C#给PDF文件添加水印

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using iTextSharp.text.html.simpleparser;using iTextSharp.text.pdf;using iTextSharp.text;using System.IO;using System.Web.UI.HtmlControls;using System.Drawing;//itextsharp.dll version:5.1.10protected void Button1_Click(object sender, EventArgs e)   {    string source =@"D:/My.Sample/C#NET/Exoport2PDF/Web2/Chap1011.pdf"; //模板路径    string output = @"D:/My.Sample/C#NET/Exoport2PDF/Web2/Chap1012.pdf"; //导出水印背景后的PDF    string watermark = @"D:/My.Sample/C#NET/Exoport2PDF/Web2/gp0.jpg";  // 水印图片    bool isSurrcess = PDFWatermark(source, output, watermark, 10, 10);       }  public bool PDFWatermark(string inputfilepath, string outputfilepath, string ModelPicName, float top, float left)  {    //throw new NotImplementedException();    PdfReader pdfReader = null;    PdfStamper pdfStamper = null;    try    {      pdfReader = new PdfReader(inputfilepath);      int numberOfPages = pdfReader.NumberOfPages;      iTextSharp.text.Rectangle psize = pdfReader.GetPageSize(1);      float width = psize.Width;      float height = psize.Height;      pdfStamper = new PdfStamper(pdfReader, new FileStream(outputfilepath, FileMode.Create));      PdfContentByte waterMarkContent;      iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(ModelPicName);      image.GrayFill = 20;//透明度，灰色填充      //image.Rotation//旋转      //image.RotationDegrees//旋转角度      //水印的位置       if (left < 0)      {        left = width - image.Width + left;      }      image.SetAbsolutePosition(left, (height - image.Height) - top);      //每一页加水印,也可以设置某一页加水印       for (int i = 1; i <= numberOfPages; i++)      {        waterMarkContent = pdfStamper.GetUnderContent(i);        waterMarkContent.AddImage(image);      }      //strMsg = "success";      return true;    }    catch (Exception ex)    {       ex.Message.Trim();      return false;    }    finally    {      if (pdfStamper != null)        pdfStamper.Close();      if (pdfReader != null)        pdfReader.Close();    }