Font Feature Type Constants

Font features are grouped into categories called feature types, within which feature selectors are used to define particular feature settings or selections. The set of feature types described in this section may not be complete. For a description of the most up-to-date set of registered typographic and layout features available to applications using Apple Advanced Typography (AAT), see the Font Feature Registry at the Apple Font Feature Registry web site:

http://fonts.apple.com/Registry/index.html.

Table D-8 contains descriptions of some of the feature types might be available in a font. You should query a font to determine which of these font features are available, then build your own list of font features.

Note that unless the feature is defaulted differently in different fonts, the zero value for the selectors represents the default value.

Table D-8 Examples of feature types

Constant	Explanation
`kAllTypographicFeaturesType`	Specifies whether or not any font features are to be applied at all. Table D-9 lists the feature selectors related to this feature type.
`kLigaturesType`	Specifies the use of required ligatures and other categories of optional ligatures. Table D-14 lists the feature selectors related to this feature type.
`kCursiveConnectionType`	Specifies whether or not cursive connections are to be used between glyphs. Table D-5 lists the feature selectors related to this feature type.
`kLetterCaseType`	Specifies case changes, such as all uppercase, all lowercase, and small caps, for scripts in which case has meaning. Table D-13 lists the feature selectors related to this feature type.
`kVerticalSubstitutionType`	Allows substitution of vertical forms of particular glyphs (such as parentheses) in vertical runs of text. Table D-28 lists the feature selectors related to this feature type.
`kLinguisticRearrangementType`	Either permits or inhibits linguistic (Indic-style) rearrangement of glyphs. Table D-15 lists the feature selectors related to this feature type.
`kNumberSpacingType`	Specifies whether to use fixed-width or proportional-width glyphs for numerals. Table D-18 lists the feature selectors related to this feature type.
`kSmartSwashType`	Controls whether swash variants of glyphs are to be substituted in specific places in the text, such as at the beginnings or ends of words or lines. Table D-22 lists the feature selectors related to this feature type.
`kDiacriticsType`	Controls whether diacritical marks are shown or hidden. Table D-7 lists the feature selectors related to this feature type.
`kVerticalPositionType`	Controls the selection of superscript and subscript glyph sets. Table D-27 lists the feature selectors related to this feature type.
`kFractionsType`	Controls automatic substitution or formation of fractions. Table D-10 lists the feature selectors related to this feature type.
`kOverlappingCharactersType`	Controls whether long tails on glyphs are permitted to collide with other glyphs. Table D-20 lists the feature selectors related to this feature type.
`kTypographicExtrasType`	Controls several effects, such as substitution of en dashes for hyphens, that are associated with sophisticated typography. Table D-25 lists the feature selectors related to this feature type.
`kMathematicalExtrasType`	Controls several features, such as changing asterisks to multiplication symbols, used for typesetting mathematical expressions. Table D-16 lists the feature selectors related to this feature type.
`kOrnamentSetsType`	Specifies certain sets of non-alphanumeric glyphs, such as decorative borders or musical symbols. Table D-19 lists the feature selectors related to this feature type.
`kCharacterAlternativesType`	Specifies, by number, any font-specific set of alternate glyph forms. Table D-3 lists the feature selector related to this feature type.
`kDesignComplexityType`	Specifies an overall complexity of appearance, as defined by the font. Table D-6 lists the feature selectors related to this feature type.
`kStyleOptionsType`	Specifies any of several named alternative forms that may be available in the font, such as engraved or cursive. Table D-21 lists the feature selectors related to this feature type.
`kCharacterShapeType`	Specifies for languages such as Chinese that have both sets whether traditional or simplified characters are to be used. Table D-4 lists the feature selectors related to this feature type.
`kNumberCaseType`	Specifies whether to use numerals that do, or do not, extend below the baseline. Table D-17 lists the feature selectors related to this feature type.
`kTextSpacingType`	Specifies whether to use proportional, monospaced and half-width forms of characters in a font. Table D-23 lists the feature selectors related to this feature type.
`kTransliterationType`	Allows text in one format to be displayed using another format. Table D-24 lists the feature selectors related to this feature type.
`kAnnotationType`	Specifies annotations (or adornments) to basic letter shapes. For instance, most Japanese fonts include versions of numbers that are circled, parenthesized, have periods after them, and so on. Table D-1 lists the feature selectors related to this feature type.
`kKanaSpacingType`	Specifies widths for Japanese Hiragana and Katakana characters. Table D-12 lists the feature selectors related to this feature type.
`kIdeographicSpacingType`	Specifies whether to use proportional or full-width forms of ideographs (that is, Han-derived characters). Table D-11 lists the feature selectors related to this feature type.
`kCJKRomanSpacingType`	Specifies whether to use proportional or half-width forms of Roman characters in a CJK (that is, Chinese, Japanese, and Korean) font. Table D-2 lists the feature selectors related to this feature type.
`kUnicodeDecompositionType`	Table D-26 lists the feature selectors related to this feature type.
`kLastFeatureType`	Represents the last Apple-reserved font feature type value.