@google/maps/lib/util.js

Node.js client library for Google Maps API Web Services

/**
 * @license
 * Copyright 2018 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */;

const { v4: uuidv4 } = require('uuid');

/**
 * Polyline encodes an array of LatLng objects.
 *
 * See {@link https://developers.google.com/maps/documentation/utilities/polylinealgorithm}
 *
 * @memberof! module:@google/maps
 * @name module:@google/maps.util.encodePath
 * @function
 * @param {LatLng[]} path
 * @return {string}
 */
exports.encodePath = function(path) {

  var result = [];
  var start = [0, 0];
  var end;

  var encodePart = function(part) {
    part = part < 0 ? ~(part << 1) : (part << 1);
    while (part >= 0x20) {
      result.push(String.fromCharCode((0x20 | (part & 0x1f)) + 63));
      part >>= 5;
    }
    result.push(String.fromCharCode(part + 63));
  };

  for (var i = 0, I = path.length || 0; i < I; ++i) {
    end = [Math.round(path[i].lat * 1e5), Math.round(path[i].lng * 1e5)];
    encodePart(end[0] - start[0]);  // lat
    encodePart(end[1] - start[1]);  // lng
    start = end;
  }

  return result.join('');
}

/**
 * Decodes a polyline encoded string.
 *
 * See {@link https://developers.google.com/maps/documentation/utilities/polylinealgorithm}
 *
 * @memberof! module:@google/maps
 * @name module:@google/maps.util.decodePath
 * @function
 * @param {string} path
 * @return {LatLng[]}
 */
exports.decodePath = function(encodedPath) {

  var len = encodedPath.length || 0;
  var path = new Array(Math.floor(encodedPath.length / 2));
  var index = 0;
  var lat = 0;
  var lng = 0;

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

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

    path[pointIndex] = {lat: lat * 1e-5, lng: lng * 1e-5};
  }
  path.length = pointIndex;

  return path;
};

exports.placesAutoCompleteSessionToken = uuidv4;