openglobus/src/og/Clock.js

/**
 * @module og/Clock
 */

'use strict';

import { Events } from './Events.js';
import * as jd from './astro/jd.js';

/**
 * Class represents application timer that stores custom current julian datetime, and time speed multiplier.
 * @class
 * @param {Object} [params]: - Clock parameters:
 * @param {number} [params.startDate=0.0] - Julian start date.
 * @param {number} [params.endDate=0.0] - Julian end date.
 * @param {number} [params.currentDate] - Julian current date. Default: current date.
 * @param {number} [params.multiplier=1.0] - Time speed multiolier.
 */
class Clock {

    static get _staticCounter() {
        if (!this._counter && this._counter !== 0) {
            this._counter = 0;
        }
        return this._counter;
    }

    static set _staticCounter(n) {
        this._counter = n;
    }

    constructor(params) {
        params = params || {};

        this._id = Clock._staticCounter++;

        /**
         * Clock name.
         * @public
         * @type {string}
         */
        this.name = params.name || "";

        /**
         * Clock events.
         * @public
         * @type {Events}
         */
        this.events = new Events([
            "tick",
            "end"
        ]);

        /**
         * Start julian date clock loop.
         * @public
         * @type {number}
         */
        this.startDate = params.startDate || 0;

        /**
         * End julian date clock loop.
         * @public
         * @type {number}
         */
        this.endDate = params.endDate || 0;

        var currentDate = params.currentDate || jd.DateToUTC(new Date());
        if (params.startDate && currentDate < params.startDate) {
            currentDate = params.startDate;
        }
        if (params.endDate && currentDate > params.endDate) {
            currentDate = params.endDate;
        }

        /**
         * Current julian datetime.
         * @public
         * @type {number}
         */
        this.currentDate = currentDate;

        /**
         * Timer speed multiplier.
         * @public
         * @type {number}
         */
        this.multiplier = params.multiplier !== undefined ? params.multiplier : 1.0;

        /**
         * Animation frame delta time.
         * @public
         * @readonly
         * @type {number}
         */
        this.deltaTicks = 0;

        /**
         * Timer activity.
         * @public
         * @type {boolean}
         */
        this.active = true;
    }

    /**
     * Sets current clock datetime.
     * @public
     * @param {Object} date - JavaScript Date object.
     */
    setDate(date) {
        var d = jd.DateToUTC(date);
        if (this.startDate && d < this.startDate) {
            d = this.startDate;
        }
        if (this.endDate && d > this.endDate) {
            d = this.endDate;
        }
        this.currentDate = d;
    }

    /**
     * Returns current application date.
     * @public
     * @returns {Date} - Current date.
     */
    getDate() {
        return jd.UTCtoDate(this.currentDate);
    }

    reset() {
        if (this.startDate) {
            this.currentDate = this.startDate;
        }
    }

    _tick(dt) {
        this.deltaTicks = dt * this.multiplier;
        if (this.active) {
            var cd = jd.addMilliseconds(this.currentDate, this.deltaTicks);
            if (this.multiplier > 0) {
                if (this.endDate && cd > this.endDate) {
                    this.currentDate = this.startDate;
                    this.events.dispatch(this.events.end, this);
                } else {
                    this.currentDate = cd;
                }
            } else {
                if (this.startDate && cd < this.startDate) {
                    this.currentDate = this.endDate;
                    this.events.dispatch(this.events.end, this);
                } else {
                    this.currentDate = cd;
                }
            }
            this.events.dispatch(this.events.tick, this);
        }
    }

    /**
     * @public
     * @param {Clock} clock - Clock instance to compare.
     * @returns {boolean} - Returns true if a clock is the same instance.
     */
    equal(clock) {
        return this._id === clock._id;
    }
};

export { Clock };