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Re: mspace default attributes

From: Roger B. Sidje <rbs@maths.uq.edu.au>
Date: Thu, 10 May 2001 07:12:23 +1000
Message-ID: <3AF9B2B7.4172D50D@maths.uq.edu.au>
To: luca.padovani@cs.unibo.it
CC: "www-math@w3.org" <www-math@w3.org>, "mozilla-mathml@mozilla.org" <mozilla-mathml@mozilla.org>
Luca Padovani wrote:
> Hi,
> I was wondering if the default attribute values for mspace are
> appropriate. At first sight, they seem to be harmless, all zero. But
> let's take the following example. Let's take an accent, say a dot in a
> LaTeX font. Well, since it's an accent, it's positioned rather high with
> respect to the normal baseline. In fact, it has a negative descent,
> meaning that the bottom most pixel of the glyph is ABOVE the baseline.
> Let us say that the descent is -10 and the ascent is 11. Thus the dot
> accent is fully contained in a box 2 pixels high. Right?

Yes, that's right. And other fonts have what would seem as weird metrics
too. The fact of the matter is that there is a glyph in a weird font that
will break default assumptions (i.e., if it isn't <mspace> next to a dot in
a LaTeX font, it might be some other combination.) I have stopped worrying
about this in Mozilla-MathML, as there is generally a workaround in the
markup for people who "really" want for the desired "presentation".

> <math>
>   <mstyle mathsize="48pt">
>     <mrow>
>       <mover accent="true">
>         <mi><mchar name="alpha"/></mi>
>         <mo>&#x0307;</mo>
>       </mover>
>       <mo>,</mo>
>       <mover accent="true">
>         <mi><mchar name="alpha"/></mi>
-         <mrow><mspace width=".3em"/><mo>&#x0307;</mo></mrow>
+         <mo lspace=".3em">&#x0307;</mo>
>       </mover>
>     </mrow>
>   </mstyle>
> </math>
Received on Wednesday, 9 May 2001 17:39:06 GMT

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