Re: [Devel] ["L. Peter Deutsch" <address@hidden>] [Gs-devel] PMingLiu and TT instructions

[David Turner]

Hello Francesco,

Francesco Zappa Nardelli a écrit :
> 
> Comments for gs-devel?
> 
> Thanks,
> -francesco
> 
> From: "L. Peter Deutsch" <address@hidden>
> To: address@hidden
> Subject: [Gs-devel] PMingLiu and TT instructions
> 
> I've investigated the hinting instructions for this font at some length.
> What I've found is that for the overwhelming majority of glyphs, the freedom
> vector and projection vector are set to either the X axis or the Y axis; and
> from examining the use of NO_APPLE_PATENT in ttinterp.c of the Freetype2
> code, it appears that the authors of the Freetype2 TT instruction
> interpreter believe(d) that the Apple patent(s) only apply when the freedom
> and projection vectors are set to positions *other than* the X and Y axis.

That's true, but I could never take the time to look for relevant prior
art.
I would be extremely surprised not to find some however.. Note also that
Apple
lawyers will certainly complain one way or the other..

There is also the problem of DELTA instructions, which are also disabled
by
the macro I believe.

Normal TrueType fonts use the patented behaviour quite a lot to hint
diagonals properly, so it's not like it's going to produce reasonable
output
for a lot of fonts, especially the Microsoft ones :-)

> So if this is true (and this should be checked with the Freetype group), and
> if Mr. Suzuki or someone else can confirm that compiling the Freetype2
> interpreter *with* the instruction interpreter but also with NO_APPLE_PATENT
> defined produces reasonable-looking output, then it appears we have a usable
> approach.
> 
probably, but I don't think we'd distribute a default build of the
library with
these settings. They're better in a controlled environment like
Ghostscript where
you can use custom font drivers for specific purposes..

Regards,

- David


> [...]
> 
> --
> 
> L. Peter Deutsch     |    Aladdin Enterprises   |  203 Santa Margarita Ave.
> address@hidden    |  http://www.aladdin.com  |  Menlo Park, CA 94025
> 
>         The future of software is at http://www.opensource.org
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