uses Printers;

procedure TForm1.Button1Click(Sender: TObject);
begin
  showmessage(inttostr(  GetDeviceCaps(Printer.Handle, LOGPIXELSX)  ));
end;

返回打印机每英寸相素值

function GetPageWidth: Integer;

begin

  Result := Screen.PixelsPerInch*GetDeviceCaps(Printer.Handle,

PHYSICALWIDTH) div GetPixelsPerInchX

end;

function GetPageHeight: Integer;

begin

  Result := Screen.PixelsPerInch*GetDeviceCaps(Printer.Handle,

PHYSICALHEIGHT) div GetPixelsPerInchY

end;

function GetPixelsPerInchX: Integer;

begin

  Result := GetDeviceCaps(Printer.Handle, LOGPIXELSX)

end;

function GetPixelsPerInchY: Integer;

begin

  Result := GetDeviceCaps(Printer.Handle, LOGPIXELSY)

end;