PNG 图片转PDF

安装依赖包

iTextSharp-LGPL-Core（1.2.0）

#region iTextSharp 合并多个PDF
  /// <param name="SourcePath">源路径</param>
  /// <param name="TargetPath">目标路径</param>
  /// <param name="NewFileName">新文件名</param>
  public static void MergePDF(string SourcePath, string TargetPath, string NewFileName)
  {
      //需要合并的pdf集合
      string[] fileList = Directory.GetFiles(SourcePath, "*.pdf", SearchOption.AllDirectories);
      //合并到的总PDF
      string outMergeFile = TargetPath + "\\" + NewFileName;
      PdfReader reader;
      iTextSharp.text.Document document = new iTextSharp.text.Document();
      PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(outMergeFile, FileMode.Create));
      document.Open();
      PdfContentByte cb = writer.DirectContent;
      PdfImportedPage newPage;
      for (int i = 0; i < fileList.Length; i++)
      {
          reader = new PdfReader(fileList[i]);
          int iPageNum = reader.NumberOfPages;
          for (int j = 1; j <= iPageNum; j++)
          {
              document.NewPage();
              newPage = writer.GetImportedPage(reader, j);
              cb.AddTemplate(newPage, 0, 0);
          }
      }
      document.Close();
  }
  #endregion 
 /// <summary>
 /// iTextSharp  图片合并成pdf
 /// </summary>
 /// <param name="files">List Png</param>
 /// <param name="pdfFileName">pdf 文件路径</param>
 /// <returns></returns>
 public bool MergeFileToPDF(List<string> files, string pdfFileName)
 {     iTextSharp.text.Document document = new iTextSharp.text.Document(iTextSharp.text.PageSize.A4, 25, 25, 25, 25);
     try
     {
         iTextSharp.text.pdf.PdfWriter.GetInstance(document, new FileStream(pdfFileName, FileMode.Create, FileAccess.ReadWrite));
         document.Open();
         iTextSharp.text.Image image;
         foreach (var item in files)
         {
             if (String.IsNullOrEmpty(item)) break;
             image = iTextSharp.text.Image.GetInstance(item);
             if (image.Height > iTextSharp.text.PageSize.A4.Height - 25)
             {
                 image.ScaleToFit(iTextSharp.text.PageSize.A4.Width - 25, iTextSharp.text.PageSize.A4.Height - 25);
             }
             else if (image.Width > iTextSharp.text.PageSize.A4.Width - 25)
             {
                 image.ScaleToFit(iTextSharp.text.PageSize.A4.Width - 25, iTextSharp.text.PageSize.A4.Height - 25);
             }
             image.Alignment = iTextSharp.text.Image.ALIGN_MIDDLE;
             document.NewPage();
             document.Add(image);
         }
         document.Close();
         return true;
     }
     catch (Exception ex)
     {
         Console.WriteLine("转换失败，原因：" + ex.Message);
     }
     return false; }