Section db

The flag compress determines whether the font index (usually luaotfload-names.lua[.gz] will be stored in compressed forms. If unset it is equivalent of passing --no-compress to luaotfload-tool. Since the file is only created for convenience and has no effect on the runtime behavior of Luaotfload, the flag should remain set. Most editors come with zlib support anyways.

The setting designsize-dimen applies when looking up fonts from families with design sizes. In Opentype, these are specified as “decipoints” where one decipoint equals ten DTP style “big points”. When indexing fonts these values are converted to sp. In order to treat the values as though they were specified in TeX points or Didot points, set designsize-dimen to pt or dd.

The list of formats must be a comma separated sequence of strings containing one or more of these elements:

It corresponds loosely to the --formats option to luaotfload-tool. Invalid or duplicate members are ignored; if the list does not contain any useful identifiers, the default list "otf,ttf,ttc" will be used.

The variable location-precedence selects where and in which order luaotfload searches for fonts. Fonts in earlier locations are preferred. The three supported locations are system for system specific font directories, texmf for fonts which are part of the TeX{} distribution and local for local fonts.

The variable max-fonts determines after processing how many font files the font scanner will terminate the search. This is useful for debugging issues with the font index and has the same effect as the option --max-fonts to luaotfload-tools.

The scan-local flag, if set, will incorporate the current working directory as a font search location. NB: This will potentially slow down document processing because a font index with local fonts will not be saved to disk, so these fonts will have to be re-indexed whenever the document is built. Setting scan_local to false is the same as removing local from location-precedence.

The skip-read flag is only useful for debugging: It makes Luaotfload skip reading fonts. The font information for rebuilding the index is taken from the presently existing one.

Unsetting the strip flag prevents Luaotfload from removing data from the index that is only useful when processing font files. NB: this can increase the size of the index files significantly and has no effect on the runtime behavior.

If update-live is set, Luaotfload will reload the database if it cannot find a requested font. Those who prefer to update manually using luaotfload-tool should unset this flag. This option does not affect rebuilds due to version mismatch.

Section default-features

By default Luaotfload enables node mode and picks the default font features that are prescribed in the OpenType standard. This behavior may be overridden in the default-features section. Global defaults that will be applied for all scripts can be set via the global option, others by the script they are to be applied to. For example, a setting of

[default-features]
    global = mode=base,color=0000FF
    dflt   = smcp,onum

would force base mode, tint all fonts blue and activate small capitals and text figures globally. Features are specified as a comma separated list of variables or variable-value pairs. Variables without an explicit value are set to true.

Section misc

With statistics enabled, extra statistics will be collected during index creation and appended to the index file. It may then be queried at the Lua end or inspected by reading the file itself.

The value of termwidth, if set, overrides the value retrieved by querying the properties of the terminal in which Luatex runs. This is useful if the engine runs with shell_escape disabled and the actual terminal dimensions cannot be retrieved.

The value of version is derived from the version string hard-coded in the Luaotfload source. Override at your own risk.

The keepnames option decides if the ConTeXt fontloader should keep names it considers useless or if they should be discarded. This option only takes effect after font caches are regenererated.

Section paths

The paths cache-dir and names-dir determine the subdirectory inside the Luaotfload subtree of the luatex-cache directory where the font cache and the font index will be stored, respectively.

Inside the index directory, the names of the index file and the font lookup cache will be derived from the respective values of index-file and lookups-file. This is the filename base for the bytecode compiled version as well as -- for the index -- the gzipped version.

Section run

Unqualified font lookups are treated with the flexible “anonymous” mechanism. This involves a chain of lookups applied successively until the first one yields a match. By default, the lookup will first search for TFM fonts using the Kpathsea library. If this wasn’t successful, an attempt is made at interpreting the request as an absolute path (like the [/path/to/font/foo.ttf] syntax) or a file name (file:foo.ttf). Finally, the request is interpreted as a font name and retrieved from the index (name:Foo Regular). This behavior can be configured by specifying a list as the value to anon-sequence. Available items are tex, path, name -- representing the lookups described above, respectively --, and file for searching a filename but not an absolute path. Also, my lookups are valid values but they should only be used from within TeX documents, because there is no means of customizing a my lookups on the command line.

The color-callback option determines the stage at which fonts that defined with a color=xxyyzz feature will be colorized. By default this happens in a post_linebreak_filter but alternatively the pre_linebreak_filter or pre_output_filter may be chosen, which is faster but might produce inconsistent output. The pre_output_filter used to be the default in the 1.x series of Luaotfload, whilst later versions up to and including 2.5 hooked into the pre_linebreak_filter which naturally didn’t affect any glyphs inserting during hyphenation. Both are kept around as options to restore the previous behavior if necessary.

The definer allows for switching the define_font callback. Apart from the default patch one may also choose the generic one that comes with the vanilla fontloader. Beware that this might break tools like Fontspec that rely on the patch_font callback provided by Luaotfload to perform important corrections on font data.

The fontloader backend can be selected by setting the value of fontloader. The most important choices are default, which will load the dedicated Luaotfload fontloader, and reference, the upstream package as shipped with Luaotfload. Other than those, a file name accessible via kpathsea can be specified.

Alternatively, the individual files that constitute the fontloader can be loaded directly. While less efficient, this greatly aids debugging since error messages will reference the actual line numbers of the source files and explanatory comments are not stripped. Currently, three distinct loading strategies are available: unpackaged will load the batch that is part of Luaotfload. These contain the identical source code that the reference fontloader has been compiled from. Another option, context will attempt to load the same files by their names in the Context format from the search path. Consequently this option allows to use the version of Context that comes with the TeX distribution. Distros tend to prefer the stable version (“current” in Context jargon) of those files so certain bugs encountered in the more bleeding edge Luaotfload can be avoided this way. A third option is to use context with a colon to specify a directory prefix where the TEXMF is located that the files should be loaded from, e. g. context:~/context/tex/texmf-context. This can be used when referencing another distribution like the Context minimals that is installed under a different path not indexed by kpathsea.

The value of log-level sets the default verbosity of messages printed by Luaotfload. Only messages defined with a verbosity of less than or equal to the supplied value will be output on the terminal. At a log level of five Luaotfload can be very noisy. Also, printing too many messages will slow down the interpreter due to line buffering being disabled (see setbuf(3)).

The resolver setting allows choosing the font name resolution function: With the default value cached Luaotfload saves the result of a successful font name request to a cache file to speed up subsequent lookups. The alternative, normal circumvents the cache and resolves every request individually. (Since to the restructuring of the font name index in Luaotfload 2.4 the performance difference between the cached and uncached lookups should be marginal.)

When luaotfload is used in DVI mode, the default_dvi_driver option determines how OpenType fonts are represented in the DVI output. In most cases the default value dvisvgm should be set, it uses a format supported by multiple backends including dvipdfmx and dvisvgm which uses GIDs to identify characters. Setting this to xdvipsk uses an unstable internal format instead which will change depending on the luaotfload, engine, or font version. No one should rely on the mapping between DVI character codes and font glyphs in this mode unless they tightly control all involved versions and are deeply familiar with the implementation.