Differentiate between two keyboards in a KeyboardHook

Question

I got this program:

https://docs.microsoft.com/en-us/archive/blogs/toub/low-level-keyboard-hook-in-c

using System;
using System.Diagnostics;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace KeyboardInput
{
    class InterceptKeys
    {
        private delegate IntPtr LowLevelKeyboardProc(int nCode, IntPtr wParam, IntPtr lParam);

        private const int WH_KEYBOARD_LL = 13;
        private const int WM_KEYDOWN = 0x0100;
        private static LowLevelKeyboardProc _proc = HookCallback;
        private static IntPtr _hookID = IntPtr.Zero;

        static void Main(string[] args)
        {
            _hookID = SetHook(_proc);
            Application.Run();
            UnhookWindowsHookEx(_hookID);
        }

        private static IntPtr SetHook(LowLevelKeyboardProc proc)
        {
            using (Process curProcess = Process.GetCurrentProcess())
            using (ProcessModule curModule = curProcess.MainModule)
            {
                return SetWindowsHookEx(WH_KEYBOARD_LL, proc,
                    GetModuleHandle(curModule.ModuleName), 0);
            }
        }

        private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
        {
            if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN)
            {
                int vkCode = Marshal.ReadInt32(lParam);
                Console.WriteLine((Keys)vkCode + "   " + nCode + "   " + wParam + "   " + lParam);
            }
            return CallNextHookEx(_hookID, nCode, wParam, lParam);
        }

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool UnhookWindowsHookEx(IntPtr hhk);

        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        private static extern IntPtr GetModuleHandle(string lpModuleName);
    }
}

It captures keyboard input, but what I want is to be able to differentiate between two keyboards. I'd like to know if the key pressed was from the keyboard on my laptop or the keyboard that's connected via an USB.

How do I accomplish this?

Answer 1

To distinguish between input devices, you may probably need to use Raw Input API

Here is a detailed example

UPDATE: The above link seems to be down. But here is a similar question answered by the blogger who provided above example.