[luatex] Ligatures

[Hans Hagen]

On 3/19/2021 11:09 AM, Philip Taylor wrote:
> Hans Hagen wrote:
> 
>> it looks ok here; the font no dflt script so you need to activate the 
>> latn script for ligatures to work
> 
> Thank you Hans, but I am suprised that it looked OK at your end.  At 
> this end, and following your suggestion, all of the lines in the 
> following example now display the correct ligatures, but in my earlier 
> example, with no 'script=latn', only the first (Adobe Minion Pro) 
> produced ligatures.  Are you able to explain why LuaTeX does the right 
> thing with Adobe Minion Pro in the absence of a 'script=latn' but does 
> not with the other three fonts tried ?
because there is a dflt/dflt script/language entry in the features table 
of those fonts and features are driven by script/language combinations 
(while the other font has latn/dflt ... it could be  that you'd have to 
set latn/eng because not all latin scripts might like these ligatures)

(i can't speak for plain/latex but context uses different heuristics 
when dealing with these issues which can be why its users observe 
different results)

Hans

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