pdf

Specifies one or more cover images for the PDF document.

Multiple cover images are only relevant when the @:select directive is used to generate different versions of the same e-book which can all have their own cover image. See the documentation for the @:select directive in the chapter "Standard Directives" in the manual for details.

Allows to override the defaults for Helium's PDF layout.

You can use the constructors found in the LengthUnit companion to create length values, e.g. LengthUnit.px(12). It's usually most convenient to import laika.ast.LengthUnit._ for your configuration code.

Most arguments should be self-explanatory. The keepTogetherDecoratedLines value controls the number of lines for decorated blocks like code examples or callouts that should always be kept on the same page. With a setting of 12 for example only blocks with more than 12 lines are allowed to be split across multiple pages. If you choose very high numbers for this setting you might see pages with a lot of blank space when it has to move a large block to the next page.

The navigation depth of the main navigation structure provided to the PDF reader.

This is a navigation structure that will usually be displayed in a separate pane by PDF reader software. For including a table of content right in the page flow, so that is also available when printing the document, see the tableOfContent method.

The depth value counts all elements that form the hierarchy, directories, documents and sections within documents.

Adds a dedicated page for a table of content, in addition to the reader-native navigation structure.