KeyboardListener.cs

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Input;
using static PInvoke.User32;
using static PInvoke.Kernel32;


namespace WpfApplication1
{
    public class KeyboardListener
    {
        public event EventHandler<KeyPressedArgs> OnKeyPressed;
        private readonly WindowsHookDelegate action;
        private SafeHookHandle safeHandle = new SafeHookHandle();

        public KeyboardListener()
        {
            action = HookCallback;
        }

        public void HookKeyboard()
        {
            safeHandle = SetHook(action);
        }

        public void UnHookKeyboard()
        {
            safeHandle.Dispose();
        }

        private SafeHookHandle SetHook(WindowsHookDelegate action)
        {
            using (Process curProcess = Process.GetCurrentProcess())
            {
                using (ProcessModule curModule = curProcess.MainModule)
                {
                    return SetWindowsHookEx(WindowsHookType.WH_KEYBOARD_LL, action,
                        GetModuleHandle(curModule.ModuleName).DangerousGetHandle(), 0);
                }
            }
        }

        private int HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode >= 0 && wParam == (IntPtr)WindowMessage.WM_KEYDOWN || wParam == (IntPtr)WindowMessage.WM_SYSKEYDOWN)
            {
                int virtualKey = Marshal.ReadInt32(lParam);

                OnKeyPressed?.Invoke(this, new KeyPressedArgs(KeyInterop.KeyFromVirtualKey(virtualKey)));
            }

            return CallNextHookEx(safeHandle.DangerousGetHandle(), nCode, wParam, lParam);
        }
    }

    public class KeyPressedArgs : EventArgs
    {
        public Key KeyPressed { get; private set; }

        public KeyPressedArgs(Key key)
        {
            KeyPressed = key;
        }
    }
}