87 lines
2.1 KiB
TypeScript
87 lines
2.1 KiB
TypeScript
// Copyright 2023 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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import { useContext, createContext, useEffect, useRef } from 'react';
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import * as log from '../logging/log';
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export type ScrollerLock = Readonly<{
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isLocked(): boolean;
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lock(reason: string, onUserInterrupt: () => void): () => void;
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onUserInterrupt(reason: string): void;
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}>;
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export function createScrollerLock(
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title: string,
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onUpdate: () => void
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): ScrollerLock {
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const locks = new Set<() => void>();
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let lastUpdate: boolean | null = null;
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function update() {
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const isLocked = locks.size > 0;
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if (isLocked !== lastUpdate) {
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lastUpdate = isLocked;
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onUpdate();
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}
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}
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return {
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isLocked() {
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return locks.size > 0;
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},
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lock(reason, onUserInterrupt) {
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log.info('ScrollerLock: Locking', title, reason);
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locks.add(onUserInterrupt);
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update();
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function release() {
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log.info('ScrollerLock: Releasing', title, reason);
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locks.delete(onUserInterrupt);
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update();
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}
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return release;
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},
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onUserInterrupt(reason) {
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// Ignore interuptions if we're not locked
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if (locks.size > 0) {
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log.info('ScrollerLock: User Interrupt', title, reason);
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locks.forEach(listener => listener());
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locks.clear();
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update();
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}
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},
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};
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}
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export const ScrollerLockContext = createContext<ScrollerLock | null>(null);
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export type ScrollLockProps = Readonly<{
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reason: string;
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lockScrollWhen: boolean;
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onUserInterrupt(): void;
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}>;
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export function useScrollerLock({
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reason,
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lockScrollWhen,
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onUserInterrupt,
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}: ScrollLockProps): void {
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const scrollerLock = useContext(ScrollerLockContext);
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if (scrollerLock == null) {
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throw new Error('Missing <ScrollLockProvider/>');
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}
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const onUserInterruptRef = useRef(onUserInterrupt);
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useEffect(() => {
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onUserInterruptRef.current = onUserInterrupt;
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}, [onUserInterrupt]);
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useEffect(() => {
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if (lockScrollWhen) {
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return scrollerLock.lock(reason, () => {
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onUserInterruptRef.current();
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});
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}
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return undefined;
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}, [reason, scrollerLock, lockScrollWhen, onUserInterrupt]);
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}
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