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#!/usr/bin/python
#
# Copyright 2015 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Post-build changes for Roboto for Android."""

import collections
import os
from os import path
import sys

from fontTools import ttLib
from nototools import font_data
from nototools import unicode_data


def drop_lookup(table, lookup_number):
    """Drop a lookup from an OpenType table by number.

    Actually remove pointers from features to the lookup, which should be less
    intrusive.
    """
    for feature in table.table.FeatureList.FeatureRecord:
        if lookup_number in feature.Feature.LookupListIndex:
            feature.Feature.LookupListIndex.remove(lookup_number)
            feature.Feature.LookupCount -= 1


def get_font_name(font):
    """Gets the name of the font from the name table."""
    return font_data.get_name_records(font)[4]


DIGITS = ['zero', 'one', 'two', 'three', 'four',
          'five', 'six', 'seven', 'eight', 'nine']

def fix_digit_widths(font):
    """Change all digit widths in the font to be the same."""
    hmtx_table = font['hmtx']
    widths = [hmtx_table[digit][0] for digit in DIGITS]
    if len(set(widths)) > 1:
        width_counter = collections.Counter(widths)
        most_common_width = width_counter.most_common(1)[0][0]
        print 'Digit widths were %s.' % repr(widths)
        print 'Setting all glyph widths to %d.' % most_common_width
        for digit in DIGITS:
            assert abs(hmtx_table[digit][0] - most_common_width) <= 1
            hmtx_table[digit][0] = most_common_width


_MAP_SPACING_TO_COMBINING = {
    'acute': 'acutecomb',
    'breve': 'brevenosp',
    'caron': 'uni030C',
    'cedilla': 'cedillanosp',
    'circumflex': 'circumflexnosp',
    'dieresis': 'dieresisnosp',
    'dotaccent': 'dotnosp',
    'grave': 'gravecomb',
    'hungarumlaut': 'acutedblnosp',
    'macron': 'macroncomb',
    'ogonek': 'ogoneknosp',
    'tilde': 'tildecomb',
    'ring': 'ringnosp',
    'tonos': 'acutecomb',
    'uni02F3': 'ringsubnosp',
}

def fix_ccmp_lookup(font):
    """Fixes the broken ccmp lookup."""
    cmap = font_data.get_cmap(font)
    reverse_cmap = {name: code for (code, name) in cmap.items()}

    # Where we know the bad 'ccmp' is
    ccmp_lookup = font['GSUB'].table.LookupList.Lookup[2]
    assert ccmp_lookup.LookupType == 4
    assert ccmp_lookup.SubTableCount == 1
    ligatures = ccmp_lookup.SubTable[0].ligatures
    for first_char, ligtable in ligatures.iteritems():
        ligatures_to_delete = []
        for index, ligature in enumerate(ligtable):
            assert len(ligature.Component) == 1
            component = ligature.Component[0]
            if (component.endswith('comb')
                or component in ['commaaccent',
                                 'commaaccentrotate',
                                 'ringacute']):
                continue
            # https://code.google.com/a/google.com/p/roboto/issues/detail?id=54
            if first_char == 'a' and component == 'uni02BE':
                ligatures_to_delete.append(index)
                continue
            char = reverse_cmap[component]
            general_category = unicode_data.category(char)
            if general_category != 'Mn': # not a combining mark
                ligature.Component[0] = _MAP_SPACING_TO_COMBINING[component]
        ligatures[first_char] = [
            ligature for (index, ligature) in enumerate(ligtable)
            if index not in ligatures_to_delete]


def apply_temporary_fixes(font):
    """Apply some temporary fixes.
    """
    # Make sure macStyle is correct
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=8
    font_name = get_font_name(font)
    bold = ('Bold' in font_name) or ('Black' in font_name)
    italic = 'Italic' in font_name
    font['head'].macStyle = (italic << 1) | bold

    # Mark the font free for installation, embedding, etc.
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=29
    os2 = font['OS/2']
    os2.fsType = 0

    # Set the font vendor to Google
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=46
    os2.achVendID = 'GOOG'

    # Drop the lookup forming the ff ligature
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=47
    drop_lookup(font['GSUB'], 5)

    # Correct the ccmp lookup to use combining marks instead of spacing ones
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=48
    fix_ccmp_lookup(font)

    # Fix the digit widths
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=49
    fix_digit_widths(font)

    # Add cmap for U+2117 SOUND RECORDING COPYRIGHT
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=44
    font_data.add_to_cmap(font, {0x2117: 'published'})

    # Fix version number from buildnumber.txt
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=50
    from datetime import date

    build_number_txt = path.join(
        path.dirname(__file__), os.pardir, 'res', 'buildnumber.txt')
    build_number = open(build_number_txt).read().strip()

    version_record = 'Version 2.%s; %d' % (build_number, date.today().year)

    for record in font['name'].names:
        if record.nameID == 5:
            if record.platformID == 1 and record.platEncID == 0:  # MacRoman
                record.string = version_record
            elif record.platformID == 3 and record.platEncID == 1:
                # Windows UCS-2
                record.string = version_record.encode('UTF-16BE')
            else:
                assert False


def apply_android_specific_fixes(font):
    """Apply fixes needed for Android."""
    # Set ascent, descent, and lineGap values to Android K values
    hhea = font['hhea']
    hhea.ascent = 1900
    hhea.descent = -500
    hhea.lineGap = 0

    # Remove combining keycap and the arrows from the cmap table:
    # https://code.google.com/a/google.com/p/roboto/issues/detail?id=52
    font_data.delete_from_cmap(font, [
        0x20E3, # COMBINING ENCLOSING KEYCAP
        0x2191, # UPWARDS ARROW
        0x2193, # DOWNWARDS ARROW
        ])

    # Drop tables not useful on Android
    for table in ['LTSH', 'hdmx', 'VDMX', 'gasp']:
        if table in font:
            del font[table]


def correct_font(source_font_name, target_font_name):
    """Corrects metrics and other meta information."""
    font = ttLib.TTFont(source_font_name)
    apply_temporary_fixes(font)
    apply_android_specific_fixes(font)
    font.save(target_font_name)


def main(argv):
    """Correct the font specified in the command line."""
    correct_font(argv[1], argv[2])


if __name__ == "__main__":
    main(sys.argv)