Function fontCovers

Whether a face has the glyphs to write labels in language — for a warning in a font picker, not a guarantee.

The language's script comes from languageScript, so language can be any text.language, 'user' included. The face needs the script's sample letters, and for a language written with letters beyond its script's basic alphabet (LANGUAGE_SAMPLES) those letters too, so a Latin face may cover 'de' but not 'vi' or 'az'.

Coverage is read, as in fontScripts, from the codeblocks the glyph server lists for the face in its font_families.json. undefined when there is nothing to check against: local, a language Intl cannot place in a script, a script this table has no sample letters for, or a face that lists no blocks — whose coverage is unknown, not empty.

MapLibre GL JS draws CJK ideographs, Hangul and kana with a local browser font by default (localIdeographFontFamily), so a false for Chinese, Japanese or Korean matters to MapLibre Native, not to GL JS in its default setting.

npm only. Not exported by the browser bundle (versatiles-style.js) — see the versatiles-style.js module for what that carries.