Re: Interpretation of OpenType MATH fraction shifts

Hi,

I was checking this again and for stacks I understand that AxisHeight is
not involved at all in the layout. Is that correct?

On 06/08/2019 20:32, Sergey Malkin wrote:
> I actually see in code that shift is relative to baseline. Look at
> PTLS7::CalcFractionOffsets function in LsMathFractionApi.cpp:
>
>     LONG dvGapNumerator = dvNumeratorShiftUp - dvNumeratorDescent -
> (dvAxisHeight + dvRuleThicknessOver2);
>     ...
>     duvNumerator.v = dvAxisHeight + dvRuleThicknessOver2 +
> dvGapNumerator + dvNumeratorDescent;
>
> Which is equivalent to 
>     duvNumerator.v = dvNumeratorShiftUp
>
> This is consistent with shifts for other math structures, e.g.
> superscript, where making it relative to math axis doesn't make sense.
>
> Thanks,
> Sergey
> ------------------------------------------------------------------------
> *From:* Murray Sargent <murrays@exchange.microsoft.com>
> *Sent:* Tuesday, August 6, 2019 10:47 AM
> *To:* Frédéric Wang <fwang@igalia.com>
> *Cc:* public-mathml4@w3.org <public-mathml4@w3.org>; Victor Kozyrev
> <victork@microsoft.com>; Sergey Malkin <sergeym@microsoft.com>; Peter
> Constable <petercon@microsoft.com>
> *Subject:* RE: Interpretation of OpenType MATH fraction shifts
>  
> Looking at the LineServices math fraction handler code, I think the
> OpenType math table numerator shift-up and denominator shift-down
> parameters are relative to the math axis.
>
> For confirmation, adding Victor, who wrote the math fraction handler
> code, Sergey, our OpenType math table expert, and Peter who has edited
> the OpenType math table spec.
>
> Thanks,
> Murray
>
> -----Original Message-----
> From: Frédéric Wang <fwang@igalia.com>
> Sent: Tuesday, August 6, 2019 7:53 AM
> To: public-mathml4@w3.org; Murray Sargent <murrays@exchange.microsoft.com>
> Subject: Interpretation of OpenType MATH fraction shifts
>
> Hi Murray,
>
> Can you please indicate whether numerator/denominator shifts should be
> relative to the fraction baseline:
>
> https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fmathml-refresh%2Fmathml%2Fissues%2F123&amp;data=04%7C01%7Csergeym%40microsoft.com%7C23418ee72935478ed7d308d71a962c85%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637007104604276097%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C-1&amp;sdata=nWBieXR82IXEct4YidbFW2XTyYiSW8pRRZl0U6otirs%3D&amp;reserved=0
>
> Thanks,
>
> --
> Frédéric Wang
>

-- 
Frédéric Wang