SelectPdf for .NET 10 - Start Conversion from Javascript - C# / .NET 10 Sample

This sample shows how to manually start the html to pdf conversion of the SelectPdf Library for .NET using a Javascript call.

SelectPdf exposes a global Javascript variable called selectpdf in the page that is being converted. Using this variable you can check if the javascript code is executed inside the converter (check if typeof(selectpdf) == "object"). The converter version can also be checked using selectpdf.version.

The most important feature of the Javascript interface is the possibility to manually start the page conversion to pdf with a javascript call. To do that, you must:
1. Set converter.Options.StartupMode = StartupMode.Manual
2. Call selectpdf.start() from javascript

Important:
- If converter.Options.StartupMode is set to StartupMode.Manual and selectpdf.start() is not called from javascript, the conversion will timeout.
- If converter.Options.StartupMode is set to the default value StartupMode.Automatic, the conversion will start without waiting for any javascript calls.

Below it's the link to a test page that waits for 3 seconds after it loads and then calls the javascript conversion method. Converting it in StartupMode.Manual mode will display the time elapsed. Converting it in StartupMode.Automatic mode will not show that 3 seconds time interval.

Test page

Url:

Rendering Engine:

Conversion start mode:

Timeout:
seconds

Sample code · C#

using System;
using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.RazorPages;
using SelectPdf.Universal;

namespace SelectPdf.Samples.Pages
{
    public class ConvertFromJsModel : PageModel
    {
        public void OnGet()
        {
            DdlRenderingEngine = "Chromium";
            TxtUrl = Helper.WWWRoot(Request) + Url.Content("~/files/js-conversion.html");
            DdlStartupMode = "Manual";
        }

        [BindProperty]
        public string TxtUrl { get; set; }

        [BindProperty]
        public string DdlRenderingEngine { get; set; } = "Chromium";

        public List<SelectListItem> RenderingEngines { get; } = new List<SelectListItem>
        {
            new SelectListItem { Value = "Chromium", Text = "Chromium" },
        };

        [BindProperty]
        public string DdlStartupMode { get; set; }

        public List<SelectListItem> StartupModes { get; } = new List<SelectListItem>
        {
            new SelectListItem { Value = "Automatic", Text = "Automatic" },
            new SelectListItem { Value = "Manual", Text = "Manual" },
        };

        [BindProperty]
        public string TxtTimeout { get; set; }


        public IActionResult OnPost()
        {
            RenderingEngine renderingEngine =
                SampleForm.ParseEnum(DdlRenderingEngine, RenderingEngine.Chromium);

            // instantiate a html to pdf converter object
            HtmlToPdf converter = new HtmlToPdf();

            // set startup mode
            converter.Options.RenderingEngine = renderingEngine;
            converter.Options.StartupMode = SampleForm.ParseEnum(DdlStartupMode, HtmlToPdfStartupMode.Manual);

            // set timeout
            int timeout = 10;
            try
            {
                timeout = Convert.ToInt32(TxtTimeout);
            }
            catch { }
            converter.Options.NavigationTimeout = Math.Min(timeout, Startup.NavigationTimeout);

            // create a new pdf document converting an url
            PdfDocument doc = converter.ConvertUrl(TxtUrl);

            // save pdf document
            byte[] pdf = doc.Save();

            // close pdf document
            doc.Close();

            // return resulted pdf document
            FileResult fileResult = new FileContentResult(pdf, "application/pdf");
            fileResult.FileDownloadName = "Document.pdf";
            return fileResult;
        }
    }
}