pico.chat/apps/screen.js

const ScreenShareConfig = {
    view() {
        const start = async () => {
            await ScreenShare.getStream()
            wire({kind: 'screen-share-start'})
        }
        const stop = () => wire({kind: 'screen-share-stop'})
        if (ScreenShare.source === null) {
            return m('button', {onclick: start}, 'start screen sharing')
        }
        else if (ScreenShare.isSelf) {
            return m('button', {onclick: stop}, 'stop screen sharing')
        }
        else {
            return m('button[disabled]', `${ScreenShare.source} is screen sharing`)
        }
    }
}
const ScreenShare = {
    source: null,
    stream: new MediaStream(),
    get isSelf() {
        return ScreenShare.source === State.username
    },
    async getStream() {
        const stream = await navigator.mediaDevices.getDisplayMedia({})
        stream.getTracks()
            .forEach(tr => ScreenShare.stream.addTrack(tr, stream))
    },
    async stopStream() {
        ScreenShare.stream.getTracks()
            .forEach(tr => tr.stop())
        ScreenShare.stream = new MediaStream()
    },
    view() {
        const style = {
            overflow: 'scroll',
            backgroundColor: 'gray',
            color: 'white',
            fontFamily: 'monospace',
            position: 'relative',
        }
        return m('.screen-share', {style},
            ScreenShare.isSelf ? m('span', 'You are sharing your screen') :
            ScreenShare.source ? m('video[playsinline][autoplay]', {srcObject: ScreenShare.stream})
            : [],
        )
    },
}
function sendScreen(target, stream) {
    signal({kind: 'screen-start', value: {target, stream}})
}
addEventListener('screen-share-start', async ({detail: {source}}) => {
    const isNew = ScreenShare.source === null
    ScreenShare.source = source
    if(isNew && ScreenShare.isSelf) {
        State.others.forEach(user => sendScreen(user, ScreenShare.stream))
    }
})
addEventListener('screen-share-stop', () => {
    ScreenShare.stopStream()
    ScreenShare.source = null
})
addEventListener('join', ({detail: {value: user}}) => {
    if(ScreenShare.isSelf) {
        wire({kind: 'screen-share-start', target: user})
        sendScreen(user, ScreenShare.stream)
    }
})
addEventListener('load', () => {
    doNotLog.add('screen-share-start')
    doNotLog.add('screen-share-stop')
    Headers.push([ScreenShareConfig])
    Apps.push([ScreenShare, {key: 'screen-share-container'}])
})