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fall back to InteractionObserver for detecting timeline resizes

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this is not nearly as smooth as using ResizeObserver, as the
callback rate is a lot lower, but seems to be quite a bit better
than what we have right now, without the 7% cpu hog that
the requestAnimationFrame polling fallback has.
This commit is contained in:
Bruno Windels 2019-02-22 18:30:22 +01:00
parent 8bb8ec141e
commit ba5f16358f
1 changed files with 27 additions and 6 deletions
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33
src/components/structures/ScrollPanel.js
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@ -78,6 +78,28 @@ if (DEBUG_SCROLL) {
* scroll down further. If stickyBottom is disabled, we just save the scroll
* offset as normal.
*/
function createTimelineResizeDetector(scrollNode, itemlist, callback) {
if (typeof ResizeObserver !== "undefined") {
const ro = new ResizeObserver(callback);
ro.observe(itemlist);
return ro;
} else if (typeof IntersectionObserver !== "undefined") {
const threshold = [];
for (let i = 0; i < 1000; ++i) {
threshold.push(i / 1000);
}
threshold.push(1);
const io = new IntersectionObserver(
callback,
{root: scrollNode, threshold},
);
io.observe(itemlist);
return io;
}
}
module.exports = React.createClass({
displayName: 'ScrollPanel',
@ -161,12 +183,11 @@ module.exports = React.createClass({
componentDidMount: function() {
this.checkScroll();
if (typeof ResizeObserver !== "undefined") {
this._timelineSizeObserver = new ResizeObserver(() => {
this._restoreSavedScrollState();
});
this._timelineSizeObserver.observe(this.refs.itemlist);
}
this._timelineSizeObserver = createTimelineResizeDetector(
this._getScrollNode(),
this.refs.itemlist,
() => { this._restoreSavedScrollState(); },
);
},
componentDidUpdate: function() {