Ligature Font Feature Selector Constants

If the font supports the ligatures feature type, you can select features related to ligature formation, such as those shown in Table D-14.

Table D-14 Feature selectors for the kLigaturesType feature type

Constant	Explanation
`kRequiredLigaturesOnSelector kRequiredLigaturesOffSelector`	Allows or prevents the use of ligatures that the font designates as required by the language (such as certain Arabic ligatures).
`kCommonLigaturesOnSelector kCommonLigaturesOffSelector`	Allows or prevents the use of ligatures that the font designates as "common," or normally used (such as the "fi" ligature in Roman text).
`kRareLigaturesOnSelector kRareLigaturesOffSelector`	Allows or prevents the use of ligatures that the font designates as "rare" (such as "ct" or "ss" ligatures).
`kLogosOnSelector kLogosOffSelector`	Allows or prevents the use of ligatures that the font designates as logotypes (typically used for trademarks or other special display text).
`kRebusPicturesOnSelector kRebusPicturesOffSelector`	Allows or prevents the use of rebuses (pictures that represent words or syllables).
`kDiphthongLigaturesOnSelector kDiphthongLigaturesOffSelector`	Specifies whether or not to replace diphthong sequences, such as "AE" and "oe", with their equivalent ligatures ("Æ" and "?" in this case).
`kSquaredLigaturesOnSelector kSquaredLigaturesOffSelector`	Allows or prevents the use of ligatures where the component letters are arranged in a lattice, such that the ligature fits into the space of a single letter. For examples, see Unicode characters `U+3300` through `U+3357` and `U+337B` through `U+337F`.
`kAbbrevSquaredLigaturesOnSelector kAbbrevSquaredLigaturesOffSelector`	Allows or prevents the use of ligatures similar to the previously described ligatures, but in abbreviated form.

Figure D-6 shows several levels of ligature formation specified through ligature feature selectors.

Figure D-6 Levels of ligature formation controlled with ligature feature selectors

Figure D-7 shows the results of selection (upper) and deselection (lower) of diphthong ligatures.

Figure D-7 Use of diphthong ligatures