C# PDF添加水印

需要iTextSharp.dll, 下载地址http://sourceforge.net/projects/itextsharp/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

using iTextSharp.text.html.simpleparser;
using iTextSharp.text.pdf;
using iTextSharp.text;
using System.IO;


namespace pdf_test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string source = @"D:\Sample\18.pdf"; //模板路径
            string output = @"D:\Sample\Chap1018.pdf"; //导出水印背景后的PDF
            string watermark = @"D:\Sample\03.gif";   // 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;   //h////////////
                }

                //image.SetAbsolutePosition(left, (height - image.Height) - top);     //h////////////
                image.SetAbsolutePosition(136, 36);

                //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();
            }
        }



        //
    }
}