phantasma/app/static/js/ascroll.js

var cache = cache || {}
var layer = 'descriptions'
var baseURL = 'https://pad.ma'
var imageResolution = 480

let lastKnownScrollPosition = 0
let ticking = false;


async function pandoraAPI(action, data) {
    var url = baseURL + '/api/'
    //var url = '/pandoraAPI/'
    var key = JSON.stringify([action, data])
    if (!cache[key]) {
        var response = await fetch(url, {
            method: 'POST',
            headers: {'Content-Type': 'application/json'},
            body: JSON.stringify({
                action: action,
                data: data
            })
        })
        cache[key] = await response.json()
    }
    return cache[key]
}

function updatePlayerPosition(video, lastKnownScrollPosition) {
    console.log('update', lastKnownScrollPosition)
    video.style.top = lastKnownScrollPosition + 'px'
    video.style.display = 'block';
}

function updatePlayer(video, frame, currentTime) {
    var rect = frame.getBoundingClientRect();
    video.style.opacity = 0
    console.log('update player', rect)
    video.style.top =  (rect.top + window.scrollY) + 'px'
    video.style.display = 'block';
    //video.poster = frame.querySelector('img').src
    video.currentTime = currentTime
    video.controls = true
    video.play()
    video.style.opacity = 1
}

function isElementInViewport (el) {
    var rect = el.getBoundingClientRect();
    return (
        rect.top >= 0 &&
        rect.left >= 0 &&
        rect.bottom <= (window.innerHeight || document.documentElement.clientHeight) && /* or $(window).height() */
        rect.right <= (window.innerWidth || document.documentElement.clientWidth) /* or $(window).width() */
    );
}

function onVisibilityChange(el, callback) {
    var old_visible;
    return function () {
        var visible = isElementInViewport(el);
        if (visible != old_visible) {
            old_visible = visible;
            if (typeof callback == 'function') {
                callback(visible);
            }
        }
    }
}


pandoraAPI('get', {id: film.id, keys: ['id', 'title', 'layers']}).then(response => {
    var ascroll = document.querySelector('#ascroll')
    var loaded = false

    var video = document.createElement('video')
    video.classList.add('player')
    video.muted = true
    video.src = `${baseURL}/${film.id}/480p.webm`
    ascroll.appendChild(video)

    var h1 = document.createElement('h1')
    h1.innerHTML = response.data.title
    ascroll.appendChild(h1)

    response.data.layers[layer].forEach(annotation => {
        var div = document.createElement('div')
        div.classList.add('annotation')
        div.innerHTML = `
            <div class="frame"><img src="${baseURL}/${annotation.id.split('/')[0]}/${imageResolution}p${annotation.in}.jpg"></div>
            <div class="text">${annotation.value}</div>

        `
        ascroll.appendChild(div)
        var frame = div.querySelector('.frame')
        document.addEventListener('scroll', onVisibilityChange(div.querySelector('.frame'), function(visible) {
            if (loaded && visible)
                updatePlayer(video, frame, annotation['in'])

        }))
    })
    loaded = true
    let frame = ascroll.querySelector('.annotation .frame')
    if (frame) {
        updatePlayer(video, frame, 0)
    }

    /*
    document.addEventListener('scroll', function(e) {
      lastKnownScrollPosition = window.scrollY;

      if (!ticking) {
        window.requestAnimationFrame(function() {
          updatePlayerPosition(video, lastKnownScrollPosition);
          ticking = false;
        });

        ticking = true;
      }
    })
    */
})