yinyunpan / html-pdf-edge

Convert HTML to PDF by Using Microsoft Edge in C#

Convert HTML to PDF by Using Microsoft Edge

Convert HTML to PDF by Using Microsoft Edge

Live Demo: http://html-pdf-edge.adriancs.com/

Nuget: https://www.nuget.org/packages/Html-PDF-Edge

PM> NuGet\Install-Package Html-PDF-Edge

Install the NUGET Package, or download the source code. Extract and add the C# class file "pdf_edge.cs" into your project.

To generate PDF and download as attachment:

pdf_edge.GeneratePdfAttachment(html, "file.pdf");

To generate PDF and display in browser:

pdf_edge.GeneratePdfInline(html);

The Basics

Microsoft Edge is a chromium based web browser which includes a built-in function that can generate PDF from HTML (or convert HTML to PDF).

Here's the basic command line syntax:

msedge
--headless
--disable-gpu
--run-all-compositor-stages-before-draw
--print-to-pdf="{filePath}"
{url}

Example of command line with parameters:

msedge --headless --disable-gpu --run-all-compositor-stages-before-draw
--print-to-pdf="D:\\mysite\temp\pdf\2059060194.pdf"
http://localhost:50964/temp/pdf/2059060194.html

With this, I have written a simple C# class library that automate this process.

Here is the C# coding that works in behind:

To start off, add the following USING statement:

using System.Diagnostics;
using System.IO;

The method that generates the PDF:

public static void GeneratePdf(string url, string filePath)
{
    using (var p = new Process())
    {
        p.StartInfo.FileName = "msedge";
        p.StartInfo.Arguments = $"--headless --disable-gpu 
            --run-all-compositor-stages-before-draw
            --print-to-pdf=\"{filePath}\" {url}";
        p.Start();
        p.WaitForExit();
    }
}

Above method requires you to supply the URL of HTML and file path, here is the method to automate the generating of URL and file path.

First, define an enum for transmission:

public enum TransmitMethod
{
    None,
    Attachment,
    Inline
}

Then the main method:

static void EdgePublish(string html, TransmitMethod transmitMethod, string filename)
{
    // Create a temporary folder for storing the PDF

    string folderTemp = HttpContext.Current.Server.MapPath("~/temp/pdf");

    if (!Directory.Exists(folderTemp))
    {
        Directory.CreateDirectory(folderTemp);
    }

    // Create 2 temporary filename

    Random rd = new Random();
    string randomstr = rd.Next(100000000, int.MaxValue).ToString();
            
    string fileHtml = HttpContext.Current.Server.MapPath($"~/temp/pdf/{randomstr}.html");
    string filePdf = HttpContext.Current.Server.MapPath($"~/temp/pdf/{randomstr}.pdf");

    // Create the HTML file

    File.WriteAllText(fileHtml, html);

    // Obtain the URL of the HTML file

    var r = HttpContext.Current.Request.Url;
    string url = $"{r.Scheme}://{r.Host}:{r.Port}/temp/pdf/{randomstr}.html";

    // Create the PDF file

    GeneratePdf(url, filePdf);

    // Obtain the file size
            
    FileInfo fi = new FileInfo(filePdf);
    string filelength = fi.Length.ToString();

    // Load the file into memory (byte array)

    byte[] ba = File.ReadAllBytes(filePdf);

    // Delete the 2 temp files from server

    try
    {
        File.Delete(filePdf);
    }
    catch { }

    try
    {
        File.Delete(fileHtml);
    }
    catch { }

    // Transmit the PDF for download

    HttpContext.Current.Response.Clear();

    if (transmitMethod == TransmitMethod.Inline)
        HttpContext.Current.Response.AddHeader("Content-Disposition", "inline");
    else if (transmitMethod == TransmitMethod.Attachment)
        HttpContext.Current.Response.AddHeader("Content-Disposition", $"attachment; filename=\"{filename}\"");

    HttpContext.Current.Response.ContentType = "application/pdf";
    HttpContext.Current.Response.AddHeader("Content-Length", filelength);
    HttpContext.Current.Response.BinaryWrite(ba);
    HttpContext.Current.Response.End();
}

Using Microsoft Edge as PDF generator is better than Chrome.exe.

Learn more about using Chrome.exe as PDF Generator: https://github.com/adriancs2/HTML-PDF-Chrome

I have tested this implementation (using Edge) in the following environment:

• Local IIS hosting
• Web Hosting (smarterasp.net)
• VPS Web Hosting

All above environment are able to generate PDF without issues. It runs smoothly without the need to configure the permission, Application Pool Identity and Website IIS authentication. I have a more seemless integration experience if compared to using Chrome.

The following screenshot shows that the execution of MS Edge is allowed even with default permission settings:

Chrome.exe, however is not so permissive in most environment. This is because executing an EXE over a web server is generally prohibitted due to security issues.

For Chrome.exe, I failed to run it at web hosting environment (smarterasp.net).

Even in Local IIS hosting, I have to set the Application Pool Identify to "LocalSystem" in order for Chrome.exe to run properly.

But Microsoft Edge does not have such requirements. Microsoft Edge is able to be executed with lowest/default permission and security settings.

Therefore, it is highly recommended to use Microsoft Edge than Chrome.exe.

Important CSS Properties

There are a few necessary CSS that you have to include in the HTML page in order for this to work properly.

1. Set page margin to 0 (zero)
2. Set paper size
3. Wrap all content within a "div" with fixed width and margin
4. Use CSS of page-break-always to split between pages.
5. All fonts must already installed or hosted in your website
6. URL links for images, external css stylesheet reference must include the root path.

1. Set page margin to 0 (zero)

@page {
    margin: 0;
}

The purpose of doing this is to hide the header and footer:

2. Set paper size

Example 1:

@page {
    margin: 0;
    size: A4 portrait;
}

Example 2:

@page {
    margin: 0;
    size: letter landscape;
}

Example 3: custom size (inch) *width then height

@page {
    margin: 0;
    size: 4in 6in;
}

Example 4: custom size (cm) *width then height

@page {
    margin: 0;
    size: 14cm 14cm;
}

For more options/info on the CSS of @page, you may refer:

https://developer.mozilla.org/en-US/docs/Web/CSS/@page/size

3. Wrap all content within a DIV with fixed width and margin

Example:

<div class="page">
    <h1>Page 1</h1>
    <img src="/pdf.jpg" style="width: 100%; height: auto;" />
    <!-- The rest of the body content -->
</div>

Style the "div" with class "page" (act as the main block/wrapper/container). Since the page has zero margin, we need to manually specified the top margin in CSS:

CSS
.page {
    width: 18cm;
    margin: auto;
    margin-top: 10mm;
}

The width has to be specified.

The "margin: auto" will align the div block at center horizontally.

"margin-top: 10mm", will provide space between the main block and the edge of the paper at top section.

4. Use CSS of "page-break-always" to split between pages.

To split pages, use a "div" and style with CSS of "page-break-after".

page-break-after: always

Example:

<div class="page">
    <h1>Page 1</h1>
    <img src="/pdf.jpg" style="width: 100%; height: auto;" />
</div>

<div style="page-break-after: always"></div>

<div class="page">
    <h1>Page 2</h1>
    <img src="/pdf.jpg" style="width: 100%; height: auto;" />
</div>

<div style="page-break-after: always"></div>

<div class="page">
    <h1>Page 3</h1>
    <img src="/pdf.jpg" style="width: 100%; height: auto;" />
</div>

5. All fonts must already installed or hosted in your website

The font rendering might not be working properly if the fonts are hosted at 3rd party's server, for example: Google Fonts. Try install the fonts into your server Windows OS or host the fonts within your website.

6. URL links for images, external css stylesheet reference must include the root path.

For example, the following img tag might not be rendered properly. The image has the potential to be missing in the final rendered PDF output.

<img src="logo.png" />
<img src="images/logo.png" />

In stead, include the root path like this:

<img src="/logo.png" />
<img src="/images/logo.png" />

The sample of full HTML page:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        h1 {
            margin: 0;
            padding: 0;
        }
        .page {
            margin: auto;
            margin-top: 10mm;
            border: 1px solid black;
            width: 18cm;
            height: 27cm;
        }

        @page {
            margin: 0;
            size: A4 portrait;
        }
    </style>
</head>

<body>

    <div class="page">
        <h1>Page 1</h1>
        <img src="/pdf.jpg" style="width: 100%; height: auto;" />
    </div>

    <div style="page-break-after: always"></div>

    <div class="page">
        <h1>Page 2</h1>
        <img src="/pdf.jpg" style="width: 100%; height: auto;" />
    </div>

    <div style="page-break-after: always"></div>

    <div class="page">
        <h1>Page 3</h1>
        <img src="/pdf.jpg" style="width: 100%; height: auto;" />
    </div>

</body>

</html>