builder.py 文件源码

def add_ligature_subst(self, location,
                           prefix, glyphs, suffix, replacement, forceChain):
        if prefix or suffix or forceChain:
            chain = self.get_lookup_(location, ChainContextSubstBuilder)
            lookup = self.get_chained_lookup_(location, LigatureSubstBuilder)
            chain.substitutions.append((prefix, glyphs, suffix, [lookup]))
        else:
            lookup = self.get_lookup_(location, LigatureSubstBuilder)

        # OpenType feature file syntax, section 5.d, "Ligature substitution":
        # "Since the OpenType specification does not allow ligature
        # substitutions to be specified on target sequences that contain
        # glyph classes, the implementation software will enumerate
        # all specific glyph sequences if glyph classes are detected"
        for g in sorted(itertools.product(*glyphs)):
            lookup.ligatures[g] = replacement