How to get a combination of keys in c#

Question

How can I capture Ctrl + Alt + K + P keys on a C# form? thanks

Answer 1

MessageFilters can help you in this case.

    public class KeystrokMessageFilter : System.Windows.Forms.IMessageFilter
    {
        public KeystrokMessageFilter() { }

        #region Implementation of IMessageFilter

        public bool PreFilterMessage(ref Message m)
        {
            if ((m.Msg == 256 /*0x0100*/))
            {
                switch (((int)m.WParam) | ((int)Control.ModifierKeys))
                {
                    case (int)(Keys.Control | Keys.Alt | Keys.K):
                        MessageBox.Show("You pressed ctrl + alt + k");
                        break;
                    //This does not work. It seems you can only check single character along with CTRL and ALT.
                    //case (int)(Keys.Control | Keys.Alt | Keys.K | Keys.P):
                    //    MessageBox.Show("You pressed ctrl + alt + k + p");
                    //    break;
                    case (int)(Keys.Control | Keys.C): MessageBox.Show("You pressed ctrl+c");
                        break;
                    case (int)(Keys.Control | Keys.V): MessageBox.Show("You pressed ctrl+v");
                        break;
                    case (int)Keys.Up: MessageBox.Show("You pressed up");
                        break;
                }
            }
            return false;
        }

        #endregion


    }

Now in your C# WindowsForm, register the MessageFilter for capturing key-strokes and combinations.

public partial class Form1 : Form
{
    KeystrokMessageFilter keyStrokeMessageFilter = new KeystrokMessageFilter();

    public Form1()
    {
        InitializeComponent();
    }       
    private void Form1_Load(object sender, EventArgs e)
    {
        Application.AddMessageFilter(keyStrokeMessageFilter);
    }
}

Somehow it only detects Ctrl + Alt + K. Please Read the comment in MessageFilter code.