PDF Merging by ItextSharp

Question

How would I merge several pdf pages into one with iTextSharp which also supports merging pages having form elements like textboxes, checkboxes, etc.

I have tried so many by googling, but nothing has worked well.

Answer 1

See my answer here Merging Memory Streams. I give an example of how to merge PDFs with itextsharp.

For updating form field names add this code that uses the stamper to change the form field names.

/// <summary>
/// Merges pdf files from a byte list
/// </summary>
/// <param name="files">list of files to merge</param>
/// <returns>memory stream containing combined pdf</returns>
public MemoryStream MergePdfForms(List<byte[]> files)
{
    if (files.Count > 1)
    {
        string[] names;
        PdfStamper stamper;
        MemoryStream msTemp = null;
        PdfReader pdfTemplate = null;
        PdfReader pdfFile;
        Document doc;
        PdfWriter pCopy;
        MemoryStream msOutput = new MemoryStream();

        pdfFile = new PdfReader(files[0]);

        doc = new Document();
        pCopy = new PdfSmartCopy(doc, msOutput);
        pCopy.PdfVersion = PdfWriter.VERSION_1_7;

        doc.Open();

        for (int k = 0; k < files.Count; k++)
        {
            for (int i = 1; i < pdfFile.NumberOfPages + 1; i++)
            {
                msTemp = new MemoryStream();
                pdfTemplate = new PdfReader(files[k]);

                stamper = new PdfStamper(pdfTemplate, msTemp);

                names = new string[stamper.AcroFields.Fields.Keys.Count];
                stamper.AcroFields.Fields.Keys.CopyTo(names, 0);
                foreach (string name in names)
                {
                    stamper.AcroFields.RenameField(name, name + "_file" + k.ToString());
                }

                stamper.Close();
                pdfFile = new PdfReader(msTemp.ToArray());
                ((PdfSmartCopy)pCopy).AddPage(pCopy.GetImportedPage(pdfFile, i));
                pCopy.FreeReader(pdfFile);
            }
        }

        pdfFile.Close();
        pCopy.Close();
        doc.Close();

        return msOutput;
    }
    else if (files.Count == 1)
    {
        return new MemoryStream(files[0]);
    }

    return null;
}