WPF TextBox event

Question

I have a textbox and I need the user to enter only Cyrillic letters. User can't enter numbers and special characters (except space) and latin characters! The Value of variable "l" I will set by myself.

How can I make the KeyDown event to do this?

In WindowsForms I do it like this:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{

    char l = e.KeyChar;
    if ((l < 'А' || l > 'я') && l != '\b' )
    {
       e.Handled = true;
    }
}

Answer 1

The most simple way I discovered is to leverage the OnPreviewTextInput event:

Markup:

<TextBox PreviewTextInput="UIElement_OnPreviewTextInput" />

Handler:

private void UIElement_OnPreviewTextInput(object sender, TextCompositionEventArgs e)
{
    bool isCyrillic = Regex.IsMatch(e.Text, @"\p{IsCyrillic}");
    e.Handled = !isCyrillic;
}