fontTools WOFF2 encoder roundtrip test

woff2_roundtrip_test.py

#!/usr/bin/env python
"""
if input font is SFNT:
    - create normalised font
    - compress input font to WOFF2
    - decompress WOFF2
    - diff normalised and decompressed font
else if input font is WOFF2:
    - decompress input font to SFNT
"""
import os
import sys
from fontTools.ttLib import TTFont
from fontTools.ttLib import woff2
from tempfile import TemporaryFile


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

    infile = sys.argv[1]
    outfile = make_output_name(infile)

    font = TTFont(infile, recalcTimestamp=False, checkChecksums=1)
    if font.flavor is None:
        # make temporary 'normalised' version of input font
        print('Normalising font %s' % infile)
        woff2.normaliseFont(font)
        normalised = TemporaryFile()
        font.save(normalised, reorderTables=True)

        # convert input sfnt to woff2
        print('Compressing font %s' % infile)
        font.flavor = "woff2"
        font.save(outfile)

        # decompress woff2 to new temporary sfnt
        print('Decompressing font %s' % outfile)
        font1 = TTFont(outfile, recalcTimestamp=False)
        font1.flavor = None
        decompressed = TemporaryFile()
        font1.save(decompressed, reorderTables=True)

        # compare normalised and decompressed fonts
        if not diff(normalised, decompressed):
            print('Success!')
        else:
            print('Failed: normalised and decompressed fonts differ.')
    else:
        # convert input woff2 to sfnt
        print('Decompressing font %s' % infile)
        font.flavor = None
        font.save(outfile, reorderTables=True)


def diff(a_file, another_file):
    """Return False if the two files' content is the same, else return True."""
    result = False
    first_is_stream = second_is_stream = True
    if not hasattr(a_file, 'read'):
        first_is_stream = False
        a_file = open(a_file, 'rb')
    if not hasattr(another_file, 'read'):
        second_is_stream = False
        another_file = open(another_file, 'rb')
    a_file.seek(0)
    another_file.seek(0)
    if a_file.read() != another_file.read():
        result = True
    if not first_is_stream:
        a_file.close()
    if not second_is_stream:
        another_file.close()
    return result


def make_output_name(infile):
    """Replace 'woff2' file extension with 'ttf' or 'otf', and viceversa."""
    basename, ext = os.path.splitext(infile)
    if ext in ['.otf', '.ttf']:
        ext = ".woff2"
    elif ext in ['.woff2']:
        with open(infile, "rb") as f:
            f.seek(4)
            sfntVersion = f.read(4)
        ext = '.ttf' if sfntVersion == b"\x00\x01\x00\x00" else ".otf"
    return basename + ext


if __name__ == '__main__':
    main()