New! This sample shows how to concatenate the pages of several PDF documents to one single file.

[STAThread]
static void Main(string[] args)
{
  Variant1();
  Variant2();
  Variant3();
  Variant4();
}
 
/// <summary>
/// Put your own code here to get the files to be concatenated.
/// </summary>
static string[] GetFiles()
{
  DirectoryInfo dirInfo = new DirectoryInfo("../../../../PDFs");
  FileInfo[] fileInfos = dirInfo.GetFiles("*.pdf");
  ArrayList list = new ArrayList();
  foreach(FileInfo info in fileInfos)
  {
    // HACK: Just skip the protected samples file...
    if (info.Name.IndexOf("protected") == -1)
      list.Add(info.FullName);
  }
  return (string[])list.ToArray(typeof(string));
}
 
/// <summary>
/// Imports all pages from a list of documents.
/// </summary>
static void Variant1()
{
  // Get some file names
  string[] files = GetFiles();
 
  // Open the output document
  PdfDocument outputDocument = new PdfDocument();
 
  // Iterate files
  foreach (string file in files)
  {
    // Open the document to import pages from it.
    PdfDocument inputDocument = PdfReader.Open(file, PdfDocumentOpenMode.Import);
 
    // Iterate pages
    int count = inputDocument.PageCount;
    for (int idx = 0; idx < count; idx++)
    {
      // Get the page from the external document...
      PdfPage page = inputDocument.Pages[idx];
      // ...and add it to the output document.
      outputDocument.AddPage(page);
    }
  }
 
  // Save the document...
  string filename = "ConcatenatedDocument1.pdf";
  outputDocument.Save(filename);
  // ...and start a viewer.
  Process.Start(filename);
}
 
/// <summary>
/// This sample adds each page twice to the output document. The output document
/// becomes only a little bit larger because the content of the pages is reused 
/// and not duplicated.
/// </summary>
static void Variant2()
{
  // Get some file names
  string[] files = GetFiles();
 
  // Open the output document
  PdfDocument outputDocument = new PdfDocument();
 
  // Show consecutive pages facing. Requires Acrobat 5 or higher.
  outputDocument.PageLayout = PdfPageLayout.TwoColumnLeft;
 
  // Iterate files
  foreach (string file in files)
  {
    // Open the document to import pages from it.
    PdfDocument inputDocument = PdfReader.Open(file, PdfDocumentOpenMode.Import);
 
    // Iterate pages
    int count = inputDocument.PageCount;
    for (int idx = 0; idx < count; idx++)
    {
      // Get the page from the external document...
      PdfPage page = inputDocument.Pages[idx];
      // ...and add them twice to the output document.
      outputDocument.AddPage(page);
      outputDocument.AddPage(page);
    }
  }
 
  // Save the document...
  string filename = "ConcatenatedDocument2.pdf";
  outputDocument.Save(filename);
  // ...and start a viewer.
  Process.Start(filename);
}
 
/// <summary>
/// This sample adds a consecutive number in the middle of each page.
/// It shows how you can add graphics to an imported page.
/// </summary>
static void Variant3()
{
  // Get some file names
  string[] files = GetFiles();
 
  // Open the output document
  PdfDocument outputDocument = new PdfDocument();
 
  // Note that the output document may look significant larger than in Variant1.
  // This is because adding graphics to an imported page causes the 
  // uncompression of its content if it was compressed in the external document.
  // To compare file sizes you should either run the sample as Release build
  // or uncomment the following line.
  //outputDocument.Options.CompressContentStreams = true;
 
  XFont font = new XFont("Verdana", 40, XFontStyle.Bold);
  XStringFormat format = XStringFormat.Center;
  int number = 0;
 
  // Iterate files
  foreach (string file in files)
  {
    // Open the document to import pages from it.
    PdfDocument inputDocument = PdfReader.Open(file, PdfDocumentOpenMode.Import);
 
    // Iterate pages
    int count = inputDocument.PageCount;
    for (int idx = 0; idx < count; idx++)
    {
      // Get the page from the external document...
      PdfPage page = inputDocument.Pages[idx];
      // ...and add it to the output document.
      // Note that the PdfPage instance returned by AddPage is a
      // different object.
      page = outputDocument.AddPage(page);
 
      // Create a graphics object for this page. To draw beneath the existing
      // content set 'Append' to 'Prepend'.
      XGraphics gfx = 
        XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Append);
      DrawNumber(gfx, font, ++number);
    }
  }
 
  // Save the document...
  string filename = "ConcatenatedDocument3.pdf";
  outputDocument.Save(filename);
  // ...and start a viewer.
  Process.Start(filename);
}
 
/// <summary>
/// This sample is the combination of Variant2 and Variant3. It shows that you 
/// can add external pages more than once and still add individual graphics on
/// each page. The external content is shared among the pages, the new graphics
/// are unique to each page. You can check this by comparing the file size
/// of Variant3 and Variant4.
/// </summary>
static void Variant4()
{
  // Get some file names
  string[] files = GetFiles();
 
  // Open the output document
  PdfDocument outputDocument = new PdfDocument();
 
  // For checking the file size uncomment next line.
  //outputDocument.Options.CompressContentStreams = true;
 
  XFont font = new XFont("Verdana", 40, XFontStyle.Bold);
  XStringFormat format = XStringFormat.Center;
  int number = 0;
 
  // Iterate files
  foreach (string file in files)
  {
    // Open the document to import pages from it.
    PdfDocument inputDocument = PdfReader.Open(file, PdfDocumentOpenMode.Import);
 
    // Show consecutive pages facing. Requires Acrobat 5 or higher.
    outputDocument.PageLayout = PdfPageLayout.TwoColumnLeft;
 
    // Iterate pages
    int count = inputDocument.PageCount;
    for (int idx = 0; idx < count; idx++)
    {
      // Get the page from the external document...
      PdfPage page = inputDocument.Pages[idx];
      // ...and add it twice to the output document.
      PdfPage page1 = outputDocument.AddPage(page);
      PdfPage page2 = outputDocument.AddPage(page);
 
      XGraphics gfx = 
        XGraphics.FromPdfPage(page1, XGraphicsPdfPageOptions.Append);
      DrawNumber(gfx, font, ++number);
 
      gfx = XGraphics.FromPdfPage(page2, XGraphicsPdfPageOptions.Append);
      DrawNumber(gfx, font, ++number);
    }
  }
 
  // Save the document...
  string filename = "ConcatenatedDocument4.pdf";
  outputDocument.Save(filename);
  // ...and start a viewer.
  Process.Start(filename);
}
 
/// <summary>
/// Draws the number in the middle of the page.
/// </summary>
static void DrawNumber(XGraphics gfx, XFont font, int number)
{
  double width = 130;
  gfx.DrawEllipse(new XPen(XColors.DarkBlue, 7), XBrushes.DarkOrange, 
    new XRect((gfx.PageSize.ToXPoint() - new XSize(width, width)) / 2, 
              new XSize(width, width)));
  gfx.DrawString(number.ToString(), font, XBrushes.Firebrick, 
    new XRect(XPoint.Empty, gfx.PageSize), XStringFormat.Center);
}