Question

好的，所以我试图将附加事件添加到控件中。现在Caliburn并不天真地支持这个，但我used code from a different article似乎提供了一种解决方法。我基本上需要一种方法来添加这种代码this.AddHandler(RadDragAndDropManager.DragInfoEvent, new EventHandler<DragDropEventArgs>(OnDragInfo), true);，但是caliburn不支持附加事件。这是我的代码：

<telerik:RadTreeView Height="250" Name="Root" Width="300" ItemTemplate="{StaticResource BusinessEntityTemplate}" IsDragDropEnabled="true"  cal:Action.TargetWithoutContext="{Binding Source={x:Static RelativeSource.Self}}">
    <i:Interaction.Triggers>
    <Helpers:RoutedEventTrigger RoutedEvent="{x:Static dragDrop:RadDragAndDropManager.DropQueryEvent}" IncludeHandledEvents="True">
        <cal:ActionMessage MethodName="OnDropQuery">
        <!--<cal:Parameter Value="$eventargs" />-->
        </cal:ActionMessage>
    </Helpers:RoutedEventTrigger>
    </i:Interaction.Triggers>
    </telerik:RadTreeViewItem>-->
</telerik:RadTreeView>

RoutedEventTrigger定义如下：

public class RoutedEventTrigger : EventTriggerBase<DependencyObject>
{
    RoutedEvent _routedEvent;
    public RoutedEvent RoutedEvent
    {
        get { return _routedEvent; }
        set { _routedEvent = value; }
    }
    bool _includeHandledEvents = false;

    public bool IncludeHandledEvents
    {
        get { return _includeHandledEvents; }
        set { _includeHandledEvents = value; }
    }

    public RoutedEventTrigger() { }
    protected override void OnAttached()
    {
        Behavior behavior = base.AssociatedObject as Behavior;
        FrameworkElement associatedElement = base.AssociatedObject as FrameworkElement;
        if (behavior != null)
        {
            associatedElement = ((IAttachedObject)behavior).AssociatedObject as FrameworkElement;
        }
        if (associatedElement == null)
        {
            throw new ArgumentException("Routed Event trigger can only be associated to framework elements");
        }
        if (RoutedEvent != null)
        //{ associatedElement.AddHandler(RoutedEvent, new RoutedEventHandler(this.OnRoutedEvent)); }
        { associatedElement.AddHandler(RoutedEvent, new RoutedEventHandler(this.OnRoutedEvent), this.IncludeHandledEvents); }

    }
    void OnRoutedEvent(object sender, RoutedEventArgs args)
    {
        base.OnEvent(args);
    }

    protected override string GetEventName() { return RoutedEvent.Name; }
}

在我的ViewModel中我只有一个像这样的处理程序：

public void OnDropQuery(object sender, DragDropQueryEventArgs e) {}

当我运行此错误时，我得到的错误是base.OnEvent(args);关于No target found for method OnDropQuery.我正在努力弄清楚为什么这不起作用。

Answer 1

发现问题，关于此问题的错误信息不是很明显。 viewmodel上的事件处理程序必须匹配xaml中目标方法的定义。在这种情况下，通过修改xaml修复了问题：

                <cal:ActionMessage MethodName="OnDropQuery">
                    <cal:Parameter Value="$source" />
                    <cal:Parameter Value="$eventargs" />
                </cal:ActionMessage>

我还必须删除cal:Action.TargetWithoutContext="{Binding Source={x:Static RelativeSource.Self}}"

Caliburn与附加事件，与目标失败

1 个答案: