fonttools/Lib/fontTools/ttLib/tables/otTables.py

"""fontTools.ttLib.tables.otTables -- A collection of classes representing the various
OpenType subtables.

Most are constructed upon import from data in otData.py, all are populated with
converter objects from otConverters.py.
"""

from otBase import BaseTable, FormatSwitchingBaseTable


class LookupOrder(BaseTable):
	"""Dummy class; this table isn't defined, but is used, and is always NULL."""


class FeatureParams(BaseTable):
	"""Dummy class; this table isn't defined, but is used, and is always NULL."""
	# XXX The above is no longer true; the 'size' feature uses FeatureParams now.


class Coverage(FormatSwitchingBaseTable):
	
	# manual implementation to get rid of glyphID dependencies
	
	def postRead(self, rawTable, font):
		if self.Format == 1:
			self.glyphs = rawTable["GlyphArray"]
		elif self.Format == 2:
			glyphs = self.glyphs = []
			ranges = rawTable["RangeRecord"]
			for r in ranges:
				assert r.StartCoverageIndex == len(glyphs), \
					(r.StartCoverageIndex, len(glyphs))
				start = r.Start
				end = r.End
				startID = font.getGlyphID(start)
				endID = font.getGlyphID(end)
				glyphs.append(start)
				for glyphID in range(startID + 1, endID):
					glyphs.append(font.getGlyphName(glyphID))
				if start != end:
					glyphs.append(end)
		else:
			assert 0, "unknown format: %s" % self.Format
	
	def preWrite(self, font):
		format = 1
		rawTable = {"GlyphArray": self.glyphs}
		if self.glyphs:
			# find out whether Format 2 is more compact or not
			glyphIDs = []
			for glyphName in self.glyphs:
				glyphIDs.append(font.getGlyphID(glyphName))
			
			last = glyphIDs[0]
			ranges = [[last]]
			for glyphID in glyphIDs[1:]:
				if glyphID == last + 1:
					pass
				else:
					ranges[-1].append(last)
					ranges.append([glyphID])
				last = glyphID
			ranges[-1].append(last)
			
			if len(ranges) * 3 < len(self.glyphs):  # 3 words vs. 1 word
				# Format 2 is more compact
				index = 0
				for i in range(len(ranges)):
					start, end = ranges[i]
					r = RangeRecord()
					r.Start = font.getGlyphName(start)
					r.End = font.getGlyphName(end)
					r.StartCoverageIndex = index
					ranges[i] = r
					index = index + end - start + 1
				format = 2
				rawTable = {"RangeRecord": ranges}
			#else:
			#	fallthrough; Format 1 is more compact
		self.Format = format
		return rawTable
	
	def toXML2(self, xmlWriter, font):
		for glyphName in self.glyphs:
			xmlWriter.simpletag("Glyph", value=glyphName)
			xmlWriter.newline()
	
	def fromXML(self, (name, attrs, content), font):
		glyphs = getattr(self, "glyphs", None)
		if glyphs is None:
			glyphs = []
			self.glyphs = glyphs
		glyphs.append(attrs["value"])


#
# For each subtable format there is a class. However, we don't really distinguish
# between "field name" and "format name": often these are the same. Yet there's
# a whole bunch of fields with different names. The following dict is a mapping
# from "format name" to "field name". _buildClasses() uses this to create a
# subclass for each alternate field name.
#
_equivalents = {
	'MarkArray': ("Mark1Array",),
	'LangSys': ('DefaultLangSys',),
	'Coverage': ('MarkCoverage', 'BaseCoverage', 'LigatureCoverage', 'Mark1Coverage',
			'Mark2Coverage', 'BacktrackCoverage', 'InputCoverage',
			'LookaheadCoverage'),
	'ClassDef': ('ClassDef1', 'ClassDef2', 'BacktrackClassDef', 'InputClassDef',
			'LookaheadClassDef', 'GlyphClassDef', 'MarkAttachClassDef'),
	'Anchor': ('EntryAnchor', 'ExitAnchor', 'BaseAnchor', 'LigatureAnchor',
			'Mark2Anchor', 'MarkAnchor'),
	'Device': ('XPlaDevice', 'YPlaDevice', 'XAdvDevice', 'YAdvDevice',
			'XDeviceTable', 'YDeviceTable', 'DeviceTable'),
	'Axis': ('HorizAxis', 'VertAxis',),
	'MinMax': ('DefaultMinMax',),
	'BaseCoord': ('MinCoord', 'MaxCoord',),
	'JstfLangSys': ('DefJstfLangSys',),
	'JstfGSUBModList': ('ShrinkageEnableGSUB', 'ShrinkageDisableGSUB', 'ExtensionEnableGSUB',
			'ExtensionDisableGSUB',),
	'JstfGPOSModList': ('ShrinkageEnableGPOS', 'ShrinkageDisableGPOS', 'ExtensionEnableGPOS',
			'ExtensionDisableGPOS',),
	'JstfMax': ('ShrinkageJstfMax', 'ExtensionJstfMax',),
}


def _buildClasses():
	import new, re
	from otData import otData
	
	formatPat = re.compile("([A-Za-z0-9]+)Format(\d+)$")
	namespace = globals()
	
	# populate module with classes
	for name, table in otData:
		baseClass = BaseTable
		m = formatPat.match(name)
		if m:
			# XxxFormatN subtable, we only add the "base" table
			name = m.group(1)
			baseClass = FormatSwitchingBaseTable
		if not namespace.has_key(name):
			# the class doesn't exist yet, so the base implementation is used.
			cls = new.classobj(name, (baseClass,), {})
			namespace[name] = cls
	
	for base, alts in _equivalents.items():
		base = namespace[base]
		for alt in alts:
			namespace[alt] = new.classobj(alt, (base,), {})
	
	global lookupTypes
	lookupTypes = {
		'GSUB': {
			1: SingleSubst,
			2: MultipleSubst,
			3: AlternateSubst,
			4: LigatureSubst,
			5: ContextSubst,
			6: ChainContextSubst,
			7: ExtensionSubst,
		},
		'GPOS': {
			1: SinglePos,
			2: PairPos,
			3: CursivePos,
			4: MarkBasePos,
			5: MarkLigPos,
			6: MarkMarkPos,
			7: ContextPos,
			8: ChainContextPos,
			9: ExtensionPos,
		},
	}
	lookupTypes['JSTF'] = lookupTypes['GPOS']  # JSTF contains GPOS
	for lookupEnum in lookupTypes.values():
		for enum, cls in lookupEnum.items():
			cls.LookupType = enum
	
	# add converters to classes
	from otConverters import buildConverters
	for name, table in otData:
		m = formatPat.match(name)
		if m:
			# XxxFormatN subtable, add converter to "base" table
			name, format = m.groups()
			format = int(format)
			cls = namespace[name]
			if not hasattr(cls, "converters"):
				cls.converters = {}
				cls.convertersByName = {}
			converters, convertersByName = buildConverters(table[1:], namespace)
			cls.converters[format] = converters
			cls.convertersByName[format] = convertersByName
		else:
			cls = namespace[name]
			cls.converters, cls.convertersByName = buildConverters(table, namespace)


_buildClasses()