在Silverlight 2中创建密码输入框

Silverlight Beta2中，没有提供密码输入框控件，估计在正式版里应该提供吧。Chris Pietschmann自己写了一个，原文地址是：

http://pietschsoft.com/post/2008/03/PasswordTextBox-for-Silverlight-2-Beta-1.aspx

创建一个PasswordTextBox.cs类，代码如下：

///  Copyright 2008 Chris Pietschmann ( http://pietschsoft.com )
///  This work is licensed under a Creative Commons Attribution 3.0 United States License
///   http://creativecommons.org/licenses/by/3.0/us/
///
///  This is a Password TextBox built for use with Silverlight 2 Beta 1
///  The reason this was built, is because the standard TextBox in
///  Silverlight 2 Beta 1 does not have Password support.
///  Original Link:  http://pietschsoft.com/post/2008/03/PasswordTextBox-for-Silverlight-2-Beta-1.aspx
///  

using  System.Windows.Controls; 

namespace  SilverlightPasswordTextBox
{
     public   partial   class  PasswordTextBox : TextBox
    {
         public  PasswordTextBox()
        {
             this .TextChanged  +=   new  TextChangedEventHandler(PasswordTextBox_TextChanged);
             this .KeyDown  +=   new  System.Windows.Input.KeyEventHandler(PasswordTextBox_KeyDown);
        } 

         #region  Event Handlers 

         public   void  PasswordTextBox_TextChanged( object  sender, TextChangedEventArgs e)
        {
             if  ( base .Text.Length  >=  _Text.Length)
                _Text  +=   base .Text.Substring(_Text.Length);
            DisplayMaskedCharacters();
        } 

         public   void  PasswordTextBox_KeyDown( object  sender, System.Windows.Input.KeyEventArgs e)
        {
             int  cursorPosition  =   this .SelectionStart;
             int  selectionLength  =   this .SelectionLength; 

             //  Handle Delete and Backspace Keys Appropriately
             if  (e.Key  ==  System.Windows.Input.Key.Back
                 ||  e.Key  ==  System.Windows.Input.Key.Delete)
            {
                 if  (cursorPosition  <  _Text.Length)
                    _Text  =  _Text.Remove(cursorPosition, (selectionLength  >   0   ?  selectionLength :  1 ));
            }
            
             base .Text  =  _Text;
             this .Select((cursorPosition  >  _Text.Length  ?  _Text.Length : cursorPosition),  0 );
            DisplayMaskedCharacters();
        } 

         #endregion  

         #region  Private Methods 

         private   void  DisplayMaskedCharacters()
        {
             int  cursorPosition  =   this .SelectionStart;
            
             //  This changes the Text property of the base TextBox class to display all Asterisks in the control
             base .Text  =   new   string (_PasswordChar, _Text.Length); 

             this .Select((cursorPosition  >  _Text.Length  ?  _Text.Length : cursorPosition),  0 );
        } 

         #endregion  

         #region  Properties 

         private   string  _Text  =   string .Empty;
         ///   <summary>
         ///  The text associated with the control.
         ///   </summary>
         public   new   string  Text
        {
             get  {  return  _Text; }
             set
            {
                _Text  =  value;
                DisplayMaskedCharacters();
            }
        } 

         private   char  _PasswordChar  =   ' * ' ;
         ///   <summary>
         ///  Indicates the character to display for password input.
         ///   </summary>
         public   char  PasswordChar
        {
             get  {  return  _PasswordChar; }
             set  { _PasswordChar  =  value; }
        } 

         #endregion
    }
} 

 

使用方法：

< UserControl  x:Class ="SilverlightApplication1.Page"
    xmlns ="http://schemas.microsoft.com/client/2007"  
    xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml"  
    xmlns:myctl ="clr-namespace:SilverlightApplication1;assembly=SilverlightApplication1"  Width ="600"  Height ="480" >
     < Grid  x:Name ="LayoutRoot"  Background ="White" >
         < Canvas  Canvas.Top ="20" >           
             < myctl:PasswordTextBox  x:Name ="UserPassword"  Width ="200"  Height ="30"  Canvas.Top ="40"  Canvas.Left ="20" ></ myctl:PasswordTextBox >
         </ Canvas >
     </ Grid >
</ UserControl >

 

注意：要先加入名称空间，具体的值是：

clr-namespace:名称空间全名;assembly=程序集名称

通过使用，发现两个问题：

1，<myctl:PasswordTextBox PasswordChar="" />设置会报错

2，Text="初始值"仍旧是明文

原帖地址:http://blog.youkuaiyun.com/net_lover/archive/2008/04/06/2254267.aspx  感谢孟宪会老师