How to create a numeric textbox in Silverlight?

Question

As the title says really. I've had a look at inheriting from TextBox, but the only sensible override was "OnKeyDown", but that just gives me a key from the Key enum (with no way to use Char.IsNumeric()).

Answer 1

I took Nidhal's suggested answer and edited it a bit to handle the shift case for the characters above the digits (ie. !@#$%^&*()) since that solution will still allow those characters in the textbox.

private void NumClient_KeyDown(object sender, KeyEventArgs e)
{       
    // Handle Shift case
    if (Keyboard.Modifiers == ModifierKeys.Shift)
    {
       e.Handled = true;
    }

    // Handle all other cases
    if (!e.Handled && (e.Key < Key.D0 || e.Key > Key.D9))
    {
        if (e.Key < Key.NumPad0 || e.Key > Key.NumPad9)
        {
            if (e.Key != Key.Back)
            {
                e.Handled = true;
            }
        }
    }           
}

Answer 2

Visit http://www.dataartist.net/blog/post/Silverlight-Behavior-Modifications-13-NumericOnlyBehavior.aspx or use TextBox behavior as below

  using System;
  using System.Windows;
  using System.Windows.Controls;
  using System.Windows.Input;
  using System.Windows.Interactivity;

  namespace DataArtist
  {
public class NumericOnly : Behavior<TextBox>
{
    private string Text { get; set; }
    private bool shiftKey;
    public bool StripOnExit { get; set; }

    public NumericOnly()
    {
        StripOnExit = false;
    }

    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.KeyDown += KeyDown;
        AssociatedObject.KeyUp += KeyUp;
        AssociatedObject.GotFocus += GotFocus;
        AssociatedObject.LostFocus += LostFocus;
    }

    void KeyUp(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Shift)
        {
            shiftKey = false;
        }
    }

    void KeyDown(object sender, KeyEventArgs e)
    {
        if (StripOnExit != false || e.Key == Key.Tab || e.Key == Key.Enter)
        {
            return;
        }

        if (e.Key == Key.Shift)
        {
            shiftKey = true;
        }
        else
        {
            if (IsNumericKey(e.Key) == false)
            {
                e.Handled = true;
            }
        }
    }

    void GotFocus(object sender, RoutedEventArgs e)
    {
        Text = AssociatedObject.Text;
    }

    private void LostFocus(object sender, RoutedEventArgs e)
    {
        if (AssociatedObject.Text == Text)
        {
            return;
        }

        string content = string.Empty;

        foreach (var c in AssociatedObject.Text)
        {
            if (Char.IsNumber(c) == true)
            {
                content += c;
            }
        }

        AssociatedObject.Text = content;
    }

    public bool IsNumericKey(Key key)
    {
        if (shiftKey == true)
        {
            return false;
        }

        string code = key.ToString().Replace("NumPad", "D");

        if (code[0] == 'D' && code.Length > 1)
        {
            return (Char.IsNumber(code[1]));
        }

        return false;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.KeyDown -= KeyDown;
        AssociatedObject.LostFocus -= LostFocus;
        AssociatedObject.GotFocus -= GotFocus;
    }
}   
    }

Answer 3

private void Numclient_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Key < Key.D0 || e.Key > Key.D9)
    {
        if (e.Key < Key.NumPad0 || e.Key > Key.NumPad9)
        {
            if (e.Key != Key.Back && e.Key != Key.Shift)
            {
                e.Handled = true;
            }
        }
    }
}