<Rectangle Width="100" Height="100" Fill="Red" local:CommandBinder.Command="{Binding ViewModel.MouseLeftDownCommand, ElementName=window}"local:CommandBinder.EventName="MouseLeftButtonDown"local:CommandBinder.Parameter="{Binding RelativeSource={RelativeSource Self}}">
</Rectangle>

　　很明显我们这里定义了3个附加属性。只是绑定的对象不同，EventName直接给了代表事件名的字符串，而Parameter没有绑定到ViewModel中的对象，而是通过ElementName绑定了我们希望传递的参数，这里是被点击的Rectangle。我们来看一下EventName和Parameter的定义。

        public static object GetParameter(DependencyObject obj){return (object)obj.GetValue(ParameterProperty);}public static void SetParameter(DependencyObject obj, object value){obj.SetValue(ParameterProperty, value);}// Using a DependencyProperty as the backing store for Parameter.  This enables animation, styling, binding, etc...public static readonly DependencyProperty ParameterProperty =DependencyProperty.RegisterAttached("Parameter", typeof(object), typeof(CommandBinder), new UIPropertyMetadata(null));public static string GetEventName(DependencyObject obj){return (string)obj.GetValue(EventNameProperty);}public static void SetEventName(DependencyObject obj, string value){obj.SetValue(EventNameProperty, value);}// Using a DependencyProperty as the backing store for EventName.  This enables animation, styling, binding, etc...public static readonly DependencyProperty EventNameProperty =DependencyProperty.RegisterAttached("EventName", typeof(string), typeof(CommandBinder), new UIPropertyMetadata(null));

        public static ICommand GetCommand(DependencyObject obj){return (ICommand)obj.GetValue(CommandProperty);}public static void SetCommand(DependencyObject obj, ICommand value){obj.SetValue(CommandProperty, value);}// Using a DependencyProperty as the backing store for CommonCommandBinder.  This enables animation, styling, binding, etc...public static readonly DependencyProperty CommandProperty =DependencyProperty.RegisterAttached("Command", typeof(ICommand), typeof(CommandBinder), new PropertyMetadata(ChangedCallback));private static void ChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e){FrameworkElement element = d as FrameworkElement;if (element != null){string eventName = element.GetValue(EventNameProperty) as string;if (eventName != null){EventInfo eventInfo = element.GetType().GetEvent(eventName);var handler = new MouseButtonEventHandler((sender, arg) => {object obj = element.GetValue(ParameterProperty);(e.NewValue as ICommand).Execute(obj);});var del = handler.GetInvocationList()[0];eventInfo.AddEventHandler(element, del);}}}

<Rectangle Width="100" Height="100" Fill="Red"  >
　　<local:Common.CommonCommand><local:CommonCommand Command="{Binding Path=MouseLeftDownCommand}"EventName="MouseLeftButtonDown"Parameter="{Binding Path=Title}">　　　　</local:CommonCommand>　　</local:Common.CommonCommand></Rectangle>

　　看似相似的绑定却始终无法在WPF中取到Parameter和Command的值。这里主要是期望把联系并不紧密的三个依赖属性EventNameProperty、ParameterProperty和CmmandProperty放置到一个叫做CommonCommand的类中，提高可读性和易用性。