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.
