Export old-style non-OpenType "kern" table

Ray Larabie

In FontLab, under Options/Generating OpenType & TrueType/Kerning there's an option for Export old-style non-OpenType "kern" table. In the past, this was necessary because so few applications supported OT hinting tables. Now we live in a futuristic font utopia where all our dreams have been realized. Should I turn this thing off now? To be honest, I just kind of forgot it was there.

James Puckett

I don't think I've ever put a non-OpenType kern feature in a font, unless Glyphs does so quietly. Nobody complains.

PabloImpallari

Yes, turn it off. In particular for webfonts, 'cause you want them to be smaller.

Christoph Koeberlin

It’s recommended to put GPOS kerning into CFF-based fonts and (TT-based) webfonts. In TT-based fonts for desktop use (especially MS Office), a kern table (and no GPOS kerning) should be included.

Georg Seifert

To get GPOS kerning to work in Office can be tricky but is very much possible. Works fine in Office 2001 for Windows (that is the oldest version I have to test) and office for Mac.

It is not that the GPOS table causes the problems but some other issues that might cause validation problems. Like the lengt of the family name. 

LeMo aka PatternMan aka Frank E Blokland

In TT-based fonts for desktop use (especially MS Office), a kern table (and no GPOS kerning) should be included.

TrueType-flavored OpenType fonts may contain both the ‘kern’ and the ‘GPOS’ table. My recommendation is to put both in such a font.

Erwin Denissen

The old kern table is legacy which is not supported with fonts with CFF outlines, as back then it was clear GPOS is way more powerful. In my opinion it should only be considered for backwards compatibility reasons in respect to OpenType fonts with TrueType based outlines. So I recommend to exclude this from new fonts.

Ray Larabie

Thanks everyone for the insight. I think I'll keep including the old kern tables. It's not an issue for my webfonts since the old kern table gets stripped out during conversion anyway. I figure, when I'm selling application licences, my TTF fonts are getting used in various game engines, some with presumably pared-down/ancient type rendering systems.

I always limit the old kern table to 2500 pairs. I find this usually takes care of the important stuff such as period, hyphen, and quote parents. It usually ends up covering the Latin1 set too.

Christoph Koeberlin

LeMo aka Frank E Blokland said:

TrueType-flavored OpenType fonts may contain both the ‘kern’ and the ‘GPOS’ table. My recommendation is to put both in such a font.

I’ve seen cases where this led to very strange results, like apps adding the values from kern to those from GPOS*. I never put both in one font.

*) Though unfortuantely I can’t remember where.

LeMo aka PatternMan aka Frank E Blokland

I’ve seen cases where this led to very strange results, like apps adding the values from kern to those from GPOS*. I never put both in one font.

Ah… that’s interesting! We have never encountered that with DTL’s TT-flavored OT fonts and also never heard of this before. I would very much like to see examples (and hence a good reason to change the production over here).

Christoph Koeberlin

Since I cannot remember where the problems occured, and my revisit of Dr. Willrodt’s OpenType status of 2009 didn’t prove me right, my suggestion might not be better than yours!

Michael Jarboe

OpenType is the future.

LeMo aka PatternMan aka Frank E Blokland

Hi Christoph,

Although I have never encountered the problem you described, it’s always possible that strange things happen. So, whenever you recall how and where the interference of the two tables occurred, please let me know.

Concerning the OpenType status PDF, it’s time for an update, I reckon.

Christoph Koeberlin

LeMo aka Frank E Blokland said:

So, whenever you recall how and where the interference of the two tables occurred, please let me know.

I’ll do so!

Concerning the OpenType status PDF, it’s time for an update, I reckon.

Yes, that’d be great! Though for backwards compatibility, it’s still good.

Thomas Phinney

I suggest you ask some of our Adobe friends; I could swear the interference was something we ran into "back in the day."

John Hudson

The last time we included both kern table and GPOS kerning in a TT font was in 2003. Actually, we didn't include the kern table: Microsoft added (subset) kern tables to the CT Collection fonts for backwards compatibility in Office. Since then, we've never been asked to provide kern tables for other Microsoft fonts, nor have they been added by Microsoft. And the kern tables in the CT Collection fonts were frozen a long time ago and not updated for extensions to the fonts, which are kerned only in GPOS.

Michael Vokits

OpenType is indeed the future, but the present has more in common with the past. Given the prevalence of Word, Abiword, LibreOffice, OpenOffice, and pretty much every word processor or office suite (or game engine!) – all of which use only the old-style kerning table for TrueType fonts – not exporting the table would leave an awful lot of people without kerning. I understand that very recent versions of Word are more up to date in this regard. Are there others?

Anyway, backwards compatibility sucks, but it makes sense.

John Hudson

GPOS kerning for TrueType in Word may be dependent on presence of DSIG table. Gabriola's GPOS-only kerning works (Word 2013), but that of a TTF without a DSIG does not. Too tired to test further or look for other differentials now.

Paul van der Laan

OpenType is indeed the future, but the present has more in common with the past. Given the prevalence of Word, Abiword, LibreOffice, OpenOffice, and pretty much every word processor or office suite (or game engine!) – all of which use only the old-style kerning table for TrueType fonts – not exporting the table would leave an awful lot of people without kerning. I understand that very recent versions of Word are more up to date in this regard. Are there others?

OpenType is the present already for more than ten years I would say. And if open source software such as Abiword, LibreOffice or OpenOffice fails to support current standards then I’m sure there will be some volunteers to fix this?

attar

> I’m sure there will be some volunteers to fix this?

@Khaled%20Hosny proposed help to Scribus some time ago but said the developers just don't care. Previously he started implementing harfbuzz for LibreOffice as well but that didn't went to completion.

Khaled Hosny

LibreOffice uses HarfBuzz on Linux and Core Text on Mac, so it supports OpenType kerning on both, as well as other default OpenType features. On Windows old releases used some ancient Windows APIs, but the latest release have OpenType kerning and other default features as well. OpenOffice is dead as far as I’m concerned, no ideas about AbiWord but it was born dead anyway.

Ray Larabie

I wonder if it's safe to assume that game engines support GPOS kerning? Unity and Unreal support kerning and they can also import OTF. I'm not sure about Source 2 or Cryengine. App/game sales are a large percentage of my sales these days so I want to make sure my kerning works. Any game devs reading this thread?

Michael Vokits

How recent for LibreOffice? 5.0.2.2 x64 for Windows definitely doesn’t use OT kerning:


Bummer. Got my hopes up, ya know? Same results when using a dummy dsig (“Gentium Bis,” I named the resulting variant). Ah well, I’ve been switching to LaTeX anyway, and pretty much every browser has good OT support.

Not everybody can update things... a great many people are still on archaic technology, whether from poverty, morality or bureaucratic decree. There are excellent reasons to abandon them (us, actually), but it still feels a little cold.

Not that it’s a big deal – it’s just kerning, after all!

Khaled Hosny

Not being a regular WIndows user/developer myself, I was relaying on second hand information about Windows and it seems to have been wrong. I’m sure about Linux and Mac OS X support though, as I was responsible for the HarfBuzz and (partially) the Core Text port myself. It is pretty hard to find good software developers who are also knowledgeable about text layout (I’m not even a software developer myself, let alone be a good one).

Michael Vokits

@Khaled: No worries. Sorry if I offended you – I’m a touch autistic, and tend to rub people the wrong way without realizing it. fwiw, OTFs and TTFs with a kern table work very well in LibreOffice.

Thomas Phinney

LibreOffice font handling is pretty awful, as I recall. Earlier this year when I was eager to switch from MS Word, I tried it out and found that the Word bugs I hated in Word 2011 Mac were more-or-less the same bugs in LibreOffice.  

Michael Vokits

Not sure if anybody is still following this, but no matter. Gentium doesn’t work correctly in the Linux version of LibreOffice either, so it’s not just a Windows thing. Still, plenty of fonts work fine – contextual alternates in a word processor was a very welcome surprise.

Thomas Phinney

I was using the Mac version of LibreOffice. I was pretty saddened and gave up after a day or two.

Ray Larabie

I having difficultly generating TrueType old-style kerning tables from Windows FontLab Studio 5.22. If I have a font with class-based kerning and Greek, Vietnamese, Cyrillic and such, some really basic pairs aren't making it into the first 10,000 pairs so they get cut off. There seems to be no logic to the expansion priority. It will export loads of useless pairs like the Irish W accents with Vietnamese but often basic pairs like FATAVAWATA are omitted. I don't expect old-style kerning to be perfect, but I expect A-Z to work. Whether or not glyphs are class parents seems to have no bearing on the expansion.

LeMo aka PatternMan aka Frank E Blokland

Have you ever tried to open a CFF-flavored OT font containing class kerning in FontForge and to subsequently export the font with as additional option the generation of an AFM file?

Ray Larabie

@LeMo aka Frank E Blokland
I just tried it but it doesn't expand the class kerns. I tried various formats and the old-style kerning checkbox but the AFM contains exactly the same table as the original CFF-flavored OT font containing class kerning. I couldn't find an option to manually expand the table.