1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
import React from 'react';
import PropTypes from 'prop-types';
import scheduleIdleTask from '../features/ui/util/schedule_idle_task';
import getRectFromEntry from '../features/ui/util/get_rect_from_entry';
// Diff these props in the "unrendered" state
const updateOnPropsForUnrendered = ['id', 'index', 'listLength', 'cachedHeight'];
export default class IntersectionObserverArticle extends React.Component {
static propTypes = {
intersectionObserverWrapper: PropTypes.object.isRequired,
id: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
index: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
listLength: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
saveHeightKey: PropTypes.string,
cachedHeight: PropTypes.number,
onHeightChange: PropTypes.func,
children: PropTypes.node,
};
state = {
isHidden: false, // set to true in requestIdleCallback to trigger un-render
}
shouldComponentUpdate (nextProps, nextState) {
const isUnrendered = !this.state.isIntersecting && (this.state.isHidden || this.props.cachedHeight);
const willBeUnrendered = !nextState.isIntersecting && (nextState.isHidden || nextProps.cachedHeight);
if (!!isUnrendered !== !!willBeUnrendered) {
// If we're going from rendered to unrendered (or vice versa) then update
return true;
}
// If we are and remain hidden, diff based on props
if (isUnrendered) {
return !updateOnPropsForUnrendered.every(prop => nextProps[prop] === this.props[prop]);
}
// Else, assume the children have changed
return true;
}
componentDidMount () {
const { intersectionObserverWrapper, id } = this.props;
intersectionObserverWrapper.observe(
id,
this.node,
this.handleIntersection,
);
this.componentMounted = true;
}
componentWillUnmount () {
const { intersectionObserverWrapper, id } = this.props;
intersectionObserverWrapper.unobserve(id, this.node);
this.componentMounted = false;
}
handleIntersection = (entry) => {
this.entry = entry;
scheduleIdleTask(this.calculateHeight);
this.setState(this.updateStateAfterIntersection);
}
updateStateAfterIntersection = (prevState) => {
if (prevState.isIntersecting !== false && !this.entry.isIntersecting) {
scheduleIdleTask(this.hideIfNotIntersecting);
}
return {
isIntersecting: this.entry.isIntersecting,
isHidden: false,
};
}
calculateHeight = () => {
const { onHeightChange, saveHeightKey, id } = this.props;
// save the height of the fully-rendered element (this is expensive
// on Chrome, where we need to fall back to getBoundingClientRect)
this.height = getRectFromEntry(this.entry).height;
if (onHeightChange && saveHeightKey) {
onHeightChange(saveHeightKey, id, this.height);
}
}
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/mastodon/mastodon/issues/2900
this.setState((prevState) => ({ isHidden: !prevState.isIntersecting }));
}
handleRef = (node) => {
this.node = node;
}
render () {
const { children, id, index, listLength, cachedHeight } = this.props;
const { isIntersecting, isHidden } = this.state;
const style = {};
if (!isIntersecting && (isHidden || cachedHeight)) {
style.height = `${this.height || cachedHeight || 150}px`;
style.opacity = 0;
style.overflow = 'hidden';
}
return (
<article
ref={this.handleRef}
aria-posinset={index + 1}
aria-setsize={listLength}
data-id={id}
tabIndex='0'
style={style}>
{children && React.cloneElement(children, { hidden: !isIntersecting && (isHidden || !!cachedHeight) })}
</article>
);
}
}
|