Combine two (or more) PDF's

Question

Background: I need to provide a weekly report package for my sales staff. This package contains several (5-10) crystal reports.

Problem:

Answer 1

Following method gets a List of byte array which is PDF byte array and then returns a byte array.

using ...;
using PdfSharp.Pdf;
using PdfSharp.Pdf.IO;

public static class PdfHelper
{
    public static byte[] PdfConcat(List lstPdfBytes)
    {
        byte[] res;

        using (var outPdf = new PdfDocument())
        {
            foreach (var pdf in lstPdfBytes)
            {
                using (var pdfStream = new MemoryStream(pdf))
                using (var pdfDoc = PdfReader.Open(pdfStream, PdfDocumentOpenMode.Import))
                    for (var i = 0; i < pdfDoc.PageCount; i++)
                        outPdf.AddPage(pdfDoc.Pages[i]);
            }

            using (var memoryStreamOut = new MemoryStream())
            {
                outPdf.Save(memoryStreamOut, false);

                res = Stream2Bytes(memoryStreamOut);
            }
        }

        return res;
    }

    public static void DownloadAsPdfFile(string fileName, byte[] content)
    {
        var ms = new MemoryStream(content);

        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.ContentType = "application/pdf";
        HttpContext.Current.Response.AddHeader("content-disposition", $"attachment;filename={fileName}.pdf");
        HttpContext.Current.Response.Buffer = true;
        ms.WriteTo(HttpContext.Current.Response.OutputStream);
        HttpContext.Current.Response.End();
    }

    private static byte[] Stream2Bytes(Stream input)
    {
        var buffer = new byte[input.Length];
        using (var ms = new MemoryStream())
        {
            int read;
            while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
                ms.Write(buffer, 0, read);

            return ms.ToArray();
        }
    }
}

So, the result of PdfHelper.PdfConcat method is passed to PdfHelper.DownloadAsPdfFile method.

PS: A NuGet package named [PdfSharp][1] need to be installed. So in the Package Manage Console window type:

Install-Package PdfSharp