import React from 'react'; import PropTypes from 'prop-types'; import ImmutablePureComponent from 'react-immutable-pure-component'; import scheduleIdleTask from '../features/ui/util/schedule_idle_task'; import getRectFromEntry from '../features/ui/util/get_rect_from_entry'; export default class IntersectionObserverArticle extends ImmutablePureComponent { static propTypes = { intersectionObserverWrapper: PropTypes.object, id: PropTypes.oneOfType([PropTypes.string, PropTypes.number]), index: PropTypes.oneOfType([PropTypes.string, PropTypes.number]), listLength: PropTypes.oneOfType([PropTypes.string, PropTypes.number]), children: PropTypes.node, }; state = { isHidden: false, // set to true in requestIdleCallback to trigger un-render } shouldComponentUpdate (nextProps, nextState) { if (!nextState.isIntersecting && nextState.isHidden) { // It's only if we're not intersecting (i.e. offscreen) and isHidden is true // that either "isIntersecting" or "isHidden" matter, and then they're // the only things that matter (and updated ARIA attributes). return this.state.isIntersecting || !this.state.isHidden || nextProps.listLength !== this.props.listLength; } else if (nextState.isIntersecting && !this.state.isIntersecting) { // If we're going from a non-intersecting state to an intersecting state, // (i.e. offscreen to onscreen), then we definitely need to re-render return true; } // Otherwise, diff based on "updateOnProps" and "updateOnStates" return super.shouldComponentUpdate(nextProps, nextState); } componentDidMount () { if (!this.props.intersectionObserverWrapper) { // TODO: enable IntersectionObserver optimization for notification statuses. // These are managed in notifications/index.js rather than status_list.js return; } this.props.intersectionObserverWrapper.observe( this.props.id, this.node, this.handleIntersection ); this.componentMounted = true; } componentWillUnmount () { if (this.props.intersectionObserverWrapper) { this.props.intersectionObserverWrapper.unobserve(this.props.id, this.node); } this.componentMounted = false; } handleIntersection = (entry) => { if (this.node && this.node.children.length !== 0) { // save the height of the fully-rendered element this.height = getRectFromEntry(entry).height; if (this.props.onHeightChange) { this.props.onHeightChange(this.props.status, this.height); } } this.setState((prevState) => { if (prevState.isIntersecting && !entry.isIntersecting) { scheduleIdleTask(this.hideIfNotIntersecting); } return { isIntersecting: entry.isIntersecting, isHidden: false, }; }); } hideIfNotIntersecting = () => { if (!this.componentMounted) { return; } // When the browser gets a chance, test if we're still not intersecting, // and if so, set our isHidden to true to trigger an unrender. The point of // this is to save DOM nodes and avoid using up too much memory. // See: https://github.com/tootsuite/mastodon/issues/2900 this.setState((prevState) => ({ isHidden: !prevState.isIntersecting })); } handleRef = (node) => { this.node = node; } render () { const { children, id, index, listLength } = this.props; const { isIntersecting, isHidden } = this.state; if (!isIntersecting && isHidden) { return (
{children && React.cloneElement(children, { hidden: true })}
); } return (
{children && React.cloneElement(children, { hidden: false })}
); } }