[Decoding]

Код:

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
   case Key of
      VK_LEFT: {влево};
      VK_RIGHT: {вправо};
      VK_UP: {вверх};
      VK_DOWN: {вниз};
   end;
end;