Get lowercase with keydown wpf

Question

I want to get the keys pressed on the keyboard either with or without caplock:

private void Window_KeyDown(object sender, System.Windows.Input.KeyEventArgs e)
{
   e.Key.ToString();
}

When I type "a" or "A" on the keyboard, the result of e.Key is always "A". How can I get 'a' for entering 'a'?

score 8 · Answer 1 · answered Sep 25 '12 at 22:22

8

You can't use the KeyDown event. You'll need to use the TextInput event. This will print the original letter with it's caption (Uppercase/Lowercase).

    private void Window_TextInput(object sender, TextCompositionEventArgs e)
    {
        Console.WriteLine(e.Text);
    }

Now, this will also print the Shift and so on if it's pressed. If you don't want those modifiers just get the last item of the string -treat it as a char array ;)-

answered Sep 25 '12 at 22:22

Erre Efe

15,387
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strange, textinput does not get fired? – olidev Sep 25 '12 at 22:36
@olidev Check the object tree to see if you're attaching it the proper UIElement. Start attaching the event to the Window and then go down. – Erre Efe Sep 25 '12 at 22:42
but textInput will get fired also from the code, I want to get event handler only from the key input – olidev Sep 25 '12 at 22:46

score 7 · Answer 2 · answered Oct 14 '12 at 07:46

You can check in your KeyDown event whether CAPS lock is on or off using Control.IsKeyLocked method. Also, you might need to check if user typed in capital using Shift key which can be identified using Modifiers enum like this -

private void Window_KeyDown(object sender, KeyEventArgs e)
{
   string key = e.Key.ToString();
   bool isCapsLockOn = System.Windows.Forms.Control
                        .IsKeyLocked(System.Windows.Forms.Keys.CapsLock);
   bool isShiftKeyPressed = (Keyboard.Modifiers & ModifierKeys.Shift)
                                == ModifierKeys.Shift;
   if (!isCapsLockOn && !isShiftKeyPressed)
   {
      key = key.ToLower();
   }
}

score 5 · Answer 3 · answered Oct 07 '12 at 23:53

5

Overriding TextInput/PreviewTextInput (or listening to the events) should work.

protected override void OnPreviewTextInput(TextCompositionEventArgs e)
{
    base.OnPreviewTextInput(e);
    Console.WriteLine(e.Text);
}

answered Oct 07 '12 at 23:53

Hadi Eskandari

25,575
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wangxt · Answer 4 · 2012-10-09T04:32:34.460

2

KeyEventArgs class has "Shift" field which indicating whether the SHIFT key was pressed.

Otherwise, because Window_KeyDown method will be called when CAPS_LOCK pressed, you can save a bool value indicating whether the CAPS_LOCK key was pressed.

    bool isCapsLockPressed;
    private void Window_KeyDown(object sender, System.Windows.Input.KeyEventArgs e) {
           if(e.KeyCode == Keys.CapsLock) {
               isCapsLockPressed = !isCapsLockPressed;
           }
    }

edited Oct 09 '12 at 04:32

answered Oct 09 '12 at 04:26

wangxt

77
7

2

What if CapsLock is on when the app is started? Wouldn't that throw everything off? – Adam Plocher Jul 29 '14 at 20:53
Or even if caps lock gets pressed when the application isn't in focus. – Phillip May 13 '21 at 02:30

score 0 · Answer 5 · answered Oct 13 '12 at 21:32

The best way to handle this is by using Window_TextInput event rather than KeyDown.

But as you said this event does not fire on your application you can rather use a hack like this :

bool iscapsLock = false;
bool isShift = false;
private void Window_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Key == Key.CapsLock)
        iscapsLock = !iscapsLock;

    if (e.Key >= Key.A && e.Key <= Key.Z)
    {
        bool shift = isShift;
        if (iscapsLock)
            shift = !shift;
        int s = e.Key.ToString()[0];
        if (!shift)
        {
            s += 32;
        }
        Debug.Write((char)s);
    }

}

This will properly print the characters based on whether capslock is turned on or not. The initial value of the Capslock can be retrieved using this link :

http://cboard.cprogramming.com/csharp-programming/105103-how-detect-capslock-csharp.html

I hope this works for you.

Get lowercase with keydown wpf

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