WPF でアニメーションさせるには Storyboard を使う方法があるが、あらかじめ用意された動作しか表現できない。もっと自由にアニメーションさせるには CompositionTarget.Rendering を使う。

サンプルとして時計を作ってみた。

まず、Visual Studio で WPF プロジェクトを作り、MainWindow.xaml の Grid を Canvas に変更しておく。

次に、MainWindow.xaml.cs を以下のように編集する。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfAnime1
{
    /// <summary>
    /// MainWindow.xaml の相互作用ロジック
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            Canvas root = this.Content as Canvas;
            var outline = new Ellipse() { Name = "outline", Width = 200, Height = 200, Fill = Brushes.Black, };
            root.Children.Add(outline);
            var hourHand = new Rectangle() { Name = "hourHand", Width = 3, Height = 60, Fill = Brushes.Red };
            root.Children.Add(hourHand);
            var minuteHand = new Rectangle() { Name = "minuteHand", Width = 3, Height = 80, Fill = Brushes.LightBlue };
            root.Children.Add(minuteHand);
            var secondHand = new Rectangle() { Name = "secondHand", Width = 2, Height = 90, Fill = Brushes.Green };
            root.Children.Add(secondHand);

            CompositionTarget.Rendering += CompositionTarget_Rendering;
        }

        private void CompositionTarget_Rendering(object sender, EventArgs e)
        {
            var root = this.Content as Canvas;
            var center = new Point(this.ActualWidth / 2.0, this.ActualHeight / 2.0);
            var now = DateTime.Now;

            foreach (FrameworkElement child in root.Children)
            {
                if (child.Name == "outline")
                {
                    Canvas.SetLeft(child, center.X - child.Width / 2);
                    Canvas.SetTop(child, center.Y - child.Height / 2);
                }
                else if (child.Name == "hourHand")
                {
                    Canvas.SetLeft(child, center.X);
                    Canvas.SetTop(child, center.Y);
                    float a = ((float)((now.Hour % 12) * 60 * 60 + now.Minute * 60 + now.Second) / (12 * 60 * 60)) * 360.0f + 180.0f;
                    child.RenderTransform = new RotateTransform { Angle = a, CenterX = 1.5, CenterY = 0 };
                }
                else if (child.Name == "minuteHand")
                {
                    Canvas.SetLeft(child, center.X);
                    Canvas.SetTop(child, center.Y);
                    float a = ((float)(now.Minute * 60 + now.Second) / (60 * 60)) * 360.0f + 180.0f;
                    child.RenderTransform = new RotateTransform { Angle = a, CenterX = 1.5, CenterY = 0 };
                }
                else if (child.Name == "secondHand")
                {
                    Canvas.SetLeft(child, center.X);
                    Canvas.SetTop(child, center.Y);
                    //float a = ((float)(now.Second) / (60)) * 360.0f + 180.0f;
                    float a = ((float)(now.Second * 1000 + now.Millisecond) / (60 * 1000)) * 360.0f + 180.0f;    // smooth
                    child.RenderTransform = new RotateTransform { Angle = a, CenterX = 1.0, CenterY = 0 };
                }
            }
        }
    }
}

ちなみに、秒針を描画している箇所に smooth とコメントがある行の代わりに、その上の行を有効にすると秒針がチクタクという動きになる。

以上。