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

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 2

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;
            }
        }
    }
}

Answer 3

    private void TextBox_KeyDown(object sender, KeyEventArgs e)
    {
        bool isDigit = e.Key >= Key.D0 && e.Key < Key.D9 || e.Key == Key.NumPad0 || e.Key == Key.NumPad1 || e.Key == Key.NumPad2 || e.Key == Key.NumPad3 || e.Key == Key.NumPad4 || e.Key == Key.NumPad5 || e.Key == Key.NumPad6 ||
        e.Key == Key.NumPad7 || e.Key == Key.NumPad8 || e.Key == Key.NumPad9 ||e.Key == Key.Back || e.Key == Key.Delete || e.Key == Key.Left || e.Key == Key.Right;

        if (isDigit) { }
        else
            e.Handled = true; 
    }

Answer 4

Why is everyone not doing the hard work of just handling them all?

Here (this is perfection):

<TextBox KeyDown="TextBox_KeyDown" />

private void TextBox_KeyDown(object sender, KeyEventArgs e)
{
    var _Letter = string.Empty;
    switch (e.Key)
    {
        case Key.A: _Letter = "A"; break;
        case Key.Add: _Letter = "+"; break;
        case Key.Alt: break;
        case Key.B: _Letter = "B"; break;
        case Key.Back: break;
        case Key.C: _Letter = "C"; break;
        case Key.CapsLock: break;
        case Key.Ctrl: break;
        case Key.D: _Letter = "D"; break;
        case Key.D0: _Letter = "0"; break;
        case Key.D1: _Letter = "1"; break;
        case Key.D2: _Letter = "2"; break;
        case Key.D3: _Letter = "3"; break;
        case Key.D4: _Letter = "4"; break;
        case Key.D5: _Letter = "5"; break;
        case Key.D6: _Letter = "6"; break;
        case Key.D7: _Letter = "7"; break;
        case Key.D8: _Letter = "8"; break;
        case Key.D9: _Letter = "9"; break;
        case Key.Decimal: _Letter = "."; break;
        case Key.Delete: break;
        case Key.Divide: _Letter = "/"; break;
        case Key.Down: break;
        case Key.E: _Letter = "E"; break;
        case Key.End: break;
        case Key.Enter: break;
        case Key.Escape: break;
        case Key.F: _Letter = "F"; break;
        case Key.F1: break;
        case Key.F10: break;
        case Key.F11: break;
        case Key.F12: break;
        case Key.F2: break;
        case Key.F3: break;
        case Key.F4: break;
        case Key.F5: break;
        case Key.F6: break;
        case Key.F7: break;
        case Key.F8: break;
        case Key.F9: break;
        case Key.G: _Letter = "G"; break;
        case Key.H: _Letter = "H"; break;
        case Key.Home: break;
        case Key.I: _Letter = "I"; break;
        case Key.Insert: break;
        case Key.J: _Letter = "J"; break;
        case Key.K: _Letter = "K"; break;
        case Key.L: _Letter = "L"; break;
        case Key.Left: break;
        case Key.M: _Letter = "M"; break;
        case Key.Multiply: _Letter = "*"; break;
        case Key.N: _Letter = "N"; break;
        case Key.None: break;
        case Key.NumPad0: _Letter = "0"; break;
        case Key.NumPad1: _Letter = "1"; break;
        case Key.NumPad2: _Letter = "2"; break;
        case Key.NumPad3: _Letter = "3"; break;
        case Key.NumPad4: _Letter = "4"; break;
        case Key.NumPad5: _Letter = "5"; break;
        case Key.NumPad6: _Letter = "6"; break;
        case Key.NumPad7: _Letter = "7"; break;
        case Key.NumPad8: _Letter = "8"; break;
        case Key.NumPad9: _Letter = "9"; break;
        case Key.O: _Letter = "O"; break;
        case Key.P: _Letter = "P"; break;
        case Key.PageDown: break;
        case Key.PageUp: break;
        case Key.Q: _Letter = "Q"; break;
        case Key.R: _Letter = "R"; break;
        case Key.Right: break;
        case Key.S: _Letter = "S"; break;
        case Key.Shift: break;
        case Key.Space: _Letter = " "; break;
        case Key.Subtract: _Letter = "-"; break;
        case Key.T: _Letter = "T"; break;
        case Key.Tab: break;
        case Key.U: _Letter = "U"; break;
        case Key.Unknown: break;
        case Key.Up: break;
        case Key.V: _Letter = "V"; break;
        case Key.W: _Letter = "W"; break;
        case Key.X: _Letter = "X"; break;
        case Key.Y: _Letter = "Y"; break;
        case Key.Z: _Letter = "Z"; break;
        default: break;
    }
    var _Text = (sender as TextBox).Text + _Letter;
    double _Double;
    e.Handled = !double.TryParse(_Text, out _Double);
}

}

Answer 5

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;
            }
        }
    }           
}