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Re: [ft-devel] Relicensing otvalid?


From: Werner LEMBERG
Subject: Re: [ft-devel] Relicensing otvalid?
Date: Tue, 21 Apr 2009 08:30:09 +0200 (CEST)

> In short, it's not clear to me what the audience for otvalid is.  Is
> it to help font designers validate their tables only?  The reason I
> can't use the code as is is that my code has a different idea of
> what is valid, or rather, good enough.  It's fair to say that I'm
> not developing a validator, more like a sanitizer.  For example, I
> don't care if the format specifier of a subtable is invalid, since
> my lookup code will simply ignore that table.

The original idea was that you validate a font's OpenType tables so
that you can access them without any further memory checking.

AFAIK, George uses the `otvalid' module in FontForge.

> One place I found otvalid being too strict is that it checks that
> glyph ids are "valid" by making sure the font has such a glyph.
> This is not required by the spec AFAIK, and indeed, multiple tables
> can use invalid glyph ids ephemerally to simply case handling.

This sounds like a bug.  In general, `otvalid' shouldn't be stricter
than FreeType.  However, this module is probably not in sync with the
rest of FreeType where I've added code to handle broken fonts here and
there.


    Werner




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