WPF如何聆聽BindingBase對象？

Question

我想創建一個繼承TriggerBase<FrameworkElement>的特殊DataTrigger。與DataTrigger類似，MyDataTrigger類中定義了BindingBase類型的屬性。

我怎樣才能聽到它的變化？

public class MyDataTrigger : TriggerBase<FrameworkElement> 
{ 
    ... 

    /// <summary> 
    /// [Wrapper property for BindingProperty] 
    /// <para> 
    /// Gets or sets the binding that produces the property value of the data object. 
    /// </para> 
    /// </summary> 
    public BindingBase Binding 
    { 
     get { return (BindingBase)GetValue(BindingProperty); } 
     set { SetValue(BindingProperty, value); } 
    } 

    public static readonly DependencyProperty BindingProperty = 
     DependencyProperty.Register("Binding", 
            typeof(BindingBase), 
            typeof(MyDataTrigger), 
            new FrameworkPropertyMetadata(null)); 

} 

更新：

的主要問題是，我不知道如何找到BindingBase相關DependencyProperty。我知道如何傾聽DP;

void ListenToDP(object component, DependencyProperty dp) 
{ 
    DependencyPropertyDescriptor dpDescriptor = DependencyPropertyDescriptor.FromProperty(dp, component.GetType()); 
    dpDescriptor.AddValueChanged(component, DPListener_ValueChanged); 
} 

凡DPListener_ValueChanged是EventHandler委託。在這裏，組件參數值是this.AssociatedObject。

Answer 1

好的，找到了！考慮到answer，綁定不是DP。所以，我試圖找到綁定關聯DP：

Type type = Binding.GetType(); 
PropertyPath propertyPath = (PropertyPath)(type.GetProperty("Path").GetValue(Binding)); 
string propertyName = propertyPath.Path; 

完整代碼：

public class MyDataTrigger : TriggerBase<FrameworkElement> 
{ 
    ... 

    public BindingBase Binding 
    { 
     get; 
     set; 
    } 

    protected override void OnAttached() 
    { 
     base.OnAttached(); 

     if (Binding != null && this.AssociatedObject.DataContext != null) 
      // 
      // Adding a property changed listener.. 
      // 
      Type type = Binding.GetType(); 
      PropertyPath propertyPath = (PropertyPath)(type.GetProperty("Path").GetValue(Binding)); 
      string propertyName = propertyPath.Path; 

      TypeDescriptor.GetProperties(this.AssociatedObject.DataContext).Find(propertyName, false).AddValueChanged(this.AssociatedObject.DataContext, PropertyListener_ValueChanged); 
    } 

    private void PropertyListener_ValueChanged(object sender, EventArgs e) 
    { 
     // Do some stuff here.. 
    } 
}