HTML to Image Generator for .NET C# WkHtmlToImage Wrapper

It is possible to include images by specifying their FULL URL or path (if they're on local filesystem). External CSS and javascript files are also supported.

ImageGenerator executes WkHtmlToImage command line tool in a separate process using System.Diagnostics.Process API and your app's hosting environment/platform should allow that.

WkHtmlToImage is based on QtWebKit 4.8 so it doesn't support modern CSS3 features (like flex/grid layout, ES2015 etc).

Component cannot be used (does NOT work) if wkhtmltoimage cannot be deployed (installed) and executed via System.Diagnostics.Process API: most shared ASP.NET hostings, UWP/Univeral Apps, mobile apps. Also this means that non-Windows environments are NOT supported by NReco.ImageGenerator nuget package and NReco.ImageGenerator.LT should be used instead (see below).

NET6/NET8+ apps
For cross-platform apps (Linux, Mac-OS, Docker images) another nuget NReco.ImageGenerator.LT should be used instead (C# API is the same). This version doesn't include wkhtmltopdf binaries so you need to deploy the latest wkhtmltoimage (builds for modern Linux are here) your target platform(s) with your .NET app separately.

LT build usage
The following C# code snippet illustrates how to initialize NReco.ImageGenerator.LT properly:

NReco.ImageGenerator.License.SetLicenseKey("your_id", "your_license_key");

var htmlToImg = new NReco.PdfGenerator.HtmlToImageConverter();

// for Linux/OS-X: "wkhtmltoimage"
htmlToImg.WkHtmlToImageExeName = "wkhtmltoimage.exe";
// specify where wkhtmltoimage binaries are installed/deployed
htmlToImg.ToolPath = "<path_to_folder_with_wkhtmltoimage>";
htmlToImg.GenerateImageFromFile("http://www.google.com", ImageFormat.Png, "google.png");

If you want to test LT nuget package you can contact support and ask for a demo key.

In some cases image generation fails with one of the following errors:

• Exit with code 1 due to network error: ContentNotFoundError
• Exit with code 1 due to network error: ProtocolUnknownError
• Exit with code 1 due to network error: HostNotFoundError

This means that HTML template has external reference (js/css/image URL) that cannot be loaded by WkHtmlToImage. In most cases image can be generated anyway by specifying additional WkHtmlToImage parameter:

var htmlToImage = new HtmlToImageConverter();
htmlToImage.CustomArgs = " --load-media-error-handling ignore ";

NReco.ImageGenerator.LT is a .NET wrapper for wkhtmltoimage and this means that wkhtmltoimage should be included into your app's Docker image.
Normally NET8+ app Linux image is based on mcr.microsoft.com/dotnet/aspnet:8.0 (Debian 12 "bookworm"), to deploy wkhtmltoimage the following commands should be added into the 'Dockerfile':

RUN apt-get update && apt-get install -y --no-install-recommends wget ca-certificates fontconfig libc6 libfreetype6 libjpeg62-turbo libpng16-16 libssl3 libstdc++6 libx11-6 libxcb1 libxext6 libxrender1 xfonts-75dpi xfonts-base zlib1g
RUN wget https://github.com/wkhtmltopdf/packaging/releases/download/0.12.6.1-3/wkhtmltox_0.12.6.1-3.bookworm_amd64.deb
RUN dpkg -i wkhtmltox_0.12.6.1-3.bookworm_amd64.deb

Do NOT install wkhtmltoimage via apt-get install -y wkhtmltopdf because most likely you'll install legacy (old) version and possibly a wrong build (without 'patched' QT).

If you want to use Windows fonts (Arial, Times New Roman, Courier New etc) add these commands into 'Dockerfile':

RUN echo "deb http://deb.debian.org/debian bookworm contrib non-free" > /etc/apt/sources.list.d/contrib.list
RUN echo "ttf-mscorefonts-installer msttcorefonts/accepted-mscorefonts-eula select true" | debconf-set-selections
RUN apt-get update -y && apt-get install -y --no-install-recommends ttf-mscorefonts-installer
RUN fc-cache -f -v