WindowsKey.cs

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;

namespace osu.Helpers
{
    class WindowsKey
    {
        private delegate int LowLevelKeyboardProcDelegate(int nCode, int wParam, ref KBDLLHOOKSTRUCT lParam);

        internal static bool IsBlocked;

        [DllImport(@"user32.dll", EntryPoint = @"SetWindowsHookExA", CharSet = CharSet.Ansi)]
        private static extern int SetWindowsHookEx(int idHook, LowLevelKeyboardProcDelegate lpfn, IntPtr hMod, int dwThreadId);

        [DllImport(@"user32.dll")]
        private static extern int UnhookWindowsHookEx(int hHook);


        [DllImport(@"user32.dll", EntryPoint = @"CallNextHookEx", CharSet = CharSet.Ansi)]
        private static extern int CallNextHookEx(int hHook, int nCode, int wParam, ref KBDLLHOOKSTRUCT lParam);

        const int WH_KEYBOARD = 2;
        const int WH_KEYBOARD_LL = 13;
        private static int keyHook;
        private KBDLLHOOKSTRUCT lParam;


        private struct KBDLLHOOKSTRUCT
        {
            public int vkCode;
            int scanCode;
            public int flags;
            int time;
            int dwExtraInfo;
        }

        private static int lowLevelKeyboardProc(int nCode, int wParam, ref KBDLLHOOKSTRUCT lParam)
        {
            switch (wParam)
            {
                case 256:
                case 257:
                case 260:
                case 261:
                    //Alt+Tab, Alt+Esc, Ctrl+Esc, Windows Key
                    if ((lParam.vkCode == 91 || lParam.vkCode == 92) && lParam.flags == 1)
                        return 1;
                    break;
            }

            return CallNextHookEx(0, nCode, wParam, ref lParam);
        }

        static LowLevelKeyboardProcDelegate del;
        internal static void Disable()
        {
            if (keyHook != 0 || IsBlocked)
                return;

            try
            {
                keyHook = SetWindowsHookEx(WH_KEYBOARD_LL, (del = lowLevelKeyboardProc), Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly().GetModules()[0]), 0);
            }
            catch { }

            IsBlocked = true;
        }

        internal static void Enable()
        {
            if (keyHook == 0 || !IsBlocked)
                return;

            try
            {
                keyHook = UnhookWindowsHookEx(keyHook);
                del = null;
            }
            catch { }
            keyHook = 0;

            IsBlocked = false;
        }
    }
}