ot2kpx

OT2KPX(1)                        Marc Penninga                       OT2KPX(1)

NAME
       ot2kpx - extract kerning information from OpenType fonts

SYNOPSIS
       ot2kpx  fontfile

DESCRIPTION
       ot2kpx extract the kerning data from OpenType fonts (both otf and ttf
       formats) and prints it (in afm format) to "stdout".

OPTIONS AND ARGUMENTS
       fontfile
           The OpenType font (in either otf or ttf format).

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) 2005-2013 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.

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

       2013-08-07  Replaced all "given/when" constructions in the source code
                   by "if"'s, to avoid warnings about experimental features in
                   Perl 5.18 and later.

       2012-02-01  Refactored the code, and fixed a number of bugs in the
                   process.  Updated the documentation.

fontools                          2013-08-07                         OT2KPX(1)
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