131 lines
4 KiB
JavaScript
131 lines
4 KiB
JavaScript
import React from 'react';
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import PropTypes from 'prop-types';
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import scheduleIdleTask from '../features/ui/util/schedule_idle_task';
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import getRectFromEntry from '../features/ui/util/get_rect_from_entry';
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// Diff these props in the "unrendered" state
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const updateOnPropsForUnrendered = ['id', 'index', 'listLength', 'cachedHeight'];
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export default class IntersectionObserverArticle extends React.Component {
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static propTypes = {
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intersectionObserverWrapper: PropTypes.object.isRequired,
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id: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
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index: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
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listLength: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
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saveHeightKey: PropTypes.string,
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cachedHeight: PropTypes.number,
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onHeightChange: PropTypes.func,
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children: PropTypes.node,
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};
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state = {
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isHidden: false, // set to true in requestIdleCallback to trigger un-render
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};
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shouldComponentUpdate (nextProps, nextState) {
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const isUnrendered = !this.state.isIntersecting && (this.state.isHidden || this.props.cachedHeight);
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const willBeUnrendered = !nextState.isIntersecting && (nextState.isHidden || nextProps.cachedHeight);
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if (!!isUnrendered !== !!willBeUnrendered) {
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// If we're going from rendered to unrendered (or vice versa) then update
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return true;
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}
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// If we are and remain hidden, diff based on props
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if (isUnrendered) {
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return !updateOnPropsForUnrendered.every(prop => nextProps[prop] === this.props[prop]);
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}
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// Else, assume the children have changed
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return true;
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}
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componentDidMount () {
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const { intersectionObserverWrapper, id } = this.props;
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intersectionObserverWrapper.observe(
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id,
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this.node,
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this.handleIntersection,
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);
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this.componentMounted = true;
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}
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componentWillUnmount () {
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const { intersectionObserverWrapper, id } = this.props;
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intersectionObserverWrapper.unobserve(id, this.node);
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this.componentMounted = false;
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}
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handleIntersection = (entry) => {
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this.entry = entry;
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scheduleIdleTask(this.calculateHeight);
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this.setState(this.updateStateAfterIntersection);
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};
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updateStateAfterIntersection = (prevState) => {
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if (prevState.isIntersecting !== false && !this.entry.isIntersecting) {
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scheduleIdleTask(this.hideIfNotIntersecting);
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}
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return {
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isIntersecting: this.entry.isIntersecting,
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isHidden: false,
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};
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};
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calculateHeight = () => {
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const { onHeightChange, saveHeightKey, id } = this.props;
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// save the height of the fully-rendered element (this is expensive
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// on Chrome, where we need to fall back to getBoundingClientRect)
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this.height = getRectFromEntry(this.entry).height;
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if (onHeightChange && saveHeightKey) {
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onHeightChange(saveHeightKey, id, this.height);
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}
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};
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hideIfNotIntersecting = () => {
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if (!this.componentMounted) {
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return;
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}
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// When the browser gets a chance, test if we're still not intersecting,
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// and if so, set our isHidden to true to trigger an unrender. The point of
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// this is to save DOM nodes and avoid using up too much memory.
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// See: https://github.com/mastodon/mastodon/issues/2900
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this.setState((prevState) => ({ isHidden: !prevState.isIntersecting }));
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};
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handleRef = (node) => {
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this.node = node;
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};
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render () {
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const { children, id, index, listLength, cachedHeight } = this.props;
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const { isIntersecting, isHidden } = this.state;
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const style = {};
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if (!isIntersecting && (isHidden || cachedHeight)) {
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style.height = `${this.height || cachedHeight || 150}px`;
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style.opacity = 0;
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style.overflow = 'hidden';
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}
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return (
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<article
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ref={this.handleRef}
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aria-posinset={index + 1}
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aria-setsize={listLength}
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data-id={id}
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tabIndex={0}
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style={style}
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>
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{children && React.cloneElement(children, { hidden: !isIntersecting && (isHidden || !!cachedHeight) })}
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</article>
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);
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}
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}
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