owncast/web/components/video/VideoPoster.tsx
2022-04-26 13:50:14 -07:00

110 lines
2.8 KiB
TypeScript

/*
VideoPoster is the image that covers up the video component and shows a
preview of the video, refreshing every N seconds.
It's more complex than it needs to be, using the "double buffer" approach to
cross-fade the two images. Now that we've moved to React we may be able to
simply use some simple cross-fading component.
*/
import { useEffect, useLayoutEffect, useState } from 'react';
import { ReactElement } from 'react-markdown/lib/react-markdown';
const REFRESH_INTERVAL = 15000;
const TEMP_IMAGE = 'http://localhost:8080/logo';
const POSTER_BASE_URL = 'http://localhost:8080/';
export default function VideoPoster(props): ReactElement {
const { active } = props;
const [flipped, setFlipped] = useState(false);
const [oldUrl, setOldUrl] = useState(TEMP_IMAGE);
const [url, setUrl] = useState(props.url);
const [currentUrl, setCurrentUrl] = useState(TEMP_IMAGE);
const [loadingImage, setLoadingImage] = useState(TEMP_IMAGE);
const [offlineImage, setOfflineImage] = useState(TEMP_IMAGE);
let refreshTimer = null;
const setLoaded = () => {
setFlipped(!flipped);
setUrl(loadingImage);
setOldUrl(currentUrl);
};
const fire = () => {
const cachebuster = Math.round(new Date().getTime() / 1000);
setLoadingImage(`${POSTER_BASE_URL}?cb=${cachebuster}`);
const img = new Image();
img.onload = setLoaded;
img.src = loadingImage;
};
const stopRefreshTimer = () => {
clearInterval(refreshTimer);
refreshTimer = null;
};
const startRefreshTimer = () => {
stopRefreshTimer();
fire();
// Load a new copy of the image every n seconds
refreshTimer = setInterval(fire, REFRESH_INTERVAL);
};
useEffect(() => {
if (active) {
fire();
startRefreshTimer();
} else {
stopRefreshTimer();
}
}, [active]);
// On component unmount.
useLayoutEffect(
() => () => {
stopRefreshTimer();
},
[],
);
// TODO: Replace this with React memo logic.
// shouldComponentUpdate(prevProps, prevState) {
// return (
// this.props.active !== prevProps.active ||
// this.props.offlineImage !== prevProps.offlineImage ||
// this.state.url !== prevState.url ||
// this.state.oldUrl !== prevState.oldUrl
// );
// }
if (!active) {
return (
<div id="oc-custom-poster">
<ThumbImage url={offlineImage} visible />
</div>
);
}
return (
<div id="oc-custom-poster">
<ThumbImage url={!flipped ? oldUrl : url} visible />
<ThumbImage url={flipped ? oldUrl : url} visible={!flipped} />
</div>
);
}
function ThumbImage({ url, visible }) {
if (!url) {
return null;
}
return (
<div
className="custom-thumbnail-image"
style={{
opacity: visible ? 1 : 0,
backgroundImage: `url(${url})`,
}}
/>
);
}