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Re: [css3-grid-layout] Negative numbers for <grid-line>

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 25 Mar 2013 14:33:50 -0700
Message-ID: <CAAWBYDArfrueSWhfQ2Kqh08aaLar0LAsKLY85XbXxpLR_B1jJA@mail.gmail.com>
To: Julien Chaffraix <julien.chaffraix@gmail.com>
Cc: www-style list <www-style@w3.org>
On Mon, Mar 25, 2013 at 2:15 PM, Julien Chaffraix
<julien.chaffraix@gmail.com> wrote:
> Hi everyone,
>
> following last week's minutes [1], negative numbers are allowed for
> grid items' grid line. I am supportive of this change (along with
> reversing grid-{end|after} to use the start | before edge).
>
> The specification is missing the following clarifications though:
>
> 1) Which negative range is allowed for <integer>?
>
> There are several options:
> * Match Python which allows negative integers up to -len(array),
> something below is in error and resolves to 'auto'. This has the
> downside of allowing the auto-placement algorithm to run in some
> cases.
> * Allow arbitrary values, knowing that they would be brought back into
> the appropriate range (e.g. using modulo).
> * Match what the specification does for numbered named grid line and
> clamp the value to - (size of the grid) thus resolving in the first
> grid line.

I'd do option 3, clamping them to the first grid line.

The -1 grid line is the last line defined by grid-definition-*.


> 2) Interaction with the Automatic Grid Item Placement Algorithm (section 6.3.1)
>
> Currently the specification allows "the position and size of any
> explicitly-defined grid items" which would cover negative positions. I
> would propose to ignore them for the purpose of sizing the grid based
> on what the resolution above.

I don't understand.  The negative value resolves to an equivalent
positive value from the other edge, at which point it's identical to a
normal explicit position.  Why would you ignore them?

~TJ
Received on Monday, 25 March 2013 21:34:41 GMT

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