WPF 附加属性的用法 (一)

public class MDCTest
    {
        public static DependencyProperty MouseDoubleClickCommandProperty = DependencyProperty.RegisterAttached(
            "MouseDoubleClick",
            typeof(ICommand),
            typeof(MDCTest),
            new FrameworkPropertyMetadata(null, new PropertyChangedCallback(MouseDoubleClickChanged))
            );
        public static void SetMouseDoubleClick(DependencyObject target, ICommand value)
        {
            target.SetValue(MDCTest.MouseDoubleClickCommandProperty, value);
        }
        public static ICommand GetMouseDoubleClick(DependencyObject target)
        {
            return (ICommand)target.GetValue(MDCTest.MouseDoubleClickCommandProperty);
        }
        private static void MouseDoubleClickChanged(DependencyObject target, DependencyPropertyChangedEventArgs e)
        {
            Control control = target as Control;
            if (control != null)
            {
                if (e.NewValue != null && e.OldValue == null)
                {
                    control.MouseDoubleClick += new MouseButtonEventHandler(control_MouseDoubleClick);
                }
                else if (e.NewValue == null && e.OldValue != null)
                {
                    control.MouseDoubleClick -= new MouseButtonEventHandler(control_MouseDoubleClick);
                }
            }
        }
        public static void control_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            Control control = sender as Control;
            ICommand command = (ICommand)control.GetValue(MDCTest.MouseDoubleClickCommandProperty);
            command.Execute(control);
        }
    }

public class RelayCommand : ICommand
    {
        private Action<object> _Execute;
        private Predicate<object> _CanExecute;

        public RelayCommand(Action<object> execte)
            : this(execte, null)
        {
        }
        public RelayCommand(Action<object> execute, Predicate<object> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("Execute");
            _Execute = execute;
            _CanExecute = canExecute;
        }
        public bool CanExecute(object parameter)
        {
            return _CanExecute == null ? true : _CanExecute(parameter);
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public void Execute(object parameter)
        {
            _Execute(parameter);
        }
    }

public class LabelViewModel
    {
        public ICommand Command
        {
            get
            {
                return new RelayCommand((m) => MessageBox.Show(m.ToString() + "command双击事件成功"));
            }
        }
    }

     <Label Name="label" local:MDCTest.MouseDoubleClick="{Binding Path=Command}">MouseDoubleClickTest</Label>

给Label附加双击事件 原文：http://www.cnblogs.com/ptfblog/archive/2011/07/11/2103183.html

绑定有两个需要注意的地方

1.如果绑定到 附加属性（Binding Attached Property），需要加上括号，这个比较特别，例如

   <TextBox x:Name="tbUserName"
               Width="200"
               Grid.Column="0"
               Margin="10,10,0,0"
               Foreground="Gray"
               nasSetting:TextBoxMaskHelper.MaskText="Please input username"
               Text="{Binding Path=(nasSetting:TextBoxMaskHelper.MaskText),Mode=OneWay,ElementName=tbUserName}"
               Height="30" CharacterCasing="Normal">

<TextBox.Foreground>
          <MultiBinding Converter="{StaticResource MaskBrushConverter}">
            <Binding Path="Text"   ElementName="tbUserName" UpdateSourceTrigger="PropertyChanged"/>
            <Binding Path="(nasSetting:TextBoxMaskHelper.MaskText)"  ElementName="tbUserName" />
          </MultiBinding>
        </TextBox.Foreground>

2.如果绑定到只读的属性(Binding to readonly property)，例如IsFocused，需要加上 Mode = OneWay

<TextBox.Text>
          <MultiBinding Converter="{StaticResource MaskTextConverter}" Mode="OneWay">
            <Binding Path="(nasSetting:TextBoxMaskHelper.MaskText)"  ElementName="tbUserName" />
            <Binding Path="IsFocused"   ElementName="tbUserName"  Mode="OneWay"/>
          </MultiBinding>
        </TextBox.Text>

https://www.cnblogs.com/gaobw/p/6553443.html