Question

I’ve a question about implementing a slider control in a browser.

I need to playback data over time, in a browser. I will have one Worker filling the playback buffer by making calls to a REST api. The UI thread will then consume the buffer and playback the data to the user.

I want to simulate YouTube progress UI control. It shows you in a single UI control how much you’ve watched, and how much has been prefetched. Is it possible to adapt a slider control to do this ? The jQuery UI range slider isn’t quite what I want

I currently use jQuery in my website, so would prefer a solution based on that framework.

Answer 1

You could just modify the jQuery UI slider a bit by using your own background image, then adjusting the width to show the load progress (demo):

$(function(){

    var ytplayer = $('#player')[0],
        // # seconds from YouTube API
        duration = ytplayer.getDuration(),
        // # bytes
        totalBytes = ytplayer.getVideoBytesTotal(),
        // start # bytes - may not be necessary
        startBytes = ytplayer.getVideoStartBytes();

    $("#slider").slider({
        range: "max",
        min: startBytes,
        max: duration,
        value: 1
    })
    // image: http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/blitzer/images/ui-bg_highlight-soft_15_cc0000_1x100.png
    // with a 30% opacity
    .css('background-image', 'url(http://i56.tinypic.com/fbjad2.png)');

    // Loop to update slider   
    function loop() {
        var time = ytplayer.getCurrentTime(),
            // make loaded a percentage
            loaded = 100 - (ytplayer.getVideoBytesLoaded() / totalBytes) * 100;

        // set limit - no one likes negative widths
        if (loaded < 0) { loaded = 0; }

        // update time on slider
        $('#slider')
            .slider('option', 'value', time)
            .find('.ui-widget-header').css('width', loaded + '%');

        // repeat loop as needed
        if (loaded < 0 || time < duration) {
            setTimeout(loop, 500);
        }
    }
    loop(); 
});