document.camera = false;
document.cam_timeout = false;

function create_list() {

    //create and add all cameras
    for (var cam in document.cam_list) {

        //create link and set attributes
        var cam_link = document.createElement('a');
        cam_link.href = 'javascript:choose_cam("' + cam + '");';
        cam_link.title = 'Показать вид с камеры "' + document.cam_list[cam].title + '"';

        var cam_title = document.createTextNode(document.cam_list[cam].title);
        cam_link.appendChild(cam_title);

        document.getElementById('camList').appendChild(cam_link);
    }
}

function show_cam() {
    $('cam').src = document.cam_list[document.camera].url + '&' +
                   Math.round(Math.random() * 10000000);
}

function renew_cam() {
    if (document.camera !== false) {

        //define how often reload camera in milliseconds
        var renew_period = $('renew_period').value.replace(/,/, '.') * 1000;

        //default reload period is 3 sec
        if (renew_period == NaN || renew_period <= 0) {
            renew_period = 3000;
        }

        document.cam_timeout = setTimeout(show_cam, renew_period);
    }
}

function choose_cam(cam) {
    document.camera = cam;
    $('CamTitle').innerHTML = document.cam_list[document.camera].title;

    if (document.cam_timeout !== false) {
        clearTimeout(document.cam_timeout);
    }

    show_cam();
}