WkHtmlToPdf-DotNet

.NET Core P/Invoke wrapper for the native wkhtmltopdf library that uses Webkit engine to convert HTML pages to PDF.

Has been successfully tested on Windows, Linux, MacOSX and docker. One of the examples is using this in docker.

Install

Library can be installed through Nuget. Run command below from the package manager console:

PM> Install-Package Haukcode.WkHtmlToPdfDotNet

Note that with this NuGet package you don't need to manually add the native binaries to your project.

Fork

This library is forked from DinkToPdf. The main changes are to include the required native binaries in the package so they don't have to be manually installed, and renamed to a more appropriate project name. The license has also been corrected to match the license for the wkhtmltopdf parent project.

Building

Download the binaries (of wkhtmltopdf) from Github Releases (currently version 0.12.5) and put them under src\WkHtmlToPdf-DotNet in the runtimes folder (with a sub folder for each platform). Note that these binaries are only needed when you build this project to generate the NuGet package, you will not need the binaries when using the NuGet package, they will be automatically added.

Basic converter

Use this converter in single threaded applications.

Create converter:

var converter = new BasicConverter(new PdfTools());

Synchronized converter

Use this converter in multi threaded applications and web servers. Conversion tasks are saved to blocking collection and executed on a single thread.

var converter = new SynchronizedConverter(new PdfTools());

Define document to convert

var doc = new HtmlToPdfDocument()
{
    GlobalSettings = {
        ColorMode = ColorMode.Color,
        Orientation = Orientation.Landscape,
        PaperSize = PaperKind.A4Plus,
    },
    Objects = {
        new ObjectSettings() {
            PagesCount = true,
            HtmlContent = @"Lorem ipsum dolor sit amet, consectetur adipiscing elit. In consectetur mauris eget ultrices  iaculis. Ut                               odio viverra, molestie lectus nec, venenatis turpis.",
            WebSettings = { DefaultEncoding = "utf-8" },
            HeaderSettings = { FontSize = 9, Right = "Page [page] of [toPage]", Line = true, Spacing = 2.812 }
        }
    }
};

Convert

If Out property is empty string (defined in GlobalSettings) result is saved in byte array.

byte[] pdf = converter.Convert(doc);

If Out property is defined in document then file is saved to disk:

var doc = new HtmlToPdfDocument()
{
    GlobalSettings = {
        ColorMode = ColorMode.Color,
        Orientation = Orientation.Portrait,
        PaperSize = PaperKind.A4,
        Margins = new MarginSettings() { Top = 10 },
        Out = @"C:\WkHtmlToPdf-DotNet\src\TestThreadSafe\test.pdf",
    },
    Objects = {
        new ObjectSettings()
        {
            Page = "http://google.com/",
        },
    }
};

converter.Convert(doc);

Dependency injection

Converter must be registered as singleton.

public void ConfigureServices(IServiceCollection services)
{
    // Add converter to DI
    services.AddSingleton(typeof(IConverter), new SynchronizedConverter(new PdfTools()));
}

Docker

If you are using a linux version of docker container for net core provided from microsoft, you will need to install a couple of libraries.

The following example is for debian based linux distros;

Insert the below lines before the WORKDIR /app command

RUN apt update
RUN apt install -y libgdiplus
RUN ln -s /usr/lib/libgdiplus.so /lib/x86_64-linux-gnu/libgdiplus.so
RUN apt-get install -y --no-install-recommends zlib1g fontconfig libfreetype6 libx11-6 libxext6 libxrender1 wget gdebi
RUN wget https://github.com/wkhtmltopdf/wkhtmltopdf/releases/download/0.12.5/wkhtmltox_0.12.5-1.stretch_amd64.deb
RUN gdebi --n wkhtmltox_0.12.5-1.stretch_amd64.deb
RUN apt install libssl1.1
RUN ln -s /usr/local/lib/libwkhtmltox.so /usr/lib/libwkhtmltox.so

Note

For any other linux distro choose the correct package from the wkhtmltopdf releases

Recommendations

Do not use wkhtmltopdf with any untrusted HTML – be sure to sanitize any user-supplied HTML/JS, otherwise it can lead to complete takeover of the server it is running on!