WPF常用代码：依赖属性

　　来源：http://www.snippetsource.net/Snippet/20/define-a-custom-dependencyproperty

1. 获取对象附加属性

   public IEnumerable<DependencyProperty> GetAttachedProperties(DependencyObject element)
   {
       var markupObject = MarkupWriter.GetMarkupObjectFor(element);
       foreach (MarkupProperty mp in markupObject.Properties)
       {
           if (mp.IsAttached && mp.DependencyProperty != null)
           {
               var dpd = DependencyPropertyDescriptor.FromProperty(mp.DependencyProperty, element.GetType());
               if (dpd != null)
               {
                   yield return dpd.DependencyProperty;
               }
           }
       }
   }

2. 监听依赖属性更改

   var descriptor = DependencyPropertyDescriptor.FromProperty(TextBox.TextProperty, typeof(TextBox));
    
   if (descriptor != null)
   {
       descriptor.AddValueChanged(myTextBox, delegate
       {
           // Add your propery changed logic here...
       });
   } 

3. 定义附加属性

   public static readonly DependencyProperty TopProperty =
       DependencyProperty.RegisterAttached("Top", 
       typeof(double), typeof(Canvas),
       new FrameworkPropertyMetadata(0d,
           FrameworkPropertyMetadataOptions.Inherits));
    
   public static void SetTop(UIElement element, double value)
   {
       element.SetValue(TopProperty, value);
   }
    
   public static double GetTop(UIElement element)
   {
       return (double)element.GetValue(TopProperty);
   }

4. 定义依赖属性

   // Dependency Property Declaration
   public static readonly DependencyProperty BackgroundProperty =
       DependencyProperty.Register("Background", typeof(Brush), typeof(MyControl),
       new FrameworkPropertyMetadata(Brushes.Transparent));
   
   // Property Wrapper
   public Brush Background
   {
       get { return (Brush)GetValue(BackgroundProperty); }
       set { SetValue(BackgroundProperty, value); }
   }

5. 只读依赖属性

   // Register the private key to set the value
   private static readonly DependencyPropertyKey IsMouseOverPropertyKey = 
         DependencyProperty.RegisterReadOnly("IsMouseOver", 
         typeof(bool), typeof(MyClass), 
         new FrameworkPropertyMetadata(false));
    
   // Register the public property to get the value
   public static readonly DependencyProperty IsMouseoverProperty = 
         IsMouseOverPropertyKey.DependencyProperty;    
    
   // .NET Property wrapper
   public int IsMouseOver
   {
      get { return (bool)GetValue(IsMouseoverProperty); }
      private set { SetValue(IsMouseOverPropertyKey, value); }
   }