Skip to content

Pandoc filter for creating diagrams in mermaid syntax blocks in markdown docs

Notifications You must be signed in to change notification settings

raghur/mermaid-filter

Repository files navigation

Sequence and Graph diagrams in your markdown files!

mermaid-filter is a pandoc filter that adds support for mermaid syntax diagrams in markdown.

Write your diagrams in fenced code blocks as usual like this:

~~~mermaid
sequenceDiagram
    Alice->>John: Hello John, how are you?
    John-->>Alice: Great!
~~~

and get this in rendered doc

Installation and usage

  1. npm install --global mermaid-filter
  2. To convert your markdown file something.md into something.html, use pandoc -t html -F mermaid-filter -o something.html something.md

WINDOWS - you need mermaid-filter.cmd in the line above

Windows 8.1 - On windows 8.1, mermaid-filter.cmd fails - apparently due to change in how the CMD.exe works for subprocesses? - see this issue thread. You have to edit the globally installed mermaid-filter.cmd located in c:\users\<username>\AppData\Roaming\npm to use ~dp$PATH:0. Unfortunately, you will need to do this each time you install/update mermaid-filter since it overwrites the cmd file.

Attributes

You have a couple of formatting options via attributes of the fenced code block to control the rendering

Note that to specify options in attribtues, you need to use the curly braces syntax and have the .mermaid class attached. Admittedly, this is uglier than the earlier syntax on top - but that's how Pandoc wants it.

// saves generated diagram in the img subfolder of the current working dir

```{.mermaid loc=img}
// Your diagram code here
```
Option Name default value env var Notes
caption MERMAID_FILTER_CAPTION Sets alt= attribute on the image
format png MERMAID_FILTER_FORMAT Allowed - svg
width 800 MERMAID_FILTER_WIDTH
theme default MERMAID_FILTER_THEME Corresponds to --theme flag of mermaid.cli
background white MERMAID_FILTER_BACKGROUND Correponds to --backgroundColor flag of mermaid.cli
filename NA MERMAID_FILTER_FILENAME Takes precedence
loc inline MERMAID_FILTER_LOC inline - generates a data url; imgur - uploads to imgur; loc=anythingelse saves images to folder anythingelse
scale 1 MERMAILD_FILTER_SCALE
imageclass MERMAID_FILTER_IMAGECLASS

You can also specify an ID to be applied to the rendered image. This may be useful to use pandoc-crossref or similar packages to reference your diagrams, for example:

```{.mermaid #fig:example}
// Your diagram code here
```

This text has a reference @fig:example which is automatically inserted.

The title attribute is set to fig: by if the id specified starts with fig:

(Note that pandoc-crossref will automatically find and use the caption= option. Also note that the order of applying the filters matters - you must apply mermaid-filter before pandoc-crossref so that pandoc-crossref can find the images.)

JSON and CSS configuration

Mermaid cli allows you to specify additional options in a json configuration file and a css file. mermaid-filter will look in the current working directory for .mermaid-config.json and .mermaid.css and if found, pass them in to mermaid cli.

Puppeteer Configuration - mermaid-filter will look in the current working directory for a .puppeteer.json and pass it on to mermaid cli (-p option of mmdc)if found