版权声明：我不生产代码，我只是代码的搬运工。 https://blog.csdn.net/qq_43307934/article/details/87249998

• WPF提供了一种基于帧的动画实现方式，由CompositionTarget类来完成。
• WPF会在每次界面刷新时调用该回调函数。
• CompositionTarget的刷新率与窗体保持一致，因此很难人工控制动画的快慢。

 1、前台

    <Grid>

        <Grid.RowDefinitions>

            <RowDefinition Height=" *" />

            <RowDefinition Height=" *" />

        </Grid.RowDefinitions>

        <Rectangle Name="rectan"

                   Width=" 30"

                   Height=" 100"

                   Fill="Blue" />

        <Button Grid.Row=" 1"

                Width=" 100"

                Height=" 30"

                Click="Button_Click" />

    </Grid>

2、后台cs

   public partial class MainWindow : Window

    {

        private double maxwi = 300;

        private double strart = 0;

        public MainWindow()

        {

            InitializeComponent();

            strart = rectan.Width;

        }

        private void Button_Click(object sender, RoutedEventArgs e)

        {

            CompositionTarget.Rendering += new EventHandler(CompositionTarget_Rendering);

        }

        private void CompositionTarget_Rendering(object sender, EventArgs e)

        {

            rectan.Width += 1;

            if (rectan.Width > maxwi)

            {

                rectan.Width = strart;

                CompositionTarget.Rendering -= new EventHandler(CompositionTarget_Rendering);

            }

        }