给已经存在的PDF文件加水印

 1   static public bool WatermarkPDF(string SourcePdfPath, string OutputPdfPath, string WatermarkPath, int positionX, int positionY, int WatermarkHeight, int WatermarkWidth, out string msg)
 2         {
 3             try
 4             {
 5                 PdfReader reader = new PdfReader(SourcePdfPath);
 6                 PdfStamper stamp = new PdfStamper(reader, new FileStream(OutputPdfPath, FileMode.Create));
 7                 int n = reader.NumberOfPages;
 8                 int i = 0;
 9                 PdfContentByte under;
10                 iTextSharp.text.Image im = iTextSharp.text.Image.GetInstance(WatermarkPath);
11                 im.SetAbsolutePosition(positionX, positionY);
12                 im.ScaleAbsolute(WatermarkWidth, WatermarkHeight);
13 
14                 while (i < n)
15                 {
16                     i++;
17                     under = stamp.GetUnderContent(i);
18                     under.AddImage(im, true);
19 
20                 }
21                 stamp.Close();
22                 reader.Close();
23             }
24             catch (Exception ex)
25             {
26                 msg = ex.Message;
27                 return false;
28             }
29             msg = "加水印成功！";
30             return true;
31         }