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Re: [csswg-drafts] [css-values] Anthropometric length and time units

From: Christoph Päper via GitHub <sysbot+gh@w3.org>
Date: Tue, 14 Feb 2017 09:48:23 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-279659299-1487065702-sysbot+gh@w3.org>
[Dael Jackson @ www-style (2017-02-13): [CSSWG] Minutes Seattle F2F 
2017-01-11 Part VI: Writings Modes, CSS Tables, Values & Units 
4](http://lists.w3.org/Archives/Public/www-style/2017Feb/0053.html)

>- dauwhe: I propose closing issue 837 with prejudice.
>- Florian: And person proposing them explicitly said, not discussing 
use cases.
>- astearns: So, resolve to close issue?
>- tantek: I propose requesting that the person proposing these units 
incubate them in the WICG. :)
>- astearns: I'm hearing no objection to close this issue per WG 
resolution.

One reason I proposed these units, obviously, is to cover the use 
cases brought forward before by other contributors to www-style for 
“real” or “true” physical units that are not anchored to `px`: `tap` ~
 centimeter, `mark` ~ inch, `pad` ~ decimeter, `sole` ~ foot. My 
partial argument here is that it would be a cleaner solution to add 
new anthropometric units than clumsy identifiers like `realcm` or 
`truein`.

As for use cases, they mostly follow from the ones raised for `tip`, 
i.e. sizing touch GUI elements. Most current touch-screen devices are 
almost exclusively operated with the tips of the fingers, some with 
styluses – the modern variant of slate pencils. Small touch targets 
like keycaps on a soft keyboard have their minimum size and distance 
to each other defined by the area covered by an (index) finger tip 
briefly touching the screen in an almost orthogonal angle → `tip`. 
Large touch targets like button height and width and margin, on the 
other hand, are determined by a full finger/thumb print in an almost 
horizontal angle → `tap` and `mark`. This is phones and tablets. 
Larger touch screens, e.g. wall-mounted ones, also have GUI widgets 
matching multiple-finger or full hand prints → `pad` and `span`. 
Lastly, `sole` is anticipating floor-mounted touch interfaces stylable
 with CSS. These may never become a (widespread) reality, but it’s 
arguably better to provide the necessary unit preemptively rather than
 too late or never, because it’s comparatively cheap and simple to 
implement it now.

As for the temporal units, `now` and `mom` are different from `beat` 
and `blink`. The former are not really expected to be adapted 
*dynamically* to the user, but only be permanently changed for 
accessibility reasons. They should be used with animations and 
transitions. Otherwise we’ll end up with yet another media query to do
 that. 
User heart rate and eye lid close times are (or may be) routinely 
measured by certain hardware, e.g. smart watches and VR/AR gears, and 
some designers may want to adapt their timings accordingly. Again, 
unless there were related media queries, there is no way to do this in
 CSS. This may be more relevant in special scenarios like car 
cockpits/dashboards than in general purpose desktop browsers.

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Received on Tuesday, 14 February 2017 09:48:30 UTC

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