Helium

Configuration API for the Helium theme settings.

Helium can be fully configured with its Scala API and does not require any configuration files.

The entry point for all configuration steps is always Helium.defaults to ensure there are sensible defaults in place for all the options you omit in your configuration.

For each configuration step you need to choose one of the four selectors, either all to specify options for all three output formats or site, epub or pdf to select a single format. Not all options are available for all formats, but the IDE's context help and the documentation below can guide you.

In the minimal example below we only specify some metadata for all formats as well as the navigation depth for EPUB and PDF:

val theme = Helium.defaults
.all.metadata(
title = Some("Project Name"),
language = Some("de"),
)
.epub.navigationDepth(4)
.pdf.navigationDepth(4)
.build

Laika also provides convenient constructors for some of the data types used frequently in its theme API. You can import laika.theme.Color._ for specifying colors with hex("ffaaff") or rgb(255, 0, 0) and laika.ast.LengthUnit._ for specifying sizes with px(12) or pt(9) or other available units.

The final call to build produces a ThemeProvider that can be passed to Laika's transformers or the laikaTheme sbt setting:

Example for sbt plugin:

 laikaTheme := theme

Example for the library API:

val transformer = Transformer
 .from(Markdown)
 .to(EPUB)
 .parallel[IO]
 .witTheme(theme)
 .build