WPF中附加属性

WPF中附加属性

在WPF当中，大部分控件，只要是可以绑定数据的Binding ，就是属于依赖属性，很方便进行数据的操作，但是的，有些控件是没有的的比如，PassWordBox，这时候就需要我们自己去写一个帮助类，让PassWordBox变成可以直接使用的bingding的
直接上代码

  public class PassWordHelper
    {
        public static readonly DependencyProperty PasswordProperty = DependencyProperty.RegisterAttached(
            "Password", typeof(string),
            typeof(PassWordHelper),
            new PropertyMetadata(new PropertyChangedCallback(OnPropertyChanged)));

        public static readonly DependencyProperty AttachProperty = DependencyProperty.RegisterAttached(
           "Attach", typeof(string),
           typeof(PassWordHelper),
           new PropertyMetadata(new PropertyChangedCallback(OnAttachChanged)));

        static bool _isUpdating = false;
        private static void OnPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            PasswordBox pb = (d as PasswordBox);
            pb.PasswordChanged -= Pb_PasswordChanged;
            if (!_isUpdating)
            {
                (d as PasswordBox).Password = e.NewValue.ToString();
                pb.PasswordChanged += Pb_PasswordChanged;
            }
        }

        private static void Pb_PasswordChanged(object sender, RoutedEventArgs e)
        {
            PasswordBox pb = sender as PasswordBox;
            _isUpdating = false;
            SetPassword(pb, pb.Password);
            _isUpdating = true;

        }       
        public static string GetPassword(DependencyObject d)
        {
            return (string)d.GetValue(PasswordProperty);
        }
        public static void SetPassword(DependencyObject d, string value)
        {
            d.SetValue(PasswordProperty, value);
        }


        public static void OnAttachChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            PasswordBox pb = (d as PasswordBox);
            pb.PasswordChanged += Pb_PasswordChanged;
        }

        public static string GetAttach(DependencyObject d)
        {
            return (string)d.GetValue(AttachProperty);
        }
        public static void SetAttach(DependencyObject d, string value)
        {
            d.SetValue(AttachProperty, value);
        }


    }

在xaml中的使用

先进行类库引用

 xmlns:passwordHelper="clr-namespace:Wpf.Common;assembly=Wpf.Common"

 <PasswordBox passwordHelper:PassWordHelper.Password="{Binding PassWord,Mode=TwoWay}" passwordHelper:PassWordHelper.Attach="True"></PasswordBox>