View Issue Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0000727||luatex||luatex bug||public||2011-10-10 13:17||2015-10-28 17:23|
|Reporter||JohannesKuester||Assigned To||Hans Hagen|
|Fixed in Version||0.85.0|
|Summary||0000727: Vertical centering of bigops and integrals is wrong|
|Description||LuaTeX (and XeTeX) vertically centers big operators and integrals on the math_axis. This seems to be a legacy from traditional TeX.|
But it is wrong for OpenType math fonts. At least it shouldn't be default behaviour of LuaTeX. Also it is not mentioned in the MATH table spec.
In an OpenType math font, the glyphs should appear in the correct vertical position by design.
The assumption that the glyphs are (or should be) symmetrical to the math_axis is obviously not valid for all cases: e.g.
u+2A1B integral with overbar
u+2A1C integral with underbar
are not symmetrical, but the integral symbol is at the same position as other integral symbols. Currently LuaTeX moves these glyphs up or down, resulting in wrong positioning.
This behaviour is correct and is already what MS implementation is doing. I attached a screenshot of XITS Math integrals in MS Office 2007, both in display and inline mode. (Note that Office provides no simple way to insert U+2A1B and as U+2A1C as big operators, simply inserting the Unicode characters will treat them as regular symbols, I had to manually edit the docx file to get them. I attached the docx file as well for reference.)
integrals.docx (10,999 bytes)
That looks utterly wrong! It shows that the MS implementation is at fault here as well. I think this is simply a legacy from Computer Modern and traditional TeX's handling of math, but it is too simplistic and does not fit for all possible cases.
So at least it should be possible to switch this behaviour off and rely on the glyph position in the font.
the only robust solution is an extra field in the char data so that it can be 'patched' per character/font at load time \Umathignoreaxis<number> or so
i'll discuss it with taco
||more control wil be provided|
|2011-10-10 13:17||JohannesKuester||New Issue|
|2011-10-10 18:02||Khaled Hosny||File Added: Screenshot.png|
|2011-10-10 18:05||Khaled Hosny||Note Added: 0000914|
|2011-10-10 18:07||Khaled Hosny||File Added: integrals.docx|
|2011-10-10 18:07||Khaled Hosny||Note Edited: 0000914|
|2011-10-11 11:44||JohannesKuester||Note Added: 0000915|
|2012-04-09 04:38||Khaled Hosny||Tag Attached: math|
|2015-10-24 16:44||Hans Hagen||Assigned To||=> Hans Hagen|
|2015-10-24 16:44||Hans Hagen||Status||new => assigned|
|2015-10-24 16:44||Hans Hagen||Note Added: 0001477|
|2015-10-28 17:23||Hans Hagen||Note Added: 0001487|
|2015-10-28 17:23||Hans Hagen||Status||assigned => closed|
|2015-10-28 17:23||Hans Hagen||Resolution||open => fixed|
|2015-10-28 17:23||Hans Hagen||Fixed in Version||=> 0.85.0|