Select in API the HTML Elements for which to Retrieve Location

EVO PDF Client for .NET Core

EVO HTML to PDF Converter API allows you to select the HTML elements for which to retrieve the location in PDF and other useful information from HTML document like tag name, class, ID or HTML code. This feature allows you to obtain the position in the generated PDF document of any HTML element. Having the position in the generated PDF document of any element from the HTML document allows you to create bookmarks for those elements, create internal links in PDF between renderings of various HTML elements, place texts or images over the HTML elements or assign a digital signature to a certain element from HTML.

This feature is controlled by HtmlToPdfConverterHtmlElementsMappingOptions property. This property allows you to define a list of CSS selectors of the HTML elements for which to retrieve position in the generated PDF document.

The HtmlToPdfConverterHtmlElementsMappingOptions property must be configured before calling the converter method. The result of HTML elements mapping is returned in the HtmlElementsMappingOptionsHtmlElementsMappingResult object of HtmlElementMappingsCollection type which is a collection of HtmlElementMapping objects which offers the PDF page index where the element was mapped by the converter and the rectangle where the element was rendered inside that page, the element HTML ID, the element tag name, the element text and the element outer HTML code.

Code Sample - Select in API the HTML Elements for which to Retrieve Location

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Http;

// Use EVO PDF Namespace
using EvoPdfClient;

namespace EvoHtmlToPdfDemo.Controllers.HTML_to_PDF.HTML_Elements_Location
{
    public class Select_in_API_Elements_to_RetrieveController : Controller
    {
        [HttpPost]
        public ActionResult ConvertHtmlToPdf(IFormCollection collection)
        {
            // Get the server options
            string serverIP = collection["textBoxServerIP"];
            uint serverPort = uint.Parse(collection["textBoxServerPort"]);
            string servicePassword = collection["textBoxServicePassword"];
            bool useServicePassword = servicePassword.Length > 0;
            bool useTcpService = collection["ServerType"] == "radioButtonUseTcpService";
            string webServiceUrl = collection["textBoxWebServiceUrl"];

            // Create the HTML to PDF converter object
            HtmlToPdfConverter htmlToPdfConverter = null;
            if (useTcpService)
                htmlToPdfConverter = new HtmlToPdfConverter(serverIP, serverPort);
            else
                htmlToPdfConverter = new HtmlToPdfConverter(true, webServiceUrl);

            // Set optional service password
            if (useServicePassword)
                htmlToPdfConverter.ServicePassword = servicePassword;

            // 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;

            // 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[] { collection["htmlElementsSelectorTextBox"] };

            // Convert HTML page to a PDF document object which can be further modified to highlight the selected elements
            Document pdfDocument = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(collection["urlTextBox"]);

            // Highlight the selected elements in PDF with colored rectangles
            for (int i = 0; i < htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.Count; i++)
            {
                HtmlElementMapping htmlElementInfo = htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.GetByIndex(i);
                // 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 (PdfRectangle htmlElementLocationInPdf in htmlElementInfo.PdfRectangles)
                {
                    // Get the HTML element location in PDF page
                    PdfPage htmlElementPdfPage = pdfDocument.GetPage(htmlElementLocationInPdf.PageIndex);
                    RectangleFloat 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 = RgbColor.Blue;
                    else if (htmlElementTagName.ToLower() == "h2")
                        highlightRectangle.ForeColor = RgbColor.Green;
                    else if (htmlElementTagName.ToLower() == "h3")
                        highlightRectangle.ForeColor = RgbColor.Red;
                    else if (htmlElementTagName.ToLower() == "h4")
                        highlightRectangle.ForeColor = RgbColor.Yellow;
                    else if (htmlElementTagName.ToLower() == "h5")
                        highlightRectangle.ForeColor = RgbColor.Indigo;
                    else if (htmlElementTagName.ToLower() == "h6")
                        highlightRectangle.ForeColor = RgbColor.Orange;
                    else
                        highlightRectangle.ForeColor = RgbColor.Navy;

                    highlightRectangle.LineStyle.LineDashStyle = LineDashStyle.Solid;

                    htmlElementPdfPage.AddElement(highlightRectangle);
                }
            }

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

            // Send the PDF file to browser
            FileResult fileResult = new FileContentResult(outPdfBuffer, "application/pdf");
            fileResult.FileDownloadName = "Select_in_API_HTML_Elements_to_Retrieve.pdf";

            return fileResult;
        }
    }
}