Fire Form KeyPress event

Question

I have a C# winform, on which I have 1 button.
Now, when I run my application, the button gets focus automatically.

The problem is KeyPress event of my form does not work because the button is focused.

I have tried this.Focus(); on FormLoad() event, but still the KeyPress event is not working.

Shriver

Answer 1

You need to override the ProcessCmdKey method for your form. That's the only way you're going to be notified of key events that occur when child controls have the keyboard focus.

Sample code:

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    // look for the expected key
    if (keyData == Keys.A)
    {
        // take some action
        MessageBox.Show("The A key was pressed");

        // eat the message to prevent it from being passed on
        return true;

        // (alternatively, return FALSE to allow the key event to be passed on)
    }

    // call the base class to handle other key events
    return base.ProcessCmdKey(ref msg, keyData);
}

As for why this.Focus() doesn't work, it's because a form can't have the focus by itself. A particular control has to have the focus, so when you set focus to the form, it actually sets the focus to the first control that can accept the focus that has the lowest TabIndex value. In this case, that's your button.

Romona

Beware that ProcessCmdKey() is not a substitute for KeyPress. There's a big difference between virtual keys and the characters that they get translated to. There is no good way to get the equivalent of KeyPress. – Provenience

Answer 2

Try setting the Form's KeyPreview property to True.

Mcnary

Ok fine, but when my button as well has keyPress event, then both keyPress events will be fired. – Shriver

This isn't really a good solution. It won't work for all possible keys, it doesn't prevent the key event from being stolen by the control, and it's more of an old school VB 6 way of handling things. Overriding ProcessCmdKey is the customary approach. – Romona

@CodyGray: However, this is a suitable alternative when the goal is to receive KeyPress events. Obviously one needs to be careful when using it, but it is often easier/simpler than trying to map specific key events to characters. – Piotrowski

Answer 3

Set keyPreview = true on main form

Saum

Answer 4

I would use one of the following:

1. Set the TabIndex property of the button to 0.

2. Set the IsDefault property of the button to true - So, It will be fired when pressing the ENTER key.

Nonlegal

Hmm, he says that the button has the focus when the form is loaded, so I can only assume that it is already responding when the user presses the Enter (or Space) key. The question doesn't specify a particular key that he wants to catch; I suspect that it's probably not Enter. – Romona

Answer 5

I had this same problem and I know this question was answered long ago, but my solution to this problem came from another stack overflow question in which my only button grabbed and kept focus. I accepted the users advice and created a button which couldn't get focus.

Maybe someone will find this useful:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace I2c_Programmer {
    class NoSelectButton : Button{

            public NoSelectButton() {

            SetStyle(ControlStyles.Selectable, false);

        }
    }
}

Go into your designer, where the button is created and switch out the new System...button with your new class "new NoSelectButton();"

Roister