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