Silverlight PropertyChanged事件未在双向文本框绑定中触发

Question

如果某个类属性是双向绑定到文本框的文本属性，那么当更改文本框中的文本时，该类的“PropertyChanged”事件应该开火吗？它不符合我的情况 - 当我更改文本框内容时，消息框永远不会弹出。如果属性更改文本框更改，则绑定仍然有效，反之亦然。

编辑：现在我意识到它会触发，但只有当文本框失去焦点。我想这背后必然有一个原因。

代码：

public class BaselineAreas : INotifyPropertyChanged 
    { 
     public event PropertyChangedEventHandler PropertyChanged; 
     private double _Impervious = 0; 
     public double Impervious 
     { 
      get { return _Impervious; } 
      set 
      { 
       if (value != this._Impervious) 
       { 
        _Impervious = value; 
        NotifyPropertyChanged("Impervious"); 
       } 
      } 
     } 
     private double _Pervious = 0; 
     public double Pervious 
     { 
      get { return _Pervious; } 
      set 
      { 
       if (value != this._Pervious) 
       { 
        _Pervious = value; 
        NotifyPropertyChanged("Pervious"); 
       } 
      } 
     } 
     public void NotifyPropertyChanged(string propertyName) 
     { 
      if (PropertyChanged != null) 
      { 
       PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 
      } 
     } 
    } 

    private BaselineAreas baselineAreas = new BaselineAreas(); 

    public MainPage() 
    { 
     InitializeComponent(); 

     baselineAreas.Impervious = 100; 
     baselineAreas.Pervious = 500; 
     textBoxTotalImperviousArea.DataContext = baselineAreas; 
     textBoxTotalPerviousArea.DataContext = baselineAreas; 
     baselineAreas.PropertyChanged += new PropertyChangedEventHandler(baselineAreas_PropertyChanged); 
    } 

    void baselineAreas_PropertyChanged(object sender, PropertyChangedEventArgs e) 
    { 
     MessageBox.Show(baselineAreas.Impervious.ToString()); 
    } 

的XAML：

   <TextBox Height="23" HorizontalAlignment="Left" Margin="138,16,0,0" Name="textBoxTotalImperviousArea" VerticalAlignment="Top" Width="62" 
         Text="{Binding Impervious, Mode=TwoWay}"/> 
       <TextBox Height="23" HorizontalAlignment="Right" Margin="0,45,226,0" Name="textBoxTotalPerviousArea" VerticalAlignment="Top" Width="62" 
         Text="{Binding Pervious, Mode=TwoWay}"/> 

Answer 1

这可能使文本框在XAML行为，使其在每一个字符的变化更新：

http://dotneteers.net/blogs/vbandi/archive/2009/12/24/make-a-silverlight-textbox-update-its-binding-on-every-character.aspx