Small caps problem/bug with some fonts

Small caps problem/bug with some fonts

[Mika Ritola]

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Hello all,

For some reason, the snippet below outputs 'ThOMAS' instead of 'THOMAS.'
This seems to be font dependent; at least Adobe Jenson Pro and Adobe
Garamond Pro produce 'Th,' while the other fonts that I've tried produce
'TH', as expected. I don't know whether the bug exists in the fonts
themselves or in the way they are handled by ConTeXt or the Simplefonts
module, or possibly some other part of the system. In any case, could you
suggest a work-around, please?

I'm using ConText version 2009.09.16 20:07 and Simplefonts version
2009.09.15.


\usemodule[simplefonts]
\setmainfont[Adobe Jenson Pro]

\starttext
{\sc Thomas}
\stoptext


Thanks in advance,

Mika

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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Mika Ritola wrote:
> Hello all,
> 
> For some reason, the snippet below outputs 'ThOMAS' instead of 'THOMAS.'
> This seems to be font dependent; at least Adobe Jenson Pro and Adobe
> Garamond Pro produce 'Th,' while the other fonts that I've tried produce
> 'TH', as expected. I don't know whether the bug exists in the fonts
> themselves or in the way they are handled by ConTeXt or the Simplefonts
> module, or possibly some other part of the system. In any case, could you
> suggest a work-around, please?
> 
> I'm using ConText version 2009.09.16 20:07 and Simplefonts version
> 2009.09.15.
> 
> 
> \usemodule[simplefonts]
> \setmainfont[Adobe Jenson Pro]
> 
> \starttext
> {\sc Thomas}
> \stoptext

could it be a bug in the font? i.e. a Th ligature showing up in 
smallcaps? if so, then simplefonts should disable ligatures in smallcaps

Hans

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Re: Small caps problem/bug with some fonts

[Derek CORDEIRO]

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On Fri, Sep 18, 2009 at 6:44 PM, Hans Hagen <pragma@wxs.nl> wrote:

> Mika Ritola wrote:
>
>> Hello all,
>>
>> For some reason, the snippet below outputs 'ThOMAS' instead of 'THOMAS.'
>> This seems to be font dependent; at least Adobe Jenson Pro and Adobe
>> Garamond Pro produce 'Th,' while the other fonts that I've tried produce
>> 'TH', as expected. I don't know whether the bug exists in the fonts
>> themselves or in the way they are handled by ConTeXt or the Simplefonts
>> module, or possibly some other part of the system. In any case, could you
>> suggest a work-around, please?
>>
>> I'm using ConText version 2009.09.16 20:07 and Simplefonts version
>> 2009.09.15.
>>
>>
>> \usemodule[simplefonts]
>> \setmainfont[Adobe Jenson Pro]
>>
>> \starttext
>> {\sc Thomas}
>> \stoptext
>>
>

That does not work for me at all. The following does work with generating
the same ThOMAS

\usemodule[simplefonts]

\setmainfont[A Jenson Pro Regular]

\starttext
{\sc Thomas}
\stoptext




>
> could it be a bug in the font? i.e. a Th ligature showing up in smallcaps?
> if so, then simplefonts should disable ligatures in smallcaps
>

I doubt it is a font bug as the following plain luatex works.

\font\body=file:AJensonPro-Regular:mode=node;script=latn;language=dflt;+liga;+dlig;+smcp
at 12pt

\body Thomas

\bye

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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Derek CORDEIRO wrote:

> That does not work for me at all. The following does work with generating
> the same ThOMAS

can you try ..

\definefontfeature[smallcaps][smallcaps][liga=no]

\usemodule[simplefonts]

\setmainfont[A Jenson Pro Regular]

\starttext
{\sc Thomas}
\stoptext

if that works, then the font is bugged

i cannot test it here as i don't have those fonts

Hans

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Re: Small caps problem/bug with some fonts

[Derek CORDEIRO]

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On Fri, Sep 18, 2009 at 11:24 PM, Hans Hagen <pragma@wxs.nl> wrote:

> Derek CORDEIRO wrote:
>
>  That does not work for me at all. The following does work with generating
>> the same ThOMAS
>>
>
> can you try ..
>
> \definefontfeature[smallcaps][smallcaps][liga=no]
>
> \usemodule[simplefonts]
>
> \setmainfont[A Jenson Pro Regular]
>
> \starttext
> {\sc Thomas}
> \stoptext
>
> if that works, then the font is bugged
>

Yes it does work, I guess the font has bugs after all.


Regards,
Derek

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Re: Small caps problem/bug with some fonts

[Barry Schwartz]

Derek CORDEIRO <derekcordeiro@gmail.com> skribis:
> On Fri, Sep 18, 2009 at 11:24 PM, Hans Hagen <pragma@wxs.nl> wrote:
> 
> > Derek CORDEIRO wrote:
> >
> >  That does not work for me at all. The following does work with generating
> >> the same ThOMAS
> >>
> >
> > can you try ..
> >
> > \definefontfeature[smallcaps][smallcaps][liga=no]
> >
> > \usemodule[simplefonts]
> >
> > \setmainfont[A Jenson Pro Regular]
> >
> > \starttext
> > {\sc Thomas}
> > \stoptext
> >
> > if that works, then the font is bugged
> >
> 
> Yes it does work, I guess the font has bugs after all.

If base mode uses the traditional TeX mechanism for ligatures, I don't
see any way the font can be blamed.




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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Barry Schwartz wrote:

> If base mode uses the traditional TeX mechanism for ligatures, I don't
> see any way the font can be blamed.

sure

Hans

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Re: Small caps problem/bug with some fonts

[Barry Schwartz]

Hans Hagen <pragma@wxs.nl> skribis:
> Barry Schwartz wrote:
> 
> > If base mode uses the traditional TeX mechanism for ligatures, I don't
> > see any way the font can be blamed.

Ant does the same thing, I believe, using the OT tables and heuristics
to run the TeX processor. That's okay, as long as the results aren't
blamed on the font. :)


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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Barry Schwartz wrote:
> Hans Hagen <pragma@wxs.nl> skribis:
>> Barry Schwartz wrote:
>>
>>> If base mode uses the traditional TeX mechanism for ligatures, I don't
>>> see any way the font can be blamed.
> 
> Ant does the same thing, I believe, using the OT tables and heuristics
> to run the TeX processor. That's okay, as long as the results aren't
> blamed on the font. :)

well, that's alway sa bit hard to determine, maybe not in this case but 
there definitely are dubious cases and heuristics that works in one case 
migh tfail in another; also, as context base mode is mostly meant for 
simple cases (and as said, it might be wise in the case of snallcaps to 
not enable ligatures) and therefore suits most cases, but as reference 
(and for more advanced work) node mode has to be used ... actually, when 
users report bugs with fonts i kind of assume node mode

in the perspective of the oriental tex project (related to luatex/mkiv) 
a complex font is being made and quite some time goes into figuring out 
what exactly the common ground in ot is (we've decided to settle for 
uniscribe/volt for final decisions as that's the most advanced machinery)

for instance there are more combinations possible on otf than the font 
generating programs can handle and some combinations are only handled by 
some renderers. of course the mkiv machinery can be blamed for much, but 
so can the specification itself, the font generating tools as wel as fonts

the best we can do is to try to deal with all but eventually i think 
that i'll end up with a couple of extra features / checks / etc; there's 
also already a patch mechanism in place

having more advanced fonts is nice, but unfortunately (for commercial 
reasons, or for stability reasons or ...) font vendors have no real bug 
fix and upgrade policy but at least i can fix my own bugs -)

btw, in most cases it helps to nail down problems when we have the font, 
which not always is the case, so in such cases we might need to gamble 
where the problem sits

Hans


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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Derek CORDEIRO wrote:

> \usemodule[simplefonts]

Question for wolfgang ... do you enable node mode?

in basemode, it might be that ligatures are loaded after smallcaps (and 
base mode is static) and then it's the order of features in the font 
that determines what happens,

if so, then maybe we should disable ligatures in the smallcaps 
featureset definition (as i don't expect many smallcaps ligs anyway and 
it might be less confusing)

Hans

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Re: Small caps problem/bug with some fonts

[Wolfgang Schuster]

Am 18.09.2009 um 19:57 schrieb Hans Hagen:

> Question for wolfgang ... do you enable node mode?

No.

Wolfgang

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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Derek CORDEIRO wrote:

> That does not work for me at all. The following does work with generating
> the same ThOMAS

another test:

\definefontfeature[default]  [default]  [mode=node]
\definefontfeature[smallcaps][smallcaps][mode=node]
\definefontfeature[oldstyle] [oldstyke] [mode=node]

Hans

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Re: Small caps problem/bug with some fonts

[Derek CORDEIRO]

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On Fri, Sep 18, 2009 at 11:31 PM, Hans Hagen <pragma@wxs.nl> wrote:

> Derek CORDEIRO wrote:
>
>  That does not work for me at all. The following does work with generating
>> the same ThOMAS
>>
>
> another test:
>
> \definefontfeature[default]  [default]  [mode=node]
> \definefontfeature[smallcaps][smallcaps][mode=node]
> \definefontfeature[oldstyle] [oldstyle] [mode=node]
>
>
This works well too.

Regards,
Derek

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Re: Small caps problem/bug with some fonts

[Barry Schwartz]

Hans Hagen <pragma@wxs.nl> skribis:
> could it be a bug in the font? i.e. a Th ligature showing up in 
> smallcaps? if so, then simplefonts should disable ligatures in smallcaps

I'm looking at AGaramondPro-Regular in fontforge and it has the lookup
for small caps well above the lookup for ligatures. The software must
be reading the lookup table out of order.

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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Barry Schwartz wrote:
> Hans Hagen <pragma@wxs.nl> skribis:
>> could it be a bug in the font? i.e. a Th ligature showing up in 
>> smallcaps? if so, then simplefonts should disable ligatures in smallcaps
> 
> I'm looking at AGaramondPro-Regular in fontforge and it has the lookup
> for small caps well above the lookup for ligatures. The software must
> be reading the lookup table out of order.

no, it's just that basemode gets two features and replacement and 
ligatures are both applied due to the definition of the smallcaps 
featureset, so it's expected behaviour

- either adapt the definition of the smallcaps featureset (i'll do that 
in the next beta)
- or switch to nodemode (in your case nodemode applies smallcaps before 
ligatures)

Hans

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Re: Small caps problem/bug with some fonts

[Barry Schwartz]

Hans Hagen <pragma@wxs.nl> skribis:
> Barry Schwartz wrote:
> > Hans Hagen <pragma@wxs.nl> skribis:
> >> could it be a bug in the font? i.e. a Th ligature showing up in 
> >> smallcaps? if so, then simplefonts should disable ligatures in smallcaps
> > 
> > I'm looking at AGaramondPro-Regular in fontforge and it has the lookup
> > for small caps well above the lookup for ligatures. The software must
> > be reading the lookup table out of order.
                   ^^^^^^^^^^^^

I should have said "lookup list table".

> 
> no, it's just that basemode gets two features and replacement and 
> ligatures are both applied due to the definition of the smallcaps 
> featureset, so it's expected behaviour

The font is unambiguous about it, though. Are you sure the software
isn't performing the feature list in order rather than lookup list? Or
is the software performing substitutions in its own ad hoc order?

Now I _make_ opentype fonts with small caps and ligatures and so want
the software to do what I tell it (except when it was I who made the
error).  :)


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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Barry Schwartz wrote:

> The font is unambiguous about it, though. Are you sure the software
> isn't performing the feature list in order rather than lookup list? Or
> is the software performing substitutions in its own ad hoc order?

in basemode we use built in traditional tex methods, so only ligatures 
and kerning; as a bonus i also support replacements, but in base mode 
the user really has to know what he/she asks for; in thsi particular 
case, asking for both ligatures (not contextual btw) and repacements 
(smsc) one gets them combined

so, this is why there is (the somewhat slower but more conforming) node 
mode as well; in that case (contextual) lookups are taken care of

but even then, if a font is not clear about issues, then one can get 
unwanted side effects (the frac feature for instance is often quite 
bugged and can only be applied selectively)

also, in context mkiv we have variants like dynamic features, user 
defined features, strategies etc (after all, nothing can stop us from 
doing a better job)

> Now I _make_ opentype fonts with small caps and ligatures and so want
> the software to do what I tell it (except when it was I who made the
> error).  :)

well, as said ... base mode has some known limitations and if you want 
the whole lot, you should use node mode (fyi: apart from isolated 
features we also support mixtures; the open type font format makes no 
assumptions about tags and gpos/gsub application so for instance the 
smallcaps feature might use one-to-one subsititutions as well as any 
other kind and complex fonts (like idris arabic font) does that)

(maybe simplefonts should default to node mode)

Hans

ps. if you run (as i demonstrated at the eurotex/context conference)

mtxrun --script server --auto

you can access an interactive features tester in your webbrouwser

there is also a trace option there where you can see what happens (in 
node mode)

Hans

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Re: Small caps problem/bug with some fonts

[Barry Schwartz]

Hans Hagen <pragma@wxs.nl> skribis:
> but even then, if a font is not clear about issues, then one can get 
> unwanted side effects (the frac feature for instance is often quite 
> bugged and can only be applied selectively)

Yeah, I think trying to be fancy with contextual substitutions is a
bit like getting drunk. I'm not even sure why there was a "frac" tag
when it was originally intended to be converted to "numr" and "dnom"
tags.

(I just looked at
http://www.microsoft.com/typography/otspec160/features_fj.htm#frac
to see what it says nowadays and now want to go get drunk.)



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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Barry Schwartz wrote:
> Hans Hagen <pragma@wxs.nl> skribis:
>> but even then, if a font is not clear about issues, then one can get 
>> unwanted side effects (the frac feature for instance is often quite 
>> bugged and can only be applied selectively)
> 
> Yeah, I think trying to be fancy with contextual substitutions is a
> bit like getting drunk. I'm not even sure why there was a "frac" tag
> when it was originally intended to be converted to "numr" and "dnom"
> tags.
> 
> (I just looked at
> http://www.microsoft.com/typography/otspec160/features_fj.htm#frac
> to see what it says nowadays and now want to go get drunk.)

actually the frac featurs, like most features is a rather generic one 
and as such it should work out of the box (some of the justitication 
features use gpos and/or assume specific renderer support, and some of 
that is rather undefined)

so, its not that frac itself is the problem dealing with in the engine, 
because if so, many features would be a problem, it's just that font 
makers stick to a couple of simple rules like:

(1) replace all
       <digits> <slash> <digits>
     by
       <sup digits> <overlapping frac slash> <sub digits>

(1) replace all
       <digits> <slash> <digits>
     by
       <sup digits> <overlapping frac slash> <sub digits>

and if they have rule 2, it will mess up things like a/b

of course it can be properly dealt with ... just make proper rules

now, one reason that metafont kind of design tools never were accepted 
as basic tool for font design is that designers are no programmers; and 
one needs programmers (or at least some of the related mindset) to make 
the more complex ot fonts (or one needs teams)

actually, as many fonts do have the sup/sub digits its rather trivial to 
provide proper frac's in mkiv but till now i had no reason (time, 
project, etc) for doing it

i fear the moment when designers start giving me rules like "use this or 
that font and turn on those features" assuming dtp like control and 
tweaking of the text (one reason for spending much time on fonts in mkiv 
is that it will give me control over bad behaving fonts; think of wrong 
glyph to unicode mapping and such)



Hans

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Re: Small caps problem/bug with some fonts

[Barry Schwartz]

Hans Hagen <pragma@wxs.nl> skribis:
> so, its not that frac itself is the problem dealing with in the engine, 
> because if so, many features would be a problem, it's just that font 
> makers stick to a couple of simple rules like:
> 
> (1) replace all
>        <digits> <slash> <digits>
>      by
>        <sup digits> <overlapping frac slash> <sub digits>
> 
> (1) replace all
>        <digits> <slash> <digits>
>      by
>        <sup digits> <overlapping frac slash> <sub digits>
> 
> and if they have rule 2, it will mess up things like a/b

Is rule (2) missing? I see (1) twice.

Are there fonts that have a or b in the "numr" and "dnom" features but
where they do not work in "frac"?

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Re: Small caps problem/bug with some fonts

[Hans Hagen]

Barry Schwartz wrote:

> Are there fonts that have a or b in the "numr" and "dnom" features but
> where they do not work in "frac"?

that is unrelated, the replacement rules refer to glyphs an doften they 
stick to digits so you get a/b with a large a and b and the fractional 
slash which then gives an ugly overlap

Hans


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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
      tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
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