winform 按顺序连续打印多个PDF文件

Process proc = new Process();
proc.StartInfo.CreateNoWindow = false;
proc.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
proc.StartInfo.UseShellExecute = true;
proc.StartInfo.FileName = itemPath;//打印文件路径（本地完整路径包括文件名和后缀名）
proc.StartInfo.Verb = "print";
proc.Start();
proc.Close();

        /// <summary>
        /// 把多个PDF文件和JPG/PNG图合并成一个PDF文档
        /// </summary>
        /// <param name="fileList">需要合并文件的完整路径列表</param>
        /// <param name="outMergeFile">输出文件完整路径</param>
        public static void MergePDFFile(List<string> fileList, string outMergeFile)
        {
            PdfReader reader;
            Document document = new Document();
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(outMergeFile, FileMode.Create));
            document.Open();
            PdfContentByte cb = writer.DirectContent;
            PdfImportedPage newPage;
            foreach (var itemFile in fileList)
            {
                if (!File.Exists(itemFile))
                {
                    string fileName = Path.GetFileName(itemFile);
                    LogMessageWrite.WriteMessage(string.Format("文件打印合并__{0} 文件不存在", fileName));
                    continue;
                }
                FileInfo fInfo = new FileInfo(itemFile);
                if (fInfo.Length < 1)
                {
                    string fileName = Path.GetFileName(itemFile);
                    LogMessageWrite.WriteMessage(string.Format("文件打印合并__文件内容为空，无法打印，{0}", fileName));
                    return;
                }
                

                var ext = Path.GetExtension(itemFile).ToLower();
                if (".pdf".Equals(ext))
                {
                    reader = new PdfReader(itemFile);
                    int iPageNum = reader.NumberOfPages;
                    for (int j = 1; j <= iPageNum; j++)
                    {
                        document.NewPage();
                        newPage = writer.GetImportedPage(reader, j);
                        cb.AddTemplate(newPage, 0, 0);
                    }
                }
                else if (".jpg".Equals(ext) || ".jpge".Equals(ext) || ".png".Equals(ext))
                {
                    FileStream rf = new FileStream(itemFile, FileMode.Open, FileAccess.Read);
                    int size = (int)rf.Length;
                    byte[] imext = new byte[size];
                    rf.Read(imext, 0, size);
                    rf.Close();

                    Image img = Image.GetInstance(imext);

                    //调整图片大小，使之适合A4
                    var imgHeight = img.Height;
                    var imgWidth = img.Width;
                    if (img.Height > iTextSharp.text.PageSize.A4.Height)
                    {
                        imgHeight = iTextSharp.text.PageSize.A4.Height;
                    }

                    if (img.Width > iTextSharp.text.PageSize.A4.Width)
                    {
                        imgWidth = iTextSharp.text.PageSize.A4.Width;
                    }
                    img.ScaleToFit(imgWidth, imgHeight);

                    //调整图片位置，使之居中
                    img.Alignment = iTextSharp.text.Image.ALIGN_MIDDLE;

                    document.NewPage();
                    document.Add(img);
                }
            }
            document.Close();
        }

            try
            {
    var mergeFilePath = string.Format("{0}mergepdf.pdf", tempDownDir);

                PDFPrintHelper.MergePDFFile(pdfList, mergeFilePath);

                Process proc = new Process();
                proc.StartInfo.CreateNoWindow = false;
                proc.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
                proc.StartInfo.UseShellExecute = true;
                proc.StartInfo.FileName = mergeFilePath;//打印文件路径（本地完整路径包括文件名和后缀名）
                proc.StartInfo.Verb = "print";
                proc.Start();
                proc.Close();
            }
            catch (Exception ex)
            {
                LogMessageWrite.WriteMessage(ex.Message);
            }