HOWTO: How to merge images into a PDF

Legacy Example NOTICE

This article predates the introduction of our PdfDocument class. PdfDocument has a Combine method which is much more efficient for combining two or more PDF files. Support strongly recommends using this newer class for this task (see links below).

This approach is still totally applicible in many situations, but the result causes the contents of any PDF merged in to be "rasterized" (made into an image).

For PDFs that are already image based, there will not be a significant change in document size, but for vector based (non-raster) PDFs, there couled be size increase on disk.

For a more modern approach please consider:

• HOWTO: Combine Multiple PDFs with Automatic Repair of Damaged PDFs
• HOWTO: Combine Multiple PDF Files With Fillable Forms (AcroForms)
• HOWTO: Separate a Multi-Page PDF With Automatic Repair of Damaged PDFs

Main Article Content

Here is the code for a console application that merges a list of files into a single PDF. If some of the source files are PDF then you need the PDF Rasterizer and you must register it before the code is called (as shown). In a WinForms application, you would typically do the registration in static constructor of your form.

You need these references in your project

• Atalasoft.dotImage
• Atalasoft.dotImage.Lib
• Atalasoft.dotImage.Pdf
• Atalasoft.dotImage.PdfReader
• Atalasoft.Shared

Here is the code:

C#

using System;
using System.IO;
using Atalasoft.Imaging;
using Atalasoft.Imaging.Codec;
using Atalasoft.Imaging.Codec.Pdf;

namespace Atalasoft.MergePDFSample
{
   class Program
   {
      static void Main(string[] args)
      {
         // in order to read PDF, you must call this somewhere in your code
         // could be at the beginning of main in a console app, or in your 
         // main form's static constructor for a winforms app
         RegisteredDecoders.Decoders.Add(new PdfDecoder());

         // merge file1.pdf, file2.pdf and file3.pdf into output.pdf
         MergeIntoPdf(
            new string[] { "file1.pdf", "file2.pdf", "file3.pdf"}, "output.pdf");
      }

      public static void MergeIntoPdf(string[] imgFilenames, string outputFile)
      {
         ImageSource pdfpages = 
              new FileSystemImageSource(imgFilenames, true);
         using (FileStream fs = 
              new FileStream(outputFile, 
              FileMode.Create, FileAccess.ReadWrite))
         {
            PdfEncoder pdfEncoder = new PdfEncoder();
            pdfEncoder.Save(fs, pdfpages, null);
         }
      }
   }
}

VB.NET

Imports System
imports System.IO

Imports Atalasoft.Imaging
Imports Atalasoft.Imaging.Codec
Imports Atalasoft.Imaging.Codec.Pdf

Module Module1

  Sub Main()

    ' in order to read PDF, you must call this somewhere in your code
    ' could be at the beginning of main in a console app, or in your 
    ' main form's static constructor for a winforms app 

    RegisteredDecoders.Decoders.Add(New PdfDecoder())

    ' merge file1.pdf, file2.pdf and file3.pdf into output.pdf
    MergeIntoPdf(New String() {"f1.pdf", "f2.pdf", "f3.pdf"}, "out.pdf")

  End Sub

  Public Sub MergeIntoPdf(ByVal imgFiles As String(), ByVal outFile As String)

    Dim pdfpgs As ImageSource = New FileSystemImageSource(imgFiles, True)

    Using fs As FileStream = _
     New FileStream(outFile, _
     FileMode.Create, FileAccess.ReadWrite)

      Dim pdfEncoder As PdfEncoder = New PdfEncoder()
      pdfEncoder.Save(fs, pdfpgs, Nothing)

    End Using

  End Sub

End Module

Original Article:
Q10203 - HOWTO: How to merge images into a PDF