ThreadCount
c89010a4f1
Uniform stock management for healthcare linen rooms: the coordinator app, the phone counter and the staff app, for your own server. Built from f976bd5 on 2026-09-15. Licensed under the Functional Source License (FSL-1.1-ALv2).
46 lines
2.1 KiB
TypeScript
46 lines
2.1 KiB
TypeScript
"use client";
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/* Keep the screen on while a count is open.
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*
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* A shelf count is minutes of handling garments with the phone held low, and Android's display
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* timeout is often fifteen seconds. Waking the phone, unlocking it and finding your place again
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* every few garments is the difference between counting a bay and giving up on it.
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*
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* This is the Screen Wake Lock API rather than a Capacitor plugin, which means it works the same
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* in the Android shell and in mobile Chrome, and needs no permission — only a secure context,
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* which /m always has. Android drops the lock whenever the page is hidden, so it is re-taken on
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* the way back from a phone call or the app switcher. */
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import { useEffect } from "react";
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type Sentinel = { released: boolean; release: () => Promise<void>; addEventListener: (t: string, f: () => void) => void };
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type WakeLockNav = Navigator & { wakeLock?: { request: (type: "screen") => Promise<Sentinel> } };
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/** Holds a screen wake lock for as long as `active` is true. A no-op where it isn't supported. */
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export function useKeepAwake(active: boolean) {
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useEffect(() => {
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if (!active) return;
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const nav = navigator as WakeLockNav;
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if (!nav.wakeLock) return; // older WebView, or an insecure origin
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let sentinel: Sentinel | null = null;
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let dropped = false;
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const take = async () => {
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if (dropped || sentinel || document.visibilityState !== "visible") return;
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try {
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sentinel = await nav.wakeLock!.request("screen");
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// The system releases it on its own terms too; forget the handle when it does.
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sentinel.addEventListener("release", () => { sentinel = null; });
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} catch { /* battery saver refuses it — the screen just times out as usual */ }
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};
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const onVisible = () => { if (document.visibilityState === "visible") void take(); };
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void take();
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document.addEventListener("visibilitychange", onVisible);
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return () => {
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dropped = true;
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document.removeEventListener("visibilitychange", onVisible);
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if (sentinel && !sentinel.released) sentinel.release().catch(() => {});
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sentinel = null;
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};
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}, [active]);
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}
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