var preLoaderAngle;
var preLoaderTimer;

function onXamlLoaded(sender, eventArgs) {
    //alert("onXamlLoaded");
    preLoaderAngle = sender.findName("RotTransform");
    preLoaderTimer = setInterval(function () {
        preLoaderAngle.Angle = preLoaderAngle.Angle + 30;
    }, 100);
}

function onSourceDownloadProgressChanged(sender, eventArgs) {
    //
}

function onSourceDownloadComplete(sender, eventArgs) {
    clearInterval(preLoaderTimer);
}