API reference / Common / FontDescriptor

Interface: FontDescriptor

One family in one bold / italic style — the atomic unit font resolution works in, and the only selection input the font system takes.

Text analysis (script segmentation, the a:latin / a:ea / a:cs slot pick, direction) happens in the text layout's itemizer — by the time a request reaches the font system it names a concrete family. bold / italic are the OOXML run toggles, faithful to the model.

There is deliberately no weight axis. Office doesn't have one: a run carries a boolean (<w:b/>, b="1"), and everything that isn't regular-or-bold is a separate family name — Calibri Light, Segoe UI Semibold, Arial Black. Where a number is genuinely needed (Google's css2 wants wght@400) the mapping is one line in the host's fulfiller, at the edge.

A descriptor does not identify a font: one descriptor fans out into many FontEntrys — the same family and style offered by several vendors — which is why loaded fonts are keyed by FontEntryId, never by descriptor.

Properties

Property	Description
family string	The typeface family name (e.g. "Calibri" or "Arial Narrow").
bold boolean	The bold toggle.
italic boolean	The italic toggle.