Размер листа печати

procedure frmComDoc_bPrint_OnClick (Sender: TObject; var Cancel: boolean);
 var
  Printer:TPrinter;
  Canvas:TCanvas;
  Image:TImage;
begin
  Printer:=TPrinter.Create;
  Canvas:=TCanvas.Create;
  Image:=TImage.Create(frmComDoc);
  Image.Picture.LoadFromFile(frmComDoc.dbImage.dbFileName);

  With Printer do Begin
  Printer.BeginDoc;
   Printer.Canvas.StretchDraw(0,0,PageHeight,PageWidth,Image.Picture.Graphic);
  Printer.EndDoc;
  end;
end;