ot2kpx

OT2KPX(1)                        Marc Penninga                       OT2KPX(1)

NAME
       ot2kpx - extract kerning information from OpenType fonts

SYNOPSIS
       ot2kpx [ -afm | -kpx | -lua ] <fontfile>

DESCRIPTION
       ot2kpx extract the kerning data from OpenType fonts and prints it to
       "stdout", either in Adobe's KPX format (for adding to an afm file) or
       as a Luatex custom feature, for use with the "\directlua" command.

OPTIONS AND ARGUMENTS
       -help
           Print a short help text and exit.

       -version
           Print ot2kpx's version and exit.

       -afm, -kpx
           Output the kerning data in Adobe's KPX format, as used in afm
           files.  This is the default output format.

       -lua
           Output the kerning data as a Luatex custom font feature, to be
           included in a "\directlua" command.

       <fontfile>
           The OpenType font (both otf and ttf format are supported).

RESTRICTIONS
       -   ot2kpx doesn't implement all of the OpenType specification.  Things
           that are missing include: support for font files containing
           multiple fonts, LookupTables with LookupTypes other than 2, "kern"
           tables with format other than 0 and ValueRecords with other types
           of data than just XAdvance data.

           Most of these limitations won't matter, since the missing features
           are rare (the only fonts I know of that use them are the non-
           western fonts that come with Adobe Reader). Furthermore, many of
           these features define (according to the OpenType specification)
           "subtle, device-dependent adjustments at specific font sizes or
           device resolutions"; since there's no way to express such
           adjustments in afm format, ignoring them seems to be the only
           option anyway.

       -   ot2kpx collects kerning data first from the "kern" table, then from
           all LookupTables associated with the "kern" feature; if a kerning
           pair occurs multiple times, the first value seen is chosen.  There
           are (or may be) several issues with this approach:

           -   The OpenType specification says that fonts in otf format
               shouldn't use the "kern" table at all, just the lookups from
               the "GPOS" table.  Many such fonts do, however, contain a
               "kern" table, but no "GPOS" table; so we use the "kern" table
               anyway.

           -   Instead of reading all LookupTables, it might be better to let
               the user specify a script and language and process only the
               LookupTables for those values.  However, at least in the fonts
               I checked, all script/language combinations eventually point to
               the same "kern" LookupTables, so this approach wouldn't make
               any difference (apart from further complicating the code).

AUTHOR
       Marc Penninga <marcpenninga@gmail.com>

COPYRIGHT
       Copyright (C) 2005-2020 Marc Penninga.

LICENSE
       This program is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as published by the
       Free Software Foundation, either version 2 of the License, or (at your
       option) any later version.  A copy of the GNU General Public License is
       included with ot2kpx; see the file GPLv2.txt.

DISCLAIMER
       This program is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       General Public License for more details.

VERSION
       This document describes ot2kpx version 20200129.

RECENT CHANGES
       (See the source code for the rest of the story.)

       2019-05-20  Added the -version option.

       2019-04-15  Added the -lua command-line option to get output in
                   Luatex's custom feature format.

fontools                          2020-01-29                         OT2KPX(1)