63 lines
2.2 KiB
TypeScript
63 lines
2.2 KiB
TypeScript
/*
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* Vencord, a modification for Discord's desktop app
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* Copyright (c) 2022 Vendicated and contributors
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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import { React, useState } from "@webpack/common";
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import { checkIntersecting } from "./misc";
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/**
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* Check if an element is on screen
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* @param intersectOnly If `true`, will only update the state when the element comes into view
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* @returns [refCallback, isIntersecting]
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*/
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export const useIntersection = (intersectOnly = false): [
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refCallback: React.RefCallback<Element>,
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isIntersecting: boolean,
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] => {
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const observerRef = React.useRef<IntersectionObserver | null>(null);
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const [isIntersecting, setIntersecting] = useState(false);
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const refCallback = (element: Element | null) => {
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observerRef.current?.disconnect();
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observerRef.current = null;
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if (!element) return;
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if (checkIntersecting(element)) {
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setIntersecting(true);
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if (intersectOnly) return;
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}
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observerRef.current = new IntersectionObserver(entries => {
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for (const entry of entries) {
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if (entry.target !== element) continue;
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if (entry.isIntersecting && intersectOnly) {
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setIntersecting(true);
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observerRef.current?.disconnect();
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observerRef.current = null;
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} else {
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setIntersecting(entry.isIntersecting);
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}
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}
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});
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observerRef.current.observe(element);
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};
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return [refCallback, isIntersecting];
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};
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