[mpeg-OTspec] Different OpenType/CFF behavior on Windows 10 with 'gasp' table

[Ken Lunde]

John,

Thank you. Seeing no other responses, particularly from our friends at Microsoft, I will conclude that this is simply an unexplored/untested area. Therefore, including a 'gasp' table in OpenType/CFF fonts is likely to have unpredictable results.

Regards...

-- Ken

> On Dec 11, 2018, at 12:58 PM, John Hudson <john at tiro.ca> wrote:
> 
> On 11122018 12:32 PM, Ken Lunde lunde at adobe.com [mpeg-OTspec] wrote:
>> They suspect that DirectWrite may be sensitive to the presence of the 'gasp' table in OpenType/CFF (aka non-TrueType) fonts, which matches their observations.
> 
> That makes sense to me; in fact, if someone had asked me to predict whether a gasp table would influence rendering of CFF fonts in DWrite, I would have guessed yes. The gasp table influences the antialiasing model applied in Windows rendering environments, so when one of those environments starts rasterising CFF fonts it makes sense that the antialiasing of those outlines becomes subject to the same influence. It's probably worth experimenting with to see if the gasp table is ever actually of beneficial use in a CFF font. Quite possibly, it isn't — since the gridfitting controls and TTF instruction interaction are not the same for CFF —, in which case the spec should clearly reserve the gasp table for TTF. But if there is a possible benefit, maybe we should allow this with caveats?
> 
> JH
> 
> 
> -- 
> 
> John Hudson
> Tiro Typeworks Ltd    https://na01.safelinks.protection.outlook.com/?url=www.tiro.com&data=02%7C01%7Clunde%40adobe.com%7C6a125bd4469a43e172e008d65fab682b%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C636801587131234164&sdata=RRWghBMmpUEsx97qBr8VgtLGGLHzj6%2FpQnZlA7TWWsE%3D&reserved=0
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