封装：WPF中可以绑定的BindPassWord控件

一、目的：本身自带的PassWord不支持绑定

二、Xaml部分

<UserControl x:Class="HeBianGu.General.WpfControlLib.BindPassWordBox"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:HeBianGu.General.WpfControlLib"
             mc:Ignorable="d" 
             d:DesignHeight="50" d:DesignWidth="300">
    <Grid>
        <PasswordBox x:Name="pb_center" PasswordChanged="pb_center_PasswordChanged" />
    </Grid>
</UserControl>

三、代码部分

/// <summary> 可以绑定的密码框 </summary>
    public partial class BindPassWordBox : UserControl
    {
        PasswordBox _password = null;

        private void pb_center_PasswordChanged(object sender, RoutedEventArgs e)
        {
            this.PassWord = this._password.Password;
        }


        public BindPassWordBox()
        {
            InitializeComponent();
        }

        public string PassWord
        {
            get { return (string)GetValue(PassWordProperty); }
            set { SetValue(PassWordProperty, value); }
        }

        // Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty PassWordProperty =
            DependencyProperty.Register("PassWord", typeof(string), typeof(BindPassWordBox), new PropertyMetadata(default(string), (d, e) =>
             {
                 BindPassWordBox control = d as BindPassWordBox;

                 if (control == null) return;

                 string config = e.NewValue as string;

                 if (control._password == null) return;

                 control._password.Password = config;
                 
                 SetPasswordBoxSelection(control._password, config.Length, 0);
             }));


        private static void SetPasswordBoxSelection(PasswordBox passwordBox, int start, int length)
        {
            var select = passwordBox.GetType().GetMethod("Select",
                            BindingFlags.Instance | BindingFlags.NonPublic);

            select.Invoke(passwordBox, new object[] { start, length });
        }
    }

四、原理

封装一层PassWordBox控件，自定义依赖属性，在PassWordBox的Changed事件中赋值依赖属性

SetPasswordBoxSelection(control._password, config.Length, 0);

此方法用来设置光标，否则输入后光标位置不正确