uwp-clock-backend.cs

using System;
using Windows.Xaml;

namespace uwp.clock.backend
{
    public sealed partial class UwpClockPage : Page
    {
        private readonly DispatcherTimer _timer;
        private double PreviousAngle = 0;
        public UwpClockPage()
        {
            this.InitializeComponent();
            _timer = new DispatcherTimer
            {
                Interval = TimeSpan.FromSeconds(1)
            };
            _timer.Tick += (s,e) => OnTick();
        }
        
        private void OnTick()
        {
            // calculate angle of rotation based on current system time seconds.
            double angle = DateTime.Now.TimeOfDay.Seconds * 360 / 60;
            lock (SpinSecHandStoryBoard)
            {
                SpinSecHandAnim.From = PreviousAngle;
                SpinSecHandAnim.To = angle;
                SpinSecHandAnim.Duration = new Duration(TimeSpan.FromSeconds(1));
                SpinSecHandStoryBoard.Begin();
            }
        }
    }
}