Re: Glyph Closure Scaling

On 05082019 9:40 am, Garret Rieger wrote:
> Thanks Myles, this is very informative. For the arabic fonts it makes 
> intuitive sense to me that they'd deviate due to them having lots of 
> inter character layout rules. However, seeing a few LGC fonts end up 
> deviating surprises me. I think it would be interesting to dig into 
> the internals of a couple of those LGC fonts to try and understand why 
> the closure on those pulls in so many extra glyphs. 

Segoe Script is a handwriting style font, so I am not surprised by the 
deviation: the font contains a lot of glyph variants that are deployed 
contextually to pseudo-randomise letter sequences and mimic the variety 
of form in handwriting.

I'm not sure why Bahnscrift would deviate so much. It is a variable 
font, but I thought the GSUB was pretty simple.

BTW, the reason the Microsoft Himalaya Tibetan font deviates so much is 
that it uses lots of contextual alternates to control the depth of 
conjunct stacks. I would expect other Tibetan fonts not to deviate this 
much.

The deviation data confirms what I assumed would be the case: Arabic 
fonts will tend to require significantly more glyph downloads because of 
the joining forms requirements, and fonts that provide contextual 
variation of letter shapes to mimic handwriting or implement traditional 
Arabic styles will also deviate significantly. Fonts like Aldhabi (BTW, 
diwani style, not nastaliq) and Urdu Typesetting combine both these 
aspects: joining forms and contextual variation, as well as 
decomposition of Arabic letters into rasm and separate dot glyphs. [I'm 
interested to see that Arabic Typesetting has a similar deviation to 
Aldhabi and Urdu Typesetting: it uses a large ligature set instead of 
relying only on contextual variants.]

JH


-- 

John Hudson
Tiro Typeworks Ltd    www.tiro.com
Salish Sea, BC        tiro@tiro.com

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Received on Monday, 5 August 2019 16:56:05 UTC