在C＃中停止keydown事件

Question

How can i stop keydown event in my current situation?

private void button1_Click(object sender, EventArgs e)
{
    textBox1.Focus();
    textBox1.KeyDown += new KeyEventHandler(MyKeyPress);
}

public void MyKeyPress(object sender, KeyEventArgs e)
{
    e.SuppressKeyPress = true;
    string first = e.Modifiers.ToString();

    if (first != "None")
    {
        if ((e.KeyCode != Keys.ShiftKey) && (e.KeyCode != Keys.Alt) && (e.KeyCode != Keys.ControlKey))
        {
            textBox1.Text = e.Modifiers.ToString() + " & " + e.KeyCode.ToString();
        }
    }
    else
    {
        textBox1.Text = e.KeyCode.ToString();
    }
    e.Handled = true;
}

As you can see - the event is triggered when user clicks on a button.. but how can I stop the it after the first output?

e.Handled = true;

does not help at all

Answer 1

If I get you right and you want to handle KeyPress event only once after clicking button, then you need unregister this handler in your MyKeyPress . Like this:

public void MyKeyPress(object sender, KeyEventArgs e)
{
  textBox1.KeyDown -= new KeyEventHandler(MyKeyPress);
  ...
}

Answer 2

just use PreviewKeyDown event instead of KeyDown. ;)

Answer 3

Based on your clarification on " first output " and the nature of your application you need to unhook the event handler, otherwise everytime you click the Capture button you will assign another delegate.

public void MyKeyPress(object sender, KeyEventArgs e) 
{ 
    e.SuppressKeyPress = true; 
    string first = e.Modifiers.ToString(); 

    if (first != "None") 
    { 
        if ((e.KeyCode != Keys.ShiftKey) && (e.KeyCode != Keys.Alt) && (e.KeyCode != Keys.ControlKey)) 
        { 
            textBox1.Text = e.Modifiers.ToString() + " & " + e.KeyCode.ToString();
            textBox1.KeyDown -= MyKeyPress; 
        } 
    } 
    else 
    { 
        textBox1.Text = e.KeyCode.ToString();
        textBox1.KeyDown -= MyKeyPress;
    } 
    e.Handled = true; 
}