创建自己的窗口过程，创建自己的定时器

a.创建自己的窗口过程AllocateHWnd，销毁DeallocateHWnd

b.创建自己的定时器，在窗口过程响应WM_TIMER消息

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
    WindowHandle: HWnd;
  public
    { Public declarations }
    procedure WndProc(var Msg:TMessage);
    procedure UpdateTimer;
  end;

var
  Form1: TForm1;
  bSetTimer: Boolean = True;

implementation

{$R *.dfm}

procedure TForm1.WndProc(var Msg: TMessage);
begin
  with Msg do
  if Msg = WM_TIMER then
    try
      Caption := FormatDateTime('HH:NN:SS',now);
    except
      Application.HandleException(Self);
    end
  else
    Result := DefWindowProc(WindowHandle, Msg, wParam, lParam);
end;

procedure TForm1.UpdateTimer;
begin
  KillTimer(WindowHandle, 1);
  if bSetTimer then
    if SetTimer(WindowHandle, 1, 1, nil) = 0 then
      raise EOutOfResources.Create('Create Timer Error!');
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  WindowHandle := AllocateHWnd(WndProc);
  if bSetTimer then UpdateTimer;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  bSetTimer := False;
  UpdateTimer;
  DeallocateHWnd(WindowHandle);
end;

end.