How to Merge Multiple Runtime-Generated PDFs Using ITextSharp?

How to Merge and Print Multiple PDFs Generated at Runtime Using ITextSharp?

To merge multiple PDFs generated at runtime using ITextSharp, you have two primary options: using the PdfCopy class family or the PdfWriter class.

PdfCopy Family

The Pdf*Copy* classes allow you to merge PDFs while preserving their original format and interactive annotations. For this approach, follow these steps:

1. Initialize an empty PDF document.
2. Create a PdfCopy object.
3. Loop through the generated PDF bytes.
4. For each byte array, create a PdfReader and import its pages into the PdfCopy object.

Example Using PdfCopy:

byte[] mergedPdf = null;
using (MemoryStream ms = new MemoryStream())
{
    using (Document document = new Document())
    {
        using (PdfCopy copy = new PdfCopy(document, ms))
        {
            document.Open();

            for (int i = 0; i < pdfBytes.Count; ++i)
            {
                PdfReader reader = new PdfReader(pdfBytes[i]);

                int n = reader.NumberOfPages;
                for (int page = 0; page < n; )
                {
                    copy.AddPage(copy.GetImportedPage(reader, ++page));
                }
            }
        }
    }
    mergedPdf = ms.ToArray();
}

PdfWriter Class

The PdfWriter class allows you to integrate pages from source PDFs into a new document without preserving their original interactivity. Use this approach if you are not concerned about annotations or other features in the source PDFs.

using (MemoryStream ms = new MemoryStream())
{
    using (Document document = new Document())
    {
        using (PdfWriter writer = PdfWriter.GetInstance(document, ms))
        {
            document.Open();

            for (int i = 0; i < pdfBytes.Count; ++i)
            {
                PdfReader reader = new PdfReader(pdfBytes[i]);

                int n = reader.NumberOfPages;
                for (int page = 0; page < n; )
                {
                    PdfImportedPage importedPage = writer.GetImportedPage(reader, ++page);
                    writer.Add(importedPage);
                }

                reader.Close();
            }
        }
    }
    mergedPdf = ms.ToArray();
}

For more details, refer to the iTextSharp documentation or the code examples provided in the linked answer.

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