[fxtf-drafts] [motion] Interaction with positioning

fantasai has just created a new issue for 
https://github.com/w3c/fxtf-drafts:

== [motion] Interaction with positioning ==
Some of the earlier discussions on polar positioning discussed its 
interaction with regular CSS positioning. Some of the topics that came
 up were
  * Do the `left`, `right`, `top`, `bottom` properties have an effect?
  * Should polar positioning respond to `position: absolute` vs 
`position: relative` vs `position: static` vs `position: fixed`?

The first question was left open, and the second question was 
concluded as "definitely yes". Under that system, polar positioning 
was ignored under `static`, used the element's normal position as its 
origin (and took up space in its container) for `relative`, and took 
the element out of flow and used the polar origin for `absolute` and 
`fixed`.

The current spec merges this system with the motion transform 
proposal, and hence operates at a layer on top of CSS positioning. 
This means the interaction with `position` is handled as simply the 
differences in determining the "containing block" when laying out the 
path, with `static` and `relative` reserving space and `absolute` and 
`fixed` taking it out of flow. The interaction with `left`, `right`, 
`top`, `bottom` is through them determining the initial position of 
`offset-position: auto` when `position` is not `static`; they are 
otherwise ignored.

This seems pretty sane, but just wanted to check that everyone is on 
board with this. It does mean we have two absolute-positioning 
coordinate systems (`left`, `right`, `top`, `bottom` vs 
`offset-position: <position>`) that work through two different 
positioning systems.

On a related note, if `left`, `right`, `top`, `bottom` don't actually 
interact directly with the `offset-` properties, that means we should 
definitely rename their logical equivalents.  
https://github.com/w3c/fxtf-drafts/issues/51 If we think they should 
have some interaction (e.g. reducing the size of the containing block,
 similar to the effect they have when applied to grids or the effect 
they have on the alignment properties), then they should have matching
 prefixes.

Please view or discuss this issue at 
https://github.com/w3c/fxtf-drafts/issues/77 using your GitHub account

Received on Saturday, 5 November 2016 04:59:13 UTC