Re: [ft-devel] Improved Arabic auto-hinting

[Werner LEMBERG]

>> I've verified that the vertical position for the joining glyphs are
>> the same in his font...
>> 
>>> I can't reproduce any improvements so far.
>>> This effect:
>>>
>>>   https://www.flickr.com/photos/behdad/34769511/
>>>
>>> still happens in my limited testing.
>> 
>> ... and apparently this doesn't work as universally as I've hoped.
>> Please send me the font privately and tell me how to reproduce this
>> image.
> 
> With this font:
> 
> https://github.com/googlei18n/noto-fonts/blob/master/unhinted/NotoNaskhArabic-Regular.ttf
> 
> and this command-line:
> 
> $ hb-view ./NotoNaskhArabic-Regular.ttf نستعلیق \
>           --font-size 400 --background 000 --foreground ffffff \
>           | display

Thanks.  IMHO, this is not a bug in the autohinter; it's a font bug:
The overlapping of glyphs isn't constructed correctly, which makes
repeated drawing of the overlapping parts problematic, as described in
your blog entry.

For comparison, here an image using a font by Titus with the same
hb-view command.  Another image shows how the joining parts are
designed to avoid (or to reduce the effects of) exactly this problem.

Perhaps the Noto people should change that...

What you envision, namely the cropping of the outline outside of the
advance width so that there is no overlapping at all (as discussed
during our meeting at ATypI) is a different topic – not sure how to
achieve that reliably in an automated way...


    Werner