界面代码（xaml）：

using System;using System.Collections.Generic;using System.Linq;using System.Text;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.Animation;using System.Windows.Media.Imaging;using System.Windows.Navigation;using System.Windows.Shapes;namespace TransAnimation{    /// 
    /// MainWindow.xaml 的交互逻辑    /// 
    public partial class MainWindow : Window    {                private bool _Expand = true;        public MainWindow()        {            InitializeComponent();        }        private void Button_Click_1(object sender, RoutedEventArgs e)        {            Expand = !_Expand;        }                public bool Expand        {            get { return _Expand; }            set            {                _Expand = value;                Duration duration = new Duration(TimeSpan.FromSeconds(2));                FillBehavior behavior = FillBehavior.HoldEnd;                DoubleAnimation translateAnim = new DoubleAnimation();                translateAnim.Duration = duration;                translateAnim.FillBehavior = behavior;                RectAnimation clipAnim = new RectAnimation();                clipAnim.Duration = duration;                clipAnim.FillBehavior = behavior;                double delta = 40; //收缩的大小                if (_Expand) // Expand                {                    translateAnim.From = -delta;                    translateAnim.To = 0;                    clipAnim.From = new Rect(delta, 0, Thumb1.ActualWidth, Thumb1.ActualHeight);                    clipAnim.To = new Rect(0, 0, Thumb1.ActualWidth, Thumb1.ActualHeight);                }                else  //Shrink                {                    translateAnim.From = 0;                    translateAnim.To = -delta;                    clipAnim.From = new Rect(0, 0, Thumb1.ActualWidth, Thumb1.ActualHeight);                    clipAnim.To = new Rect(delta, 0, Thumb1.ActualWidth, Thumb1.ActualHeight);                }                spt1.BeginAnimation(TranslateTransform.XProperty, translateAnim);                spc1.BeginAnimation(RectangleGeometry.RectProperty, clipAnim);            }        }    }}