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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
import { actionCreators as ac } from "common/Actions.sys.mjs";
import React from "react";
const VISIBLE = "visible";
const VISIBILITY_CHANGE_EVENT = "visibilitychange";
// Per analytical requirement, we set the minimal intersection ratio to
// 0.5, and an impression is identified when the wrapped item has at least
// 50% visibility.
//
// This constant is exported for unit test
export const INTERSECTION_RATIO = 0.5;
/**
* Impression wrapper for a TopSite tile.
*
* It makses use of the Intersection Observer API to detect the visibility,
* and relies on page visibility to ensure the impression is reported
* only when the component is visible on the page.
*/
export class TopSiteImpressionWrapper extends React.PureComponent {
_dispatchImpressionStats() {
const { actionType, tile } = this.props;
if (!actionType) {
return;
}
this.props.dispatch(
ac.OnlyToMain({
type: actionType,
data: {
type: "impression",
...tile,
},
})
);
}
setImpressionObserverOrAddListener() {
const { props } = this;
if (!props.dispatch) {
return;
}
if (props.document.visibilityState === VISIBLE) {
this.setImpressionObserver();
} else {
// We should only ever send the latest impression stats ping, so remove any
// older listeners.
if (this._onVisibilityChange) {
props.document.removeEventListener(
VISIBILITY_CHANGE_EVENT,
this._onVisibilityChange
);
}
this._onVisibilityChange = () => {
if (props.document.visibilityState === VISIBLE) {
this.setImpressionObserver();
props.document.removeEventListener(
VISIBILITY_CHANGE_EVENT,
this._onVisibilityChange
);
}
};
props.document.addEventListener(
VISIBILITY_CHANGE_EVENT,
this._onVisibilityChange
);
}
}
/**
* Set an impression observer for the wrapped component. It makes use of
* the Intersection Observer API to detect if the wrapped component is
* visible with a desired ratio, and only sends impression if that's the case.
*
* See more details about Intersection Observer API at:
* https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
*/
setImpressionObserver() {
const { props } = this;
if (!props.tile) {
return;
}
this._handleIntersect = entries => {
if (
entries.some(
entry =>
entry.isIntersecting &&
entry.intersectionRatio >= INTERSECTION_RATIO
)
) {
this._dispatchImpressionStats();
this.impressionObserver.unobserve(this.refs.topsite_impression_wrapper);
}
};
const options = { threshold: INTERSECTION_RATIO };
this.impressionObserver = new props.IntersectionObserver(
this._handleIntersect,
options
);
this.impressionObserver.observe(this.refs.topsite_impression_wrapper);
}
componentDidMount() {
if (this.props.tile) {
this.setImpressionObserverOrAddListener();
}
}
componentWillUnmount() {
if (this._handleIntersect && this.impressionObserver) {
this.impressionObserver.unobserve(this.refs.topsite_impression_wrapper);
}
if (this._onVisibilityChange) {
this.props.document.removeEventListener(
VISIBILITY_CHANGE_EVENT,
this._onVisibilityChange
);
}
}
render() {
return (
<div
ref={"topsite_impression_wrapper"}
className="topsite-impression-observer"
>
{this.props.children}
</div>
);
}
}
TopSiteImpressionWrapper.defaultProps = {
IntersectionObserver: global.IntersectionObserver,
document: global.document,
actionType: null,
tile: null,
};
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