原文:WPF中PasswordBox控件的Password属性的数据绑定
英文原文：http://www.wpftutorial.net/PasswordBox.html
中文原文：http://blog.csdn.net/oyi319/article/details/6551532
WPF的PasswordBox控件的Password属性不是依赖属性，无法直接进行数据绑定，为使其在MVVM模式中正常使用，可以为PasswordBox增加一个助手类，代码如下：
注：代码摘自：http://www.wpftutorial.net/PasswordBox.html
using System.Windows;
using System.Windows.Controls;
namespace Oyi319.Helper
{
/// <summary>
/// 为PasswordBox控件的Password增加绑定功能
/// </summary>
public static class PasswordBoxHelper
{
public static readonly DependencyProperty PasswordProperty =
DependencyProperty.RegisterAttached("Password",
typeof(string), typeof(PasswordBoxHelper),
new FrameworkPropertyMetadata(string.Empty, OnPasswordPropertyChanged));
public static readonly DependencyProperty AttachProperty =
DependencyProperty.RegisterAttached("Attach",
typeof(bool), typeof(PasswordBoxHelper), new PropertyMetadata(false, Attach));
private static readonly DependencyProperty IsUpdatingProperty =
DependencyProperty.RegisterAttached("IsUpdating", typeof(bool),
typeof(PasswordBoxHelper)); public static void SetAttach(DependencyObject dp, bool value)
{
dp.SetValue(AttachProperty, value);
}
public static bool GetAttach(DependencyObject dp)
{
return (bool)dp.GetValue(AttachProperty);
}
public static string GetPassword(DependencyObject dp)
{
return (string)dp.GetValue(PasswordProperty);
}
public static void SetPassword(DependencyObject dp, string value)
{
dp.SetValue(PasswordProperty, value);
}
private static bool GetIsUpdating(DependencyObject dp)
{
return (bool)dp.GetValue(IsUpdatingProperty);
}
private static void SetIsUpdating(DependencyObject dp, bool value)
{
dp.SetValue(IsUpdatingProperty, value);
}
private static void OnPasswordPropertyChanged(DependencyObject sender,
DependencyPropertyChangedEventArgs e)
{
PasswordBox passwordBox = sender as PasswordBox;
passwordBox.PasswordChanged -= PasswordChanged;
if (!(bool)GetIsUpdating(passwordBox))
{
passwordBox.Password = (string)e.NewValue;
}
passwordBox.PasswordChanged += PasswordChanged;
}
private static void Attach(DependencyObject sender,
DependencyPropertyChangedEventArgs e)
{
PasswordBox passwordBox = sender as PasswordBox;
if (passwordBox == null)
return;
if ((bool)e.OldValue)
{
passwordBox.PasswordChanged -= PasswordChanged;
}
if ((bool)e.NewValue)
{
passwordBox.PasswordChanged += PasswordChanged;
}
}
private static void PasswordChanged(object sender, RoutedEventArgs e)
{
PasswordBox passwordBox = sender as PasswordBox;
SetIsUpdating(passwordBox, true);
SetPassword(passwordBox, passwordBox.Password);
SetIsUpdating(passwordBox, false);
}
}
}
那么XAML绑定代码如下：
<PasswordBox Helper:PasswordBoxHelper.Attach="True" Helper:PasswordBoxHelper.Password="{Binding Path=Password,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
MVVM模式XAML窗口声明代码如下：
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Helper="clr-namespace:Oyi319.Helper"
xmlns:ViewModels="clr-namespace:Oyi319.ViewModels"
x:Class="Oyi319.Views.Login"
x:Name="Window"
Title="Login"
FocusManager.FocusedElement="{Binding ElementName=txt_UserName}" >
<Window.DataContext>
<ViewModels:LoginViewModel />
</Window.DataContext>
</Window>