sphinxcontrib-svgbob

A Sphinx extension to render ASCII diagrams into SVG using Svgbob.

🗺️ Overview

Diagrams to be included into Sphinx documentation are commonly described with a dedicated markup language, and converted into an image by Sphinx when the documentation is built. However, this reduces the legibility of the documentation source for readers that are not browsing the HTML version.

Svgbob is a diagramming model implemented in Rust that can convert ASCII diagrams into SVG. Using it allows you to:

• Keep a textual version of the diagram in your documentation, so that it remains legible.
• Render a nicer version as SVG for HTML or PDF versions of the documentation.

This Sphinx extension builds Svgbob statically and lets you use it to render ASCII diagrams within Sphinx documentation. Since it does not require any external dependency, it's also suitable to use on readthedocs.org.

🔧 Installing

sphinxcontrib-svgbob can be installed from PyPI, which hosts some pre-built CPython wheels for x86-64 Linux and OSX, as well as the code required to compile from source:

$ pip install sphinxcontrib-svgbob

If a Rust compiler is not available, the setup.py script will attempt to install a temporary copy if the package is compiled on a UNIX system. If it doesn't work, see the documentation on rust-lang.org to learn how to install Rust on your machine.

Then add this extension to the Sphinx extensions in your conf.py file to make the svgbob directive available:

extensions = [
    ...,
    "sphinxcontrib.svgbob",
]

That's it, you're all set!

💡 Example

Use the svgbob directive in a function docstring to show a diagram of what is being computed:

def hamming(x, y):
    """Compute the Hamming distance between two strings.

    Hamming distance between two strings of equal length is the number of
    positions at which the corresponding symbols are different. For instance,
    Hamming distance for a 3-bit string can be computed visually using a
    3-bit binary cube:

    .. svgbob::
       :align: center

                         110              111                          
                            *-----------*      
                           /|          /|
                          / |     011 / |     
                     010 *--+--------*  |
                         |  | 100    |  |
                         |  *--------+--* 101
                         | /         | /
                         |/          |/
                     000 *-----------*  001


    The minimum distance between any two vertices is the Hamming distance
    between the two bit vectors (e.g. 100→011 has distance 3).

    """

When Sphinx (and autodoc) renders the docstring of this function, you'll get the following HTML page (here shown with the Sphinx theme for readthedocs.org):

And yet, the help(hamming) will still look nice and helpful:

🔩 Configuration

The svgbob directive supports the following arguments:

• font-size (integer): the size of the text to be rendered, defaults to 14.
• font-family: the family of the font used to render the text, defaults to monospace.
• fill-color (CSS color): the color to use to fill closed shapes.
• stroke-color (CSS color): the color to use to paint strokes, defaults to black.
• scale (float): the SVG scale of the figure, defaults to 8.0.
• align (CSS align value): the alignment of the resulting image.
• class (HTML class): an arbitrary class to add to the resulting HTML element.

For instance, use the following to use Arial with size 12, to render nicer text in the diagram blocks:

.. svgbob::
   :font-family: Arial
   :font-size: 12

   +-------+       +--------+
   | Hello |------>| World! |
   +-------+       +--------+

💭 Feedback

⚠️ Issue Tracker

Found a bug ? Have an enhancement request ? Head over to the GitHub issue tracker if you need to report or ask something. If you are filing in on a bug, please include as much information as you can about the issue, and try to recreate the same bug in a simple, easily reproducible situation.

🏗️ Contributing

Contributions are more than welcome! See CONTRIBUTING.md for more details.

📚 Alternatives

• sphinxcontrib-kroki also lets you use Svgbob to convert ASCII diagrams, but it queries the kroki.io website to do so, and does not support the new options from Svgbob v0.5.
• sphinxcontrib-aafig uses the aafigure binary to convert ASCII diagrams.

🔨 Credits

sphinxcontrib-svgbob is developped and maintained by:

• Martin Larralde

The structure of this repository was adapted from the aforementioned sphinxcontrib-kroki repository, as I had no experience setting up a Sphinx extension otherwise.

⚖️ License

This library is provided under the MIT License.