1285807 - mfrac stacks are not aligned around the axis

Status: NEW

(Core :: MathML, defect, P5)

Description

[James Kitchener (:jkitch)]

Followup from bug 1240799.

I was able to get the test case to pass by adapting Rule 15d, App. G, TeXbook (used for bar case) to the stack case

Differences from the bar case:
actualRuleThickness is set to 0
minClearanceNum == minClearanceDen == minClearance/2

Patch to come tomorrow.

Comment 1

[Frédéric Wang (:fredw)]

Interestingly, the axis alignment is now also incorrect on WebKit after https://bugs.webkit.org/show_bug.cgi?id=155714. We'll have to figure out whether it's a bug in implementations, in the implementation documents or if it's just the expected TeX / OpenType MATH behavior (and so the test should be fixed):

https://github.com/MathML/MathMLinHTML5-tests/issues/2

Comment 2

[James Kitchener (:jkitch)]

Attachment: patch

Patch.

I won't flag it for review until there is a decision over the correct behaviour.

Comment 3

[Frédéric Wang (:fredw)]

(In reply to James Kitchener (:jkitch) from comment #2)
> Created attachment 8771610 [details] [diff] [review]
> patch
> 
> Patch.
> 
> I won't flag it for review until there is a decision over the correct
> behaviour.

Wrong patch? (this seems to be for bug 1274796)

Comment 4

[James Kitchener (:jkitch)]

Attachment: patch

Sigh.

Correct patch this time.

Comment 5

[Frédéric Wang (:fredw)]

Thanks James. So as I understand the MATH table, nothing ensures that the stack gap is split symmetrically around the axis height, even if that sounds natural and makes things more consistent with the fraction case. I guess we would have to ask to Murray Sargent but for now I disabled the tests for stacks: https://github.com/MathML/MathMLinHTML5-tests/commit/630c20db3337b68ec137153ebef20099bcf7049b