wpf - 在 ListboxItem 上添加自定义混合行为

Question

我正在创建一个自定义混合行为来作用于 ListboxItem，即

public class DragtestBehaviour : Behavior<ListBoxItem>
{
    public DragtestBehaviour()
    { // Insert code required on object creation below this point.
    }
    protected override void OnAttached()
    {
        base.OnAttached();
        // Insert code that you would want run when the Behavior is attached to an object.
    }
    protected override void OnDetaching()
    {
        base.OnDetaching();
        // Insert code that you would want run when the Behavior is removed from an object.
    }
}

我无法弄清楚的是如何将它附加到列表框项？

或者，我是否必须为 Listbox 项目设置样式并将其附加到 Border 或任何其他样式元素？如果这是真的，那么我是否还必须从 Border(即框架元素)派生我的行为类？

DragtestBehaviour : Behavior<Frameworkelement>

Answer 1

我基本上已经完成了 Eran otzap 在他的评论中所建议的以及 this article 中所描述的内容。通过马克史密斯。这允许仍然使用混合行为及其好处(如 AssociatedObject )，但在附加它时更加灵活。它是正常附加行为与混合行为的融合。

为了完整起见，这里还有相关的代码。

在 ItemContainerStyle 中附加行为:

<ListBox.ItemContainerStyle>
    <Style TargetType="{x:Type ListBoxItem}" BasedOn="{StaticResource {x:Type ListBoxItem}}">
        <Setter Property="behaviors:DragDropBehavior.IsAttached" Value="True" />
    </Style>
</ListBox.ItemContainerStyle>

行为

public class DragDropBehavior : Behavior<ListBoxItem>
{
    // IsAttached
    public static DependencyProperty IsAttachedProperty = DependencyProperty.RegisterAttached("IsAttached",typeof(bool), typeof(DragDropBehavior),new FrameworkPropertyMetadata(false, OnIsAttachedChanged));
    public static bool GetIsAttached(DependencyObject o){return (bool)o.GetValue(IsAttachedProperty);}
    public static void SetIsAttached(DependencyObject o, bool value){o.SetValue(IsAttachedProperty, value);}

    // is called the same as when attached in Interaction.Behaviors tag
    protected override void OnAttached()
    {            
        base.OnAttached();
    }

    // manual attachement to listbox item
    private static void OnIsAttachedChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
    {
        var el = o as UIElement;
        if (el != null)
        {
            var behColl = Interaction.GetBehaviors(el);
            var existingBehavior = behColl.FirstOrDefault(b => b.GetType() == typeof(DragDropBehavior)) as DragDropBehavior;
            if ((bool)e.NewValue == false && existingBehavior != null)
            {
                behColl.Remove(existingBehavior);
            }
            else if ((bool)e.NewValue == true && existingBehavior == null)
            {
                behColl.Add(new DragDropBehavior());
            }
        }
    }
}