Re: [ft-devel] Patented bytecode interpretter and fallback to autohinter

[Werner LEMBERG]

> In Fedora rawhide I enabled the patented bytecode interpretter a
> while ago since the patents expired.  I've received reports since
> that this has resulted in degraded rendering of some fonts.
> 
> Apparently, from what I hear, with Medium hinting, the autohinter is
> not used even if the font doesn't have any bytecode.

This is the right behaviour IMHO.  A TrueType font is expected to be
self-contained, this is, the rendering result should always be the
same, independent of the rasterizer.

> The desired behavior is to use the autohinter for any glyphs without
> bytecode hints.

Definitely not!  Either the whole font gets autohinted, or the
bytecode interpreter is used.  Mixing those two hinting strategies
doesn't give good results since the global hints are calculated
differently.

Basically, I think this is a FontConfig issue; all TrueType fonts
which need autohinting should be configured as such.

On the other hand I see the problem you have.  However, there is
currently no possibility (built into FreeType, I mean) to find out
whether a font has TrueType hints or not.  It's straightforward to add
such a function, and FontConfig might use it during the creation of
the cache.

What kind of interface would you like to have?  I can imagine that you
want to check the presence of a font's hinting instructions for a
given range of input codes (not that I would really like this, but...)


    Werner