# [NTG-context] optical bounds with hanging diacritics

Pablo Rodriguez oinos at gmx.es
Tue Nov 27 17:08:25 CET 2018

```On 11/27/18 12:33 AM, Hans Hagen wrote:
> On 11/24/2018 10:02 PM, Pablo Rodriguez wrote:
>> [...]
>> BTW, to get pure lfbd values, I had to replace line 361 from
>> font-imp-quality lua with:
>>
>>     local p = d/1000
>
> two issues:
>
> - no 1000 but units
> - we need to be able to go less extreme, so we keep factor
>
> so something
>
> local p = lfactor * d/units

The new definition is fine for me.

BTW, I have an issue issue with the font feature. I cannot have both
default and the opbd as font features, such as in:

\definefontfeature[newfeature]
[protrusion=opentype, opbd=yes, script=grek]
\definefontfamily[mainface][rm]
[GFS Didot][features={default, newfeature}]
\setupbodyfont[mainface, 325pt]
\setupalign[hanging]
\starttext
Α\\Ἇ
\stoptext

I guess this may be related to "script=grek", but I don’t know whehter
I’m doing something wrong.

>> I hope it is clear now why raw values from the font are needed.
>
> fwiw it looks a  bit too excessive to me (i'm not sure if graphical
> elements like those accents which are part of the character needs that
> much protrusion)

I agree. These are excessive values, but this is rather a very
particular case.

Hanging diacritics are used only in poetry, not in prose:
https://www.researchgate.net/publication/2417759_From_Unicode_to_Typography_a_Case_Study_the_Greek_Script
(section “1.6.2 Hanging Diacritics” on page 21).