Insert Simple Text Watermark into PDF with iTextSharp

Today I was in the need of printing a simple "Preview" watermark into an in-memory created pdf document and I have done it like that:
var memoryStream = new MemoryStream();

PdfReader reader = new PdfReader(path2pdfTemplate);
PdfStamper stamper = new PdfStamper(reader, memoryStream);

stamper.GetOverContent(1);
var cb = stamper.GetOverContent(1);

//activate Opacity for the next strokes/strings
var gstate = new PdfGState();
gstate.FillOpacity = 0.5f;
gstate.StrokeOpacity = 0.5f;

cb.SaveState();
cb.SetGState(gstate);

stamper.GetUnderContent(1);
cb.SetFontAndSize(BaseFont.CreateFont(), 130f);
cb.BeginText();

cb.SetColorFill(new BaseColor(Color.LightGray));

//print the text from lower left to upper right corner with angle of 40%
cb.ShowTextAligned(Element.ALIGN_LEFT, "Preview", 110, 20, 40);

cb.EndText();
cb.Stroke();

//Restore old state without any opacity
cb.RestoreState();

stamper.Writer.CloseStream = false;
stamper.Close();

return memoryStream.GetBuffer();

        pdf_preview