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