[NTG-context] Re: Kerning ignored on some macOS TTC fonts

[Henning Hraban Ramm <texml@fiee.net>]

Am 03.02.25 um 22:12 schrieb Paul Schalck via ntg-context:
> Hello,
> 
> I'm trying to set up typescripts for a few classic TTC font collections shipped with macOS (see script below).
> 
> No problems with:
> 
> /System/Library/Fonts/Avenir Next Condensed.ttc
> /System/Library/Fonts/Avenir Next.ttc
> /System/Library/Fonts/Avenir.ttc
> /System/Library/Fonts/Supplemental/Charter.ttc
> /System/Library/Fonts/Supplemental/Futura.ttc
> /System/Library/Fonts/Supplemental/Seravek.ttc
> 
> However, the kerning and the standard ligatures aren't picked up by ConTeXt on those:
> 
> /System/Library/Fonts/Helvetica.ttc
> /System/Library/Fonts/HelveticaNeue.ttc
> /System/Library/Fonts/Optima.ttc
> /System/Library/Fonts/Palatino.ttc
> /System/Library/Fonts/Times.ttc
> /System/Library/Fonts/Supplemental/Baskerville.ttc
> /System/Library/Fonts/Supplemental/Bodoni 72.ttc
> /System/Library/Fonts/Supplemental/Didot.ttc
> /System/Library/Fonts/Supplemental/GillSans.ttc
> /System/Library/Fonts/Supplemental/Hoefler Text.ttc
> 
> As an example, running
> 
> mtxrun --script fonts --list --info --file Optima.ttc
> 
> gives:
> 
> mtx-fonts       |
> mtx-fonts       | mapping   : 1
> mtx-fonts       | fontname  : optimaextrablack
> mtx-fonts       | fullname  : optimaextrablack
> mtx-fonts       | filename  : /System/Library/Fonts/Optima.ttc
> mtx-fonts       | family    : optima
> mtx-fonts       | weight    : black
> mtx-fonts       | style     : normal
> mtx-fonts       | width     : normal
> mtx-fonts       | variant   : normal
> mtx-fonts       | subfont   : 5
> fonts           | otf loading | loading '/System/Library/Fonts/Optima.ttc', hash 'optima'
> otf reader      | ignoring empty kern table of feature 'kern'
> fonts           | otf loading | loading done
> fonts           | otf loading | saving '/System/Library/Fonts/Optima.ttc' in cache
> system          | lua | compiling '/Users/benutzer/.local/share/tex/texmf-cache/luametatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/fonts/otl/optima.tma' into '/Users/benutzer/.local/share/tex/texmf-cache/luametatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/fonts/otl/optima.tmd'
> system          | lua | dumping '/Users/benutzer/.local/share/tex/texmf-cache/luametatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/fonts/otl/optima.tma' into '/Users/benutzer/.local/share/tex/texmf-cache/luametatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/fonts/otl/optima.tmd' stripped
> fonts           | otf loading | loading, optimizing, packing and caching time 0.004
> mtx-fonts       |
> 
> It seems that ConTeXt cannot find the kern values ("ignoring empty kern table of feature 'kern'"). What I usually do when I encounter kerning issues with older TrueType fonts is to generate new ones with FontForge. It never fails. I wonder though if there is a clean, native ConTeXt solution to this.
> 
> Testing environment:
> - LuaMetaTeX 2.11.06 20241230 + ConTeXt LMTX 2024.12.30 (the current version)
> - macOS Sequoia 15.3. I'm assuming that most TTC files on older Mac systems are identical, given their internal version date.

Why do you think these fonts have kern tables at all?
I looked at Optima.ttc with Fontforge and can’t find one.

Hraban
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