wpf - 一般行为

Question

我想创建通用行为。我的问题是 XAML 中的泛型声明。

    public class GenericBehavior<T> : Behavior<DataGrid>
        where T : class 
    {
    }

我不能使用 x:TypeArguments因为我没有松散的 XAML 文件。

In WPF and when targeting .NET Framework 4, you can use XAML 2009 features together with x:TypeArguments but only for loose XAML (XAML that is not markup-compiled). Markup-compiled XAML for WPF and the BAML form of XAML do not currently support the XAML 2009 keywords and features

我找到了一些 workaround使用 MarkupExtension 但使用 Behaviors 不起作用。

在我当前的解决方案中 I attach behavior in code .

有什么想法吗？

Answer 1

您可以在 View 模型中创建通用行为，然后使用附加属性将其注入(inject)到您的控件中。

public class ViewModel
{
    public Behavior MyBehavior
    { 
        get 
        {
            return new GenericBehavior<SomeType>();
        } 
    }
}

public class AttachedBehaviors
{
    public static Behavior GetBehavior(DependencyObject sender) => (Behavior)sender.GetValue(BehaviorProperty);
    public static void SetBehavior(DependencyObject sender, Behavior value) => sender.SetValue(BehaviorProperty, value);

    public static readonly DependencyProperty BehaviorProperty =
        DependencyProperty.RegisterAttached("Behavior", typeof(Behavior), typeof(AttachedBehaviors),
            new PropertyMetadata(null, new PropertyChangedCallback(BehaviorChanged)));

    private static void BehaviorChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        if (sender is FrameworkElement elem)
        {
            if (e.NewValue is Behavior behavior)
            {
                BehaviorCollection Behaviors = Interaction.GetBehaviors(elem);
                Behaviors.Add(behavior);
            }
        }
    }

}

public class GenericBehavior<T> : Behavior<DataGrid> where T : class
{
    public T TestValue { get; set; }

    protected override void OnAttached()
    {
    }
}

现在你可以像这样使用它了

<DataGrid local:AttachedBehaviors.Behavior="{Binding MyBehavior}" > 
</DataGrid>

PS:你只需要安装 Microsoft.Xaml.Behaviors.Wpf NuGet 包。