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Re: mrow - child vertical align

From: David Carlisle <davidc@nag.co.uk>
Date: Mon, 18 Feb 2013 16:25:58 +0000
Message-ID: <51225616.9070303@nag.co.uk>
To: Ionel Alexandru <ionel.alexandru@gmail.com>
Cc: www-math@w3.org
On 18/02/2013 15:49, Ionel Alexandru wrote:
> Hi,
>
> In a mrow tag I think we need to have a vertical align attribute: top,
> bottom, center or baseline - like rowalign.
>
> If we have children of type mtext with different mathsize I think is
> better to be rendered using baseline (also center could be a good choice ).
> If we have a list of fractions in mrow is better to be centered.
> ...
>
> What do you think ?
> Do I miss something ?

I believe the intended default alignment should work OK for both text 
and fractions.
The normal rendering should be such that the fraction lines are centred 
on the axis (that is a fixed distance up from the baseline)
This means that a row of fractions would have their bars aligned even if 
they had different size numerator. Centering them would typically make 
the bars move up or down. depending.

For special circumstances you can of course use mpadded to offset one 
term, or use a one row table with its alignment options. We already get 
feedback from css-based browser implementations that mrow/mstyle have 
too much style attribute possibilities so it isn't clear that adding 
more would be universally popular:-)

I attach the rendering of firefox and mathplayer with the following 
example, which shows fractions of different sizes aligning such that 
their bars match that of + (which is also what TeX would do).

David




<!DOCTYPE html>
<html>
<title>test</title>
<body>
<math xmlns="http://www.w3.org/1998/Math/MathML">
<mrow>
<mtext>aaa</mtext>
<mo>+</mo>
<mfrac><mn>1</mn><mn>2</mn></mfrac>
<mtext>aaa</mtext>
<mo>+</mo>
<mfrac><msup><mi>A</mi><mi>A</mi></msup><mi>b</mi></mfrac>
</mrow>
</math>
</body>
</html>


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mrow-ff.png
(image/png attachment: mrow-ff.png)

mrow-mp.png
(image/png attachment: mrow-mp.png)

Received on Monday, 18 February 2013 16:26:22 GMT

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