private void OnCanvasLoaded(object sender, RoutedEventArgs e)
{
const double offset = Math.PI;
const double step = Math.PI*2/10.0;
SetPosition(_circle0, offset, 0.0, step);
SetPosition(_circle1, offset, 1.0, step);
SetPosition(_circle2, offset, 2.0, step);
SetPosition(_circle3, offset, 3.0, step);
SetPosition(_circle4, offset, 4.0, step);
SetPosition(_circle5, offset, 5.0, step);
SetPosition(_circle6, offset, 6.0, step);
SetPosition(_circle7, offset, 7.0, step);
SetPosition(_circle8, offset, 8.0, step);
}