Reorder pages in a pdf file using itextsharp

Question

I'm trying to reorder several pages in a PDF file. I found some code in a blog but couldn't get it to work. I have a two page pdf, and I want to get the last page to appear as first. I always get an exception saying that page number has to match with order. When I checked the document object, it shows 0 pages. But the PDF passed into has two pages.

public void reOrder(string inputFile)
{ 
    Document document = new Document();
    FileStream fs = new FileStream(inputFile, FileMode.Open);
    PdfWriter writer = PdfWriter.GetInstance(document, fs);
    document.AddDocListener(writer);                
    writer.SetLinearPageMode();
    int[] order = {2,1};
    writer.ReorderPages(order);
}

Answer 1

Whenever you use iTextSharp to write something you need to create a new document, it will never write to an existing document. In your case, page reordering would require writing so you need create a new document, bring over the pages and then reorder them. (Of course, you could also just reorder them upon import, too.)

        var inputFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Test.pdf");
        var output = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Output.pdf");

        //Bind a reader to our input file
        var reader = new PdfReader(inputFile);

        //Create our output file, nothing special here
        using (FileStream fs = new FileStream(output, FileMode.Create, FileAccess.Write, FileShare.None)) {
            using (Document doc = new Document(reader.GetPageSizeWithRotation(1))) {
                //Use a PdfCopy to duplicate each page
                using (PdfCopy copy = new PdfCopy(doc, fs)) {
                    doc.Open();
                    copy.SetLinearPageMode();
                    for (int i = 1; i <= reader.NumberOfPages; i++) {
                        copy.AddPage(copy.GetImportedPage(reader, i));
                    }
                    //Reorder pages
                    copy.ReorderPages(new int[] { 2, 1 });
                    doc.Close();
                }
            }
        }

Answer 2

From @Mathew Leger's answer :

An option for trimming pages is to use the PdfReader.SelectPages() combined with PdfStamper. I wrote the code below with iTextSharp 5.5.1.

public void SelectPages(string inputPdf, string pageSelection, string outputPdf)
{
    using (PdfReader reader = new PdfReader(inputPdf))
    {
        reader.SelectPages(pageSelection);

        using (PdfStamper stamper = new PdfStamper(reader, File.Create(outputPdf)))
        {
            stamper.Close();
        }
    }
}

Then you just have to call this method with the correct page selection for each condition.

Condition 1:

SelectPages(inputPdf, "1-4", outputPdf);

Condition 2:

SelectPages(inputPdf, "1-4,6", outputPdf);

or

SelectPages(inputPdf, "1-6,!5", outputPdf);

Condition 3:

SelectPages(inputPdf, "1-5", outputPdf);

Here's the comment from the iTextSharp source code on what makes up a page selection. This is in the SequenceList class which is used to process a page selection:

/**
* This class expands a string into a list of numbers. The main use is to select a
* range of pages.
* <p>
* The general systax is:<br>
* [!][o][odd][e][even]start-end
* <p>
* You can have multiple ranges separated by commas ','. The '!' modifier removes the
* range from what is already selected. The range changes are incremental, that is,
* numbers are added or deleted as the range appears. The start or the end, but not both, can be ommited.
*/

Answer 3

@Chris Haas' answer is good, but it's not the only way.

Here was my situation:

1. I first generated a document with XMLWorker and a Razor view.
2. Then I appended zero-to-many images, each as their own page.
3. The customer wanted to reorder the document so that the image pages would follow page 1 (ie As pages 2, 3, 4, etc.).

Here was the code that I used to do this:

    private static void MoveImagesToPage2(ICollection imagesToBePrintedOnSeparatePages, IDocListener pdfDocument, PdfWriter pdfWriter)
    {
        pdfDocument.NewPage(); // required - http://itextpdf.com/examples/iia.php?id=98

        var numberOfPages = pdfWriter.ReorderPages(null);
        var newOrder = new int[numberOfPages];
        newOrder[0] = 1; // Keep page 1 as page 1

        var i = 1;
        for (var j = imagesToBePrintedOnSeparatePages.Count - 1; 0 <= j; j--)
        {
            newOrder[i] = numberOfPages - j;
            i++;
        }

        for (; i < numberOfPages; i++)
        {
            newOrder[i] = i - (imagesToBePrintedOnSeparatePages.Count - 1);
        }

        pdfWriter.ReorderPages(newOrder);
    }

Please be mindful of this line:

pdfDocument.NewPage(); // required - http://itextpdf.com/examples/iia.php?id=98

This line is necessary if you want to move the last page in the document. ( I have no idea why. )

But if it's necessary, then you'll need this line to delete the blank page after you're done:

    private static byte[] RemoveTheLastPageWhichWasAddedForReordering(byte[] renderedBuffer)
    {
        var originalPdfReader = new PdfReader(renderedBuffer);

        using (var msCopy = new MemoryStream())
        {
            using (var docCopy = new Document())
            {
                using (var copy = new PdfCopy(docCopy, msCopy))
                {
                    docCopy.Open();
                    for (var pageNum = 1; pageNum <= originalPdfReader.NumberOfPages - 1; pageNum++)
                    {
                        copy.AddPage(copy.GetImportedPage(originalPdfReader, pageNum));
                    }
                    docCopy.Close();
                }
            }

            return msCopy.ToArray();
        }
    }

Special thanks to @Craig Howard for the snippet above .