Graphviz Diagrams Preprocessor for Foliant

Graphviz is an open source graph visualization tool. This preprocessor converts Graphviz diagram definitions in the source and converts them into images on the fly during project build.

Installation

$ pip install foliantcontrib.graphviz

Config

To enable the preprocessor, add graphviz to preprocessors section in the project config:

preprocessors:
    - graphviz

The preprocessor has a number of options:

preprocessors:
    - graphviz:
        cache_dir: !path .diagramscache
        graphviz_path: dot
        engine: dot
        format: png
        as_image: true
        fix_svg_size: true
        compress_svg: true
        params:
            ...

cache_dir : Path to the directory with the generated diagrams. It can be a path relative to the project root or a global one; you can use ~/ shortcut.

To save time during build, only new and modified diagrams are rendered. The generated images are cached and reused in future builds.

graphviz_path : Path to Graphviz launcher. By default, it is assumed that you have the dot command in your PATH, but if Graphviz uses another command to launch, or if the dot launcher is installed in a custom place, you can define it here.

engine : Layout engine used to process the diagram source. Available engines: (circo, dot, fdp, neato, osage, patchwork, sfdp twopi). Default: dot

format : Output format of the diagram image. Available formats: tons of them. Default: png

as_image : If true — inserts scheme into document as md-image. If false — inserts the file generated by GraphViz directly into the document (may be handy for svg images). Default: true

fix_svg_size : If true — If True, replaces fixed width/height values (e.g., "500px", "300") with "100%" to make SVG responsive and scale to container size. Default: true

compress_svg : If true — removes whitespace and line breaks between tags to create a compact, single-line SVG. This helps prevent SVG from breaking HTML layout and reduces file size. Default: true

params : Params passed to the image generation command:

    preprocessors:
        - graphviz:
            params:
                Gdpi: 100

To see the full list of params, run the command that launches Graphviz, with -? command line option.

Usage

To insert a diagram definition in your Markdown source, enclose it between <graphviz>...</graphviz> tags:

Here’s a diagram:

<graphviz>
    a -> b
</graphviz>

You can set any parameters in the tag options. Tag options have priority over the config options so you can override some values for specific diagrams while having the default ones set up in the config.

Tags also have two exclusive options: caption option — the markdown caption of the diagram image and src — path to diagram source (relative to current file).

If src tag option is supplied, tag body is ignored. Diagram source is loaded from external file.

Diagram with a caption:

<graphviz caption="Deployment diagram"
           params="Earrowsize: 0.5"
           src="diags/sample.gv">
</graphviz>

Note that command params listed in the params option are stated in YAML format. Remember that YAML is sensitive to indentation so for several params it is more suitable to use JSON-like mappings: {key1: 1, key2: 'value2'}.