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Re: [csswg-drafts] [css-grid] Regarding the 'subgrid' feature

From: Mats Palmgren via GitHub <sysbot+gh@w3.org>
Date: Thu, 02 Feb 2017 00:07:16 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-276824829-1485994035-sysbot+gh@w3.org>
Well, just to give you one example: the `display:subgrid` value, which
 implies a subgrid's tracks must be tied to its parent grid in both 
axes.  This is something that wasn't in the spec originally, but was 
added for vague reasons of maybe being "simpler".
https://www.w3.org/TR/2015/WD-css-grid-1-20150317/#track-sizing

>From my experience in implementing the rest of the Grid spec in Gecko,
 this seems misguided.  Pretty much all algorithms so far are 
implemented in a way that they apply to each axis independently, i.e. 
you have  some data/state per track, and a set of those for each axis,
 then you run _the same algorithm_ once for the column axis and then 
for the row axis.  I don't see why `subgrid` poses any problem in this
 respect.  So I think we should, as a starting point for 
implementation, use the original `subgrid` keyword in 
`grid-template-rows/columns`, which allows for this:
https://www.w3.org/TR/2015/WD-css-grid-1-20150917/#track-sizing

Removing the ability to specify `subgrid` in just one axis takes away 
creative freedom from authors,  something I, unlike the CSSWG 
apparently, take very seriously.  We shouldn't do that without 
**strong** reasons based on _actual_ implementation experience. There 
is no evidence to support that `display:subgrid` is in any way simpler
 than the previous version of the spec. (I could be wrong of course, 
but I don't think anyone can tell before trying to implement it.)

Regarding "Grid is already in CR" -- `subgrid` is marked as 
**at-risk**, thus it can be removed from the L1 CR version of the spec
 (or better, replaced with "TBD in Level 2"). I think it's clear that 
the subgrid part of CSS Grid is **not** mature enough to be 
standardized in its current form and that doing so is actually 
harmful.

To be clear, personally I'm **not** even going to start implementing 
the `subgrid` feature unless I have assurances that Grid spec changes 
are welcome, and that for example supporting `subgrid` in just one 
axis will be accepted if implementation experience shows that it is in
 fact not hard to support.  And as long as `subgrid` is in the L1 CR, 
I'm not confident that would be the case.


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Received on Thursday, 2 February 2017 00:07:27 UTC

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