Design systems

A design system is a directory of data files. It holds a manifest, D2 style files, fonts and icons. inkline embeds it in the binary.

<name>/
  manifest.json
  tokens-light.d2, tokens-dark.d2   colour vars + d2-config theme overrides
  base.d2                           shared styles, modifiers, marker classes
  diagrams/<type>.d2                role classes for one diagram type
  fonts/, icons/

Design systems form a chain through extends. Every chain ends at plain. plain supplies the structural defaults, such as the D2 shape for each role, and uses D2’s default styles. A role you leave out keeps the parent’s styling.

What inkline assembles

For diagram T in theme light, from the base design system to the most specific:

tokens[light], then styles, then diagrams/T.d2
render settings: layout engine, theme, padding
your source
the role overlay

Manifest

{
  "name": "carbon",
  "extends": "plain",
  "tokens": {"light": "tokens-light.d2", "dark": "tokens-dark.d2"},
  "styles": ["base.d2"],
  "layout": {"treeview": "dagre"},
  "pad": 48,
  "fonts": {"regular": "fonts/IBMPlexSans-Regular.ttf", "bold": "fonts/IBMPlexSans-SemiBold.ttf"},
  "decorators": [
    {"type": "bar", "side": "left", "size": 4, "classes": ["lane"], "diagrams": ["swimlanes"]}
  ]
}

name must match the kit’s directory. layout overrides the core’s layout engine for a diagram type. The value is dagre or elk. Both are open source. D2’s third engine, TALA, is proprietary and needs a paid licence, so inkline does not support it.

Decorators

Decorators draw elements that D2’s style model cannot express. D2 writes an element’s classes onto its SVG group. A decorator selects elements by class and can be limited to certain diagram types. It takes its colour from the element’s stroke.

Type	Draws
`bar`	a band on the `left`, `top` or `bottom` of a node; left bars push the label right
`block`	a square at the left of a node with its icon centred in it; the label moves past it
`icon`	an icon centred in a node, rectangle or circle
`avatar`	a round or square badge at the left of a node, holding its icon; the label moves past it
`fill`	fills a node with its stroke colour, for legend swatches
`legend`	removes the legend’s border, shadow and rounded frame
`chevron`	draws filled arrowheads as open chevrons
`pill`	a rounded outline around a connection label
`strike`	a diagonal line through a node

inkline clips bars and blocks to the node’s outline, so they follow rounded corners.

inkline checks a manifest when it loads it. The name must match the kit’s directory, and an unknown decorator type, side or shape is an error.

D2 behaviour

These D2 behaviours affect how the style files are written. The source has a comment on each one.

A spread takes precedence over a map’s own keys. {...${carbon.node}; style.fill: red} keeps the spread’s fill. Put only keys that no class overrides in shared maps. Set fill, stroke and corners in each class.
Variables must be declared before the classes that spread them, so inkline hoists every vars block above all classes.
sql_table and class shapes use fill for the header and stroke for the body.
Arrowheads appear only at ends that have an arrow. The core makes er and class relationships bidirectional, and each role sets both ends.

Roles Carbon