1OT2KPX(1)                        Marc Penninga                       OT2KPX(1)
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NAME

6       ot2kpx - extract kerning information from OpenType fonts
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SYNOPSIS

9       ot2kpx [ -afm | -kpx | -lua ] <fontfile>
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DESCRIPTION

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

17       -help
18           Print a short help text and exit.
19
20       -version
21           Print ot2kpx's version and exit.
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23       -afm, -kpx
24           Output the kerning data in Adobe's KPX format, as used in afm
25           files.  This is the default output format.
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27       -lua
28           Output the kerning data as a Luatex custom font feature, to be
29           included in a "\directlua" command.
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31       <fontfile>
32           The OpenType font (both otf and ttf format are supported).
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RESTRICTIONS

35       -   ot2kpx doesn't implement all of the OpenType specification.  Things
36           that are missing include: support for font files containing
37           multiple fonts, LookupTables with LookupTypes other than 2, "kern"
38           tables with format other than 0 and ValueRecords with other types
39           of data than just XAdvance data.
40
41           Most of these limitations won't matter, since the missing features
42           are rare (the only fonts I know of that use them are the non-
43           western fonts that come with Adobe Reader). Furthermore, many of
44           these features define (according to the OpenType specification)
45           "subtle, device-dependent adjustments at specific font sizes or
46           device resolutions"; since there's no way to express such
47           adjustments in afm format, ignoring them seems to be the only
48           option anyway.
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50       -   ot2kpx collects kerning data first from the "kern" table, then from
51           all LookupTables associated with the "kern" feature; if a kerning
52           pair occurs multiple times, the first value seen is chosen.  There
53           are (or may be) several issues with this approach:
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55           -   The OpenType specification says that fonts in otf format
56               shouldn't use the "kern" table at all, just the lookups from
57               the "GPOS" table.  Many such fonts do, however, contain a
58               "kern" table, but no "GPOS" table; so we use the "kern" table
59               anyway.
60
61           -   Instead of reading all LookupTables, it might be better to let
62               the user specify a script and language and process only the
63               LookupTables for those values.  However, at least in the fonts
64               I checked, all script/language combinations eventually point to
65               the same "kern" LookupTables, so this approach wouldn't make
66               any difference (apart from further complicating the code).
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AUTHOR

69       Marc Penninga <marcpenninga@gmail.com>
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72       Copyright (C) 2005-2023 Marc Penninga.
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LICENSE

75       This program is free software; you can redistribute it and/or modify it
76       under the terms of the GNU General Public License as published by the
77       Free Software Foundation, either version 2 of the License, or (at your
78       option) any later version.  A copy of the GNU General Public License is
79       included with ot2kpx; see the file GPLv2.txt.
80

DISCLAIMER

82       This program is distributed in the hope that it will be useful, but
83       WITHOUT ANY WARRANTY; without even the implied warranty of
84       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
85       General Public License for more details.
86

VERSION

88       This document describes ot2kpx version 20230201.
89

RECENT CHANGES

91       (See the source code for the rest of the story.)
92
93       2019-05-20  Added the -version option.
94
95       2019-04-15  Added the -lua command-line option to get output in
96                   Luatex's custom feature format.
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100fontools                          2023-02-01                         OT2KPX(1)
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