Aspose.PDF for .NET 26.2

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ConvertRtfToPdf()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_DocumentConversion();

    // Initialize RTF load options
    var options = new Aspose.Pdf.RtfLoadOptions();

    // Open RTF document
    using (var document = new Aspose.Pdf.Document(dataDir + "ConvertRtfToPdf.rtf", options))
    {
        // Save the document as PDF
        document.Save(dataDir + "ConvertRtfToPdf_out.pdf");
    }
}

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AddTableAfterLastElement()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Load source PDF document
    using (Aspose.Pdf.Document doc = new Aspose.Pdf.Document(dataDir + "HelloWorld.pdf"))
    {
        // Initializes a new instance of the Table
        Aspose.Pdf.Table table = new Aspse.Pdf.Table();

        // Determine the existing content area on the page
        double contentAreaLLY = doc.Pages[1].CalculateContentBBox().LLY;
        float topMargin = 20;

        // Add the table after the existing content, with the 20pt margin before the table.
        table.Top = (float)(doc.Pages[1].Rect.Height - (contentAreaLLY - topMargin));

        // Set the top margin for the new pages added.
        doc.PageInfo.Margin.Top = topMargin;

        // Create a loop to add 10 rows
        for (int row_count = 1; row_count < 10; row_count++)
        {
            // Add row to table
            Aspose.Pdf.Row row = table.Rows.Add();
            // Add table cells
            row.Cells.Add("Column (" + row_count + ", 1)");
            row.Cells.Add("Column (" + row_count + ", 2)");
            row.Cells.Add("Column (" + row_count + ", 3)");
        }

        // Add table object to first page of input document
        doc.Pages[1].Paragraphs.Add(table);

        // Save updated document containing table object
        doc.Save(dataDir + "document_with_table.pdf");
    }
}

// Load source PDF document
using (Aspose.Pdf.Document doc = new Aspose.Pdf.Document(myDir + "HelloWorld.pdf"))
{
    // Initializes a new instance of the Table
    Aspose.Pdf.Table table = new Aspose.Pdf.Table();

    // Determine the existing content area on the page
    Aspose.Pdf.Rectangle contentArea = doc.Pages[1].CalculateContentBBox();

    // Add the table after the existing content, with the 20pt margin before the table.
    table.Top = (float)(doc.Pages[1].Rect.Height - (contentArea.LLY - 20));

    // Set the top margin for the new pages added.
    doc.PageInfo.Margin.Top = topMargin;

    // create a loop to add 10 rows
    for (int row_count = 1; row_count < 10; row_count++)
    {
        // add row to table
        Aspose.Pdf.Row row = table.Rows.Add();
        // add table cells
        row.Cells.Add("Column (" + row_count + ", 1)");
        row.Cells.Add("Column (" + row_count + ", 2)");
        row.Cells.Add("Column (" + row_count + ", 3)");
    }

    // Add table object to first page of input document
    doc.Pages[1].Paragraphs.Add(table);

    // Save updated document containing table object
    doc.Save(myDir + "document_with_table.pdf");
}

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void RemoveInvisibleText()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    Document pdfDoc = new Document(dataDir + "test.pdf");

    foreach (Page page in pdfDoc.Pages)
    {
        TextFragmentAbsorber absorber = new TextFragmentAbsorber();
        page.Accept(absorber);

        var fragmentsToRemove = absorber.TextFragments
            .Where(x => x.TextState.Invisible
                || x.TextState.RenderingMode == TextRenderingMode.Invisible
                || (x.TextState.ForegroundColor != null && x.TextState.ForegroundColor.A == 0))
            .ToList();

        foreach (var fragment in fragmentsToRemove)
        {
            absorber.TextFragments.Remove(fragment); // Now properly removes text from document
        }
    }

    pdfDoc.Save(dataDir + "output.pdf");
}