Class: Fontisan::Ufo::Compile::FeatureWriters::Kern

Inherits:
Base
  • Object
show all
Defined in:
lib/fontisan/ufo/compile/feature_writers/kern.rb

Overview

GPOS PairPos (lookup type 2) — kerning pairs.

Reads font.kerning (parsed from kerning.plist) and emits a FeatureOutput whose data is a structured list of pairs ready for the GPOS PairPos builder. Returns nil when the UFO has no kerning data — the compiler then omits the GPOS table entirely.

Group-based kerning keys (e.g. "@MMK_L_A @MMK_R_B") are emitted verbatim with group: true; the GPOS builder is responsible for resolving group references via the UFO's groups.plist data (TODO: groups.plist support is partial).

Constant Summary collapse

LOOKUP_TYPE =

GPOS lookup type 2 — PairPos (pair-positioning).

2
FEATURE_TAG = 
"kern"
TABLE_TAG = 
"GPOS"

Instance Attribute Summary

Attributes inherited from Base

#font

Instance Method Summary collapse

Methods inherited from Base

#initialize

Constructor Details

This class inherits a constructor from Fontisan::Ufo::Compile::FeatureWriters::Base

Instance Method Details

#write ⇒ FeatureOutput?

Returns:



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# File 'lib/fontisan/ufo/compile/feature_writers/kern.rb', line 26

def write
  return nil if font.kerning.nil? || font.kerning.empty?

  pairs = font.kerning.pairs.map do |key, value|
    left, right = key.to_s.split(" ", 2)
    {
      left: left,
      right: right,
      value: value.to_f,
      group_left: left.to_s.start_with?("@"),
      group_right: right.to_s.start_with?("@"),
    }
  end

  FeatureOutput.new(
    table_tag: TABLE_TAG,
    feature_tag: FEATURE_TAG,
    lookup_type: LOOKUP_TYPE,
    data: { pairs: pairs },
  )
end