:true, smarttabs:true*/
/*global L:true, console:true*/
// Inject functionality into Leaflet
(function (L) {
if (!(L.Polyline.prototype.fromEncoded)) {
L.Polyline.fromEncoded = function (encoded, options) {
return new L.Polyline(L.PolylineUtil.decode(encoded), options);
};
}
if (!(L.Polygon.prototype.fromEncoded)) {
L.Polygon.fromEncoded = function (encoded, options) {
return new L.Polygon(L.PolylineUtil.decode(encoded), options);
};
}
var encodeMixin = {
encodePath: function () {
return L.PolylineUtil.encode(this.getLatLngs());
}
};
if (!L.Polyline.prototype.encodePath) {
L.Polyline.include(encodeMixin);
}
if (!L.Polygon.prototype.encodePath) {
L.Polygon.include(encodeMixin);
}
})(L);
// Utility functions.
L.PolylineUtil = {};
L.PolylineUtil.encode = function (latlngs) {
var i, dlat, dlng;
var plat = 0;
var plng = 0;
var encoded_points = "";
for (i = 0; i < latlngs.length; i++) {
var lat = latlngs[i].lat;
var lng = latlngs[i].lng;
var late5 = Math.floor(lat * 1e5);
var lnge5 = Math.floor(lng * 1e5);
dlat = late5 - plat;
dlng = lnge5 - plng;
plat = late5;
plng = lnge5;
encoded_points +=
L.PolylineUtil.encodeSignedNumber(dlat) +
L.PolylineUtil.encodeSignedNumber(dlng);
}
return encoded_points;
};
// This function is very similar to Google's, but I added
// some stuff to deal with the double slash issue.
L.PolylineUtil.encodeNumber = function (num) {
var encodeString = "";
var nextValue, finalValue;
while (num >= 0x20) {
nextValue = (0x20 | (num & 0x1f)) + 63;
encodeString += (String.fromCharCode(nextValue));
num >>= 5;
}
finalValue = num + 63;
encodeString += (String.fromCharCode(finalValue));
return encodeString;
};
// This one is Google's verbatim.
L.PolylineUtil.encodeSignedNumber = function (num) {
var sgn_num = num << 1;
if (num < 0) {
sgn_num = ~(sgn_num);
}
return (L.PolylineUtil.encodeNumber(sgn_num));
};
L.PolylineUtil.decode = function (encoded) {
var len = encoded.length;
var index = 0;
var latlngs = [];
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;
latlngs.push(new L.LatLng(lat * 1e-5, lng * 1e-5));
}
return latlngs;
};