DocFx MermaidJS

Mission Statement

To provide a plugin to convert MermaidJS notations to diagrams during the build of a DocFX project.

Introduction

This DocFX MermaidJS plugin is a wrapper around the mermaid NPM package. It is aimed at doing build time generation of the mermaid diagram so:

• The syntax can be validated at build time.
• The image is only built once.
• The image can be embedded in a pdf.
• You can work on custom docfx templates that minimise javascript and\ or packages.

NOTES:

• Only inline PNG is supported, this is due to a limitation in the plug in model and adding new files to the file cache on the fly. I may revisit this in future. The plug in itself exposes SVG data if you want to play with it.
• This package was originally written around the DFM flavor of Markdown in DocFX. With that now unsupported in DocFX you can in theory just use Whipstaff.Mermaid which this package now effectively acts as a wrapper to.

Credits

• https://dotnet.github.io/docfx/
• https://mermaid.js.org/
• https://github.com/mermaid-js/mermaid-cli
• https://github.com/mermaid-js/mermaid
• https://github.com/dpvreony/article-statiq-mermaid
• https://github.com/KevReed/DocFx.Plugins.PlantUml

Getting Started

1. Create a console application (or similar)

2. Add a nuget package reference to "Dhgms.DocFX.Mermaid.Plugin" in your docfx_project

3. Add the following initialisation

                using (var loggerFactory = new Microsoft.Extensions.Logging.Abstractions.NullLoggerFactory())
                {
                    var playwrightRenderer = PlaywrightRenderer.Default(loggerFactory);
                    var browserSession = await playwrightRenderer.GetBrowserSessionAsync(PlaywrightBrowserTypeAndChannel.Chrome())
                        .ConfigureAwait(false);

                    var markdownJsExtensionSettings = new MarkdownJsExtensionSettings(
                        browserSession,
                        OutputMode.Svg);

                    var options = new BuildOptions
                    {
                        // Enable MermaidJS markdown extension
                        ConfigureMarkdig = pipeline => pipeline.UseMermaidJsExtension(
                                markdownJsExtensionSettings,
                                loggerFactory)
                    };
                    await Docset.Build("docfx.json", options);
                }

You can see an example of this in

1. The sample console application in this repository (github.com/dpvreony/docfx-mermaidjs/tree/main/src/Dhgms.DocFx.MermaidJs.Sample.Cmd)
2. The console application in my main documentation repository (github.com/dpvreony/documentation/tree/main/src/docfx_project)

You can adjust the settings by viewing the detailed documentation.

4. Adding a diagram

In your markdown files add a code block with a mermaid descriptor like so:

```mermaid
graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;
```

Then you can run the build and you should see the image output in place of the mermaid markdown syntax.

graph TD;
    A-->B;
    A-->C;
    B-->D;
    C-->D;

Loading

Viewing the documentation

The documentation can be found at https://docs.dpvreony.com/projects/docfx-mermaidjs/

Contributing to the code

See the contribution guidelines.