Question

我在运行时生成它时将行为（Blend SDK中的行为）附加到UIElement。我还有两个按钮来触发分离（）和附加（） - 基本上是为了启用或禁用该行为。

问题是：在 Detach（）行为之后， Attach（）无法将行为还原到依赖项对象，然后保持无行为：< / p>

// Declare the dependency object and behavior at class scope 
MyControl c = new MyControl();
MyBehavior b = new MyBehavior();

// Function that generate UI Controls with behavior attached
b.Attach(c);

// Function that detach behavior from dependency object
b.Detach();

// Function that re-attach behavior to the same object after it has been detached
b.Attach(c); // <-- Do not see the behavior...

为什么行为没有重新附加？是否有解决方案或解决方案来打开或关闭行为？

Answer 1

似乎问题是你行为逻辑的具体问题。在下面的测试中，行为重新连接没有问题：

public class ColorBehavior : Behavior<Border>
{
    public Brush OriginalBrush { get; set; }

    protected override void OnAttached()
    {
        base.OnAttached();

        this.OriginalBrush = this.AssociatedObject.Background;
        this.AssociatedObject.Background = Brushes.CadetBlue;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        this.AssociatedObject.Background = this.OriginalBrush;
    }
}

public partial class MainWindow : Window
{
    private ColorBehavior behavior = new ColorBehavior();
    private bool isAttached;

    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        if (!this.isAttached)
        {
            this.behavior.Attach(this.Border);
            this.isAttached = true;
        }
        else
        {
            this.behavior.Detach();
            this.isAttached = false;
        }
    }
}

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    xmlns:local="clr-namespace:WpfApplication1"
    Title="MainWindow"
    Width="525"
    Height="350">
<Grid>
    <Border x:Name="Border" Background="Red" />
    <Button Width="50"
            Height="20"
            Click="Button_Click"
            Content="Hey" />
</Grid>

分离后无法将行为重新附加到依赖项对象

1 个答案: