TextBox KeyDown触发器事件不适用于Backspace和Delete键

Question

我有一个文本框,对于该文本框,我附加了一个keydown事件.一切正常,但我注意到当我按下"Backspace"和"Delete"键时,没有调用绑定命令.

我的查看xaml文件: -

<TextBox x:Name="textBox" Width="500" Text="{Binding TextBoxText, UpdateSourceTrigger=PropertyChanged}">
<i:Interaction.Triggers>                
    <i:EventTrigger EventName="KeyDown">  
        <cmd:EventToCommand Command="{BindingPath=TextBoxKeyDownEvent}" PassEventArgsToCommand="True" />                
    </i:EventTrigger>            
</i:Interaction.Triggers>
</TextBox>

我的ViewModel cs文件: -

    //TextBox Key Down Event Handler
    private DelegateCommand _textBoxKeyDownEvent;
    public ICommand TextBoxKeyDownEvent
    {
        get
        {
            if (_textBoxKeyDownEvent == null)
            {
                _textBoxKeyDownEvent = new DelegateCommand(TextBoxKeyDownEventHandler);
            }
            return _textBoxKeyDownEvent;
        }
        set { }
    }

有人可以给我一些建议

Answer 1

编辑: 你必须使用PreviewKeyDown它的工作原理.不会在Space和Delete上触发KeyDown.如果忽略MVVM并将处理程序KeyDown置于代码隐藏中,它也将失败.

如何将Text-Property绑定到viewmodel中的字符串？

我构建了一个快速,简单的例子.

结果

左侧TextBox中的文本只是填充到右侧的Textblock.

视图

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <StackPanel Orientation="Horizontal">
        <TextBox Text="{Binding TextBoxValue, UpdateSourceTrigger=PropertyChanged}"  Width="250"/>
        <StackPanel Orientation="Horizontal">
            <TextBlock>"</TextBlock>
            <TextBlock Text="{Binding TextBoxValue, UpdateSourceTrigger=PropertyChanged}" />
            <TextBlock>"</TextBlock>
        </StackPanel>
    </StackPanel>
</Window>

视图模型

public class MainWindowViewModel : INotifyPropertyChanged
{
    private string textBoxValue;

    public string TextBoxValue
    {
        get { return textBoxValue; }
        set
        {
            textBoxValue = value;
            OnTextBoxValueChanged();
            RaisePropertyChanged();
        }
    }

    void OnTextBoxValueChanged()
    {
        // you logic here, if needed.
    }

    #region INotifyPropertyChanged implementation

    public event PropertyChangedEventHandler PropertyChanged;

    void RaisePropertyChanged([CallerMemberName] string propertyName = null)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    #endregion
}