给一个PDF的所有页加上文字水印 ， 效果如下
新建一个项目，直接上代码了：
using iTextSharp.text;using iTextSharp.text.pdf;using System;using System.IO;using System.Windows.Forms;namespace _111{public partial class Form1 : Form{public Form1(){InitializeComponent();}private void button1_Click(object sender, EventArgs e){string p = Application.StartupPath"\";string r = AddTextShuiYin(p"test.pdf", p"test1.pdf", 0.5f,"HELLO");MessageBox.Show(r);}public static string AddTextShuiYin(string PdfPath, string OutPdfPath, float toumingdu, string ShuiYinText){if (File.Exists(OutPdfPath)){File.Delete(OutPdfPath);}PdfReader reader = null;PdfStamper ShuiYinOBJ = null;PdfContentByte ShuiYinQu;try{reader = new PdfReader(PdfPath);//得到原PDF的页数和宽高PDFATT att = new PDFATT(PdfPath);int n = att.PageCount();float w = att.Width();float h = att.Height();//从第0页开始int i = 0;ShuiYinOBJ = new PdfStamper(reader, new FileStream(OutPdfPath, FileMode.Create));PdfGState gs = new PdfGState();//设置透明度gs.FillOpacity = toumingdu;BaseFont font = BaseFont.CreateFont(@"C:WINDOWSFontsSIMFANG.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);while (i < n){i;//在正文内容下加水印，不挡内容ShuiYinQu = ShuiYinOBJ.GetUnderContent(i);//在正文内容上加水印，挡内容//ShuiYinQu = ShuiYinOBJ.GetOverContent(i);ShuiYinQu.SetGState(gs);for (float left = 0; left < w; left= 200){for (float top = 0; top < h; top= 100){//透明度gs.FillOpacity = toumingdu;ShuiYinQu.SetGState(gs);//开始写入文本ShuiYinQu.BeginText();ShuiYinQu.SetColorFill(iTextSharp.text.Color.RED);ShuiYinQu.SetFontAndSize(font, 180);ShuiYinQu.SetTextMatrix(2, 2);ShuiYinQu.ShowTextAligned(Element.ALIGN_CENTER, ShuiYinText, w / 2, h / 2, 30);//ShuiYinQu.AddImage(im);}}ShuiYinQu.EndText();}ShuiYinOBJ.Close();reader.Close();return "OK";}catch (Exception ex){return ex.ToString();}}class PDFATT{PdfReader reader;public PDFATT(string iPdfFilePath){reader = new PdfReader(iPdfFilePath);}public int PageCount(){return reader.NumberOfPages;}public float Width(){return reader.GetPageSize(1).Width;}public float Height(){return reader.GetPageSize(1).Height;}}}}调用方法说明
string p = Application.StartupPath"\";【c#给PDF所有页加上文字水印】//参数：源文件地址 ， 新文件地址 ， 透明度(float型),水印文本
string r = AddTextShuiYin(p"test.pdf", p"test1.pdf", 0.5f, "HELLO");
MessageBox.Show(r);
水印位置
//这里我是w/2和h/2 ， 大概在页中间，当然这里我为了演示没有精确计算，//30 是旋转角度
ShuiYinQu.ShowTextAligned(Element.ALIGN_CENTER, ShuiYinText, w / 2, h / 2, 30);