Add text watermark to PDF using iTextSharp

AddPDFWatermark.cs

using iTextSharp.text;
using iTextSharp.text.pdf;

/// <summary>
/// This method adds watermark text under pdf content
/// </summary>
/// <param name="pdfData">pdf content bytes</param>
/// <param name="watermarkText">text to be shown as watermark</param>
/// <param name="font">base font</param>
/// <param name="fontSize">font sieze</param>
/// <param name="angle">angle at which watermark needs to be shown</param>
/// <param name="color">water mark color</param>
/// <param name="realPageSize">pdf page size</param>
public static void AddWaterMarkText(PdfContentByte pdfData, string watermarkText, BaseFont font, float fontSize, float angle, BaseColor color, Rectangle realPageSize)
{
    var gstate = new PdfGState {FillOpacity = 0.35f, StrokeOpacity = 0.3f};
    pdfData.SaveState();
    pdfData.SetGState(gstate);
    pdfData.SetColorFill(color);
    pdfData.BeginText();
    pdfData.SetFontAndSize(font, fontSize);
    var x = (realPageSize.Right + realPageSize.Left)/2;
    var y = (realPageSize.Bottom + realPageSize.Top)/2;
    pdfData.ShowTextAligned(Element.ALIGN_CENTER, watermarkText, x, y, angle);
    pdfData.EndText();
    pdfData.RestoreState();
}

// <summary>
/// This method calls another method to add watermark text for each page
/// </summary>
/// <param name="bytes">byte array of Pdf</param>
/// <param name="baseFont">Base font</param>
/// <param name="watermarkText">Text to be added as watermark</param>
/// <returns>Pdf bytes array having watermark added</returns>
private static byte[] AddWatermark(byte[] bytes, BaseFont baseFont, string watermarkText)
{
    using (var ms = new MemoryStream(10 * 1024))
    {
        using (var reader = new PdfReader(bytes))
        using (var stamper = new PdfStamper(reader, ms))
    {
    var pages = reader.NumberOfPages;
    for (var i = 1; i <= pages; i++)
    {
        var dc = stamper.GetOverContent(i);
        AddWaterMarkText(dc, watermarkText, baseFont, 50, 45, BaseColor.GRAY, reader.GetPageSizeWithRotation(i));
        }
            stamper.Close();
        }
        return ms.ToArray();
    }
}