Split a Pdf into byte array pages with IText7

Question

I need to split a Pdf file into byte array pages without using the file system. I found the next code from @AlexeySubach which seems to work, but I have problems to export the contents from DocumentReadyListener:

class ByteArrayPdfSplitter : PdfSplitter {

    private MemoryStream currentOutputStream;

    public ByteArrayPdfSplitter(PdfDocument pdfDocument) : base(pdfDocument) {
    }

    protected override PdfWriter GetNextPdfWriter(PageRange documentPageRange) {
        currentOutputStream = new MemoryStream();
        return new PdfWriter(currentOutputStream);
    }

    public MemoryStream CurrentMemoryStream {
        get { return currentOutputStream; }
    }

    public class DocumentReadyListender : IDocumentReadyListener {

        private ByteArrayPdfSplitter splitter;

        public DocumentReadyListender(ByteArrayPdfSplitter splitter) {
            this.splitter = splitter;
        }

        public void DocumentReady(PdfDocument pdfDocument, PageRange pageRange) {
            pdfDocument.Close();
            byte[] contents = splitter.CurrentMemoryStream.ToArray();
            String pageNumber = pageRange.ToString();
        }
    }
}

Usage:

    public static List<Byte[]> SplitOnPages(Byte[] bytes)
    {
        using (MemoryStream memoryStream = new MemoryStream(bytes))
        {
            using (PdfReader reader = new PdfReader(memoryStream))
            {
                PdfDocument docToSplit = new PdfDocument(reader);
                ByteArrayPdfSplitter splitter = new ByteArrayPdfSplitter(docToSplit);
                splitter.SplitByPageCount(1, new ByteArrayPdfSplitter.DocumentReadyListender(splitter));
            }
        }

        //How do I get here the array of byte array pages??
        return ...
    }

Answer 1

The code from Alexey Subach you found expects that you add some sensible operation in the DocumentReadyListender method DocumentReady. As you eventually want a list of result PDF bytes, you should in your case add the bytes of the ready document to such a list, e.g. by improving the DocumentReadyListender like this:

public class DocumentReadyListender : IDocumentReadyListener
{
    public List<byte[]> splitPdfs;

    private ByteArrayPdfSplitter splitter;

    public DocumentReadyListender(ByteArrayPdfSplitter splitter, List<byte[]> results)
    {
        this.splitter = splitter;
        this.splitPdfs = results;
    }

    public void DocumentReady(PdfDocument pdfDocument, PageRange pageRange)
    {
        pdfDocument.Close();
        byte[] contents = splitter.CurrentMemoryStream.ToArray();
        splitPdfs.Add(contents);
    }
}

(ByteArrayPdfSplitter, improved helper class DocumentReadyListender)

With that change you can make your SplitOnPages operational:

public static List<Byte[]> SplitOnPages(Byte[] bytes)
{
    List <byte[]> result = new List<byte[]>();
    using (MemoryStream memoryStream = new MemoryStream(bytes))
    {
        using (PdfReader reader = new PdfReader(memoryStream))
        {
            PdfDocument docToSplit = new PdfDocument(reader);
            ByteArrayPdfSplitter splitter = new ByteArrayPdfSplitter(docToSplit);
            splitter.SplitByPageCount(1, new DocumentReadyListender(splitter, result));
        }
    }

    return result;
}

(SplitInMemory test, improved method SplitOnPages)