KeyBoard Hook (DLL) 사용 예제

unit UKeyHookUsingDll;
interface
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;
type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Timer1: TTimer;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
    procedure Button1KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form1: TForm1;
implementation
{$R *.dfm}
{ Functions prototypes for the hook dll }
type
  TGetHookRecPointer = function: pointer stdcall;
  TStartKeyBoardHook = procedure stdcall;
  TStopKeyBoardHook = procedure stdcall;
  { The record type filled in by the hook dll }
  THookRec = packed record
    TheHookHandle: HHOOK;
    TheAppWinHandle: HWND;
    TheCtrlWinHandle: HWND;
    TheKeyCount: DWORD;
  end;
  { A pointer type to the hook record }
  PHookRec = ^THookRec;
var
  hHookLib: THANDLE; { A handle to the hook dll }
  GetHookRecPointer: TGetHookRecPointer; { Function pointer }
  StartKeyBoardHook: TStartKeyBoardHook; { Function pointer }
  StopKeyBoardHook: TStopKeyBoardHook; { Function pointer }
  LibLoadSuccess: bool; { If the hook lib was successfully loaded }
  lpHookRec: PHookRec; { A pointer to the hook record }
  EnterKeyCount: DWORD; { An internal count of the Enter Key }

procedure TForm1.Button1KeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
  { Process message sent from hook dll and display }
  { number of time the enter key was pressed }
  if (Key = 0) then begin
    Inc(EnterKeyCount);
    Label2.Caption := IntToStr(EnterKeyCount) + ' Enter Keys Logged';
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  { Set our initial variables }
  Timer1.Enabled := FALSE;
  Timer1.Interval := 1000;
  Label1.Caption := '0 Keys Logged';
  Label2.Caption := '0 Enter Keys Logged';
  EnterKeyCount := 0;
  lpHookRec := NIL;
  LibLoadSuccess := FALSE;
  @GetHookRecPointer := NIL;
  @StartKeyBoardHook := NIL;
  @StopKeyBoardHook := NIL;
  { Try to load the hook dll }
  hHookLib := LoadLibrary('THEHOOK.DLL');
  { If the hook dll was loaded successfully }
  if hHookLib <> 0 then begin
    { Get the function addresses }
    @GetHookRecPointer := GetProcAddress(hHookLib, 'GETHOOKRECPOINTER');
    @StartKeyBoardHook := GetProcAddress(hHookLib, 'STARTKEYBOARDHOOK');
    @StopKeyBoardHook := GetProcAddress(hHookLib, 'STOPKEYBOARDHOOK');
    { Did we find all the functions we need? }
    if ((@GetHookRecPointer <> NIL) AND (@StartKeyBoardHook <> NIL) AND (@StopKeyBoardHook <> NIL)) then begin
      LibLoadSuccess := TRUE;
      { Get a pointer to the hook record }
      lpHookRec := GetHookRecPointer;
      { Were we successfull in getting a ponter to the hook record }
      if (lpHookRec <> nil) then begin
        { Fill in our portion of the hook record }
        lpHookRec^.TheHookHandle := 0;
        lpHookRec^.TheCtrlWinHandle := Button1.Handle;
        lpHookRec^.TheKeyCount := 0;
        { Start the keyboard hook }
        StartKeyBoardHook;
        { Start the timer if the hook was successfully set }
        if (lpHookRec^.TheHookHandle <> 0) then begin
          Timer1.Enabled := TRUE;
        end;
      end;
    end else begin
      { We failed to find all the functions we need }
      FreeLibrary(hHookLib);
      hHookLib := 0;
      @GetHookRecPointer := NIL;
      @StartKeyBoardHook := NIL;
      @StopKeyBoardHook := NIL;
    end;
  end;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  { Did we load the dll successfully? }
  if (LibLoadSuccess = TRUE) then begin
    { Did we sucessfully get a pointer to the hook record? }
    if (lpHookRec <> nil) then begin
      { Did the hook get set? }
      if (lpHookRec^.TheHookHandle <> 0) then begin
        Timer1.Enabled := FALSE;
        StopKeyBoardHook;
      end;
    end;
    { Free the hook dll }
    FreeLibrary(hHookLib);
  end;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  { Display the number of keystrokes logged }
  Label1.Caption := IntToStr(lpHookRec^.TheKeyCount) + ' Keys Logged';
end;
end.