C#生成PDF文件流

static BaseFont FontBase = BaseFont.CreateFont("C:\\WINDOWS\\FONTS\\STSONG.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
    static iTextSharp.text.Font bodyFont = new iTextSharp.text.Font(FontBase, 12);
    static iTextSharp.text.Font titleFont = new iTextSharp.text.Font(FontBase, 18);
    static iTextSharp.text.Font paragraphFont = new iTextSharp.text.Font(FontBase, 15);
    static iTextSharp.text.Font linkFont = new iTextSharp.text.Font(FontBase, 12, Font.UNDERLINE, BaseColor.BLUE);

public byte[] DocCreate(System.Drawing.Image image, List<TreeNodes> list)
    {
      MemoryStream file = new MemoryStream();

      string fileName = string.Empty;
      Rectangle page = PageSize.A4;
      float y = page.Height;
      Document document = new Document(page, 15, 15, 30, 30);
      float docWidth = page.Width - 15 * 2;
      float docHeight = page.Height - document.BottomMargin - document.TopMargin;
      PdfWriter writer = PdfWriter.GetInstance(document, file);
      writer.CloseStream = false;
      writer.Open();
      PdfContentByte cb = writer.DirectContent;
      document.Open();
      //标题
      Paragraph title = new Paragraph(new Chunk("标题", titleFont));
      title.Alignment = Element.ALIGN_CENTER;
      document.Add(title);
      //图片
      iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(image, ImageFormat.Png);
      float widthSzie = (page.Width - 30) / img.Width;
      if (widthSzie < 1)
      {
        img.ScalePercent(widthSzie * 100);
      }
      document.Add(img);
      //文献出处
      Paragraph p2 = new Paragraph(new Chunk("出处", paragraphFont));
      p2.IndentationLeft = indentationLeft;
      document.Add(p2);
      InitData(list);//初始化业务数据
      CreateSteps(list, document, list.FirstOrDefault(it => it.PID == 0));//添加业务数据
      ////添加印章
      //iTextSharp.text.Image whyz = iTextSharp.text.Image.GetInstance(whyzPath);
      //whyz.ScalePercent(50);
      //whyz.PaddingTop = 100;
      //whyz.Alignment = Element.ALIGN_RIGHT;
      //document.Add(whyz);
      //添加日期
      Paragraph createtime = new Paragraph(new Chunk(DateTime.Now.ToLongDateString().ToString(), bodyFont));
      createtime.Alignment = Element.ALIGN_RIGHT;
      //createtime.SpacingBefore = -80;
      createtime.PaddingTop = 200;

      document.Add(createtime);


      document.Close();
      file.Position = 0;
      MemoryStream newfile = SetWaterMark(file, "水印内容", docWidth, docHeight);//添加水印，见另外一篇博客
      newfile.Position = 0;//重置流指针位置
      byte[] bytes = new byte[newfile.Length];
      newfile.Read(bytes, 0, bytes.Length);
      return bytes;
    }