iTextSharp Split document and Bates Stamp

Sample.cs

private static Action<iTextSharp.text.Rectangle, PdfImportedPage, PdfSmartCopy, int> shrinkForBateStamp =
        (pageSizeWithRotation, page, copier, pageNumber) =>
{
    // shrink percentage
    const float shrinkPercentage = .95f;

    var stamp = copier.CreatePageStamp(page);

    var w = page.Width > page.Height ? page.Height : page.Width;
    var h = page.Width > page.Height ? page.Width : page.Height;

    var offsetX = (w * (1 - shrinkPercentage)) / 2;
    var offsetY = (h * (1 - shrinkPercentage)) / 2;

    // Shrink the page content by x percentage and center the contents. Page itself remains the same size.
    stamp.GetUnderContent()
            .SetLiteral($"\nq {shrinkPercentage} 0 0 {shrinkPercentage} {offsetX} {offsetY} cm\nq\n");

    var cb = stamp.GetOverContent();

    cb.SetLiteral("\nQ\nQ\n");

    // Get bottom right points
    var point = GetRightBottom(page.Rotation, pageSizeWithRotation, 10);
        
    // Add the page number to the bottom right
    ColumnText.ShowTextAligned(cb, Element.ALIGN_RIGHT
        , new Phrase($"{pageNumber:00000}", _baseFont), point.X, point.Y, page.Rotation);

    // mark contents as altered
    stamp.AlterContents();
};
                    
private static Point GetRightBottom(int pageRotation, iTextSharp.text.Rectangle rectangle, int margin)
{
    switch (pageRotation)
    {
        case 0:
            return new Point((int)rectangle.Right - margin, (int)rectangle.Bottom + margin);
        case 90:
            return new Point((int)rectangle.Right - margin, (int)rectangle.Top - margin);
        case 180:
            return new Point((int)rectangle.Left + margin, (int)rectangle.Top - margin);
        case 270:
            return new Point((int)rectangle.Left + margin, (int)rectangle.Bottom + margin);
        default:
            throw new ArgumentException($"Unsupported pageRotation value of {pageRotation}", nameof(pageRotation));
    }
}
 
private static readonly iTextSharp.text.Font _baseFont = 
        new iTextSharp.text.Font(BaseFont.CreateFont(BaseFont.HELVETICA_BOLD, BaseFont.CP1252, BaseFont.NOT_EMBEDDED), 8);

public static void Split(PdfReader srcReader, string outFilePath, int startPage, int stopPage
    , Action<iTextSharp.text.Rectangle, PdfImportedPage, PdfSmartCopy, int> onPage = null)
{
    using (var destStream = new FileStream(outFilePath, FileMode.Create))
    {
        // create our destination document for iTextSharp to build our PDF

        using (var destDocument = new Document())
        {
            // get our copier so we can copy pages from our source reader

            using (var copier = GetCopier(destDocument, destStream))
            {
                copier.RotateContents = false;

                // open our itext document so we can start writing to it.

                destDocument.Open();

                // loop through and get our pages

                for (var pageNumber = startPage; pageNumber <= stopPage; pageNumber++)
                {
                    // add the page to our copier which in turn will write it to our dest document

                    var page = copier.GetImportedPage(srcReader, pageNumber);
                    var pageSizeWithRotation = srcReader.GetPageSizeWithRotation(pageNumber);

                    // run an page logic here
                    onPage?.Invoke(pageSizeWithRotation, page, copier, pageNumber);

                    copier.AddPage(page);
                }
            }
        }
    }
}