WPF 附加属性 | 易学教程

最近在学习WPF，虽其依赖属性非常优美，而附加属性更为漂亮，以此已记之：

主要实现label双击事件

先定义所需要的附加属性

 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);        }    }

然后实现ICommand接口

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);        }    }

接在定义viewmodel（旨在实现这个附加属性，所以比较简单）

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

最后为前台显示

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

来源：https://www.cnblogs.com/ptfblog/archive/2011/07/11/2103183.html

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