Unable to capture Enter Key

问题

I have a simple form by which I take input:

12 Buttons, 1 Textbox (disabled & read-only)

this is what I do to handle input

Login_KeyDown() is common method I call for all the KeyDown of every UI component & the form itself..

private void Login_KeyDown(object sender, KeyEventArgs e)
{            
  if (e.KeyCode == Keys.Escape)
  {
    Application.Exit();
  }
  else if (e.KeyCode == Keys.NumPad9 || e.KeyCode == Keys.D9)
  {
    button3.BackgroundImage = Properties.Resources.button_hover;
    button3.ForeColor = Color.White;
    pin.Text = pin.Text + "9";
  }
  else if (e.KeyCode == Keys.Back)
  {
    button11.BackgroundImage = Properties.Resources.button_hover;
    button11.ForeColor = Color.White;
    if (pin.Text.Length > 0)
      pin.Text = pin.Text.Substring(0, pin.Text.Length - 1);
  }
  else if (e.KeyCode == Keys.Enter)
  {
    MessageBox.Show(pin.Text);
  }
}

This code works fine when I start the app but after I have clicked on any component, rest of the code works fine but "Enter Key Condition" doesn't work.

My guess is as "Enter Key Condition" is not working for UI components or something like that.

I have also tried using "Key Press Event" which uses KeyPressEventArgs then checking KeyChar == 13 but that is also not working.

What is the problem, and how can I solve it?

p.s. I have not set any button click events for any button, the app is 100% KBoard based.

回答1:

Check out PreviewKeyDown. Return raises that event on button controls.

    private void Form1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
    {
        if (e.KeyCode == Keys.Return)
            MessageBox.Show("I found return");

    }

Or alternatively you can force it to raise those special keys in the KeyDown Event by using:

    private void Form1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
    {
        if (e.KeyCode == Keys.Return)
            e.IsInputKey = true;
    }

More information: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.previewkeydown.aspx

回答2:

Have you tried to use

Keys.Return

Instead

Edit: Just thought of this. Do you have the acceptbutton set for the main form?

回答3:

This is because your Form has AcceptButton defined. For example, you have a "OK", "Accept" or "Confirm" button with DialogResult set to "OK". This tells its parent form that there is an AcceptButton, and the Enter event on the form would go to this button.

What you should do is to catch the Enter key at form level. Add this code to the form:

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if ((this.ActiveControl == myTextBox) && (keyData == Keys.Return))
    {
        //do something
        return true;
    }
    else
    {
        return base.ProcessCmdKey(ref msg, keyData);
    }
}

来源：https://stackoverflow.com/questions/10641721/unable-to-capture-enter-key

标签

keyevent

enter