Re: [ft-devel] ttfautohint: How to install

[vernon adams]

> 
> Thanks again for your invaluable help in testing ttfautohint!
> 
My pleasure. Very keen to see a working autohinter available to font
designers :) 

> >
> > The feedback i'm getting from my screenshots is that the ttfautohint
> > output is overall superior under DirectWrite to the original hinted
> > fonts.  Just seems to be a little extra 'something' needed to get
> > the GDI sorted too :)
> 
> Please try the current git snapshot and play with the options
> --hinting-range-min and --hinting-range-max.
> 
> Currently, the default value for hinting-range-max is 1000; this means
> that the autohinter tests all ppem values up to 1000 to find hinting
> sets.  However, the larger the ppem, the larger the blue zones.  And
> by design, the autohinter ignores blue zones which are larger than 3/4
> pixels.
> 
> If you limit hinting-range-max to a value where the blue zones are
> still handled, the generated bytecode uses this hinting set for all
> larger sizes also.  Finding a good value for hinting-range-max has to
> be done with trial and error, but a waterfall already indicates bad
> sizes, so hinting-range-max must be less than that).

Yep. I will test these ranges & make available any relevant screenshots.

> 
> The adverse effects of having a very small value for hinting-range-max
> must be analyzed also; it essentially means that some horizontal
> segments which at larger ppem values no longer align are still treated
> as edges.  Maybe it helps if I introduce options to manipulate the
> `gasp' table, making it possible to set an upper limit for applying
> hints.
> 
> Finally, I don't know yet whether it makes sense to directly
> manipulate the 3/4 pixels limit (perhaps by deactivating this
> threshold completely).  This needs further testing.
> 

I am curious - as i understand it(?) ttfautohint uses freetype to find
snap zones etc from which it bases it's TT instructions output. So what
mileage could there be in using a patched freetype tree with
ttfautohint? I'm thinking of some of Infinality patches that have
attempted to tweak Freetype's hinting routines. Some i think were
attempting to give more aggressive, cleartype-like rendering. Is there
anything to learn from those patches when tweaking ttfautohint?


many thanks

-vern


> 
>     Werner