import React, { PureComponent } from 'react'; import ScrollContainer from 'mastodon/containers/scroll_container'; import PropTypes from 'prop-types'; import IntersectionObserverArticleContainer from '../containers/intersection_observer_article_container'; import LoadMore from './load_more'; import LoadPending from './load_pending'; import IntersectionObserverWrapper from '../features/ui/util/intersection_observer_wrapper'; import { throttle } from 'lodash'; import { List as ImmutableList } from 'immutable'; import classNames from 'classnames'; import { supportsPassiveEvents } from 'detect-passive-events'; import { attachFullscreenListener, detachFullscreenListener, isFullscreen } from '../features/ui/util/fullscreen'; import LoadingIndicator from './loading_indicator'; import { connect } from 'react-redux'; const MOUSE_IDLE_DELAY = 300; const mapStateToProps = (state, { scrollKey }) => { return { preventScroll: scrollKey === state.getIn(['dropdown_menu', 'scroll_key']), }; }; class ScrollableList extends PureComponent { static contextTypes = { router: PropTypes.object, }; static propTypes = { scrollKey: PropTypes.string.isRequired, onLoadMore: PropTypes.func, onLoadPending: PropTypes.func, onScrollToTop: PropTypes.func, onScroll: PropTypes.func, trackScroll: PropTypes.bool, isLoading: PropTypes.bool, showLoading: PropTypes.bool, hasMore: PropTypes.bool, numPending: PropTypes.number, prepend: PropTypes.node, append: PropTypes.node, alwaysPrepend: PropTypes.bool, emptyMessage: PropTypes.node, children: PropTypes.node, bindToDocument: PropTypes.bool, preventScroll: PropTypes.bool, }; static defaultProps = { trackScroll: true, }; state = { fullscreen: null, cachedMediaWidth: 250, // Default media/card width using default Mastodon theme }; intersectionObserverWrapper = new IntersectionObserverWrapper(); handleScroll = throttle(() => { if (this.node) { const scrollTop = this.getScrollTop(); const scrollHeight = this.getScrollHeight(); const clientHeight = this.getClientHeight(); const offset = scrollHeight - scrollTop - clientHeight; if (400 > offset && this.props.onLoadMore && this.props.hasMore && !this.props.isLoading) { this.props.onLoadMore(); } if (scrollTop < 100 && this.props.onScrollToTop) { this.props.onScrollToTop(); } else if (this.props.onScroll) { this.props.onScroll(); } if (!this.lastScrollWasSynthetic) { // If the last scroll wasn't caused by setScrollTop(), assume it was // intentional and cancel any pending scroll reset on mouse idle this.scrollToTopOnMouseIdle = false; } this.lastScrollWasSynthetic = false; } }, 150, { trailing: true, }); mouseIdleTimer = null; mouseMovedRecently = false; lastScrollWasSynthetic = false; scrollToTopOnMouseIdle = false; _getScrollingElement = () => { if (this.props.bindToDocument) { return (document.scrollingElement || document.body); } else { return this.node; } }; setScrollTop = newScrollTop => { if (this.getScrollTop() !== newScrollTop) { this.lastScrollWasSynthetic = true; this._getScrollingElement().scrollTop = newScrollTop; } }; clearMouseIdleTimer = () => { if (this.mouseIdleTimer === null) { return; } clearTimeout(this.mouseIdleTimer); this.mouseIdleTimer = null; }; handleMouseMove = throttle(() => { // As long as the mouse keeps moving, clear and restart the idle timer. this.clearMouseIdleTimer(); this.mouseIdleTimer = setTimeout(this.handleMouseIdle, MOUSE_IDLE_DELAY); if (!this.mouseMovedRecently && this.getScrollTop() === 0) { // Only set if we just started moving and are scrolled to the top. this.scrollToTopOnMouseIdle = true; } // Save setting this flag for last, so we can do the comparison above. this.mouseMovedRecently = true; }, MOUSE_IDLE_DELAY / 2); handleWheel = throttle(() => { this.scrollToTopOnMouseIdle = false; }, 150, { trailing: true, }); handleMouseIdle = () => { if (this.scrollToTopOnMouseIdle && !this.props.preventScroll) { this.setScrollTop(0); } this.mouseMovedRecently = false; this.scrollToTopOnMouseIdle = false; }; componentDidMount () { this.attachScrollListener(); this.attachIntersectionObserver(); attachFullscreenListener(this.onFullScreenChange); // Handle initial scroll position this.handleScroll(); } getScrollPosition = () => { if (this.node && (this.getScrollTop() > 0 || this.mouseMovedRecently)) { return { height: this.getScrollHeight(), top: this.getScrollTop() }; } else { return null; } }; getScrollTop = () => { return this._getScrollingElement().scrollTop; }; getScrollHeight = () => { return this._getScrollingElement().scrollHeight; }; getClientHeight = () => { return this._getScrollingElement().clientHeight; }; updateScrollBottom = (snapshot) => { const newScrollTop = this.getScrollHeight() - snapshot; this.setScrollTop(newScrollTop); }; getSnapshotBeforeUpdate (prevProps) { const someItemInserted = React.Children.count(prevProps.children) > 0 && React.Children.count(prevProps.children) < React.Children.count(this.props.children) && this.getFirstChildKey(prevProps) !== this.getFirstChildKey(this.props); const pendingChanged = (prevProps.numPending > 0) !== (this.props.numPending > 0); if (pendingChanged || someItemInserted && (this.getScrollTop() > 0 || this.mouseMovedRecently || this.props.preventScroll)) { return this.getScrollHeight() - this.getScrollTop(); } else { return null; } } componentDidUpdate (prevProps, prevState, snapshot) { // Reset the scroll position when a new child comes in in order not to // jerk the scrollbar around if you're already scrolled down the page. if (snapshot !== null) { this.setScrollTop(this.getScrollHeight() - snapshot); } } cacheMediaWidth = (width) => { if (width && this.state.cachedMediaWidth !== width) { this.setState({ cachedMediaWidth: width }); } }; componentWillUnmount () { this.clearMouseIdleTimer(); this.detachScrollListener(); this.detachIntersectionObserver(); detachFullscreenListener(this.onFullScreenChange); } onFullScreenChange = () => { this.setState({ fullscreen: isFullscreen() }); }; attachIntersectionObserver () { let nodeOptions = { root: this.node, rootMargin: '300% 0px', }; this.intersectionObserverWrapper .connect(this.props.bindToDocument ? {} : nodeOptions); } detachIntersectionObserver () { this.intersectionObserverWrapper.disconnect(); } attachScrollListener () { if (this.props.bindToDocument) { document.addEventListener('scroll', this.handleScroll); document.addEventListener('wheel', this.handleWheel, supportsPassiveEvents ? { passive: true } : undefined); } else { this.node.addEventListener('scroll', this.handleScroll); this.node.addEventListener('wheel', this.handleWheel, supportsPassiveEvents ? { passive: true } : undefined); } } detachScrollListener () { if (this.props.bindToDocument) { document.removeEventListener('scroll', this.handleScroll); document.removeEventListener('wheel', this.handleWheel); } else { this.node.removeEventListener('scroll', this.handleScroll); this.node.removeEventListener('wheel', this.handleWheel); } } getFirstChildKey (props) { const { children } = props; let firstChild = children; if (children instanceof ImmutableList) { firstChild = children.get(0); } else if (Array.isArray(children)) { firstChild = children[0]; } return firstChild && firstChild.key; } setRef = (c) => { this.node = c; }; handleLoadMore = e => { e.preventDefault(); this.props.onLoadMore(); }; handleLoadPending = e => { e.preventDefault(); this.props.onLoadPending(); // Prevent the weird scroll-jumping behavior, as we explicitly don't want to // scroll to top, and we know the scroll height is going to change this.scrollToTopOnMouseIdle = false; this.lastScrollWasSynthetic = false; this.clearMouseIdleTimer(); this.mouseIdleTimer = setTimeout(this.handleMouseIdle, MOUSE_IDLE_DELAY); this.mouseMovedRecently = true; }; render () { const { children, scrollKey, trackScroll, showLoading, isLoading, hasMore, numPending, prepend, alwaysPrepend, append, emptyMessage, onLoadMore } = this.props; const { fullscreen } = this.state; const childrenCount = React.Children.count(children); const loadMore = (hasMore && onLoadMore) ? <LoadMore visible={!isLoading} onClick={this.handleLoadMore} /> : null; const loadPending = (numPending > 0) ? <LoadPending count={numPending} onClick={this.handleLoadPending} /> : null; let scrollableArea = null; if (showLoading) { scrollableArea = ( <div className='scrollable scrollable--flex' ref={this.setRef}> <div role='feed' className='item-list'> {prepend} </div> <div className='scrollable__append'> <LoadingIndicator /> </div> </div> ); } else if (isLoading || childrenCount > 0 || numPending > 0 || hasMore || !emptyMessage) { scrollableArea = ( <div className={classNames('scrollable', { fullscreen })} ref={this.setRef} onMouseMove={this.handleMouseMove}> <div role='feed' className='item-list'> {prepend} {loadPending} {React.Children.map(this.props.children, (child, index) => ( <IntersectionObserverArticleContainer key={child.key} id={child.key} index={index} listLength={childrenCount} intersectionObserverWrapper={this.intersectionObserverWrapper} saveHeightKey={trackScroll ? `${this.context.router.route.location.key}:${scrollKey}` : null} > {React.cloneElement(child, { getScrollPosition: this.getScrollPosition, updateScrollBottom: this.updateScrollBottom, cachedMediaWidth: this.state.cachedMediaWidth, cacheMediaWidth: this.cacheMediaWidth, })} </IntersectionObserverArticleContainer> ))} {loadMore} {!hasMore && append} </div> </div> ); } else { scrollableArea = ( <div className={classNames('scrollable scrollable--flex', { fullscreen })} ref={this.setRef}> {alwaysPrepend && prepend} <div className='empty-column-indicator'> {emptyMessage} </div> </div> ); } if (trackScroll) { return ( <ScrollContainer scrollKey={scrollKey}> {scrollableArea} </ScrollContainer> ); } else { return scrollableArea; } } } export default connect(mapStateToProps, null, null, { forwardRef: true })(ScrollableList);