@woosh/meep-engine/src/engine/graphics/FrameRunner.js

Pure JavaScript game engine. Fully featured and production ready.

import { current_time_in_seconds } from "../../core/time/current_time_in_seconds.js";

/**
 *
 * @type {number}
 */
let global_count = 0;

/**
 * Fires a given function every frame. Typical usage is to create an instance, invoke {@link #startup} and once no longer required - invoke {@link #shutdown}
 * Wraps {@link requestAnimationFrame}
 */
export class FrameRunner {
    /**
     *
     * @type {boolean}
     */
    #running = false;
    /**
     *
     * @type {number}
     */
    #animationFrameId = -1;

    /**
     *
     * @param {function(time_delta_sectonds?:number, current_time_seconds?:number):*} action
     */
    constructor(action) {
        /**
         *
         * @type {Function}
         */
        this.action = action;
    }

    /**
     * Begins animation loop. Does nothing and returns false if already running.
     * @returns {boolean}
     */
    startup() {
        if (this.#running) {
            return false;
        }

        // console.warn(`FrameFunner.started[${global_count}]`);

        global_count++;

        this.#running = true;

        let last_time_stamp = current_time_in_seconds();

        const cycle = () => {
            if (!this.#running) {
                //not supposed to be running, bail
                return;
            }

            const current_time = current_time_in_seconds();

            const time_delta = current_time - last_time_stamp;

            last_time_stamp = current_time;

            this.action(time_delta, current_time);

            this.#animationFrameId = requestAnimationFrame(cycle);
        }

        this.#animationFrameId = requestAnimationFrame(cycle);

        return true;
    }

    /**
     * Stops animation loop. Does nothing and returns false if not currently running.
     * @returns {boolean}
     */
    shutdown() {
        if (!this.#running) {
            return false;
        }

        global_count--;

        // console.warn(`FrameFunner.stopped[${global_count}]`);

        this.#running = false;
        cancelAnimationFrame(this.#animationFrameId);

        this.#animationFrameId = -1;

        return true;
    }

    /**
     *
     * @returns {boolean}
     */
    isRunning() {
        return this.#running;
    }
}