FontFeature

Remarks

CSS Fonts 4 gives two ways to ask for one and they arrive here as the same thing. font-feature-settings: "tnum" 1 names the tag directly; font-variant-numeric: tabular-nums names a typographic intention that is that tag. So the high-level property is a table of these and the low-level one is a parser for them, and the shaper below never learns which of the two a feature came from.

⚠ No range. CSS and OpenType both allow a feature to be switched on over part of a run — "liga" 1 [3:7] in HarfBuzz's own syntax — and CSS's grammar does not expose it, so neither does this. A feature here applies to the whole shaped paragraph, which is what every declaration a stylesheet can write means.

Fields and properties (2)

• public uint Tag

  The four-character OpenType tag, packed big-endian as HarfBuzz packs it.

• public uint Value

  What to set it to. Zero is off, one is on, and a larger number selects an alternate for the features that number theirs.

Methods (5)

• public FontFeature(uint Tag, uint Value)

  One OpenType feature, switched on or off for a whole run.

• public static uint Pack(ReadOnlySpan<char> tag)

  Packs a four-character tag.

• public static string Unpack(uint tag)

  Unpacks a tag back into its four characters.

• public static bool TryParse(ReadOnlySpan<char> text, out FontFeature feature)

  Reads one <feature-tag-value>, as CSS Fonts 4 § 6.4 spells it.

• public override string ToString()

  Returns the fully qualified type name of this instance.

Used by (7)

• FontFeatureSetVixen.Ui.Text
• FontFeatureStyleTestsVixen.Ui.Tests
• FontFeatureTestsVixen.Ui.Text.Tests
• NumericFigureVisibilityTestsVixen.Ui.Styling.Utilities.Tests
• TextShaperVixen.Ui.Text
• UiDocumentVixen.Ui
• UtilityFamilySupportTestsVixen.Editor.Ui.Tests