特效一：
procedure TForm1.Button1Click(Sender: TObject);
var
    r:thandle;
    i:integer;
    begin
      for i:=1 to trunc(width/1.414) do
      begin
        r:=CreateEllipticRgn(trunc(width/2)-i,trunc(height/2)-i,trunc(width/2)+i,trunc(height/2)+i);
        SetWindowRgn(handle,r,true);
        Application.ProcessMessages;
        sleep(1);
      end;
    end;


特效二：
procedure TForm1.FormCreate(Sender: TObject);
    begin
      AnimateWindow (Handle, 400, AW_CENTER);
    end;