自定义行为实现

重载 OnAttached() 和 OnDetaching()方法 ，AssociatedObject 属性对应放置行为的元素，在OnAttach()中关联事件处理器，通过事件处理器来实现业务，OnDetaching() 中做事件移除操作

命空间应用以及xaml代码

自定义行为

public class MyBehavior : Behavior<Button>
    {
        protected override void OnAttached()
        {
            base.OnAttached();
            this.AssociatedObject.Click += AssociatedObject_Click;
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();
            this.AssociatedObject.Click -= AssociatedObject_Click;
        }

        private void AssociatedObject_Click(object sender, RoutedEventArgs e)
        {
            if (sender is Button btn)
            {
                DoubleAnimation doubleAnimation = new DoubleAnimation();
                doubleAnimation.Duration = new TimeSpan(100);
                doubleAnimation.To = 100;
                btn.BeginAnimation(Button.WidthProperty, doubleAnimation);
            }
        }
    }


<!-- 命名空间
xmlns: i="clr-namespace=System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:mybehavior="clr-namespace:---"
-->
<i:interaction.Behavior>
    <mybehavior:MyBehavoir/>
</i:interaction.Behavior>

行为基用法

<!--xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"-->

<i:Interaction.Triggers>
    <i:EventTrigger EventName="IsMouseOver">
        <i:InvokeCommandAction Command="{Binding MouseOverCommand}" />
    </i:EventTrigger>
</i:Interaction.Triggers>