How to get character entered on Keydown Event in WPF C# - character

Question

i'm using wpf c# in visual studio
i want to prevent user can enter Arabic character , Just Persian Character
like when user entered this value on keyboard → "ي" change it to "ی"
my means something like this :
when user press button to type "A" on keyboard i want to change this character, first check if is "A" change to "B"
i did it in Windows Form Application , but that code does not work in WPF
My Code in Windows From :
if (e.KeyChar.ToString() == "ي")
{
e.KeyChar = Convert.ToChar("ی");
}
My Code in WPF :
if (e.Key.ToString() == "ي")
{
e.Key.ToString("ی");
}
These codes not working in WPF
Please Help

Answer 1

It's a bit different in WPF.
This works using a english keyboard. Don't know if it will work with Arabic, as the rules might be a little different for inserting characters.
You can try handling the PreviewTextInput event of the TextBox.
XAML:
<TextBox PreviewTextInput="TextBox_OnTextInput" ...
Code:
private void TextBox_OnTextInput(object sender, TextCompositionEventArgs e)
{
var box = (sender as TextBox);
var text = box.Text;
var caret = box.CaretIndex;
if (e.TextComposition.Text == "ي")
{
var newValue = "ی";
//Update the TextBox' text..
box.Text = text.Insert(caret, newValue);
//..move the caret accordingly..
box.CaretIndex = caret + newValue.Length;
//..and make sure the keystroke isn't handled again by the TextBox itself:
e.Handled = true;
}
}