Animate Form OnShow

private
    { Private declarations }
    procedure animin(Sender: TObject);
    
//

procedure TForm1.animin(Sender: TObject);

  procedure delay(msec: Longint);
  var
    start, stop: Longint;
  begin
    start := GetTickCount;
    repeat
      stop := GetTickCount;
      Application.ProcessMessages;
    until (stop - start) >= msec;
  end;
var
  maxx, maxy: Integer;

  MyHand: HWND;
  MyDc: HDC;
  MyCanvas: TCanvas;
  hal, hat, hak, haa: Integer;
begin
  maxx := (Sender as TForm).Width;
  maxy := (Sender as TForm).Height;
  hal  := 2;
  hat  := 2;

  MyHand   := GetDesktopWindow;
  MyDc     := GetWindowDC(MyHand);
  MyCanvas := TCanvas.Create;
  MyCanvas.Handle := MyDC;
  MyCanvas.Brush.Color := (Sender as TForm).Color;

  repeat
    if hat + (maxy div 24) >= maxy then
    begin
      hat := maxy
    end
    else
    begin
      hat := hat + (maxy div 24);
    end;

    if hal + (maxx div 24) >= maxx then
    begin
      hal := maxx
    end
    else
    begin
      hal := hal + (maxx div 24);
    end;
    hak := (Sender as TForm).Left + ((Sender as TForm).Width div 2) - (hal div 2);
    haa := (Sender as TForm).Top + ((Sender as TForm).Height div 2) - (hat div 2);
    MyCanvas.Rectangle(hak, haa, hak + hal, haa + hat);
    delay(10);
  until (hal = maxx) and (hat = maxy);
  (Sender as TForm).Show;
end;


procedure TForm1.FormShow(Sender: TObject);
begin
  animin(form1);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  animin(form2);
end;