DESCRIPTIONot2kpx extract the kerning data from OpenType fonts (both otf and ttf formats) and prints it (in afm format) to "stdout".
OPTIONS AND ARGUMENTS
- The OpenType font (in either otf or ttf format).
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).
AUTHORMarc Penninga <[email protected]>
COPYRIGHTCopyright (C) 2005-2013 Marc Penninga.
LICENSEThis 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.
DISCLAIMERThis 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.)
- Replaced all "given/when" constructions in the source code by "if"'s, to avoid warnings about experimental features in Perl 5.18 and later.
Refactored the code, and fixed a number of bugs in the process.
Updated the documentation.