交互触发器不在Keyboard.LostKeyboardFocus

问题描述：

触发我的问题是交互触发器不能在Keyboard.LostKeyboardFocus事件上工作。但是当我从后面的代码中完成工作。我有一个文本框与下面的代码，交互触发器不在Keyboard.LostKeyboardFocus

     <TextBox 
         Text="{Binding PostRunPlateNotes, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" 
         Height="113" 
         Width="Auto" 
         ScrollViewer.HorizontalScrollBarVisibility="Auto" 
         ScrollViewer.VerticalScrollBarVisibility="Auto"> 
         <i:Interaction.Triggers> 
          <i:EventTrigger 
           EventName="Keyboard.LostKeyboardFocus"> 
           <i:InvokeCommandAction 
            Command="{Binding SavePlateNotesCommand}"></i:InvokeCommandAction> 
          </i:EventTrigger> 
         </i:Interaction.Triggers> 
        </TextBox>

而且在这里的视图模型是代码，

#region CommandData 
     private ICommand _savePlateNotesCommand; 
     public ICommand SavePlateNotesCommand 
     { 
      get 
      { 
       return _savePlateNotesCommand ?? (_savePlateNotesCommand = new RelayCommand(OnSaveClick)); 
      } 
      set 
      { 
       _savePlateNotesCommand = value; 
       OnPropertyChanged("SavePlateNotesCommand"); 
      } 
     } 
     #endregion

在后面的代码，

public partial class RunInformationUserControl : UserControl, INotifyPropertyChanged 
    { 
     #region Accessors 
     public RunInformationParameters RunInfoParams { get; set; } 
     public RunInformationViewModel RunViewModel { get; set; } 
     #endregion 

     #region Constructor 
     public RunInformationUserControl() 
     { 
      InitializeComponent(); 
      RunViewModel = null; 
     } 
     #endregion 

     #region Methods 
     public void SetParameters(RunInformationParameters parameters) 
     { 
      this.RunInfoParams = parameters; 
      RunViewModel = new RunInformationViewModel(RunInfoParams); 
      this.DataContext = RunViewModel; 
     } 

     #endregion 

     #region EventHandlers 
     private void UserControl_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e) 
     { 
      if (RunViewModel != null) 
      { 
       OnPropertyChanged("runInfoParams"); 
      } 
     } 

     #endregion 

     #region INotifyPropertyChangedEvent 
     public event PropertyChangedEventHandler PropertyChanged; 
     protected virtual void OnPropertyChanged(string propertyName) 
     { 
      PropertyChangedEventHandler handler = PropertyChanged; 
      if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName)); 
     } 

     #endregion 

    }

问题是，当我提高键盘在代码后面失去焦点。所有其他属性都被正确绑定。但交互触发器不起作用，请帮助。

如果在XAML中将'Keyboard.LostKeyboardFocus'更改为'LostKeyboardFocus'，它会工作吗？ –

@SzabolcsDézsi感谢它的工作方式。 – nikhil

答

内部的EventTrigger最终会在它的源代码中调用typeof(TextBox).GetEvent("Keyboard.LostKeyboardFocus")，并且将返回null，因为TextBox没有Keyboard.LostKeyboardFocus事件。由于Keyboard.LostKeyboardFocus是附加事件，因此WPF/XAML概念GetEvent无法将其返回，并且EventTrigger无法订阅它。

另一方面TextBox从UIElement继承LostKeyboardFocus，所以使用它将工作。

交互触发器不在Keyboard.LostKeyboardFocus

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