The font database made one style per font file, so a variable font
such as Figtree[wght].ttf listed only its default instance (Light).
Faces now also yield their fvar named instances, each a style of the
family named by its subfamily name (the default instance is the face
itself; unnamed or duplicate instances are left out; axes and
instances read are capped). The system font scan reads the fvar table
beside the name table, so installed instances are listed before the
file is loaded and found by name and by PostScript name.
An instance face carries its axis settings: skrifa draws its outlines
and reads its metrics and advances at that location, harfrust shapes
with a ShaperInstance, so layout, the canvas, Create Outlines and hit
testing all use the instance. PDF export embeds it through krilla's
Font::new_variable, SVG @font-face through subsetter's
subset_with_variations: both write a static font of that instance.
Tests build a small variable font in code (test_fonts, via
write-fonts; no font file is committed) and check listing, resolving,
glyphs and advances, PDF and SVG export and damaged fvar/gvar tables;
Bahnschrift and Segoe UI Variable are checked where installed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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