Hi Behdad,
The required features are marked in the published specifications where applicable. For example: Feature Feature function Layout operation Required Language based forms: ccmp Character composition/decomposition substitution GSUB Typographical forms: liga Standard ligature substitution GSUB clig Contextual ligature substitution GSUB Positioning features: kern Pair kerning GPOS mark Mark to base positioning GPOS X mkmk Mark to mark positioning GPOS X During Win 8, we added <dist> to the list of required features. Your question has made me realize that I need to update this document. Note that not all of our engines currently accept custom feature lists. I’m currently working on updating our documentation in this area, and will make sure that specification of all of the required features is up to date. Cheers, Andrew -----Original Message----- From: Behdad Esfahbod [mailto:[email protected]] On Behalf Of Behdad Esfahbod Sent: Friday, August 9, 2013 8:53 AM To: Andrew Glass (WINDOWS) Cc: Peter Constable; Harfbuzz Subject: Re: OpenType features in ScriptShape/PlaceOpenType Thanks Andrew. That's what I suspected. Can you please clarify which features are considered non-required? Is that exactly kern, liga, clig, and calt? Cheers, behdad On 13-08-09 11:50 AM, Andrew Glass (WINDOWS) wrote: > Hi Behdad, > > Yes, this is the design. If a caller passes a list specifying features they > wish to have applied, the need to specify all non-required features. For > example, if they want to turn off kern and add tnum they just pass the set of > optional features that they want to have applied. > > Cheers, > > Andrew > > -----Original Message----- > From: Behdad Esfahbod [mailto:[email protected]] On Behalf Of > Behdad Esfahbod > Sent: Friday, August 9, 2013 6:45 AM > To: Andrew Glass (WINDOWS) > Cc: Peter Constable; Harfbuzz > Subject: OpenType features in ScriptShape/PlaceOpenType > > Hi Andrew, > > Is it intentional that specifying any features in ScriptShape/PlaceOpenType > disables kern, calt, clig, liga? > > Thanks, > -- > behdad > http://behdad.org/ > -- behdad http://behdad.org/
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