[XeTeX] Problem with ocrb10.otf ligature 'fi'

[mskala at ansuz.sooke.bc.ca]

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.

The current version of my own OCR B fonts, available on ansuz.sooke.bc.ca,
is also based on Schwarz's, but via a more manual conversion process
(rewriting the Metafont sources to work with MetaType1), and I've
attempted to put all glyphs at their correct Unicode code points.  It
contains a GSUB table for alternate forms of glyphs, but none for
ligatures.

> > I just downloaded the demo from here:
> >       http://www.barcodesoft.com/ocr_font.aspx

> Maybe TeX Live should use these OTF files?

Barcodesoft's "free" version is a watermarked demo of an expensive
commercial product, basically just an advertisement, and for that reason I
wouldn't recommend its distribution in TeXLive; I'm not even sure that the
license agreement would allow such distribution.
-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before principles.
http://ansuz.sooke.bc.ca/