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Re: auto units versus 'auto' value

From: Andrew Fedoniouk <news@terrainformatica.com>
Date: Sat, 22 May 2004 11:44:51 -0700
Message-ID: <000a01c4402c$de876390$0301a8c0@ATHLON>
To: "Lachlan Hunt" <lachlan.hunt@iinet.net.au>, "W3C Style List" <www-style@w3.org>

Hi, Lachlan, thanks for your comments,

>    As a concept, it seems reasonable to want a method that can calculate
> a length based on the /free space/ available (either vertically or
> horizontally) however, the proposal you have given for %% units, has
> some serious problems.
>
>    Firstly, you wrote in a previous post [1] that it would make no sense
> to apply the units to the positioning proerties, 'top', 'right',
> 'bottom' and 'left', but if a unit is defined correctly, then I see no
> reason why it shouldn't apply to those.

Let's say I am not yet sure about 'top', 'right', 'bottom' and 'left'.

Initially %% idea was to position elements in normal flow.
[http://www.w3.org/TR/CSS21/visuren.html#positioning-scheme]

I can see so far how %% units will be applied to entities having 'space'
meainig:
margin, width, padding, etc. Values of these attributes can participate in
free space
distribution.
In contrary, attributes 'top', 'right', 'bottom' and 'left' measure
coordinates or offsets - therefore out of scope of %% units.
It is my guess. I'll honestly appreciate if somebody will propose
interpretation of the units for 'top' and 'left'.

As far as I understand "free space" is not applicable for absolutely
positioned elements. No?

This is why, I guess, 'top', 'right', 'bottom' and 'left' have no 'auto'
value currently.

> Secondly, you make the assumption [2] that whenever the units are
> used, then the sum should be normalised to be no more than 100% of the
> free space, whereas the author may actually want the sum to be exactly
> what was given.  (correct me if I've misunderstood this)

Not so. Correct statement is:
"whenever the units are used, then the sum should be normalised to be *not
less*
than 100% of the free space"

This 'not less'  is key point here as it implies the following:

'Free space' can be 'underdistributed' (some portion of  'free space' can be
left empty)
 but cannot be 'overdistributed' (no one %% value in children shall force
changing of containers space).

Therefore in your example below each 'col' will take width value
equal to 60/180*container-inner-width. What is exactly
1/3*container-inner-width.
Constraint col:first-child { width: 100px; } will be taken in consideartion
at first step - calculation of free space.

Andrew Fedoniouk.
http://terrainformatica.com


> eg.
> the elements to make three columns are:
> <container>
>    <col/><col/><col/>
> </container>
>
> with the style:
> container { display: block; }
> col:first-child { width: 100px; }
> col { width: 60%%; float: left; }
>
>    The last two cols should add up to 120% of the free space, however,
> if I've understood correctly (and haven't become totally confused), your
> current proposal would mean that each element would only get 50% of the
> free space.  If the calculations do add up to be more than 100% of the
> free space, then it should just overflow using the normal overflow rules.
>
> [1] http://lists.w3.org/Archives/Public/www-style/2004May/0146.html
> [2] http://lists.w3.org/Archives/Public/www-style/2004May/0403.html
> --
> Lachlan Hunt
>
> http://www.lachy.id.au/
> lachlan.hunt@lachy.id.au
>
Received on Saturday, 22 May 2004 14:44:56 GMT

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