Add HTML Stamp with Page Numbering to Existing PDF

using System;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System.Threading.Tasks;

using HiQPdf.Chromium;

namespace HiQPdf_Chromium_AspNetDemo.Controllers
{
    public class Stamp_with_HTML_Existing_PDFController : Controller
    {
        private readonly IWebHostEnvironment m_hostingEnvironment;
        public Stamp_with_HTML_Existing_PDFController(IWebHostEnvironment hostingEnvironment)
        {
            m_hostingEnvironment = hostingEnvironment;
        }

        public IActionResult Index()
        {
            SetCurrentViewData();

            return View();
        }

        [HttpPost]
        public async Task<IActionResult> StampPdf(IFormCollection collection)
        {
            // Replace the demo serial number with the serial number received upon purchase
            // to run the converter in licensed mode
            Licensing.SerialNumber = "YCgJMTAE-BiwJAhIB-EhlWTlBA-UEBRQFBA-U1FOUVJO-WVlZWQ==";

            // Get the pdf file to convert
            string pdfUrl = collection["pdfFileUrlTextBox"][0].Trim();
            if (string.IsNullOrWhiteSpace(pdfUrl))
                throw new Exception("No PDF file to stamp");

            byte[] inputPdfBytes;

            if (pdfUrl.StartsWith("file://", StringComparison.OrdinalIgnoreCase))
            {
                string localPath = new Uri(pdfUrl).LocalPath;
                inputPdfBytes = await System.IO.File.ReadAllBytesAsync(localPath);
            }
            else
            {
                using var httpClient = new System.Net.Http.HttpClient();
                inputPdfBytes = await httpClient.GetByteArrayAsync(pdfUrl);
            }

            var pdfEditor = new PdfEditor(inputPdfBytes);

            bool stampEnabled = collection["stampEnabledCheckBox"].Count > 0;
            if (stampEnabled)
            {
                PdfHtmlTemplate stamp = null;

                // Get stamp width
                int stampWidth = int.Parse(collection["stampWidthTextBox"]);

                // Get stamp height
                int stampHeight = 0;
                string stampHeightValueString = collection["stampHeightTextBox"];
                if (!string.IsNullOrEmpty(stampHeightValueString))
                    stampHeight = int.Parse(stampHeightValueString);

                // Get stamp top left corner X and Y position
                int x = int.Parse(collection["stampXPositionTextBox"]);
                int y = int.Parse(collection["stampYPositionTextBox"]);

                // Get horizontal alignment, which takes precedence over the X coordinate when specified
                PdfTemplateHorizontalAlign horizontalAlign = SelectedHorizontalAlign(collection["horizontalAlignDropDownList"]);

                // Get vertical alignment, which takes precedence over the Y coordinate when specified
                PdfTemplateVerticalAlign verticalAlign = SelectedVerticalAlign(collection["verticalAlignDropDownList"]);

                // Set the stamp HTML from an URL or from a HTML string
                bool stampHtmlFromUrl = collection["StampHtmlSource"] == "stampUrlRadioButton";
                if (stampHtmlFromUrl)
                {
                    string stampUrl = collection["stampUrlTextBox"];

                    if (stampHeight > 0)
                    {
                        // The stamp has a specified height
                        stamp = pdfEditor.AddHtmlTemplate(x, y, stampWidth, stampHeight,
                            horizontalAlign, verticalAlign, stampUrl);
                    }
                    else
                    {
                        // The stamp size is automatically determined from the HTML content when AutoSizeContentHeight is true
                        stamp = pdfEditor.AddHtmlTemplate(x, y, stampWidth, stampHeight,
                           horizontalAlign, verticalAlign, stampUrl);
                    }
                }
                else
                {
                    string stampHtml = collection["stampHtmlTextBox"];
                    string stampHtmlBaseUrl = collection["stampHtmlBaseUrlTextBox"];

                    if (stampHeight > 0)
                    {
                        // The stamp has a specified height
                        stamp = pdfEditor.AddHtmlTemplate(x, y, stampWidth, stampHeight,
                            horizontalAlign, verticalAlign, stampHtml, stampHtmlBaseUrl);
                    }
                    else
                    {
                        // The stamp size is automatically determined from the HTML content when AutoSizeContentHeight is true
                        stamp = pdfEditor.AddHtmlTemplate(x, y, stampWidth, stampHeight,
                            horizontalAlign, verticalAlign, stampHtml, stampHtmlBaseUrl);
                    }
                }

                // If AutoSizeContentHeight is true, the Height property is positive and FitHeight is true,
                // the content may be scaled down to fit the specified height
                bool fitStampHeight = collection["fitStampHeightCheckBox"].Count > 0;
                stamp.FitHeight = fitStampHeight;

                // Set the auto resize stamp option to allow the stamp height adjust based on HTML content
                bool autoSizeStampContentHeight = collection["autoSizeStampContentHeightCheckBox"].Count > 0;
                stamp.AutoSizeContentHeight = autoSizeStampContentHeight;

                // Set Min and Max content height used when the AutoSizeContentHeight property is true
                stamp.MinContentHeight = int.Parse(collection["stampMinContentHeightTextBox"]);
                stamp.MaxContentHeight = int.Parse(collection["stampMaxContentHeightTextBox"]);

                // Set stamp visibility in PDF for the first page, odd pages, and even pages
                stamp.ShowInFirstPage = collection["showStampInFirstPageCheckBox"].Count > 0;
                stamp.ShowInOddPages = collection["showStampInOddPagesCheckBox"].Count > 0;
                stamp.ShowInEvenPages = collection["showStampInEvenPagesCheckBox"].Count > 0;

                // Sets the opacity for the entire stamp content, including text.
                // To apply opacity only to the background, use the alpha channel
                // in the CSS background-color property of the body element,
                // e.g., background-color: rgba(255, 255, 255, 0.75);
                int opacity = int.Parse(collection["stampOpacityTextBox"]);
                stamp.Opacity = ((float)opacity) / 100;

                // Optimize the stamp rendering time by providing a hint if the HTML template contains variables such as { page_number} or { total_pages}
                stamp.SkipVariablesParsing = collection["skipVariablesParsingCheckBox"].Count > 0;

                // Optionally set additional time to wait for the asynchronous stamp HTML content before rendering
                if (collection["waitBeforeConvertTextBox"][0].Length > 0)
                    stamp.WaitBeforeConvert = int.Parse(collection["waitBeforeConvertTextBox"]);
            }

            // Stamp the PDF and save the resulted PDF document in a memory buffer
            byte[] outPdfBuffer = pdfEditor.Save();

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

            return fileResult;
        }

        private PdfTemplateHorizontalAlign SelectedHorizontalAlign(string selectedValue)
        {
            switch (selectedValue)
            {
                case "None":
                    return PdfTemplateHorizontalAlign.None;
                case "Left":
                    return PdfTemplateHorizontalAlign.Left;
                case "Center":
                    return PdfTemplateHorizontalAlign.Center;
                case "Right":
                    return PdfTemplateHorizontalAlign.Right;
                default:
                    return PdfTemplateHorizontalAlign.None;
            }
        }

        private PdfTemplateVerticalAlign SelectedVerticalAlign(string selectedValue)
        {
            switch (selectedValue)
            {
                case "None":
                    return PdfTemplateVerticalAlign.None;
                case "Top":
                    return PdfTemplateVerticalAlign.Top;
                case "Center":
                    return PdfTemplateVerticalAlign.Center;
                case "Bottom":
                    return PdfTemplateVerticalAlign.Bottom;
                default:
                    return PdfTemplateVerticalAlign.None;
            }
        }

        private void SetCurrentViewData()
        {
            ViewData["ContentRootPath"] = m_hostingEnvironment.ContentRootPath + "/wwwroot";

            HttpRequest request = ControllerContext.HttpContext.Request;
            UriBuilder uriBuilder = new UriBuilder();
            uriBuilder.Scheme = request.Scheme;
            uriBuilder.Host = request.Host.Host;
            if (request.Host.Port != null)
                uriBuilder.Port = (int)request.Host.Port;
            uriBuilder.Path = request.PathBase.ToString() + request.Path.ToString();
            uriBuilder.Query = request.QueryString.ToString();

            ViewData["CurrentPageUrl"] = uriBuilder.Uri.AbsoluteUri;
        }
    }
}

<!DOCTYPE html>
<html>
<head>
    <title>HTML Stamp with Page Numbers</title>
</head>
<!-- Use background-color: rgba(r, g, b, a) to apply background opacity (a = 0 transparent, 1 opaque) -->
<body style="background-color: rgba(255, 255, 255, 0.9); font-family: 'Times New Roman'; font-size: 16px; margin: 5px">
    <table style="width: 100%; border: 3px solid royalblue">
        <tr>
            <td>
                <a href="http://www.hiqpdf.com">
                    <img alt="Logo Image" src="Images/HiQPdfLogo.png" />
                </a>
            </td>
            <td>
                <table>
                    <tr>
                        <td style="font-size: 30px; font-weight: bold; color: #BE1200">
                            HTML Stamp with Page Numbers
                        </td>
                    </tr>
                    <tr>
                        <td>
                            <span style="font-size: 16px">Page <span style="color:blue">{page_number}</span> of <span style="color:green">{total_pages}</span> pages</span>
                        </td>
                    </tr>
                </table>
            </td>
        </tr>
    </table>
</body>
</html>