fontTools WOFF2 glyf table roundtrip test

woff2_glyf_test.py

#!/usr/bin/env python
"""
Test that reconstructed 'glyf' and 'loca' table data are bitwise identical to
the original, 'normalised' table data.
"""
from __future__ import print_function
import sys
import struct
from fontTools.misc.py23 import *
from fontTools.ttLib import TTFont
from fontTools.ttLib import woff2
from fontTools.ttLib.sfnt import calcChecksum


def pretty_print_tables(glyfData, locaData, indexFormat):
    glyfCheckSum = "0x%08X" % calcChecksum(glyfData)
    locaCheckSum = "0x%08X" % calcChecksum(locaData)
    print("  glyf.length            ", len(glyfData))
    print("  glyf.checkSum          ", glyfCheckSum)
    print("  loca.length            ", len(locaData))
    print("  loca.checkSum          ", locaCheckSum)
    print("  indexFormat            ", indexFormat)


def main():
    if not sys.argv[1:]:
        print("No input font")
        sys.exit(1)

    infile = sys.argv[1]
    font = TTFont(infile, recalcTimestamp=False, checkChecksums=1)

    if font.sfntVersion != "\000\001\000\000":
        print("Not a TrueType font")
        sys.exit(1)

    print("Read original 'glyf' and 'loca' tables...")
    glyfData = font.reader['glyf']
    locaData = font.reader['loca']
    indexFormat, = struct.unpack(">H", font.reader['head'][50:52])
    pretty_print_tables(glyfData, locaData, indexFormat)

    print("Normalise 'glyf' and 'loca' tables...")
    font.flavor = "woff2"
    font.recalcBBoxes = True
    font.lazy = False  # 'expand' glyph data on decompile
    if not font.isLoaded('glyf'):
        font['glyf']
    glyfData = font.getTableData('glyf')
    locaData = font.getTableData('loca')
    indexFormat = font['head'].indexToLocFormat
    pretty_print_tables(glyfData, locaData, indexFormat)

    print("Transform 'glyf' and 'loca' tables...")
    encoder = woff2.WOFF2GlyfTable()
    encoder.setLocaData(locaData, indexFormat, font['maxp'].numGlyphs)
    transformedGlyfData = encoder.transform(glyfData)
    transformedLocaData = b""
    pretty_print_tables(transformedGlyfData, transformedLocaData,
                        indexFormat)

    print("Reconstruct 'glyf' and 'loca' tables...")
    decoder = woff2.WOFF2GlyfTable()
    reconstructedGlyfData = decoder.reconstruct(transformedGlyfData)
    reconstructedLocaData = decoder.getLocaData()
    pretty_print_tables(reconstructedGlyfData, reconstructedLocaData,
                        decoder.indexFormat)

    if (glyfData != reconstructedGlyfData or
            locaData != reconstructedLocaData):
        print("FAILED: reconstructed tables are different from normalised ones")
    else:
        print("OK: reconstructed tables are identical to normalised ones")


if __name__ == '__main__':
    main()