Capturing KeyDown events in a UserControl

Question

I have a user control with several child controls. I need the user interface to react to keypresses, so I decided to put the handling code in a MainControl_KeyDown event. However, when I press a key in my application, this event does not fire.

I have found a solution through a search engine which relies upon use of the Windows API, which I would like to avoid, as it seems like overkill for what should be a function that is properly supported by the .NET framework.

Answer 1

maybe you should handle all the events locally and then fire dummy events to communicate with the main control?

or maybe this may be a focus issue; if there are many child controls and only one of them is focused, the other ones would not react the key down action.

maybe you could post some code snippets here to be sure.

Answer 2

You could add a KeyDown event handler for every child control in your user control and fire the KeyDown event of your user control in each, like so:

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    this.OnKeyDown(e);
}

Answer 3

Here is an example that loop throw each control in the form to attach the KeyDown event. It's like the previouly answer in this post but handle more cases:

using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;

public class UserControlKeyboardProcessor
{
    private void Control_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
    {
        base.OnKeyDown(e);
    }

    private void UserControlKeyboardProcessor_Disposed(object sender, System.EventArgs e)
    {
        foreach (System.Windows.Forms.Control control in this.GetAllControls(this)) {
            control.KeyDown -= Control_KeyDown;
        }
    }

    private void UserControlKeyboardProcessor_Load(object sender, System.EventArgs e)
    {
        foreach (System.Windows.Forms.Control control in this.GetAllControls(this)) {
            control.KeyDown += Control_KeyDown;
        }
    }

    public Generic.List<System.Windows.Forms.Control> GetAllControls(System.Windows.Forms.Control control)
    {
        Generic.List<System.Windows.Forms.Control> controls = new Generic.List<System.Windows.Forms.Control>();

        foreach (System.Windows.Forms.Control subControl in control.Controls) {
            controls.Add(subControl);
            controls.AddRange(this.GetAllControls(subControl));
        }

        return controls;
    }
    public UserControlKeyboardProcessor()
    {
        Load += UserControlKeyboardProcessor_Load;
        Disposed += UserControlKeyboardProcessor_Disposed;
    }
}