[XeTeX] [tex-live] Problem with ocrb10.otf ligature 'fi'

[Zdenek Wagner]

2011/6/13 Pander <pander at users.sourceforge.net>:
> On 2011-06-13 15:27, Zdenek Wagner wrote:
>> 2011/6/13 Pander <pander at users.sourceforge.net>:
>>> TeX Live list members: see full thread here:
>>> http://tug.org/pipermail/xetex/2011-June/020681.html for now keep the
>>> discussion at XeTeX's list.
>>>
>>> On 2011-06-13 14:22, mskala at ansuz.sooke.bc.ca wrote:
>>>> On Mon, 13 Jun 2011, Pander wrote:
>>>>> TeX Live 2010
>>>>>
>>>>> /usr/local/texlive/2010/texmf-dist/fonts/opentype/public/ocr-b-outline/ocrb10.otf
>>>>
>>>> That is Zdeněk Wagner's auto-conversion of Norbert Schwarz's Metafont
>>>> source.  It doesn't contain f-ligatures no matter what the GSUB table may
>>>> say.  I took a look at it with Fontforge and I see that it contains a GSUB
>>>> table pointing the ligatures at "alternate" and added non-ASCII characters
>>>> from the Schwarz version, some of which happen to be ligature-like but not
>>>> the correct ones.  For instance, "fl" points at the Æ glyph.
>>>>
>>>> I recogize that pattern because it happened in an earlier version of my
>>>> own version of the font, as a result of auto-conversion.  The thing is,
>>>> Schwarz's Metafont files used a nonstandard custom encoding.  If you
>>>> simply convert the font code point for code point to whatever the default
>>>> 8-bit Adobe encoding might be, you end up with Schwarz's extra glyphs at
>>>> the "f-ligature" code points (as well as some distortions at quotation
>>>> mark, dotless i and j, and similar code points).  The existence of a GSUB
>>>> table pointing at those points can probably be explained by defaults from
>>>> the auto-conversion.  So in summary, yes, it's a bug in the font.
>>>
>>> Could the conversion software generate a warning when it recognises such
>>> a situation?
>>>
>> The fonts were first converted to PFB by mftrace, then opened in
>> FontForge and saved as OTF. No warning was displayed.
>
> Sorry, I mean, should those software packages be improved to generate
> warnings for these kind of situations to prevent it in the future?
>
Yes, it would certainly be helpful. Since mftrace is a python script
running mf and potrace together with (or inside of) FontForge, it
should probably be reported to FontForge developers. I do not know
pythom myself, I am not a font expert, I just used the tool as a black
box.


-- 
Zdeněk Wagner
http://hroch486.icpf.cas.cz/wagner/
http://icebearsoft.euweb.cz