mirror of
https://github.com/Jermolene/TiddlyWiki5
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696 lines
26 KiB
JavaScript
696 lines
26 KiB
JavaScript
// Copyright 2014 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the 'License');
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an 'AS IS' BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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* Convert locations to and from short codes.
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*
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* Open Location Codes are short, 10-11 character codes that can be used instead
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* of street addresses. The codes can be generated and decoded offline, and use
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* a reduced character set that minimises the chance of codes including words.
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*
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* Codes are able to be shortened relative to a nearby location. This means that
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* in many cases, only four to seven characters of the code are needed.
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* To recover the original code, the same location is not required, as long as
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* a nearby location is provided.
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*
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* Codes represent rectangular areas rather than points, and the longer the
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* code, the smaller the area. A 10 character code represents a 13.5x13.5
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* meter area (at the equator. An 11 character code represents approximately
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* a 2.8x3.5 meter area.
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*
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* Two encoding algorithms are used. The first 10 characters are pairs of
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* characters, one for latitude and one for longitude, using base 20. Each pair
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* reduces the area of the code by a factor of 400. Only even code lengths are
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* sensible, since an odd-numbered length would have sides in a ratio of 20:1.
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*
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* At position 11, the algorithm changes so that each character selects one
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* position from a 4x5 grid. This allows single-character refinements.
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*
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* Examples:
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*
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* Encode a location, default accuracy:
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* var code = OpenLocationCode.encode(47.365590, 8.524997);
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*
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* Encode a location using one stage of additional refinement:
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* var code = OpenLocationCode.encode(47.365590, 8.524997, 11);
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*
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* Decode a full code:
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* var coord = OpenLocationCode.decode(code);
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* var msg = 'Center is ' + coord.latitudeCenter + ',' + coord.longitudeCenter;
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*
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* Attempt to trim the first characters from a code:
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* var shortCode = OpenLocationCode.shorten('8FVC9G8F+6X', 47.5, 8.5);
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*
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* Recover the full code from a short code:
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* var code = OpenLocationCode.recoverNearest('9G8F+6X', 47.4, 8.6);
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* var code = OpenLocationCode.recoverNearest('8F+6X', 47.4, 8.6);
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*/
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(function(root, factory) {
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/* global define, module */
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if (typeof define === 'function' && define.amd) {
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// AMD. Register as an anonymous module.
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define(['b'], function(b) {
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return (root.returnExportsGlobal = factory(b));
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});
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} else if (typeof module === 'object' && module.exports) {
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// Node. Does not work with strict CommonJS, but
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// only CommonJS-like environments that support module.exports,
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// like Node.
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module.exports = factory(require('b'));
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} else {
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// Browser globals
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root.OpenLocationCode = factory();
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}
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}(this, function() {
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var OpenLocationCode = {};
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/**
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* Provides a normal precision code, approximately 14x14 meters.
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* @const {number}
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*/
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OpenLocationCode.CODE_PRECISION_NORMAL = 10;
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/**
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* Provides an extra precision code, approximately 2x3 meters.
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* @const {number}
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*/
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OpenLocationCode.CODE_PRECISION_EXTRA = 11;
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// A separator used to break the code into two parts to aid memorability.
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var SEPARATOR_ = '+';
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// The number of characters to place before the separator.
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var SEPARATOR_POSITION_ = 8;
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// The character used to pad codes.
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var PADDING_CHARACTER_ = '0';
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// The character set used to encode the values.
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var CODE_ALPHABET_ = '23456789CFGHJMPQRVWX';
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// The base to use to convert numbers to/from.
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var ENCODING_BASE_ = CODE_ALPHABET_.length;
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// The maximum value for latitude in degrees.
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var LATITUDE_MAX_ = 90;
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// The maximum value for longitude in degrees.
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var LONGITUDE_MAX_ = 180;
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// The max number of digits to process in a plus code.
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var MAX_DIGIT_COUNT_ = 15;
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// Maximum code length using lat/lng pair encoding. The area of such a
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// code is approximately 13x13 meters (at the equator), and should be suitable
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// for identifying buildings. This excludes prefix and separator characters.
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var PAIR_CODE_LENGTH_ = 10;
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// First place value of the pairs (if the last pair value is 1).
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var PAIR_FIRST_PLACE_VALUE_ = Math.pow(
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ENCODING_BASE_, (PAIR_CODE_LENGTH_ / 2 - 1));
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// Inverse of the precision of the pair section of the code.
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var PAIR_PRECISION_ = Math.pow(ENCODING_BASE_, 3);
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// The resolution values in degrees for each position in the lat/lng pair
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// encoding. These give the place value of each position, and therefore the
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// dimensions of the resulting area.
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var PAIR_RESOLUTIONS_ = [20.0, 1.0, .05, .0025, .000125];
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// Number of digits in the grid precision part of the code.
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var GRID_CODE_LENGTH_ = MAX_DIGIT_COUNT_ - PAIR_CODE_LENGTH_;
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// Number of columns in the grid refinement method.
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var GRID_COLUMNS_ = 4;
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// Number of rows in the grid refinement method.
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var GRID_ROWS_ = 5;
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// First place value of the latitude grid (if the last place is 1).
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var GRID_LAT_FIRST_PLACE_VALUE_ = Math.pow(
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GRID_ROWS_, (GRID_CODE_LENGTH_ - 1));
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// First place value of the longitude grid (if the last place is 1).
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var GRID_LNG_FIRST_PLACE_VALUE_ = Math.pow(
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GRID_COLUMNS_, (GRID_CODE_LENGTH_ - 1));
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// Multiply latitude by this much to make it a multiple of the finest
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// precision.
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var FINAL_LAT_PRECISION_ = PAIR_PRECISION_ *
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Math.pow(GRID_ROWS_, (MAX_DIGIT_COUNT_ - PAIR_CODE_LENGTH_));
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// Multiply longitude by this much to make it a multiple of the finest
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// precision.
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var FINAL_LNG_PRECISION_ = PAIR_PRECISION_ *
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Math.pow(GRID_COLUMNS_, (MAX_DIGIT_COUNT_ - PAIR_CODE_LENGTH_));
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// Minimum length of a code that can be shortened.
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var MIN_TRIMMABLE_CODE_LEN_ = 6;
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/**
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@return {string} Returns the OLC alphabet.
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*/
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OpenLocationCode.getAlphabet = function() {
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return CODE_ALPHABET_;
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};
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/**
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* Determines if a code is valid.
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*
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* To be valid, all characters must be from the Open Location Code character
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* set with at most one separator. The separator can be in any even-numbered
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* position up to the eighth digit.
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*
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* @param {string} code The string to check.
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* @return {boolean} True if the string is a valid code.
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*/
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var isValid = OpenLocationCode.isValid = function(code) {
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if (!code || typeof code !== 'string') {
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return false;
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}
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// The separator is required.
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if (code.indexOf(SEPARATOR_) == -1) {
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return false;
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}
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if (code.indexOf(SEPARATOR_) != code.lastIndexOf(SEPARATOR_)) {
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return false;
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}
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// Is it the only character?
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if (code.length == 1) {
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return false;
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}
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// Is it in an illegal position?
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if (code.indexOf(SEPARATOR_) > SEPARATOR_POSITION_ ||
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code.indexOf(SEPARATOR_) % 2 == 1) {
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return false;
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}
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// We can have an even number of padding characters before the separator,
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// but then it must be the final character.
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if (code.indexOf(PADDING_CHARACTER_) > -1) {
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// Short codes cannot have padding
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if (code.indexOf(SEPARATOR_) < SEPARATOR_POSITION_) {
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return false;
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}
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// Not allowed to start with them!
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if (code.indexOf(PADDING_CHARACTER_) == 0) {
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return false;
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}
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// There can only be one group and it must have even length.
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var padMatch = code.match(new RegExp('(' + PADDING_CHARACTER_ + '+)', 'g'));
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if (padMatch.length > 1 || padMatch[0].length % 2 == 1 ||
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padMatch[0].length > SEPARATOR_POSITION_ - 2) {
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return false;
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}
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// If the code is long enough to end with a separator, make sure it does.
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if (code.charAt(code.length - 1) != SEPARATOR_) {
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return false;
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}
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}
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// If there are characters after the separator, make sure there isn't just
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// one of them (not legal).
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if (code.length - code.indexOf(SEPARATOR_) - 1 == 1) {
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return false;
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}
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// Strip the separator and any padding characters.
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code = code.replace(new RegExp('\\' + SEPARATOR_ + '+'), '')
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.replace(new RegExp(PADDING_CHARACTER_ + '+'), '');
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// Check the code contains only valid characters.
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for (var i = 0, len = code.length; i < len; i++) {
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var character = code.charAt(i).toUpperCase();
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if (character != SEPARATOR_ && CODE_ALPHABET_.indexOf(character) == -1) {
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return false;
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}
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}
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return true;
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};
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/**
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* Determines if a code is a valid short code.
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*
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* @param {string} code The string to check.
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* @return {boolean} True if the string can be produced by removing four or
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* more characters from the start of a valid code.
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*/
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var isShort = OpenLocationCode.isShort = function(code) {
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// Check it's valid.
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if (!isValid(code)) {
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return false;
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}
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// If there are less characters than expected before the SEPARATOR.
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if (code.indexOf(SEPARATOR_) >= 0 &&
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code.indexOf(SEPARATOR_) < SEPARATOR_POSITION_) {
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return true;
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}
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return false;
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};
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/**
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* Determines if a code is a valid full Open Location Code.
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*
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* @param {string} code The string to check.
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* @return {boolean} True if the code represents a valid latitude and
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* longitude combination.
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*/
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var isFull = OpenLocationCode.isFull = function(code) {
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if (!isValid(code)) {
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return false;
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}
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// If it's short, it's not full.
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if (isShort(code)) {
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return false;
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}
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// Work out what the first latitude character indicates for latitude.
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var firstLatValue = CODE_ALPHABET_.indexOf(
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code.charAt(0).toUpperCase()) * ENCODING_BASE_;
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if (firstLatValue >= LATITUDE_MAX_ * 2) {
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// The code would decode to a latitude of >= 90 degrees.
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return false;
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}
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if (code.length > 1) {
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// Work out what the first longitude character indicates for longitude.
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var firstLngValue = CODE_ALPHABET_.indexOf(
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code.charAt(1).toUpperCase()) * ENCODING_BASE_;
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if (firstLngValue >= LONGITUDE_MAX_ * 2) {
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// The code would decode to a longitude of >= 180 degrees.
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return false;
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}
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}
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return true;
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};
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/**
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* Encode a location into an Open Location Code.
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*
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* @param {number} latitude The latitude in signed decimal degrees. It will
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* be clipped to the range -90 to 90.
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* @param {number} longitude The longitude in signed decimal degrees. Will be
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* normalised to the range -180 to 180.
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* @param {?number} codeLength The length of the code to generate. If
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* omitted, the value OpenLocationCode.CODE_PRECISION_NORMAL will be used.
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* For a more precise result, OpenLocationCode.CODE_PRECISION_EXTRA is
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* recommended.
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* @return {string} The code.
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* @throws {Exception} if any of the input values are not numbers.
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*/
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var encode = OpenLocationCode.encode = function(latitude,
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longitude, codeLength) {
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latitude = Number(latitude);
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longitude = Number(longitude);
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if (typeof codeLength == 'undefined') {
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codeLength = OpenLocationCode.CODE_PRECISION_NORMAL;
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} else {
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codeLength = Math.min(MAX_DIGIT_COUNT_, Number(codeLength));
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}
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if (isNaN(latitude) || isNaN(longitude) || isNaN(codeLength)) {
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throw new Error('ValueError: Parameters are not numbers');
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}
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if (codeLength < 2 ||
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(codeLength < PAIR_CODE_LENGTH_ && codeLength % 2 == 1)) {
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throw new Error('IllegalArgumentException: Invalid Open Location Code length');
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}
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// Ensure that latitude and longitude are valid.
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latitude = clipLatitude(latitude);
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longitude = normalizeLongitude(longitude);
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// Latitude 90 needs to be adjusted to be just less, so the returned code
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// can also be decoded.
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if (latitude == 90) {
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latitude = latitude - computeLatitudePrecision(codeLength);
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}
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var code = '';
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// Compute the code.
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// This approach converts each value to an integer after multiplying it by
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// the final precision. This allows us to use only integer operations, so
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// avoiding any accumulation of floating point representation errors.
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// Multiply values by their precision and convert to positive.
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// Force to integers so the division operations will have integer results.
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// Note: JavaScript requires rounding before truncating to ensure precision!
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var latVal =
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Math.floor(Math.round((latitude + LATITUDE_MAX_) * FINAL_LAT_PRECISION_ * 1e6) / 1e6);
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var lngVal =
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Math.floor(Math.round((longitude + LONGITUDE_MAX_) * FINAL_LNG_PRECISION_ * 1e6) / 1e6);
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// Compute the grid part of the code if necessary.
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if (codeLength > PAIR_CODE_LENGTH_) {
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for (var i = 0; i < MAX_DIGIT_COUNT_ - PAIR_CODE_LENGTH_; i++) {
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var latDigit = latVal % GRID_ROWS_;
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var lngDigit = lngVal % GRID_COLUMNS_;
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var ndx = latDigit * GRID_COLUMNS_ + lngDigit;
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code = CODE_ALPHABET_.charAt(ndx) + code;
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// Note! Integer division.
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latVal = Math.floor(latVal / GRID_ROWS_);
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lngVal = Math.floor(lngVal / GRID_COLUMNS_);
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}
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} else {
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latVal = Math.floor(latVal / Math.pow(GRID_ROWS_, GRID_CODE_LENGTH_));
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lngVal = Math.floor(lngVal / Math.pow(GRID_COLUMNS_, GRID_CODE_LENGTH_));
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}
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// Compute the pair section of the code.
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for (var i = 0; i < PAIR_CODE_LENGTH_ / 2; i++) {
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code = CODE_ALPHABET_.charAt(lngVal % ENCODING_BASE_) + code;
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code = CODE_ALPHABET_.charAt(latVal % ENCODING_BASE_) + code;
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latVal = Math.floor(latVal / ENCODING_BASE_);
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lngVal = Math.floor(lngVal / ENCODING_BASE_);
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}
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// Add the separator character.
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code = code.substring(0, SEPARATOR_POSITION_) +
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SEPARATOR_ +
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code.substring(SEPARATOR_POSITION_);
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// If we don't need to pad the code, return the requested section.
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if (codeLength >= SEPARATOR_POSITION_) {
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return code.substring(0, codeLength + 1);
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}
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// Pad and return the code.
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return code.substring(0, codeLength) +
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Array(SEPARATOR_POSITION_ - codeLength + 1).join(PADDING_CHARACTER_) + SEPARATOR_;
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};
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/**
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* Decodes an Open Location Code into its location coordinates.
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*
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* Returns a CodeArea object that includes the coordinates of the bounding
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* box - the lower left, center and upper right.
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*
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* @param {string} code The code to decode.
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* @return {OpenLocationCode.CodeArea} An object with the coordinates of the
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* area of the code.
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* @throws {Exception} If the code is not valid.
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*/
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var decode = OpenLocationCode.decode = function(code) {
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// This calculates the values for the pair and grid section separately, using
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// integer arithmetic. Only at the final step are they converted to floating
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// point and combined.
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if (!isFull(code)) {
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throw new Error('IllegalArgumentException: ' +
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'Passed Open Location Code is not a valid full code: ' + code);
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}
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// Strip the '+' and '0' characters from the code and convert to upper case.
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code = code.replace('+', '').replace(/0/g, '').toLocaleUpperCase('en-US');
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// Initialise the values for each section. We work them out as integers and
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// convert them to floats at the end.
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var normalLat = -LATITUDE_MAX_ * PAIR_PRECISION_;
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var normalLng = -LONGITUDE_MAX_ * PAIR_PRECISION_;
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var gridLat = 0;
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var gridLng = 0;
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// How many digits do we have to process?
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var digits = Math.min(code.length, PAIR_CODE_LENGTH_);
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// Define the place value for the most significant pair.
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var pv = PAIR_FIRST_PLACE_VALUE_;
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// Decode the paired digits.
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for (var i = 0; i < digits; i += 2) {
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normalLat += CODE_ALPHABET_.indexOf(code.charAt(i)) * pv;
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normalLng += CODE_ALPHABET_.indexOf(code.charAt(i + 1)) * pv;
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if (i < digits - 2) {
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pv /= ENCODING_BASE_;
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}
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}
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// Convert the place value to a float in degrees.
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var latPrecision = pv / PAIR_PRECISION_;
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var lngPrecision = pv / PAIR_PRECISION_;
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// Process any extra precision digits.
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if (code.length > PAIR_CODE_LENGTH_) {
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// Initialise the place values for the grid.
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var rowpv = GRID_LAT_FIRST_PLACE_VALUE_;
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var colpv = GRID_LNG_FIRST_PLACE_VALUE_;
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// How many digits do we have to process?
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digits = Math.min(code.length, MAX_DIGIT_COUNT_);
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for (var i = PAIR_CODE_LENGTH_; i < digits; i++) {
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var digitVal = CODE_ALPHABET_.indexOf(code.charAt(i));
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var row = Math.floor(digitVal / GRID_COLUMNS_);
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var col = digitVal % GRID_COLUMNS_;
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gridLat += row * rowpv;
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gridLng += col * colpv;
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if (i < digits - 1) {
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rowpv /= GRID_ROWS_;
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colpv /= GRID_COLUMNS_;
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}
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}
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// Adjust the precisions from the integer values to degrees.
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latPrecision = rowpv / FINAL_LAT_PRECISION_;
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lngPrecision = colpv / FINAL_LNG_PRECISION_;
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}
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// Merge the values from the normal and extra precision parts of the code.
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var lat = normalLat / PAIR_PRECISION_ + gridLat / FINAL_LAT_PRECISION_;
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var lng = normalLng / PAIR_PRECISION_ + gridLng / FINAL_LNG_PRECISION_;
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// Multiple values by 1e14, round and then divide. This reduces errors due
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// to floating point precision.
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return new CodeArea(
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Math.round(lat * 1e14) / 1e14, Math.round(lng * 1e14) / 1e14,
|
|
Math.round((lat + latPrecision) * 1e14) / 1e14,
|
|
Math.round((lng + lngPrecision) * 1e14) / 1e14,
|
|
Math.min(code.length, MAX_DIGIT_COUNT_));
|
|
};
|
|
|
|
/**
|
|
* Recover the nearest matching code to a specified location.
|
|
*
|
|
* Given a valid short Open Location Code this recovers the nearest matching
|
|
* full code to the specified location.
|
|
*
|
|
* @param {string} shortCode A valid short code.
|
|
* @param {number} referenceLatitude The latitude to use for the reference
|
|
* location.
|
|
* @param {number} referenceLongitude The longitude to use for the reference
|
|
* location.
|
|
* @return {string} The nearest matching full code to the reference location.
|
|
* @throws {Exception} if the short code is not valid, or the reference
|
|
* position values are not numbers.
|
|
*/
|
|
OpenLocationCode.recoverNearest = function(
|
|
shortCode, referenceLatitude, referenceLongitude) {
|
|
if (!isShort(shortCode)) {
|
|
if (isFull(shortCode)) {
|
|
return shortCode.toUpperCase();
|
|
} else {
|
|
throw new Error(
|
|
'ValueError: Passed short code is not valid: ' + shortCode);
|
|
}
|
|
}
|
|
referenceLatitude = Number(referenceLatitude);
|
|
referenceLongitude = Number(referenceLongitude);
|
|
if (isNaN(referenceLatitude) || isNaN(referenceLongitude)) {
|
|
throw new Error('ValueError: Reference position are not numbers');
|
|
}
|
|
// Ensure that latitude and longitude are valid.
|
|
referenceLatitude = clipLatitude(referenceLatitude);
|
|
referenceLongitude = normalizeLongitude(referenceLongitude);
|
|
|
|
// Clean up the passed code.
|
|
shortCode = shortCode.toUpperCase();
|
|
// Compute the number of digits we need to recover.
|
|
var paddingLength = SEPARATOR_POSITION_ - shortCode.indexOf(SEPARATOR_);
|
|
// The resolution (height and width) of the padded area in degrees.
|
|
var resolution = Math.pow(20, 2 - (paddingLength / 2));
|
|
// Distance from the center to an edge (in degrees).
|
|
var halfResolution = resolution / 2.0;
|
|
|
|
// Use the reference location to pad the supplied short code and decode it.
|
|
var codeArea = decode(
|
|
encode(referenceLatitude, referenceLongitude).substr(0, paddingLength)
|
|
+ shortCode);
|
|
// How many degrees latitude is the code from the reference? If it is more
|
|
// than half the resolution, we need to move it north or south but keep it
|
|
// within -90 to 90 degrees.
|
|
if (referenceLatitude + halfResolution < codeArea.latitudeCenter &&
|
|
codeArea.latitudeCenter - resolution >= -LATITUDE_MAX_) {
|
|
// If the proposed code is more than half a cell north of the reference location,
|
|
// it's too far, and the best match will be one cell south.
|
|
codeArea.latitudeCenter -= resolution;
|
|
} else if (referenceLatitude - halfResolution > codeArea.latitudeCenter &&
|
|
codeArea.latitudeCenter + resolution <= LATITUDE_MAX_) {
|
|
// If the proposed code is more than half a cell south of the reference location,
|
|
// it's too far, and the best match will be one cell north.
|
|
codeArea.latitudeCenter += resolution;
|
|
}
|
|
|
|
// How many degrees longitude is the code from the reference?
|
|
if (referenceLongitude + halfResolution < codeArea.longitudeCenter) {
|
|
codeArea.longitudeCenter -= resolution;
|
|
} else if (referenceLongitude - halfResolution > codeArea.longitudeCenter) {
|
|
codeArea.longitudeCenter += resolution;
|
|
}
|
|
|
|
return encode(
|
|
codeArea.latitudeCenter, codeArea.longitudeCenter, codeArea.codeLength);
|
|
};
|
|
|
|
/**
|
|
* Remove characters from the start of an OLC code.
|
|
*
|
|
* This uses a reference location to determine how many initial characters
|
|
* can be removed from the OLC code. The number of characters that can be
|
|
* removed depends on the distance between the code center and the reference
|
|
* location.
|
|
*
|
|
* @param {string} code The full code to shorten.
|
|
* @param {number} latitude The latitude to use for the reference location.
|
|
* @param {number} longitude The longitude to use for the reference location.
|
|
* @return {string} The code, shortened as much as possible that it is still
|
|
* the closest matching code to the reference location.
|
|
* @throws {Exception} if the passed code is not a valid full code or the
|
|
* reference location values are not numbers.
|
|
*/
|
|
OpenLocationCode.shorten = function(
|
|
code, latitude, longitude) {
|
|
if (!isFull(code)) {
|
|
throw new Error('ValueError: Passed code is not valid and full: ' + code);
|
|
}
|
|
if (code.indexOf(PADDING_CHARACTER_) != -1) {
|
|
throw new Error('ValueError: Cannot shorten padded codes: ' + code);
|
|
}
|
|
code = code.toUpperCase();
|
|
var codeArea = decode(code);
|
|
if (codeArea.codeLength < MIN_TRIMMABLE_CODE_LEN_) {
|
|
throw new Error(
|
|
'ValueError: Code length must be at least ' +
|
|
MIN_TRIMMABLE_CODE_LEN_);
|
|
}
|
|
// Ensure that latitude and longitude are valid.
|
|
latitude = Number(latitude);
|
|
longitude = Number(longitude);
|
|
if (isNaN(latitude) || isNaN(longitude)) {
|
|
throw new Error('ValueError: Reference position are not numbers');
|
|
}
|
|
latitude = clipLatitude(latitude);
|
|
longitude = normalizeLongitude(longitude);
|
|
// How close are the latitude and longitude to the code center.
|
|
var range = Math.max(
|
|
Math.abs(codeArea.latitudeCenter - latitude),
|
|
Math.abs(codeArea.longitudeCenter - longitude));
|
|
for (var i = PAIR_RESOLUTIONS_.length - 2; i >= 1; i--) {
|
|
// Check if we're close enough to shorten. The range must be less than 1/2
|
|
// the resolution to shorten at all, and we want to allow some safety, so
|
|
// use 0.3 instead of 0.5 as a multiplier.
|
|
if (range < (PAIR_RESOLUTIONS_[i] * 0.3)) {
|
|
// Trim it.
|
|
return code.substring((i + 1) * 2);
|
|
}
|
|
}
|
|
return code;
|
|
};
|
|
|
|
/**
|
|
* Clip a latitude into the range -90 to 90.
|
|
*
|
|
* @param {number} latitude
|
|
* @return {number} The latitude value clipped to be in the range.
|
|
*/
|
|
var clipLatitude = function(latitude) {
|
|
return Math.min(90, Math.max(-90, latitude));
|
|
};
|
|
|
|
/**
|
|
* Compute the latitude precision value for a given code length.
|
|
* Lengths <= 10 have the same precision for latitude and longitude, but
|
|
* lengths > 10 have different precisions due to the grid method having
|
|
* fewer columns than rows.
|
|
* @param {number} codeLength
|
|
* @return {number} The latitude precision in degrees.
|
|
*/
|
|
var computeLatitudePrecision = function(codeLength) {
|
|
if (codeLength <= 10) {
|
|
return Math.pow(ENCODING_BASE_, Math.floor(codeLength / -2 + 2));
|
|
}
|
|
return Math.pow(ENCODING_BASE_, -3) / Math.pow(GRID_ROWS_, codeLength - 10);
|
|
};
|
|
|
|
/**
|
|
* Normalize a longitude into the range -180 to 180, not including 180.
|
|
*
|
|
* @param {number} longitude
|
|
* @return {number} Normalized into the range -180 to 180.
|
|
*/
|
|
var normalizeLongitude = function(longitude) {
|
|
while (longitude < -180) {
|
|
longitude = longitude + 360;
|
|
}
|
|
while (longitude >= 180) {
|
|
longitude = longitude - 360;
|
|
}
|
|
return longitude;
|
|
};
|
|
|
|
/**
|
|
* Coordinates of a decoded Open Location Code.
|
|
*
|
|
* The coordinates include the latitude and longitude of the lower left and
|
|
* upper right corners and the center of the bounding box for the area the
|
|
* code represents.
|
|
* @param {number} latitudeLo
|
|
* @param {number} longitudeLo
|
|
* @param {number} latitudeHi
|
|
* @param {number} longitudeHi
|
|
* @param {number} codeLength
|
|
*
|
|
* @constructor
|
|
*/
|
|
var CodeArea = OpenLocationCode.CodeArea = function(
|
|
latitudeLo, longitudeLo, latitudeHi, longitudeHi, codeLength) {
|
|
return new OpenLocationCode.CodeArea.fn.Init(
|
|
latitudeLo, longitudeLo, latitudeHi, longitudeHi, codeLength);
|
|
};
|
|
CodeArea.fn = CodeArea.prototype = {
|
|
Init: function(
|
|
latitudeLo, longitudeLo, latitudeHi, longitudeHi, codeLength) {
|
|
/**
|
|
* The latitude of the SW corner.
|
|
* @type {number}
|
|
*/
|
|
this.latitudeLo = latitudeLo;
|
|
/**
|
|
* The longitude of the SW corner in degrees.
|
|
* @type {number}
|
|
*/
|
|
this.longitudeLo = longitudeLo;
|
|
/**
|
|
* The latitude of the NE corner in degrees.
|
|
* @type {number}
|
|
*/
|
|
this.latitudeHi = latitudeHi;
|
|
/**
|
|
* The longitude of the NE corner in degrees.
|
|
* @type {number}
|
|
*/
|
|
this.longitudeHi = longitudeHi;
|
|
/**
|
|
* The number of digits in the code.
|
|
* @type {number}
|
|
*/
|
|
this.codeLength = codeLength;
|
|
/**
|
|
* The latitude of the center in degrees.
|
|
* @type {number}
|
|
*/
|
|
this.latitudeCenter = Math.min(
|
|
latitudeLo + (latitudeHi - latitudeLo) / 2, LATITUDE_MAX_);
|
|
/**
|
|
* The longitude of the center in degrees.
|
|
* @type {number}
|
|
*/
|
|
this.longitudeCenter = Math.min(
|
|
longitudeLo + (longitudeHi - longitudeLo) / 2, LONGITUDE_MAX_);
|
|
},
|
|
};
|
|
CodeArea.fn.Init.prototype = CodeArea.fn;
|
|
|
|
return OpenLocationCode;
|
|
}));
|