Graphviz¶

This theme adds several improvements to the built-in sphinx.ext.graphviz extension:

• default fonts and colors are set to match the fonts and colors used by the theme, including support for both light and dark mode;

  Only compatible with Google fonts

  When not using a Google font via font in conf.py (eg. using a system/custom/self-hosted font), this extension will use the metrics from Graphviz’s default font, rather than the actual font, for the purpose of computing the graph layout. However, the text will still be displayed in the browser using the user-specified font.

• the rendered diagram is included as inline svg content to allow hyperlinks to work;

• colors can be manually specified in terms of CSS variables defined by the theme, such as var(--md-primary-fg-color);

• labels can be specified as Sphinx cross references (rather than just plain URLs).

Configuration¶

This functionality is available as a separate optional extension included with this theme, which must be specified manually in your conf.py file:

extensions = [
    "sphinx_immaterial",
    # other extensions...
    "sphinx_immaterial.graphviz",
]

The graphviz_dot and graphviz_dot_args configuration options from sphinx.ext.graphviz are supported.

graphviz_ignore_incorrect_font_metrics : bool = False¶

This extension relies on the LibGD graphviz plugin to load the same font used by this theme, in order to correctly determine the size of text labels. While the LibGD plugin is normally included in the Linux and macOS graphviz builds, the official x86_64 Windows build does not include it. If the plugin is not found, by default this theme logs a warning. This option may be set to True silence that warning.

Add to conf.py to silence the warning¶

graphviz_ignore_incorrect_font_metrics = True

Warning

If LibGD is not available, graphviz will compute the size of labels using a default system font. Labels will still be rendered in the browser using the correct font; the layout may just be slightly incorrect.

Usage¶

Using the graphviz directive, graphs can be specified either inline or included from an external file.

.. graphviz::

   digraph {
     graph [
       rankdir = LR
     ]

     node [
       shape=rectangle
     ]

     A [label="Start"]
     B [label="Error?", shape=diamond]
     C [
       label="Hmm...",
       style="solid,filled",
       fillcolor="var(--md-primary-fg-color, green)"
     ]
     D [label="Debug"]
     E [xref=":py:obj:`~tensorstore_demo.DimensionSelection`"]

     A -> B
     B -> C [label="Yes"]
     C -> D
     D -> B
     B -> E [label="No"]
     D -> E [style=invis]
   }

graph {
  // use a radial layout (because mermaid.js cannot)
  layout=twopi

  A [shape=diamond]
  B [shape=box]
  C [shape=circle]

  A -- B [style=dashed]
  // edge using a static color with transparent fill
  A -- C [color="black:invis:black"]
  A -- D [penwidth=5, arrowhead=none]

}

.. graphviz:: test.dot

Colors specified using CSS variables¶

As demonstrated in the example above, this extension adds support for specifying color attributes using the CSS syntax "var(--css-var)" or "var(--css-var, fallback)". This may be used to specify colors defined by the theme that vary depending on whether light or dark mode is enabled. When the latex builder is used, the fallback color, if specified, will be used instead. If no fallback value is specified, only HTML builders may be used.

Cross-references¶

This extension adds support for a special xref attribute, which may be set to a string value containing reStructuredText. This is demonstrated in the example above.

The reStructuredText will be parsed as a document fragment, and after resolving any cross references, will be substituted back into the graph definition as follows:

• A label attribute will be generated from the parsed fragment’s text content.

• If the parsed fragment contains at least one hyperlink, only the last such hyperlink is considered, and:

  • an href attribute will be generated from its URL.

  • a tooltip attribute will be generated from its title/tooltip, if any.

  • a target attribute will be generated from its target, if any.

Overriding the cross-reference label¶

The label attribute generated with the new xref attribute uses graphviz’ HTML-like attribute syntax, but any HTML characters found within the xref parsed fragments’ text are escaped (eg. < f0 > becomes < f0 >). In some graphs, it is preferable to use unescaped HTML characters in the label attribute. In this case, the generated label attribute can be overridden by manually specifying the label attribute after the xref attribute.

.. graphviz::

   digraph {
       graph [rankdir = "LR"]
       module [
           xref=":py:mod:`test_py_module.test`"
           label="<f0> test_py_module.test | <f1> functions | <f2> classes"
           shape = record
       ]
       class [
           xref = ":py:class:`test_py_module.test.Foo`"
           label = "<f0> Foo | <f1> attributes | <f2> methods"
           shape = record
       ]
       method [
           xref = ":py:meth:`test_py_module.test.Foo.capitalize()`"
           label = "<f0> capitalize() | <f1> variables"
           shape = record
       ]
       function [
           xref = ":py:func:`test_py_module.test.func()`"
           label = "<f0> func() | <f1> variables"
           shape = record
       ]
       class_attr [
           // NOTE: cannot adequately angle brackets in xref's text
           xref = ":py:attr:`spam | object <test_py_module.test.Foo.spam>`"
           shape = record
       ]
       module:f2 -> class:f0
       module:f1 -> function:f0
       class:f2 -> method:f0
       class:f1 -> class_attr // edge will point toward center of class_attr
   }