{******************************************************************************}
{* Module:  DisableLowLevelKeys.cpp                                           *}
{* Notices: Written 2000 Jeffrey Richter                                      *}
{*                                                                            *}
{* Translated by: Dmitry Muratov                                              *}
{* 2008                                                                       *}
{******************************************************************************}

program DisableLowLevelKeys;

uses
 Windows, Messages;

const
 LLKHF_ALTDOWN  = KF_ALTDOWN shr 8;
 WH_KEYBOARD_LL = 13;

type

 TKBDLLHOOKSTRUCT = record
   vkCode: DWORD;
   scanCode: DWORD;
   flags: DWORD;
   time: DWORD;
   dwExtraInfo: DWORD;
 end;
 PKBDLLHOOKSTRUCT = ^TKBDLLHOOKSTRUCT;

var
 hhkLowLevelKybd: HHOOK;

//------------------------------------------------------------------------------

function LowLevelKeyboardProc(nCode: integer;  wParam: WPARAM;  lParam: LPARAM): LRESULT; stdcall;
var
 fEatKeystroke: boolean;
 p: PKBDLLHOOKSTRUCT;
begin
 fEatKeystroke := false;
 if nCode = HC_ACTION then
   begin
     case wParam of
       WM_KEYDOWN,
       WM_SYSKEYDOWN,
       WM_KEYUP,
       WM_SYSKEYUP:
         begin
           p := PKBDLLHOOKSTRUCT(lParam);
           fEatKeystroke := ((p^.vkCode = VK_LWIN) or (p^.vkCode = VK_RWIN)) or
                            ((p^.vkCode = VK_TAB) and ((p^.flags and LLKHF_ALTDOWN) <> 0)) or
                            ((p^.vkCode = VK_ESCAPE) and ((p^.flags and LLKHF_ALTDOWN) <> 0)) or
                            ((p^.vkCode = VK_ESCAPE) and ((GetKeyState(VK_CONTROL) and $8000) <> 0)) or
                            ((p^.vkCode = VK_F4) and ((p^.flags and LLKHF_ALTDOWN) <> 0));
         end;
     end;
   end;
 if fEatKeystroke then
   result := 1
 else
   result :=  CallNextHookEx(0, nCode, wParam, lParam);
end;

//------------------------------------------------------------------------------

begin
 // Install the low-level keyboard & mouse hooks
 hhkLowLevelKybd := SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hInstance, 0);

 // Keep this app running until we're told to stop
 MessageBox(0,
            PChar('Alt+Esc, Ctrl+Esc, WIN, Alt+F4, and Alt+Tab are now disabled.' + #13#10 +
                  'Click "Ok" to terminate this application and re-enable these keys.'),
            PChar('Disable Low-Level Keys'),
            MB_OK);

 // Remove hooks
 UnhookWindowsHookEx(hhkLowLevelKybd);
end.