Xaml中的EventTrigger

Question

我试图在我的风格中添加一个事件触发器，但由于某些原因它不起作用。它抛给我一个错误{“值不能为空。\r\n参数名: routedEvent"}我的目标是在它的KeyDown事件中添加我的控件的修复逻辑，有人知道这是怎么回事吗？

下面的样式在我的Theme.xaml中。

    <Style.Triggers>
            <EventTrigger>
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="KeyDown">
                    <Behaviors:ExecuteCommandAction Command="{Binding TabKeyDownCommand}" />
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </EventTrigger>
    </Style.Triggers>

下面是我的ExecuteCommandAction类：

/// <summary>
/// Behaviour helps to bind any RoutedEvent of UIElement to Command.
/// </summary>
[DefaultTrigger(typeof (UIElement), typeof (EventTrigger), "KeyDown")]
public class ExecuteCommandAction : TargetedTriggerAction<UIElement>
{
    /// <summary>
    /// Dependency property represents the Command of the behaviour.
    /// </summary>
    public static readonly DependencyProperty CommandParameterProperty =
        DependencyProperty.RegisterAttached("CommandParameter",
                                            typeof (object),
                                            typeof (ExecuteCommandAction),
                                            new FrameworkPropertyMetadata(null));

    /// <summary>
    /// Dependency property represents the Command parameter of the behaviour.
    /// </summary>
    public static readonly DependencyProperty CommandProperty = DependencyProperty.RegisterAttached("Command",
                                                                                                    typeof (ICommand
                                                                                                        ),
                                                                                                    typeof (
                                                                                                        ExecuteCommandAction
                                                                                                        ),
                                                                                                    new FrameworkPropertyMetadata
                                                                                                        (null));

    /// <summary>
    /// Gets or sets the Commmand.
    /// </summary>
    public ICommand Command
    {
        get { return (ICommand) GetValue(CommandProperty); }
        set { SetValue(CommandProperty, value); }
    }

    /// <summary>
    /// Gets or sets the CommandParameter.
    /// </summary>
    public object CommandParameter
    {
        get { return GetValue(CommandParameterProperty); }
        set { SetValue(CommandParameterProperty, value); }
    }


    /// <summary>
    /// Invokes the action.
    /// </summary>
    /// <param name="parameter">The parameter to the action. If the action does not require a parameter, the parameter may be set to a null reference.</param>
    protected override void Invoke(object parameter)
    {
        if (Command != null)
        {
            if (Command.CanExecute(CommandParameter))
            {
                Command.Execute(CommandParameter);
            }
        }
    }
}

Answer 1

Interactivity功能不能这样使用，它不属于普通的Triggers、EventTriggers，甚至不属于样式本身。您可以对元素使用它，如下所示：

<Button>
    <i:Interaction.Triggers>
         <!-- ... -->
    </i:Interaction.Triggers>
</Button>

这个错误是由于没有在包含的EventTrigger上设置RoutedEvent而导致的，但是即使您设置了它，也会出现新的错误。