CodeTyphon 7.1 + Windows 10.

Onderstaande code werkt goed, maar ik zou graag de afdruk in het centrum van de A4 pagina krijgen.
De print is "nu" in landscape, in de linker bovenhoek..
Kan iemand mij de code doorgeven a.u.b.

Code:
procedure TForm1.BtnPRINTFORMClick(Sender: TObject);
var
  myBitMap : TBitMap;
  rct: TRect;
  HScaleFactor, VScaleFactor: Single;
begin
  if not PrintDialog1.Execute then Exit;
  HScaleFactor:=Printer.XDPI/Screen.PixelsPerInch;
  VScaleFactor:=Printer.YDPI/Screen.PixelsPerInch;
  myBitMap := TBitMap.Create;
  try
    myBitMap.LoadFromDevice(Canvas.Handle);
    rct:=Rect(0, 0, trunc(myBitMap.Width*HScaleFactor), trunc(myBitMap.Height*VScaleFactor));
    Printer.Refresh;
    Printer.Orientation:=poLandscape;
    Printer.BeginDoc;
    Printer.Canvas.StretchDraw(rct, myBitMap);
  finally
      Printer.EndDoc;
      myBitMap.Free;
  end;
end;