Query/Query/Core/KeyboardHook.cs

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

namespace Query.Core{
    sealed class KeyboardHook{
        public event EventHandler Triggered;
        
        // ReSharper disable once PrivateFieldCanBeConvertedToLocalVariable
        private readonly NativeMethods.HookProc keyboardHookDelegate;
        private IntPtr keyboardHook;
        
        public KeyboardHook(){
            keyboardHookDelegate = KeyboardHookProc;
        }

        public void StartHook(){
            if (keyboardHook != IntPtr.Zero){
                NativeMethods.UnhookWindowsHookEx(keyboardHook);
            }

            keyboardHook = NativeMethods.SetWindowsHookEx(NativeMethods.WH_KEYBOARD_LL, keyboardHookDelegate, IntPtr.Zero, 0);
        }

        public void StopHook(){
            if (keyboardHook != IntPtr.Zero){
                NativeMethods.UnhookWindowsHookEx(keyboardHook);
                keyboardHook = IntPtr.Zero;
            }
        }

        private IntPtr KeyboardHookProc(int nCode, IntPtr wParam, IntPtr lParam){
            if (wParam == (IntPtr)NativeMethods.WM_KEYDOWN){
                Keys key = (Keys)Marshal.ReadInt32(lParam);

                if ((key == Keys.LWin || key == Keys.RWin) && Control.ModifierKeys.HasFlag(Keys.Control)){
                    Triggered?.Invoke(this, EventArgs.Empty);
                    return NativeMethods.HookHandled;
                }
            }

            return NativeMethods.CallNextHookEx(keyboardHook, nCode, wParam, lParam);
        }

        private static class NativeMethods{
            public const int WH_KEYBOARD_LL = 13;
            public const int WM_KEYDOWN = 0x0100;
            public const int WM_KEYUP = 0x0101;

            public static readonly IntPtr HookHandled = new IntPtr(-1);

            public delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);

            [DllImport("user32.dll")]
            public static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

            [DllImport("user32.dll")]
            public static extern bool UnhookWindowsHookEx(IntPtr idHook);

            [DllImport("user32.dll")]
            public static extern IntPtr CallNextHookEx(IntPtr idHook, int nCode, IntPtr wParam, IntPtr lParam);
        }
    }
}