how to add confidential watermark in pdf

spire.pdf.annotations;using spire.pdf.annotations.appearance;using spire.pdf.graphics;namespace addanimagestamptoapdf_file{Public partial Class Form1:form {public Form1 () {InitializeComponent (); } private void Button1_Click (object sender, EventArgs e) {pdfdocument doc = new pdfdocument (); Doc. LoadFromFile (@ "E:\Visual studio\sample\template7\sample.pdf"); Pdfpagebase page = doc. Pages[0]; Pdfrubberstampannotation Lostamp = new Pdfrubberstampannotation (New Re

location of the stencil display}//Ga Shuiyin public void Addwatermark (PDFWriter writer) {//watermark picture image; try {image = Image.getinstance ("./web/images/001.jpg"); Pdfcontentbyte content = Writer.getdirectcontentunder (); Content.begintext (); Start writing watermark for (int k=0;k　　Import Com.itextpdf.text.font;import com.itextpdf.tool.xml.xmlworkerfontprovider;/