在現有PDF文件上添加水印

 
          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:5.1.10

protected  void Button1_Click( object sender, EventArgs e)
     {
         string source = @" D:\My.Sample\C#NET\Exoport2PDF\Web2\Chap1011.pdf "; //模板路徑
         string output =  @" D:\My.Sample\C#NET\Exoport2PDF\Web2\Chap1012.pdf "; //導出水印背景后的PDF
         string watermark =  @" D:\My.Sample\C#NET\Exoport2PDF\Web2\gp0.jpg ";   // 水印圖片

         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 // 旋轉
             // image.RotationDegrees // 旋轉角度
             // 水印的位置 
             if (left <  0)
            {
                left = width - image.Width + left;
            }

            image.SetAbsolutePosition(left, (height - image.Height) - top);


             // 每一頁加水印,也可以設置某一頁加水印 
             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();
        }