Forward a KeyPress-event

Question

I have a TextBox and would like to forward a KeyPress-event from another Form.

So far I have my Form:

private readonly Action<KeyPressEventArgs> m_KeyPress;

public KeyboardForm( Action<KeyPressEventArgs> keyPress )
{
  m_KeyPress = keyPress;
}

protected override void OnKeyPress( KeyPressEventArgs e )
{
  m_KeyPress( e );
  base.OnKeyPress( e );
}

And a derived TextBox, which initializes the Form:

var keyboardForm = new KeyboardForm( OnKeyPress );
keyboardForm.Show();

Now, the OnKeyPress-method gets called as expected (of the Form, then of the TextBox). But nevertheless nothing happens ... when I press 'a' I expected an 'a' to appear in my TextBox ...

Does anyone have an idea what's the problem here?

It is not working with KeyDown, too, and attaching to the regular exposed event KeyPress does not help me either. I think, that the problem is the explicit call of OnKeyPress. Is it allowed?

Answer 1

From this answer: https://social.msdn.microsoft.com/Forums/windows/en-US/92215fdf-8be0-4e3a-b796-dd7c0f131666/keypreview-true-how-do-you-then-detect-enterreturn?forum=winforms

If you have a button on your form that is catching the Enter key presses, you can allow the enter key to be handled as a normal KeyPreview key with the following code:

void button_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
{
    if (e.KeyData == Keys.Enter)
    {
        e.IsInputKey = true;
    }
}

Answer 2

This should do what you want. Make the text of the buttons on the Keyboard Form based on the SendKey characters. For example, if you want lower case a, just put "a" for the keyboard button text. If you want a backspace button, just put "backspace" as the text of the button. All the keyboard buttons Click events can register for the ButtonClick function

Keyboard Form:

public partial class KeyboardForm : Form
{
    public delegate void ButtonPressed(string keyPressed);
    public event ButtonPressed ButtonPressedEvent;

    public KeyboardForm()
    {
        InitializeComponent();
    }

    private void ButtonClick(object sender, EventArgs e)
    {
        Button button = sender as Button;
        if (button != null)
        {
            if ((ButtonPressedEvent != null))
            {
                ButtonPressedEvent("{"+button.Text+"}");
            }
        }
    }
}

Form with textbox that the user types things into:

public partial class Form1 : Form
{
    private KeyboardForm mKeyboardForm = new KeyboardForm();
    private bool mIsKeyboardCode = false;

    public Form1()
    {
        InitializeComponent();
        mKeyboardForm.ButtonPressedEvent += new KeyboardForm.ButtonPressed(KeyboardFormButtonPressedEvent);
    }

    void KeyboardFormButtonPressedEvent(string keyPressed)
    {
        mIsKeyboardCode = true;
        textBox1.Focus();
        SendKeys.SendWait(keyPressed.ToString());
        mKeyboardForm.Focus();
        mIsKeyboardCode = false;
    }

    private void TextBoxKeyUp(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.ControlKey)
        {
            if (!mKeyboardForm.Visible)
            {
                mKeyboardForm.Show(this);
                e.Handled = true;
            }
        }
        else if (!mIsKeyboardCode)
        {
            mKeyboardForm.Hide();
        }
    }
}

Note: I did not use an extended textbox with a form inside of it. I dont think its a good design to have a form be shown/hidden from a custom textbox.

Answer 3

Form1:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        Form2 f = new Form2();
        f.mEvent += new Form2.TestEvent(f_mEvent);
        f.Show();
    }

    void f_mEvent(KeyPressEventArgs e)
    {
        textBox1.Text += e.KeyChar;
    }
}

Form2:

public partial class Form2 : Form
{
    public delegate void TestEvent(KeyPressEventArgs e);
    public event TestEvent mEvent;

    public Form2()
    {
        InitializeComponent();
    }

    protected override void OnKeyPress(KeyPressEventArgs e)
    {
        if (mEvent != null)
        {
            mEvent(e);
        }
        base.OnKeyPress(e);
    }
}