c# - iText 7, Extract layers from document

Question

I am trying to use the IText 7 library to extract specific layers by name from a PDF file to create a new one.

Main problem - what I have achieved is a document with extracted layer visible and other layers locked/invisible. I would like to get them removed. Method input and result

Second problem - code fails with multi-page documents, result file has only one page

  public string ExtractLayer(string pdfLayerName, string sourceFilePath)
    {
        // returns empty 0b file with .pdf extension
        var layerFile = TmpFilesProvider.GetTemporaryFile.Pdf();


        PdfDocument pdfDoc = new PdfDocument(new PdfReader(sourceFilePath), new PdfWriter(layerFile));

        List<PdfLayer> layers = pdfDoc.GetCatalog().GetOCProperties(true).GetLayers().ToList();


        foreach (var layer in layers)
        {
            var layerName = (layer.GetPdfObject().Get(PdfName.Name));
            if (layerName == null) continue;

            if (layerName.ToString() != pdfLayerName)
            {
                layer.SetOn(false);
                layer.SetLocked(true);
            }
            else
            {
                RectangleEventHandler handler = new RectangleEventHandler();
                pdfDoc.AddEventHandler(PdfDocumentEvent.END_PAGE, handler);
            }
        }

        pdfDoc.Close();
        return layerFile;
    }

Answer 1

等待大神答复