drab/dist/wakelock/index.js

Interactivity for You

import { Announce, Content, Lifecycle, Trigger, } from "../base/index.js";
/**
 * `WakeLock` uses the
 * [WakeLock API](https://developer.mozilla.org/en-US/docs/Web/API/Screen_Wake_Lock_API)
 * to ensure the screen does not turn off when viewing the page on supported devices.
 * Use your best judgement for when this is necessary, for example, if you have a timer
 * that needs to stay on, or you are displaying a QR code.
 *
 * - Use `content` and `swap` elements to adjust the UI based on the current state.
 * - `trigger` is disabled if not supported.
 * - WakeLock is released when the element is removed from the DOM.
 *
 * ### Attributes
 *
 * `auto-lock`
 *
 * By default, the WakeLock will be released when the tab is not active. Use the
 * `auto-lock` attribute to automatically request the WakeLock when the user views
 * the tab again.
 *
 * `locked`
 *
 * WakeLock can be toggled with a `trigger`, or will be requested if the element has
 * a `locked` attribute when connected.
 */
export class WakeLock extends Lifecycle(Trigger(Content(Announce()))) {
    #wakeLock = null;
    constructor() {
        super();
    }
    /** If the WakeLock API is supported on the user's device. */
    #wakeLockSupported() {
        return "wakeLock" in navigator;
    }
    /**
     * the `auto-lock` attribute controls whether an active WakeLock should be restored when navigating back to
     *  the page.
     */
    get #autoLock() {
        return this.hasAttribute("auto-lock");
    }
    /** Requests WakeLock on the current page. */
    async request() {
        if (this.#wakeLockSupported() && document.visibilityState === "visible") {
            this.#wakeLock = await navigator.wakeLock.request("screen");
            this.setAttribute("locked", "");
            this.announce("screen wake lock activated");
            this.swap(false);
            this.#wakeLock.addEventListener("release", () => {
                this.removeAttribute("locked");
                this.announce("screen wake lock deactivated");
                this.swap(false);
                if (!this.#autoLock) {
                    // set to null is required, used to determine if screen should be
                    // locked again, see visibilitychange listener
                    this.#wakeLock = null;
                }
            });
        }
    }
    /** Releases the WakeLock, sets `this.wakeLock` to null. */
    async release() {
        await this.#wakeLock?.release();
        this.#wakeLock = null;
    }
    mount() {
        // lock on mount if the `locked` attribute is present
        if (this.hasAttribute("locked")) {
            this.request();
        }
        this.listener(() => {
            // toggle
            if (this.#wakeLock) {
                this.release();
            }
            else {
                this.request();
            }
        });
        for (const trigger of this.triggers()) {
            if (!this.#wakeLockSupported() && "disabled" in trigger) {
                // disable `trigger` if not supported
                trigger.disabled = true;
            }
        }
        if (this.#autoLock) {
            this.safeListener("visibilitychange", () => {
                // When the tab is not visible, the wakeLock is automatically released.
                // This requests it back if it exists, if it is `null`, that
                // means it was removed. In which case, it shouldn't be requested again.
                if (this.#wakeLock) {
                    this.request();
                }
            }, document);
        }
    }
    destroy() {
        this.release();
    }
}