pyotlss.py

#!/usr/bin/python

# Python OpenType Layout Subsetter
# Writte by: Behdad Esfahbod

import fontTools.ttx


def add_method (*clazzes):
	def wrapper(method):
		for clazz in clazzes:
			setattr (clazz, method.func_name, method)
	return wrapper

# Subset

@add_method(fontTools.ttLib.tables.otTables.Coverage)
def subset (self, glyphs):
	indices = [i for (i,g) in enumerate (self.glyphs) if g in glyphs]
	self.glyphs = [g for g in self.glyphs if g in glyphs]
	return indices

@add_method(fontTools.ttLib.tables.otTables.Coverage)
def __nonzero__ (self):
	return bool (self.glyphs)

@add_method(fontTools.ttLib.tables.otTables.ClassDef)
def subset (self, glyphs):
	self.classDefs = {g:v for g,v in self.classDefs.items() if g in glyphs}
	return len (self.classDefs)

@add_method(fontTools.ttLib.tables.otTables.ClassDef)
def __nonzero__ (self):
	return bool (self.classDefs)

@add_method(fontTools.ttLib.tables.otTables.SingleSubst)
def subset (self, glyphs):
	if self.Format in [1, 2]:
		self.mapping = {g:v for g,v in self.mapping.items() if g in glyphs}
		return len (self.mapping)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.MultipleSubst)
def subset (self, glyphs):
	if self.Format == 1:
		indices = self.Coverage.subset (glyphs)
		self.Sequence = [self.Sequence[i] for i in indices]
		self.SequenceCount = len (self.Sequence)
		return self.SequenceCount
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.AlternateSubst)
def subset (self, glyphs):
	if self.Format == 1:
		self.alternates = {g:v for g,v in self.alternates.items() if g in glyphs}
		return len (self.alternates)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.LigatureSubst)
def subset (self, glyphs):
	if self.Format == 1:
		self.ligatures = {g:v for g,v in self.ligatures.items() if g in glyphs}
		self.ligatures = {g:[seq for seq in seqs if all(c in glyphs for c in seq.Component)]
				  for g,seqs in self.ligatures.items()}
		self.ligatures = {g:v for g,v in self.ligatures.items() if v}
		return len (self.ligatures)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.ReverseChainSingleSubst)
def subset (self, glyphs):
	if self.Format == 1:
		indices = self.Coverage.subset (glyphs)
		self.Substitute = [self.Substitute[i] for i in indices]
		self.GlyphCount = len (self.Substitute)
		return self.GlyphCount and all (c.subset (glyphs) for c in self.LookAheadCoverage + self.BacktrackCoverage)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.SinglePos)
def subset (self, glyphs):
	if self.Format == 1:
		return len (self.Coverage.subset (glyphs))
	elif self.Format == 2:
		indices = self.Coverage.subset (glyphs)
		self.Value = [self.Value[i] for i in indices]
		self.ValueCount = len (self.Value)
		return self.ValueCount
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.PairPos)
def subset (self, glyphs):
	if self.Format == 1:
		indices = self.Coverage.subset (glyphs)
		self.PairSet = [self.PairSet[i] for i in indices]
		for p in self.PairSet:
			p.PairValueRecord = [r for r in p.PairValueRecord if r.SecondGlyph in glyphs]
			p.PairValueCount = len (p.PairValueRecord)
		self.PairSet = [p for p in self.PairSet if p.PairValueCount]
		self.PairSetCount = len (self.PairSet)
		return self.PairSetCount
	elif self.Format == 2:
		self.Coverage.subset (glyphs)
		self.ClassDef1.subset (glyphs)
		self.ClassDef2.subset (glyphs)
		# TODO Prune empty classes
		return self.Coverage and self.ClassDef1 and self.ClassDef2
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.CursivePos)
def subset (self, glyphs):
	if self.Format == 1:
		indices = self.Coverage.subset (glyphs)
		self.EntryExitRecord = [self.EntryExitRecord[i] for i in indices]
		self.EntryExitCount = len (self.EntryExitRecord)
		return self.EntryExitCount
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.MarkBasePos)
def subset (self, glyphs):
	if self.Format == 1:
		mark_indices = self.MarkCoverage.subset (glyphs)
		self.MarkArray.MarkRecord = [self.MarkArray.MarkRecord[i] for i in mark_indices]
		self.MarkArray.MarkCount = len (self.MarkArray.MarkRecord)
		base_indices = self.BaseCoverage.subset (glyphs)
		self.BaseArray.BaseRecord = [self.BaseArray.BaseRecord[i] for i in base_indices]
		self.BaseArray.BaseCount = len (self.BaseArray.BaseRecord)
		# TODO Prune empty classes
		return self.MarkArray.MarkCount and self.BaseArray.BaseCount
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.MarkLigPos)
def subset (self, glyphs):
	if self.Format == 1:
		mark_indices = self.MarkCoverage.subset (glyphs)
		self.MarkArray.MarkRecord = [self.MarkArray.MarkRecord[i] for i in mark_indices]
		self.MarkArray.MarkCount = len (self.MarkArray.MarkRecord)
		ligature_indices = self.LigatureCoverage.subset (glyphs)
		self.LigatureArray.LigatureAttach = [self.LigatureArray.LigatureAttach[i] for i in ligature_indices]
		self.LigatureArray.LigatureCount = len (self.LigatureArray.LigatureAttach)
		# TODO Prune empty classes
		return self.MarkArray.MarkCount and self.LigatureArray.LigatureCount
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.MarkMarkPos)
def subset (self, glyphs):
	if self.Format == 1:
		mark1_indices = self.Mark1Coverage.subset (glyphs)
		self.Mark1Array.MarkRecord = [self.Mark1Array.MarkRecord[i] for i in mark1_indices]
		self.Mark1Array.MarkCount = len (self.Mark1Array.MarkRecord)
		mark2_indices = self.Mark2Coverage.subset (glyphs)
		self.Mark2Array.Mark2Record = [self.Mark2Array.Mark2Record[i] for i in mark2_indices]
		self.Mark2Array.MarkCount = len (self.Mark2Array.Mark2Record)
		# TODO Prune empty classes
		return self.Mark1Array.MarkCount and self.Mark2Array.MarkCount
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.ContextSubst, fontTools.ttLib.tables.otTables.ContextPos)
def subset (self, glyphs):
	if self.Format == 1:
		indices = self.Coverage.subset (glyphs)
		self.SubRuleSet = [self.SubRuleSet[i] for i in indices]
		self.SubRuleSetCount = len (self.SubRuleSet)
		for rs in self.SubRuleSet:
			rs.SubRule = [r for r in rs.SubRule
				      if all (g in glyphs for g in r.Input)]
			rs.SubRuleCount = len (rs.SubRule)
		# Prune empty subrulesets
		return self.SubRuleSetCount
	elif self.Format == 2:
		return self.Coverage.subset (glyphs) and self.ClassDef.subset (glyphs)
	elif self.Format == 3:
		return all (c.subset (glyphs) for c in self.Coverage)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.ChainContextSubst, fontTools.ttLib.tables.otTables.ChainContextPos)
def subset (self, glyphs):
	if self.Format == 1:
		indices = self.Coverage.subset (glyphs)
		self.ChainSubRuleSet = [self.ChainSubRuleSet[i] for i in indices]
		self.ChainSubRuleSetCount = len (self.ChainSubRuleSet)
		for rs in self.ChainSubRuleSet:
			rs.ChainSubRule = [r for r in rs.ChainSubRule
					   if all (g in glyphs for g in r.Backtrack + r.Input + r.LookAhead)]
			rs.ChainSubRuleCount = len (rs.ChainSubRule)
		# Prune empty subrulesets
		return self.ChainSubRuleSetCount
	elif self.Format == 2:
		return self.Coverage.subset (glyphs) and \
		       self.LookAheadClassDef.subset (glyphs) and \
		       self.BacktrackClassDef.subset (glyphs) and \
		       self.InputClassDef.subset (glyphs)
	elif self.Format == 3:
		return all (c.subset (glyphs) for c in self.InputCoverage + self.LookAheadCoverage + self.BacktrackCoverage)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.ExtensionSubst, fontTools.ttLib.tables.otTables.ExtensionPos)
def subset (self, glyphs):
	if self.Format == 1:
		return self.ExtSubTable.subset (glyphs)
	else:
		assert 0, "unknown format: %s" % self.Format

@add_method(fontTools.ttLib.tables.otTables.Lookup)
def subset (self, glyphs):
	self.SubTable = [s for s in self.SubTable if s.subset (glyphs)]
	self.SubTableCount = len (self.SubTable)
	return self.SubTableCount

@add_method(fontTools.ttLib.tables.otTables.LookupList)
def subset (self, glyphs):
	"Returns the indices of nonempty lookups."
	return [i for (i,l) in enumerate (self.Lookup) if l.subset (glyphs)]

@add_method(fontTools.ttLib.tables.otTables.LookupList)
def subset_lookups (self, lookup_indices):
	self.Lookup = [self.Lookup[i] for i in lookup_indices]
	self.LookupCount = len (self.Lookup)

@add_method(fontTools.ttLib.tables.otTables.Feature)
def subset_lookups (self, lookup_indices):
	self.LookupListIndex = [l for l in self.LookupListIndex if l in lookup_indices]
	# Now map them.
	self.LookupListIndex = [lookup_indices.index (l) for l in self.LookupListIndex]
	self.LookupCount = len (self.LookupListIndex)
	return self.LookupCount

@add_method(fontTools.ttLib.tables.otTables.FeatureList)
def subset_lookups (self, lookup_indices):
	"Returns the indices of nonempty features."
	feature_indices = [i for (i,f) in enumerate (self.FeatureRecord) if f.Feature.subset_lookups (lookup_indices)]
	self.FeatureRecord = [self.FeatureRecord[i] for i in feature_indices]
	self.FeatureCount = len (self.FeatureRecord)
	return feature_indices

@add_method(fontTools.ttLib.tables.otTables.DefaultLangSys, fontTools.ttLib.tables.otTables.LangSys)
def subset_features (self, feature_indices):
	if self.ReqFeatureIndex not in feature_indices:
		self.ReqFeatureIndex = 65535
	self.FeatureIndex = [f for f in self.FeatureIndex if f in feature_indices]
	self.FeatureCount = len (self.FeatureIndex)
	return self.FeatureCount

@add_method(fontTools.ttLib.tables.otTables.Script)
def subset_features (self, feature_indices):
	if self.DefaultLangSys and not self.DefaultLangSys.subset_features (feature_indices):
		self.DefaultLangSys = None
	self.LangSysRecord = [l for l in self.LangSysRecord if l.LangSys.subset_features (feature_indices)]
	self.LangSysCount = len (self.LangSysRecord)
	return self.LangSysCount

@add_method(fontTools.ttLib.tables.otTables.ScriptList)
def subset_features (self, feature_indices):
	self.ScriptRecord = [s for s in self.ScriptRecord if s.Script.subset_features (feature_indices)]
	self.ScriptCount = len (self.ScriptRecord)
	return self.ScriptCount

@add_method(fontTools.ttLib.tables.otTables.GSUB, fontTools.ttLib.tables.otTables.GPOS)
def subset (self, glyphs):
	lookup_indices = self.LookupList.subset (glyphs)
	self.subset_lookups (lookup_indices)
	return True # Retain the possibly empty table

@add_method(fontTools.ttLib.tables.otTables.GSUB, fontTools.ttLib.tables.otTables.GPOS)
def subset_lookups (self, lookup_indices):
	"Retrains specified lookups, then removes empty features, language systems, and scripts."
	self.LookupList.subset_lookups (lookup_indices)
	feature_indices = self.FeatureList.subset_lookups (lookup_indices)
	self.ScriptList.subset_features (feature_indices)

@add_method(fontTools.ttLib.tables.otTables.GDEF)
def subset (self, glyphs):
	if self.LigCaretList:
		indices = self.LigCaretList.Coverage.subset (glyphs)
		self.LigCaretList.LigGlyph = [self.LigCaretList.LigGlyph[i] for i in indices]
		self.LigCaretList.LigGlyphCount = len (self.LigCaretList.LigGlyph)
		if not self.LigCaretList.LigGlyphCount:
			self.LigCaretList = None
	if self.MarkAttachClassDef:
		self.MarkAttachClassDef.classDefs = {g:v for g,v in self.MarkAttachClassDef.classDefs.items() if g in glyphs}
		if not self.MarkAttachClassDef.classDefs:
			self.MarkAttachClassDef = None
	if self.GlyphClassDef:
		self.GlyphClassDef.classDefs = {g:v for g,v in self.GlyphClassDef.classDefs.items() if g in glyphs}
		if not self.GlyphClassDef.classDefs:
			self.GlyphClassDef = None
	if self.AttachList:
		indices = self.AttachList.Coverage.subset (glyphs)
		self.AttachList.AttachPoint = [self.AttachList.AttachPoint[i] for i in indices]
		self.AttachList.GlyphCount = len (self.AttachList.AttachPoint)
		if not self.AttachList.GlyphCount:
			self.AttachList = None
	return True # Retain the possibly empty table


if __name__ == '__main__':

	import sys

	if len (sys.argv) < 3:
		print >>sys.stderr, "usage: pyotlss.py font-file glyph..."
		sys.exit (1)

	fontfile = sys.argv[1]
	glyphs   = sys.argv[2:]

	font = fontTools.ttx.TTFont (fontfile)

	names = font.getGlyphNames()
	# Convert to glyph names
	glyphs = [g if g in names else font.getGlyphName(int(g)) for g in glyphs]

	for tag in ['GDEF', 'GSUB', 'GPOS']:
		if tag not in font:
			continue
		if not font[tag].table.subset (glyphs):
			del font[tag]

	font.save (fontfile + '.subset')