code/Device/KeyboardHook.cs

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using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;

namespace Sylloge.Device
{
    public static class GlobalKeyHandler
    {
        #region Events

        public delegate void DelegateKeyPressed(int wParam, Sylloge.WinAPI.KeybdInput keyCode);
        public static event DelegateKeyPressed KeyPressed;

        public static void OnKeyPress(int wParam, Sylloge.WinAPI.KeybdInput keyCode)
        {
            if (KeyPressed != null) { KeyPressed(wParam, keyCode); }
        }

        #endregion

        #region Local Attributes

        public static bool IsInitialized = false;

        #endregion

        #region Exceptions

        public class UninitializedException : System.Exception
        {
            public UninitializedException()
                : base("The GlobalKeyHandler low level hook has not been initialized")
            {
            }
        }

        #endregion

        #region External Calls (Keyboard Specific)

        [DllImport("User32.dll", SetLastError = true)]
        public static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProcDelegate lpfn, IntPtr hmod, int dwThreadId);
        [DllImport("User32.dll", SetLastError = true)]
        public static extern IntPtr CallNextHookEx(IntPtr hHook, int nCode, int wParam, ref Sylloge.WinAPI.KeybdInput lParam);

        public delegate IntPtr LowLevelKeyboardProcDelegate(int nCode, int wParam, ref Sylloge.WinAPI.KeybdInput lParam);

        public static IntPtr HookLowLevelKeyboard;

        public static LowLevelKeyboardProcDelegate KeyboardDelegate;// = new LowLevelKeyboardProcDelegate(LowLevelKeyboardProc);

        #endregion

        #region Class Methods and Properties

        public static void Initialize()
        {
            if (IsInitialized) { return; } // Don't allow multiple initializations
            KeyboardDelegate += new LowLevelKeyboardProcDelegate(LowLevelKeyboardProc);
            HookLowLevelKeyboard = SetWindowsHookEx(Sylloge.WinAPI.Constants.WH_KEYBOARD_LL, KeyboardDelegate, System.Diagnostics.Process.GetCurrentProcess().MainModule.BaseAddress, 0);
            IsInitialized = true;
        }

        public static void Dispose()
        {
            Sylloge.WinAPI.User32.UnhookWindowsHookEx(HookLowLevelKeyboard);
            KeyboardDelegate -= new LowLevelKeyboardProcDelegate(LowLevelKeyboardProc);
        }

        private static IntPtr LowLevelKeyboardProc(int nCode, int wParam, ref Sylloge.WinAPI.KeybdInput lParam)
        {
            OnKeyPress(wParam, lParam);
            return CallNextHookEx(HookLowLevelKeyboard, nCode, wParam, ref lParam);
        }

        #endregion
    }
}