64 lines
3.2 KiB
TypeScript
64 lines
3.2 KiB
TypeScript
/*
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* Copyright 2024 Adobe. All rights reserved.
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* This file is licensed to you under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License. You may obtain a copy
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* of the License at http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software distributed under
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* the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
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* OF ANY KIND, either express or implied. See the License for the specific language
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* governing permissions and limitations under the License.
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*/
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import type {AsyncLoadable, Collection} from '@react-types/shared';
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import {getScrollParent} from './getScrollParent';
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import {RefObject, useRef} from 'react';
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import {useEffectEvent} from './useEffectEvent';
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import {useLayoutEffect} from './useLayoutEffect';
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export interface LoadMoreSentinelProps extends Omit<AsyncLoadable, 'isLoading'> {
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collection: Collection<any>,
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/**
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* The amount of offset from the bottom of your scrollable region that should trigger load more.
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* Uses a percentage value relative to the scroll body's client height. Load more is then triggered
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* when your current scroll position's distance from the bottom of the currently loaded list of items is less than
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* or equal to the provided value. (e.g. 1 = 100% of the scroll region's height).
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* @default 1
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*/
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scrollOffset?: number
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}
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export function useLoadMoreSentinel(props: LoadMoreSentinelProps, ref: RefObject<HTMLElement | null>): void {
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let {collection, onLoadMore, scrollOffset = 1} = props;
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let sentinelObserver = useRef<IntersectionObserver>(null);
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let triggerLoadMore = useEffectEvent((entries: IntersectionObserverEntry[]) => {
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// Use "isIntersecting" over an equality check of 0 since it seems like there is cases where
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// a intersection ratio of 0 can be reported when isIntersecting is actually true
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for (let entry of entries) {
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// Note that this will be called if the collection changes, even if onLoadMore was already called and is being processed.
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// Up to user discretion as to how to handle these multiple onLoadMore calls
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if (entry.isIntersecting && onLoadMore) {
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onLoadMore();
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}
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}
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});
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useLayoutEffect(() => {
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if (ref.current) {
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// Tear down and set up a new IntersectionObserver when the collection changes so that we can properly trigger additional loadMores if there is room for more items
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// Need to do this tear down and set up since using a large rootMargin will mean the observer's callback isn't called even when scrolling the item into view beause its visibility hasn't actually changed
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// https://codesandbox.io/p/sandbox/magical-swanson-dhgp89?file=%2Fsrc%2FApp.js%3A21%2C21
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sentinelObserver.current = new IntersectionObserver(triggerLoadMore, {root: getScrollParent(ref?.current) as HTMLElement, rootMargin: `0px ${100 * scrollOffset}% ${100 * scrollOffset}% ${100 * scrollOffset}%`});
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sentinelObserver.current.observe(ref.current);
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}
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return () => {
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if (sentinelObserver.current) {
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sentinelObserver.current.disconnect();
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}
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};
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}, [collection, ref, scrollOffset]);
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}
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