unit Hook;

interface

uses
  System.SysUtils,
  System.Classes,
  Windows,
  Messages;
type
  tagKBDLLHOOKSTRUCT =  packed record
    vkCode: DWORD;
    scanCode: DWORD;
    flags: DWORD;
    time: DWORD;
    dwExtraInfo: Integer;
  end;
  KBDLLHOOKSTRUCT = tagKBDLLHOOKSTRUCT;
  PKBDLLHOOKSTRUCT = ^KBDLLHOOKSTRUCT;

const
  LLKHF_UP = $0080;
var
 CurrentHook: HHook;
 DestHandle: THandle;
 Msg: cardinal;

function KeyboardProc(Code, wParam, lParam: Integer): Integer; stdcall;
procedure SetHook(aDestHandle: THandle; aMsg: cardinal); stdcall;
procedure UnHook; stdcall;

implementation

function KeyboardProc(Code, wParam, lParam: Integer): Integer; stdcall;
var
  zKeyState: TKeyBoardState;
  zChr: Char;
  zCount: Integer;
  zHookInfo : PKBDLLHOOKSTRUCT;
begin
  Result := CallNextHookEx(CurrentHook, Code, wParam, lParam);
  if Code <> HC_ACTION then Exit;
  zHookInfo := Pointer(lParam);
  if (zHookInfo^.flags And LLKHF_UP) <> 0 then
  begin
    GetKeyboardState(zKeyState);
    zCount :=  ToAscii(zHookInfo.vkCode, zHookInfo.scanCode, zKeyState, @zChr, 0);
    if zCount = 1 then
      if DestHandle <> 0 then SendMessage(DestHandle, Msg, Ord(zChr), 0);
  end;
end;

procedure SetHook(aDestHandle: THandle; aMsg: cardinal); stdcall;
begin
  DestHandle := aDestHandle;
  Msg := aMsg;
  CurrentHook := SetWindowsHookEx(WH_KEYBOARD_LL, @KeyboardProc, HInstance, 0);
end;

procedure UnHook; stdcall;
begin
  UnhookWindowshookEx(CurrentHook);
end;

end.