Question

我已经在本文中实现了代码：http://wblo.gs/YvF。一切都按预期工作，但我不知道如何在事件触发时访问传递给事件处理程序的Arguments。我知道有命令参数，但我如何使用它来访问EventArgs？这是我实施的代码......

DragEnter Class

using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;

public class DragEnter : Attachment<Control, DragEnterBehavior, DragEnter>
{
    private static readonly DependencyProperty behaviorProperty = Behavior();
    public static readonly DependencyProperty CommandProperty = Command(behaviorProperty);
    public static readonly DependencyProperty CommandParameterProperty = Parameter(behaviorProperty);

    public static void SetCommand(Control control, ICommand command) { control.SetValue(CommandProperty, command); }
    public static ICommand GetCommand(Control control) { return control.GetValue(CommandProperty) as ICommand; }
    public static void SetCommandParameter(Control control, object parameter) { control.SetValue(CommandParameterProperty, parameter); }
    public static object GetCommandParameter(Control buttonBase) { return buttonBase.GetValue(CommandParameterProperty); }
}

DragEnterBehavior类

using System.Windows.Controls;
using Microsoft.Practices.Prism.Commands;

public class DragEnterBehavior : CommandBehaviorBase<Control>
{
    public DragEnterBehavior(Control selectableObject)
        : base(selectableObject)
    {
        selectableObject.DragEnter += (sender, args) => ExecuteCommand();
    }
}

实施守则

public ICommand EditItemCommand
{
    get
    {
        if (editItemCommand == null)
            editItemCommand = new RelayCommand(param => EditItemControl(), pre => IsItemEditButtonEnabled());

        return editItemCommand;
    }
}

public void EditItemControl()
{
    ...
    ChangedView(itemEditorViewModel);
}

<ListBox Behaviors:DragEnter.Command="{Binding EditItemCommand}" ...

对此有任何帮助将不胜感激。谢谢！

Answer 1

这是未经测试的，但

将DragEnterBehaviour更改为

public class DragEnterBehavior : CommandBehaviorBase<Control>
{
    public DragEnterBehavior(Control selectableObject)
        : base(selectableObject)
    {
        selectableObject.DragEnter += (sender, args) =>
                                      {
                                          CommandParameter = args;
                                          ExecuteCommand();
                                      };
    }
}

将您的RelayCommand（我假设这是来自MVVM Light）更改为

public ICommand EditItemCommand 
{ 
    get 
    { 
        if (editItemCommand == null) 
            editItemCommand = new RelayCommand<DragEventArgs>(
                EditItemControl, IsItemEditButtonEnabled); 

        return editItemCommand; 
    } 
} 

public void EditItemControl(DragEventArgs args) 
{ 
    ... 
}

如果您正在使用MVVM Light，那么您将获得相同的结果：

<i:Interaction.Triggers> 
    <i:EventTrigger EventName="DragEnter"> 
        <cmd:EventToCommand Command="{Binding DragEnterCommand}" 
            PassEventArgsToCommand="True" /> 
    </i:EventTrigger> 
</i:Interaction.Triggers>

命令行为附件参数

1 个答案: