Microsoft Silverlight – Hidden Password Textbox

The Textbox in Silverlight currently does not support masking the text when entering for an example a password. This may be supported in the future, but for now a work around was needed. By using a couple event handlers in the the Silverlight control, along with a few public methods in a separate class, it can be done.

The following code needs to be in the Silverlight control that hosts your textbox that needs to be masked.

Public strPassword As String = ""
 
Private Sub txtPassword_KeyDown(ByVal sender As System.Object, ByVal e As System.Windows.Input.KeyEventArgs) 
    Try
        If e.Key = Key.Enter Then
            btnLogon_Click(sender, e)
            Exit Sub
        End If
 
    Catch ex As Exception
 
    End Try
 
    Try
        Dim mpassword As New HidePassword
        mpassword.ParentObject = Me
        mpassword.hpKeyDown(e)
    Catch ex As Exception
 
    End Try
End Sub
 
Private Sub txtPassword_TextChanged(ByVal sender As System.Object, ByVal e As System.Windows.Controls.TextChangedEventArgs) 
    Dim mpassword As New HidePassword
    mpassword.ParentObject = Me
    mpassword.hpTextChanged()
End Sub

Create a class called ‘HidePassword’ and populate with the following logic:

 
Public Class HidePassword 
Private mText As String = String.Empty
Private mPasswordChar As Char = "*"
Private mIPAddress As String = ""
Public ParentObject As New Logon(mIPAddress)

Public Sub hpTextChanged()
    If ParentObject.txtPassword.Text.Length >= ParentObject.strPassword.Length Then
       ParentObject.strPassword += ParentObject.txtPassword.Text.Substring(ParentObject.strPassword.Length)
    End If
    
	DisplayMaskedCharacters()
 
End Sub
 
Public Sub hpKeyDown(ByVal e)
    Dim cursorPosition As Integer = ParentObject.txtPassword.SelectionStart
    Dim selectionLength As Integer = ParentObject.txtPassword.SelectionLength
    ' Handle Delete and Backspace Keys Appropriately

    If e.Key = Key.Back Or e.Key = Key.Delete Then
        If cursorPosition < ParentObject.strPassword.Length Then
            Dim lengthToRemove As Integer = 1
            If selectionLength > 0 Then lengthToRemove = selectionLength
            ParentObject.strPassword = ParentObject.strPassword.Remove(cursorPosition, lengthToRemove)
        End If
    End If

    ParentObject.txtPassword.Text = ParentObject.strPassword

    If cursorPosition > ParentObject.strPassword.Length Then
        ParentObject.txtPassword.Select(ParentObject.strPassword.Length, 0)
    Else
        ParentObject.txtPassword.Select(cursorPosition, 0)
    End If
    DisplayMaskedCharacters()
End Sub
 
Private Sub DisplayMaskedCharacters()
    Dim cursorPosition As Integer = ParentObject.txtPassword.SelectionStart
    ' This changes the Text property of the base TextBox class to display all Asterisks in the control
    ParentObject.txtPassword.Text = New String(mPasswordChar, ParentObject.strPassword.Length)

    If cursorPosition > ParentObject.strPassword.Length Then
        ParentObject.txtPassword.Select(ParentObject.strPassword.Length, 0)
    Else
        ParentObject.txtPassword.Select(cursorPosition, 0)
    End If
End Sub