Module: Fontisan::Ufo::Compile::Cff2

Defined in:
lib/fontisan/ufo/compile/cff2.rb

Overview

Builds the OpenType CFF2 table from UFO glyphs.

CFF2 is simpler than CFF1: no Name INDEX, String INDEX, Encoding, or Charset. The Top DICT references CharStrings and a Font DICT INDEX (which wraps at least one Font DICT pointing to a Private DICT).

Layout (static font, single Font DICT, empty Private DICT):

Header (5 bytes)
Top DICT (variable — offsets to CharStrings + Font DICT INDEX)
Global Subr INDEX (4 bytes — empty)
CharStrings INDEX (variable)
Font DICT INDEX (variable — wraps one Font DICT)
Font DICT: DICT with Private operator [0, 0] (empty Private)

The Top DICT offsets depend on the Top DICT's own size — a circular dependency resolved with fixed-point iteration (the same pattern as the CFF1 builder).

See Also:

Constant Summary collapse

CHARSTRINGS_OPERATOR =

CFF2 Top DICT operator encodings.

17
VARIATION_STORE_OPERATOR =

0x11

24
FONT_DICT_INDEX_OPERATOR =

0x18

[12, 36].freeze
PRIVATE_OPERATOR =

0x12

18

Class Method Summary collapse

Class Method Details

.build(font, glyphs:, masters: nil, axis_count: nil, variation_store: nil) ⇒ String

Returns CFF2 table bytes.

Parameters:

  • font (Fontisan::Ufo::Font)
  • glyphs (Array<Fontisan::Ufo::Glyph>) —

    in gid order

  • masters (Array<Hash>, nil) (defaults to: nil) —

    variation masters for variable CFF2. Each hash: { font:, axes: }. When present, charstrings emit blend operators and a VariationStore is embedded.

  • axis_count (Integer, nil) (defaults to: nil) —

    number of variation axes

  • variation_store (String, nil) (defaults to: nil) —

    ItemVariationStore bytes for variable CFF2 fonts. When present, embedded between the GlobalSubr INDEX and CharStrings INDEX, and referenced from the Top DICT via operator 24.

Returns:

  • (String) —

    CFF2 table bytes



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# File 'lib/fontisan/ufo/compile/cff2.rb', line 45

def self.build(font, glyphs:, masters: nil, axis_count: nil,
               variation_store: nil)
  if masters&.any?
    build_variable(font, glyphs, masters, axis_count)
  else
    build_static(font, glyphs, variation_store:)
  end
end