使用的是iTextSharp添加PDF水印，由于是接口动态生成PDF，所以采用的是全部是内存流的形式，而且水印是平铺是。iTextSharp版本是5.5
1 /// <summary> 2 /// 添加倾斜水印 3 /// </summary> 4 /// <param name="pdfStream">pdf文件流</param> 5 /// <param name="waterMarkName">水印字符串</param> 6 /// <param name="width">页面宽度</param> 7 /// <param name="height">页面高度</param> 8 public MemoryStream SetWaterMark(MemoryStream pdfStream, string waterMarkName, float width, float height) 9 { 10 try 11 { 12 int fontSize = 50;//设置字体大小 13 int span = 40;//设置垂直位移 14 MemoryStream outStream = new MemoryStream(); 15 PdfReader pdfReader = new PdfReader(pdfStream); 16 PdfStamper pdfStamper = new PdfStamper(pdfReader, outStream); 17 pdfStamper.Writer.CloseStream = false; 18 int total = pdfReader.NumberOfPages + 1; 19 PdfContentByte content; 20 BaseFont font = BaseFont.CreateFont(@"C:WINDOWSFontsSTCAIYUN.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);//华文云彩字体 21 PdfGState gs = new PdfGState(); 22 gs.FillOpacity = 0.15f;//透明度 23 int waterMarkNameLenth = waterMarkName.Length; 24 char c; 25 int rise = 0; 26 string spanString = " ";//水平位移 27 for (int i = 1; i < total; i++) 28 { 29 rise = waterMarkNameLenth * span; 30 content = pdfStamper.GetOverContent(i);//在内容上方加水印 31 //content = pdfStamper.GetUnderContent(i);//在内容下方加水印 32 content.SetGState(gs); 33 content.BeginText(); 34 content.SetColorFill(BaseColor.GREEN); 35 content.SetFontAndSize(font, fontSize); 36 int heightNumbert = (int)Math.Ceiling((decimal)height / (decimal)rise);//垂直重复的次数，进一发 37 int panleWith = (fontSize + span) * waterMarkNameLenth; 38 int widthNumber = (int)Math.Ceiling((decimal)width / (decimal)panleWith);//水平重复次数 39 40 // 设置水印文字字体倾斜 开始 41 for (int w = 0; w < widthNumber; w++) 42 { 43 for (int h = 1; h <= heightNumbert; h++) 44 { 45 int yleng = rise * h; 46 content.SetTextMatrix(w * panleWith, yleng);//x,y设置水印开始的绝对左边，以左下角为x，y轴的起点 47 for (int k = 0; k < waterMarkNameLenth; k++) 48 { 49 content.SetTextRise(yleng);//指定的y轴值处添加 50 c = waterMarkName[k]; 51 content.ShowText(c + spanString); 52 yleng -= span; 53 } 54 } 55 } 56 content.EndText(); 57 } 58 if (pdfStamper != null) 59 pdfStamper.Close(); 60 61 if (pdfReader != null) 62 pdfReader.Close(); 63 64 return outStream; 65 } 66 catch (Exception ex) 67 { 68 throw ex; 69 } 70 }