我想在wpf中自定义路由事件，要求当超过一个值时，小灯开始闪烁

首先，我们需要定义一个路由事件。在WPF中，我们可以使用`RoutedEvent`类来定义一个路由事件。下面是一个示例：

public class MyCustomControl : Control
{
    // 定义路由事件
    public static readonly RoutedEvent MyCustomEvent = EventManager.RegisterRoutedEvent(
        "MyCustom", // 事件名
        RoutingStrategy.Bubble, // 事件路由策略
        typeof(RoutedEventHandler), // 事件处理委托类型
        typeof(MyCustomControl) // 定义事件的所有者类型
    );

    // 添加路由事件处理程序
    public event RoutedEventHandler MyCustom
    {
        add { AddHandler(MyCustomEvent, value); }
        remove { RemoveHandler(MyCustomEvent, value); }
    }

    // 触发路由事件
    private void RaiseMyCustomEvent()
    {
        RoutedEventArgs args = new RoutedEventArgs(MyCustomEvent);
        RaiseEvent(args);
    }
}

接下来，我们需要在`MyCustomControl`类中添加一个依赖属性来存储阈值，并在属性值发生变化时触发路由事件。下面是一个示例：

public class MyCustomControl : Control
{
    // 定义路由事件和依赖属性
    public static readonly RoutedEvent MyCustomEvent = EventManager.RegisterRoutedEvent(...);
    public static readonly DependencyProperty ThresholdProperty = DependencyProperty.Register(
        "Threshold", typeof(double), typeof(MyCustomControl), 
        new PropertyMetadata(0.0, OnThresholdChanged)
    );

    // 添加依赖属性的包装器
    public double Threshold
    {
        get { return (double)GetValue(ThresholdProperty); }
        set { SetValue(ThresholdProperty, value); }
    }

    // 属性值变化时触发路由事件
    private static void OnThresholdChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        MyCustomControl control = d as MyCustomControl;
        double newValue = (double)e.NewValue;
        if (newValue > control.Threshold)
        {
            control.RaiseMyCustomEvent();
        }
    }

    // ...
}

最后，我们可以在XAML中使用`MyCustomControl`并添加路由事件处理程序来控制小灯的闪烁。下面是一个示例：

<Window x:Class="WpfApp1.MainWindow"
        xmlns:local="clr-namespace:WpfApp1"
        ...>
    <Grid>
        <local:MyCustomControl Threshold="50" MyCustom="MyCustomControl_MyCustom"/>
        <Ellipse x:Name="Light" Fill="Green" Width="20" Height="20"/>
    </Grid>
</Window>

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void MyCustomControl_MyCustom(object sender, RoutedEventArgs e)
    {
        Light.Fill = Brushes.Red;
        Storyboard blinkStoryboard = new Storyboard();
        DoubleAnimation opacityAnimation = new DoubleAnimation
        {
            From = 1,
            To = 0,
            Duration = TimeSpan.FromSeconds(0.5),
            RepeatBehavior = RepeatBehavior.Forever,
            AutoReverse = true
        };
        Storyboard.SetTarget(opacityAnimation, Light);
        Storyboard.SetTargetProperty(opacityAnimation, new PropertyPath(Ellipse.OpacityProperty));
        blinkStoryboard.Children.Add(opacityAnimation);
        blinkStoryboard.Begin();
    }
}

在`MyCustomControl_MyCustom`事件处理程序中，我们可以控制小灯的颜色和闪烁动画。当`Threshold`属性的值超过50时，路由事件将被触发，并且小灯将开始闪烁。