Re: Bug in math integral

* Re: Bug in math integral
       [not found]   ` <AF7A3DC0-8F6B-4CCC-B99E-156F37889D9F@gmail.com>
@ 2012-10-22 22:05     ` Hans Hagen
  2012-10-23  6:22       ` Marco Pessotto
  0 siblings, 1 reply; 2+ messages in thread
From: Hans Hagen @ 2012-10-22 22:05 UTC (permalink / raw)
  To: Otared Kavian; +Cc: mailing list for ConTeXt users, Marco Pessotto

On 22-10-2012 21:41, Otared Kavian wrote:
>
> On 22 oct. 2012, at 18:47, Marco Pessotto <melmothx@gmail.com> wrote:
>
>> […]
>> Should the attached (compiled with the latest beta, as fixed by Hans) be
>> used as referenced?
>>
>
> Hi Marco and Hans,
>
> Thanks to everyone for your attention, and many thanks to Hans for having tried to fix the bug in mkiv.
> Unfortunately the bug is still there, as it can be seen from the comparison of the two PDF files I am sending with this message: they are both the result of typesetting the same source file I sent you. The one typeset with mkii has the correct output, while the one with mkiv is not correct (the spacing of the bounds of the integrals and the spacing between the integrals when they are invoked with \iint or \iiint are incorrect). (I tried this with ConTeXt version 2012-10-22, 11:01).
> The « reference » output should be the file « math-integral-mkii-2012-10-22.pdf »

Keep in mind that mkiv and mkii will never produce the same results 
(e.g.: more granularity in font metrics in mkiv, less juggling with 
combined shapes in mkiv, etc). SO, it can never be the pixel wise reference.

The issue with italic correction is complex. First of all italic 
corrections are a tex thing while in otf advanced kerning mechanism is 
used. This means that the engine has to deal with traditional as well ad 
new mechanisms. In the process of developing luatex and mkiv, we went 
through several phases, one is that the italic correction had to be 
added to the width (a handicap is that luatex has to make some guesses, 
and the mkiv vf is a wide font on the one hand but still a traditional 
one).

Anyhow, already quite a while ago, mkiv got two mechanisms to deal with 
italic correction, one for text and one for math (otf text fonts have no 
italic correction). Both mechanism can be configured to adapt themselves 
to the situation. For math we have 4 variants.

\setupmathematics[italics=1] % fontitalics
\setupmathematics[italics=2] % fontdata
\setupmathematics[italics=3] % quad based
\setupmathematics[italics=4] % combination of 1 and 3
\setupmathematics[italics=none]

Depending on available italic info or the lack of it, correction is 
applied. Of course this can be improved.

Once they are complete, we can make the new gyre math fonts default and 
some of the problems will go away. The virtuals will then be kept as an 
example of defining virtual fonts.

Concerning the issue: i removed adding the italic correction to the 
width (something that was needed in a previous version of luatex).

Hans

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