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Add IntersectionObserverWrapper to cut down on re-renders (#3406)

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Nolan Lawson 2017-05-29 09:17:51 -07:00 • committed by Eugen Rochko
parent 922fb74197
commit 34a93ccf57
3 changed files with 100 additions and 79 deletions
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65
app/javascript/mastodon/components/status_list.js
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@ -5,6 +5,7 @@ import PropTypes from 'prop-types';
import StatusContainer from '../containers/status_container';
import LoadMore from './load_more';
import ImmutablePureComponent from 'react-immutable-pure-component';
import IntersectionObserverWrapper from '../features/ui/util/intersection_observer_wrapper';
class StatusList extends ImmutablePureComponent {
@ -26,12 +27,7 @@ class StatusList extends ImmutablePureComponent {
trackScroll: true,
};
state = {
isIntersecting: {},
intersectionCount: 0,
}
statusRefQueue = []
intersectionObserverWrapper = new IntersectionObserverWrapper();
handleScroll = (e) => {
const { scrollTop, scrollHeight, clientHeight } = e.target;
@ -64,53 +60,14 @@ class StatusList extends ImmutablePureComponent {
}
attachIntersectionObserver () {
const onIntersection = (entries) => {
this.setState(state => {
entries.forEach(entry => {
const statusId = entry.target.getAttribute('data-id');
// Edge 15 doesn't support isIntersecting, but we can infer it from intersectionRatio
// https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/12156111/
state.isIntersecting[statusId] = entry.intersectionRatio > 0;
});
// isIntersecting is a map of DOM data-id's to booleans (true for
// intersecting, false for non-intersecting).
//
// We always want to return true in shouldComponentUpdate() if
// this object changes, because onIntersection() is only called if
// something has changed.
//
// Now, we *could* use an immutable map or some other structure to
// diff the full map, but that would be pointless because the browser
// has already informed us that something has changed. So we can just
// use a regular object, which will be diffed by ImmutablePureComponent
// based on reference equality (i.e. it's always "unchanged") and
// then we just increment intersectionCount to force a change.
return {
isIntersecting: state.isIntersecting,
intersectionCount: state.intersectionCount + 1,
};
});
};
const options = {
this.intersectionObserverWrapper.connect({
root: this.node,
rootMargin: '300% 0px',
};
this.intersectionObserver = new IntersectionObserver(onIntersection, options);
if (this.statusRefQueue.length) {
this.statusRefQueue.forEach(node => this.intersectionObserver.observe(node));
this.statusRefQueue = [];
}
});
}
detachIntersectionObserver () {
this.intersectionObserver.disconnect();
this.intersectionObserverWrapper.disconnect();
}
attachScrollListener () {
@ -125,15 +82,6 @@ class StatusList extends ImmutablePureComponent {
this.node = c;
}
handleStatusRef = (node) => {
if (node && this.intersectionObserver) {
const statusId = node.getAttribute('data-id');
this.intersectionObserver.observe(node);
} else {
this.statusRefQueue.push(node);
}
}
handleLoadMore = (e) => {
e.preventDefault();
this.props.onScrollToBottom();
@ -141,7 +89,6 @@ class StatusList extends ImmutablePureComponent {
render () {
const { statusIds, onScrollToBottom, scrollKey, shouldUpdateScroll, isLoading, isUnread, hasMore, prepend, emptyMessage } = this.props;
const { isIntersecting } = this.state;
let loadMore = null;
let scrollableArea = null;
@ -164,7 +111,7 @@ class StatusList extends ImmutablePureComponent {
{prepend}
{statusIds.map((statusId) => {
return <StatusContainer key={statusId} id={statusId} isIntersecting={isIntersecting[statusId]} onRef={this.handleStatusRef} />;
return <StatusContainer key={statusId} id={statusId} intersectionObserverWrapper={this.intersectionObserverWrapper} />;
})}
{loadMore}