MetaTools/roundTrip.py

#! /usr/bin/env python3

"""usage: ttroundtrip [options] font1 ... fontN

    Dump each TT/OT font as a TTX file, compile again to TTF or OTF
    and dump again. Then do a diff on the two TTX files. Append problems
    and diffs to a file called "report.txt" in the current directory.
    This is only for testing FontTools/TTX, the resulting files are
    deleted afterwards.

    This tool supports some of ttx's command line options (-i, -t
    and -x). Specifying -t or -x implies ttx -m <originalfile> on
    the way back.
"""


import sys
import os
import tempfile
import getopt
import traceback
from fontTools import ttx


class Error(Exception):
    pass


def usage():
    print(__doc__)
    sys.exit(2)


def roundTrip(ttFile1, options, report):
    fn = os.path.basename(ttFile1)
    xmlFile1 = tempfile.mkstemp(".%s.ttx1" % fn)
    ttFile2 = tempfile.mkstemp(".%s" % fn)
    xmlFile2 = tempfile.mkstemp(".%s.ttx2" % fn)

    try:
        ttx.ttDump(ttFile1, xmlFile1, options)
        if options.onlyTables or options.skipTables:
            options.mergeFile = ttFile1
        ttx.ttCompile(xmlFile1, ttFile2, options)
        options.mergeFile = None
        ttx.ttDump(ttFile2, xmlFile2, options)

        diffcmd = 'diff -U2 -I ".*modified value\|checkSumAdjustment.*" "%s" "%s"' % (
            xmlFile1,
            xmlFile2,
        )
        output = os.popen(diffcmd, "r", 1)
        lines = []
        while True:
            line = output.readline()
            if not line:
                break
            sys.stdout.write(line)
            lines.append(line)
        if lines:
            report.write(
                "=============================================================\n"
            )
            report.write('  "%s" differs after round tripping\n' % ttFile1)
            report.write(
                "-------------------------------------------------------------\n"
            )
            report.writelines(lines)
        else:
            print("(TTX files are the same)")
    finally:
        for tmpFile in (xmlFile1, ttFile2, xmlFile2):
            if os.path.exists(tmpFile):
                os.remove(tmpFile)


def main(args):
    try:
        rawOptions, files = getopt.getopt(args, "it:x:")
    except getopt.GetoptError:
        usage()

    if not files:
        usage()

    with open("report.txt", "a+") as report:
        options = ttx.Options(rawOptions, len(files))
        for ttFile in files:
            try:
                roundTrip(ttFile, options, report)
            except KeyboardInterrupt:
                print("(Cancelled)")
                break
            except:
                print("*** round tripping aborted ***")
                traceback.print_exc()
                report.write(
                    "=============================================================\n"
                )
                report.write("  An exception occurred while round tripping")
                report.write('  "%s"\n' % ttFile)
                traceback.print_exc(file=report)
                report.write(
                    "-------------------------------------------------------------\n"
                )


main(sys.argv[1:])