Description

This function encapsulates the specification of OpenType font features. Some specific features have named arguments, but all available features can be set by using its specific 4-letter tag For a list of the 4-letter tags available see e.g. the overview on Wikipedia.

Usage

Arguments

Details

OpenType features are defined by a 4-letter tag along with an integer value. Often that value is a simple 0 (off) or 1 (on), but some features support additional values, e.g. stylistic alternates (salt) where a font may provide multiple variants of a letter and the value will be used to chose which one to use.

Common features related to appearance may be given with a long form name to either the ligatures, letters, or numbers argument to avoid remembering the often arbitrary 4-letter tag. Providing a long form name is the same as setting the tag to 1 and can thus not be used to set tags to other values.

The possible long form names are given below with the tag in parenthesis:

Ligatures

• standard (liga): Turns on standard multiple letter substitution

• historical (hlig): Use obsolete historical ligatures

• contextual (clig): Apply secondary ligatures based on the character patterns surrounding the potential ligature

• discretionary (dlig): Use ornamental ligatures

Letters

• swash (cswh): Use contextual swashes (ornamental decorations)

• alternates (calt): Use alternate letter forms based on the sourrounding pattern

• historical (hist): Use obsolete historical forms of the letters

• localized (locl): Use alternate forms preferred by the script language

• randomize (rand): Use random variants of the letters (e.g. to mimick handwriting)

• alt_annotation (nalt): Use alternate annotations (e.g. circled digits)

• stylistic (salt): Use a stylistic alternative form of the letter

• subscript (subs): Set letter in subscript

• superscript (sups): Set letter in superscript

• titling (titl): Use letter forms well suited for large text and titles

• small_caps (smcp): Use small caps variants of the letters

Numbers

• lining (lnum): Use number variants that rest on the baseline

• oldstyle (onum): Use old style numbers that use descender and ascender for various numbers

• proportional (pnum): Let numbers take up width based on the visual width of the glyph

• tabular (tnum): Enforce all numbers to take up the same width

• fractions (frac): Convert numbers separated by / into a fraction glyph

• fractions_alt (afrc): Use alternate fraction form with a horizontal divider

Value

A font_feature object

Examples