c# - ReactiveCommand 传递命令参数

Question

我想用command实现textbox的KeyDown事件，

我想让命令可以识别KeyDown事件中的KeyEventArgs之类的键输入并做一些其他事情，

所以我想将命令参数传递给 ReactiveCommand(就像 Eventargs 在事件方法中所做的那样)，

但是我不知道怎么做。

我有 WPF Xaml 代码:

<Window x:Class="NameSpaceTest.OpenFileW"
        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:command="http://www.galasoft.ch/mvvmlight"
        Title="OpenFileWVieModel" Height="50" Width="200" WindowStyle="None">
    <Grid>
        <TextBox Name="Box" Text="{Binding OpenFPth, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" >
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="KeyDown">
                    <i:InvokeCommandAction Command="{Binding OpenFCmd}" CommandParameter=""/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </TextBox>
    </Grid>
</Window>

两类代码首先是 View ，其次是 View 模型:

   public partial class OpenFileW : Window
    {
        OpenFileWVieModel OFVM  = new OpenFileWVieModel();
        public OpenFileW()
        {
            this.DataContext = OFVM;
            InitializeComponent();
        }
    }


    public class OpenFileWVieModel : ReactiveObject
    {
        public string OpenFPth { get { return _openFpth; } set { this.RaiseAndSetIfChanged(ref _openFpth, value); } }
        private string _openFpth;

        public IReactiveCommand OpenFCmd { get; set; }

        public OpenFileWVieModel()
        {
          var TextChange = this.WhenAny(
                    x => x.OpenFPth,
                x =>
                {
                    MessageBox.Show("HI");
                    return true;
                });

       OpenFCmd = ReactiveCommand.CreateAsyncTask(
        TextChange,  //CanExecute
         async _ =>//Execute
         {
             MessageBox.Show("HI");
         }
           );

        }
    }

下一步如何将文本框 KeyInput 作为参数传递给命令？

Answer 1

您可以自行传递文本框或仅传递文本。我不知道你想用它做什么，但如果你必须与文本框交互，那么我建议你自己传递文本框:

传递文本:

<i:Interaction.Triggers>
   <i:EventTrigger EventName="KeyDown">
     <i:InvokeCommandAction Command="{Binding OpenFCmd}" 
        CommandParameter="{Binding ElementName=Box, Path=Text}" />
   </i:EventTrigger>
</i:Interaction.Triggers>

传递文本框:

<i:Interaction.Triggers>
   <i:EventTrigger EventName="KeyDown">
     <i:InvokeCommandAction Command="{Binding OpenFCmd}" 
        CommandParameter="{Binding ElementName=Box}" />
   </i:EventTrigger>
</i:Interaction.Triggers>

编辑:

使用上面的代码，您可以在代码中创建一个事件处理程序:

void OpenFCmn_OnClick(object obj)
    {
        var tb = (TextBox) obj;

        tb.KeyDown += TbOnKeyDown;

    }

    private void TbOnKeyDown(object sender, KeyEventArgs keyEventArgs)
    {
        MessageBox.Show(keyEventArgs.Key.ToString());
        keyEventArgs.Handled = true;

    }