protected override void OnTrackedElementTouchMove(object sender, TouchEventArgs e)
{
if (!engineStatuses.ContainsKey(e.TouchDevice))
return;
DateTime timestamp = TimestampToDateTime(e.Timestamp);
Point position = e.GetTouchPoint(null).Position;
engineStatuses[e.TouchDevice].TrackTouchMove(position, timestamp);
base.OnTrackedElementTouchMove(sender, e);
}