Lib/fontTools/ttLib/tables/T_S_I__0.py

""" TSI{0,1,2,3,5} are private tables used by Microsoft Visual TrueType (VTT)
tool to store its hinting source data.

TSI0 is the index table containing the lengths and offsets for the glyph
programs and 'extra' programs ('fpgm', 'prep', and 'cvt') that are contained
in the TSI1 table.
"""
from __future__ import print_function, division, absolute_import
from fontTools.misc.py23 import *
from . import DefaultTable
import struct

tsi0Format = '>HHL'

def fixlongs(glyphID, textLength, textOffset):
	return int(glyphID), int(textLength), textOffset


class table_T_S_I__0(DefaultTable.DefaultTable):

	dependencies = ["TSI1"]

	def decompile(self, data, ttFont):
		numGlyphs = ttFont['maxp'].numGlyphs
		indices = []
		size = struct.calcsize(tsi0Format)
		for i in range(numGlyphs + 5):
			glyphID, textLength, textOffset = fixlongs(*struct.unpack(tsi0Format, data[:size]))
			indices.append((glyphID, textLength, textOffset))
			data = data[size:]
		assert len(data) == 0
		assert indices[-5] == (0XFFFE, 0, 0xABFC1F34), "bad magic number"
		self.indices = indices[:-5]
		self.extra_indices = indices[-4:]

	def compile(self, ttFont):
		if not hasattr(self, "indices"):
			# We have no corresponding table (TSI1 or TSI3); let's return
			# no data, which effectively means "ignore us".
			return b""
		data = b""
		for index, textLength, textOffset in self.indices:
			data = data + struct.pack(tsi0Format, index, textLength, textOffset)
		data = data + struct.pack(tsi0Format, 0XFFFE, 0, 0xABFC1F34)
		for index, textLength, textOffset in self.extra_indices:
			data = data + struct.pack(tsi0Format, index, textLength, textOffset)
		return data

	def set(self, indices, extra_indices):
		# gets called by 'TSI1' or 'TSI3'
		self.indices = indices
		self.extra_indices = extra_indices

	def toXML(self, writer, ttFont):
		writer.comment("This table will be calculated by the compiler")
		writer.newline()