iText 7 Text Watermark annotation not recognized by Adobe Reader - uneditable text

问题

I am able to add and remove a page header using a text watermark annotation using itext 7 and C#. I am able to see and print the PDF via Adobe Acrobat Reader. @remy

However, I am unable to use Adobe Acrobat Pro DC to remove the pager header. When I do a search and replace, it says text is un-editable.

The PDF files are located here: PDF Files Original, With Watermark Step2 and WaterMark Removed Step3

    public static string CompanyName= "ACME77";
    public static string AnnotName = CompanyName + "WatermarkHDR";

    public byte[] Add(string infile, string outFile)
    {
        PdfFont baseFont = PdfFontFactory.CreateFont(StandardFonts.HELVETICA_BOLD, Encoding.ASCII.EncodingName, false);
        Rectangle pageSize;
        string NoOfPagesPadded = string.Empty;
        string PageNoPadded = string.Empty;
        string HdrLeft = string.Empty;
        string HdrRight = string.Empty;

        int xLeft = 30;
        int xRight = 110;  //was 100
        int xTop = 30;

        float watermarkTrimmingRectangleWidth;  //= 300;
        float watermarkTrimmingRectangleHeight = 300; 

        float formXOffset = 0;  
        float formYOffset = -5;  // was zero  set to -5 because dangling letters (e.g. g) were being cut-off
        byte[] outByteFile;
        byte[] inByteFile = null;

        try
        {
            inByteFile = File.ReadAllBytes(infile);
            IRandomAccessSource inSourceFile = new RandomAccessSourceFactory().CreateSource(inByteFile);
            using (PdfReader reader = new PdfReader(inSourceFile, new ReaderProperties()).SetUnethicalReading(true))
            {
                using (var outMemoryFile = new MemoryStream())
                {
                    using (PdfWriter pdfWrite = new PdfWriter(outMemoryFile))
                    {
                        using (PdfDocument pdfDoc = new PdfDocument(reader, pdfWrite))
                        {
                            using (Document doc = new Document(pdfDoc))
                            {
                                int n = pdfDoc.GetNumberOfPages();

                                for (int i = 1; i <= n; i++)
                                {
                                    PdfPage page = pdfDoc.GetPage(i);
                                    pageSize = page.GetMediaBox();

                                    watermarkTrimmingRectangleWidth = pageSize.GetWidth();
                                    float PageWidth = pageSize.GetWidth();
                                    float PageHeight = pageSize.GetHeight();
                                    int rotation = page.GetRotation();
                                    Rectangle watermarkTrimmingRectangle = new Rectangle(pageSize.GetLeft() + xLeft, pageSize.GetTop() - xTop, watermarkTrimmingRectangleWidth, watermarkTrimmingRectangleHeight);

                                    PdfWatermarkAnnotation watermark = new PdfWatermarkAnnotation(watermarkTrimmingRectangle);

                                    watermark.SetName(new PdfString(AnnotName));
                                    Rectangle formRectangle = new Rectangle(formXOffset, formYOffset, watermarkTrimmingRectangleWidth, watermarkTrimmingRectangleHeight);

                                    PdfFormXObject form = new PdfFormXObject(formRectangle);   //Observation: font XObject will be resized to fit inside the watermark rectangle.  If it is larger, your text will be stretched.
                                    PdfCanvas canvasOver = new PdfCanvas(form, pdfDoc);

                                    canvasOver.SetFillColor(iText.Kernel.Colors.ColorConstants.RED);
                                    canvasOver.SetFontAndSize(baseFont, 10);
                                    canvasOver.SaveState();

                                    string SDSNo = "z2345678";
                                    HdrLeft = CompanyName + $" SDS# {SDSNo}";
                                     NoOfPagesPadded = (n.ToString());
                                    PageNoPadded = i.ToString();
                                    HdrRight = $"Page {PageNoPadded} of {NoOfPagesPadded}";
                                    canvasOver.BeginText()
                                              .SetColor(iText.Kernel.Colors.ColorConstants.RED, true)
                                              .SetFontAndSize(baseFont, 10)
                                              .ShowText(HdrLeft)
                                              .EndText();
                                    canvasOver.BeginText()
                                              .MoveText(formRectangle.GetRight() - xRight, 0)
                                              .SetColor(iText.Kernel.Colors.ColorConstants.RED, true)
                                              .SetFontAndSize(baseFont, 10)
                                              .ShowText(HdrRight)                                                  
                                              .EndText();
                                    canvasOver.SaveState();

                                    canvasOver.RestoreState();
                                    canvasOver.Release();

                                    watermark.SetAppearance(PdfName.N, new PdfAnnotationAppearance(form.GetPdfObject()));
                                    watermark.SetFlags(PdfAnnotation.PRINT);

                                    page.AddAnnotation(watermark);
                                }
                            }
                        }
                        outByteFile = outMemoryFile.ToArray();
                    }
                }
            }
            File.WriteAllBytes(outFile, outByteFile);

        }    
        catch (Exception ex)
        {
            Console.WriteLine("Error:" + ex.ToString());
            return inByteFile;
            throw;
        }
        return outByteFile;
    } 

    public void RemovetWatermarkPDF(string sourceFile, string destinationPath)
    {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader(sourceFile), new PdfWriter(destinationPath));
        var numberOfPages = pdfDoc.GetNumberOfPages();

        for (var i = 1; i <= numberOfPages; i++)
        {
            // PdfAnnotation 
            PdfDictionary pageDict = pdfDoc.GetPage(i).GetPdfObject();
            PdfArray annots = pageDict.GetAsArray(PdfName.Annots);
            for (int j = 0; j < annots.Size(); j++)
            {
                PdfDictionary annotation = annots.GetAsDictionary(j);
                if (PdfName.Watermark.Equals(annotation.GetAsName(PdfName.Subtype)))
                {
                    string x = annotation.GetAsString(PdfName.NM).GetValue();
                    if (x == AnnotName)
                    {
                        annotation.Clear();
                    }
                }
            }
        }
        pdfDoc.Close();
    }
}

来源：https://stackoverflow.com/questions/57843823/itext-7-text-watermark-annotation-not-recognized-by-adobe-reader-uneditable-te