lng_lat.js

// @flow

import { wrap } from '../util/util';
import LngLatBounds from './lng_lat_bounds';

/**
 * A `LngLat` object represents a given longitude and latitude coordinate, measured in degrees.
 *
 * Mapbox GL uses longitude, latitude coordinate order (as opposed to latitude, longitude) to match GeoJSON.
 *
 * Note that any Mapbox GL method that accepts a `LngLat` object as an argument or option
 * can also accept an `Array` of two numbers and will perform an implicit conversion.
 * This flexible type is documented as {@link LngLatLike}.
 *
 * @param {number} lng Longitude, measured in degrees.
 * @param {number} lat Latitude, measured in degrees.
 * @example
 * var ll = new mapboxgl.LngLat(-73.9749, 40.7736);
 * @see [Get coordinates of the mouse pointer](https://www.mapbox.com/mapbox-gl-js/example/mouse-position/)
 * @see [Display a popup](https://www.mapbox.com/mapbox-gl-js/example/popup/)
 * @see [Highlight features within a bounding box](https://www.mapbox.com/mapbox-gl-js/example/using-box-queryrenderedfeatures/)
 * @see [Create a timeline animation](https://www.mapbox.com/mapbox-gl-js/example/timeline-animation/)
 */
class LngLat {
    lng: number;
    lat: number;

    constructor(lng: number, lat: number) {
        if (isNaN(lng) || isNaN(lat)) {
            throw new Error(`Invalid LngLat object: (${lng}, ${lat})`);
        }
        this.lng = +lng;
        this.lat = +lat;
        if (this.lat > 90 || this.lat < -90) {
            throw new Error('Invalid LngLat latitude value: must be between -90 and 90');
        }
    }

    /**
     * Returns a new `LngLat` object whose longitude is wrapped to the range (-180, 180).
     *
     * @returns {LngLat} The wrapped `LngLat` object.
     * @example
     * var ll = new mapboxgl.LngLat(286.0251, 40.7736);
     * var wrapped = ll.wrap();
     * wrapped.lng; // = -73.9749
     */
    wrap() {
        return new LngLat(wrap(this.lng, -180, 180), this.lat);
    }

    /**
     * Returns the coordinates represented as an array of two numbers.
     *
     * @returns {Array<number>} The coordinates represeted as an array of longitude and latitude.
     * @example
     * var ll = new mapboxgl.LngLat(-73.9749, 40.7736);
     * ll.toArray(); // = [-73.9749, 40.7736]
     */
    toArray() {
        return [this.lng, this.lat];
    }

    /**
     * Returns the coordinates represent as a string.
     *
     * @returns {string} The coordinates represented as a string of the format `'LngLat(lng, lat)'`.
     * @example
     * var ll = new mapboxgl.LngLat(-73.9749, 40.7736);
     * ll.toString(); // = "LngLat(-73.9749, 40.7736)"
     */
    toString() {
        return `LngLat(${this.lng}, ${this.lat})`;
    }

    /**
     * Returns a `LngLatBounds` from the coordinates extended by a given `radius`.
     *
     * @param {number} radius Distance in meters from the coordinates to extend the bounds.
     * @returns {LngLatBounds} A new `LngLatBounds` object representing the coordinates extended by the `radius`.
     * @example
     * var ll = new mapboxgl.LngLat(-73.9749, 40.7736);
     * ll.toBounds(100).toArray(); // = [[-73.97501862141328, 40.77351016847229], [-73.97478137858673, 40.77368983152771]]
     */
    toBounds(radius: number) {
        const earthCircumferenceInMetersAtEquator = 40075017;
        const latAccuracy = 360 * radius / earthCircumferenceInMetersAtEquator,
            lngAccuracy = latAccuracy / Math.cos((Math.PI / 180) * this.lat);

        return new LngLatBounds(new LngLat(this.lng - lngAccuracy, this.lat - latAccuracy),
            new LngLat(this.lng + lngAccuracy, this.lat + latAccuracy));
    }

    /**
     * Converts an array of two numbers to a `LngLat` object.
     *
     * If a `LngLat` object is passed in, the function returns it unchanged.
     *
     * @param {LngLatLike} input An array of two numbers to convert, or a `LngLat` object to return.
     * @returns {LngLat} A new `LngLat` object, if a conversion occurred, or the original `LngLat` object.
     * @example
     * var arr = [-73.9749, 40.7736];
     * var ll = mapboxgl.LngLat.convert(arr);
     * ll;   // = LngLat {lng: -73.9749, lat: 40.7736}
     */
    static convert(input: LngLatLike): LngLat {
        if (input instanceof LngLat) {
            return input;
        }
        if (Array.isArray(input) && (input.length === 2 || input.length === 3)) {
            return new LngLat(Number(input[0]), Number(input[1]));
        }
        if (!Array.isArray(input) && typeof input === 'object' && input !== null) {
            return new LngLat(Number(input.lng), Number(input.lat));
        }
        throw new Error("`LngLatLike` argument must be specified as a LngLat instance, an object {lng: <lng>, lat: <lat>}, or an array of [<lng>, <lat>]");
    }
}

/**
 * A {@link LngLat} object, an array of two numbers representing longitude and latitude,
 * or an object with `lng` and `lat` properties.
 *
 * @typedef {LngLat | {lng: number, lat: number} | [number, number]} LngLatLike
 * @example
 * var v1 = new mapboxgl.LngLat(-122.420679, 37.772537);
 * var v2 = [-122.420679, 37.772537];
 */
export type LngLatLike = LngLat | {lng: number, lat: number} | [number, number];

export default LngLat;