Merge PDF Using iTextSharp ACRO Fields

In this article we’ll learn how we can merge PDF ACRO Fields using C#.

Prerequisites

1. Prior knowledge of C#.
2. A development machine with Visual Studio 2010 or Higher version installed.

Step-by-step tutorial for how we can merge PDF ACRO Fields using C#

• Step 1: Prepare 2 or more PDF

• Step 2: Open your URL in browser

URL: https://www.pdfescape.com/windows/

• Step 3: Click on Free Online and Open PDF.

• Step 4: Set the ACRO Field.

• Step 5: Enter and then Place your mouse cursor any where in the PDF in order to set the ACRO Field.

• Step 6: And then right click on object properties.

• Step 7: Set the name of ACRO field from this pop up of field properties and select read only property

• Step 8: After click on OK and in the header disable is there click on that in order to disable the form field and finally it will look like this.

• Step 9: Click on green symbol you can see in left side bar it will download your PDF with ACRO field.

• Step 10: Finally PDF is created with the ACRO Fields similarly you can create other two PDF which you want to merge using ACRO Field.
• Step 11: We’re going to use this below function which will merge your PDF files including ACRO field.
  • How to use this function?

var myFileList = new List<string>();  // Prepare List of Files which we’re going to merge 
long fileTimeStamp = DateTime.Now.ToFileTime(); // prepare temp folder
System.IO.Directory.CreateDirectory(Server.MapPath("~/Document/"+ fileTimeStamp.ToString())); 
for (int i = 0; i < dir.GetFiles().Length; i++)
{
 	firstPDFPath = Server.MapPath("~/Document/Test" + (i + 1) + ".pdf");

       PdfReader _readerPayment = new PdfReader(firstPDFPath);

       using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
       {
           PdfStamper stamper = new PdfStamper(_readerPayment, ms);
           using (stamper)
           {
           	 Dictionary<string, string> info = _readerPayment.Info;
        stamper.MoreInfo = info;
       	 _commonService.SetPDFFields(stamper.AcroFields);
            }
   System.IO.MemoryStream msn = new System.IO.MemoryStream(ms.ToArray());
   System.IO.FileStream file = new System.IO.FileStream(Server.MapPath("~/Document/" +     fileTimeStamp.ToString() + "/" + (++counter) + ".pdf"), FileMode.Create, FileAccess.Write);
myFileList.Add(Server.MapPath("~/Document/" + fileTimeStamp.ToString() + "/" + (counter) + ".pdf"));
msn.WriteTo(file);
file.Close();
msn.Close();
          }
}
string[] _allFiles = System.IO.Directory.GetFiles(Server.MapPath("~/Document/" + fileTimeStamp.ToString()));
MergePDFs(Server.MapPath("~/Document/MainApp_"+fileTimeStamp+".pdf"), _allFiles);
public void MergePDFs(string outPutFilePath, params string[] filesPath)
        {
            try
            {
                List<PdfReader> readerList = new List<PdfReader>();
                foreach (string filePath in filesPath)
                {
                    PdfReader pdfReader = new PdfReader(filePath);
                    readerList.Add(pdfReader);
                }

                //Define a new output document and its size, type
iTextSharp.text.Document document = new iTextSharp.text.Document(iTextSharp.text.PageSize.A4, 0f, 0f, 0f, 20f);
       //Create blank output pdf file and get the stream to write on it.
       iTextSharp.text.pdf.PdfCopy writer = new iTextSharp.text.pdf.PdfCopy(document, new                             FileStream(outPutFilePath, FileMode.Create));

                document.Open();
                foreach (PdfReader reader in readerList)
                {
                    for (int i = 1; i <= reader.NumberOfPages; i++)
                    {
                        PdfImportedPage page = writer.GetImportedPage(reader, i);
                        document.Add(iTextSharp.text.Image.GetInstance(page));
                    }

                    writer.AddDocument(reader);
                    reader.Close();
                }
                document.Close();
                writer.Close();
            }
            catch (Exception ex)
            {
                ex.ToString();
            }
 }

GitHub Repository URL: https://github.com/sandipmalaviya07/merge-pdf-accrofield

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