    protected void convertToPdfButton_Click(object sender, EventArgs e)
    {
        // Create a HTML to PDF converter object with default settings
        HtmlToPdfConverter htmlToPdfConverter = new HtmlToPdfConverter();

        // Set license key received after purchase to use the converter in licensed mode
        // Leave it not set to use the converter in demo mode
        htmlToPdfConverter.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

        // Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
        // Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
        htmlToPdfConverter.ConversionDelay = 2;

        // Select the HTML elements for which to retrieve location and other information from HTML document
        htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementSelectors = new string[] { htmlElementsSelectorTextBox.Text };

        Document pdfDocument = null;
        try
        {
            // Convert HTML page to a PDF document object which can be further modified to highlight the selected elements
            pdfDocument = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(urlTextBox.Text);

            // Highlight the selected elements in PDF with colored rectangles
            foreach (HtmlElementMapping htmlElementInfo in htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult)
            {
                // Get other information about HTML element
                string htmlElementTagName = htmlElementInfo.HtmlElementTagName;
                string htmlElementID = htmlElementInfo.HtmlElementId;

                // Hightlight the HTML element in PDF

                // A HTML element can span over many PDF pages and therefore the mapping of the HTML element in PDF document consists
                // in a list of rectangles, one rectangle for each PDF page where this element was rendered
                foreach (HtmlElementPdfRectangle htmlElementLocationInPdf in htmlElementInfo.PdfRectangles)
                {
                    // Get the HTML element location in PDF page
                    PdfPage htmlElementPdfPage = htmlElementLocationInPdf.PdfPage;
                    RectangleF htmlElementRectangleInPdfPage = htmlElementLocationInPdf.Rectangle;

                    // Highlight the HTML element element with a colored rectangle in PDF
                    RectangleElement highlightRectangle = new RectangleElement(htmlElementRectangleInPdfPage.X, htmlElementRectangleInPdfPage.Y,
                        htmlElementRectangleInPdfPage.Width, htmlElementRectangleInPdfPage.Height);

                    if (htmlElementTagName.ToLower() == "h1")
                        highlightRectangle.ForeColor = Color.Blue;
                    else if (htmlElementTagName.ToLower() == "h2")
                        highlightRectangle.ForeColor = Color.Green;
                    else if (htmlElementTagName.ToLower() == "h3")
                        highlightRectangle.ForeColor = Color.Red;
                    else if (htmlElementTagName.ToLower() == "h4")
                        highlightRectangle.ForeColor = Color.Yellow;
                    else if (htmlElementTagName.ToLower() == "h5")
                        highlightRectangle.ForeColor = Color.Indigo;
                    else if (htmlElementTagName.ToLower() == "h6")
                        highlightRectangle.ForeColor = Color.Orange;
                    else
                        highlightRectangle.ForeColor = Color.Navy;

                    highlightRectangle.LineStyle.LineDashStyle = LineDashStyle.Solid;

                    htmlElementPdfPage.AddElement(highlightRectangle);
                }
            }

            // Save the PDF document in a memory buffer
            byte[] outPdfBuffer = pdfDocument.Save();

            // Send the PDF as response to browser

            // Set response content type
            Response.AddHeader("Content-Type", "application/pdf");

            // Instruct the browser to open the PDF file as an attachment or inline
            Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Select_in_API_HTML_Elements_to_Retrieve.pdf; size={0}", outPdfBuffer.Length.ToString()));

            // Write the PDF document buffer to HTTP response
            Response.BinaryWrite(outPdfBuffer);

            // End the HTTP response and stop the current page processing
            Response.End();
        }
        finally
        {
            // Close the PDF document
            if (pdfDocument != null)
                pdfDocument.Close();
        }
    }