New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[css-sizing] Computing min-width/min-height: auto to zero #2230

Closed
fantasai opened this Issue Jan 27, 2018 · 7 comments

Comments

Projects
None yet
5 participants
@fantasai
Contributor

fantasai commented Jan 27, 2018

When exactly does 'auto' compute to zero?

http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cstyle%3E%0A%20%20html%20%7B%20display%3A%20flex%3B%20%7D%0A%3C%2Fstyle%3E%0ATest%0A%3Cscript%3E%0A%20%20w(window.getComputedStyle(document.body%2C%20null).getPropertyValue(%27min-height%27))%3B%0A%3C%2Fscript%3E

The wording in Flexbox https://www.w3.org/TR/css-flexbox-1/#min-size-auto isn't particularly clear.

On a flex item whose overflow is visible in the main axis, when specified on the flex item’s main-axis min-size property, specifies an automatic minimum size. It otherwise computes to 0 (unless otherwise defined by a future specification).

Does it compute to zero

  • on flex items, in the main axis, when 'overflow' is visible?
  • on flex items, in the main axis, always? (Firefox does this)
  • on flex items, in both axes? (Chrome does this)

We should probably bias towards computing to auto in as many cases as is Web-compatible, but we should also fix the spec to say exactly what happens.

fantasai added a commit that referenced this issue Jan 27, 2018

@fantasai fantasai added the Agenda+ label Jan 27, 2018

@Loirooriol

This comment has been minimized.

Collaborator

Loirooriol commented Jan 27, 2018

I get other results:

  • On Chrome and Edge, on flex items, auto always computes to itself in both axes, even if overflow is not visible.
  • On Firefox, on flex items, auto computes to itself in the main axis when overflow is visible. Otherwise it computes to 0.
@css-meeting-bot

This comment has been minimized.

Member

css-meeting-bot commented Jan 31, 2018

The Working Group just discussed [css-sizing] Computing min-width/min-height: auto to zero, and agreed to the following resolutions:

  • RESOLVED: compute min-width/min-height: auto to auto
The full IRC log of that discussion <dael> Topic: [css-sizing] Computing min-width/min-height: auto to zero
<dael> github: https://github.com//issues/2230
<dael> fantasai: I noticed we don't have consistancy on if the min height or min width go to auto or 0 on flex items. Spec isn't clear. WE should do something to make spec clear.
<dael> fantasai: I think it's in our best interest to compute to auto as many places as possible. Given blink is always auto we should go ahead and do that.
<dael> fantasai: This would change flexbox and grid spec to clarify that. min-width and min-height computes to auto
<dael> Rossen_: I thought we had a resolution. I believe in edge we're always doing auto so you can round to computed value and be able to round trip.
<dael> fantasai: The cases where it goes to 0 it would round trip. Flex items the only dimension were auto isn't 0 is the main axis. IN the cross axis it doesn't have any effect. It's effectively 0 not computed to 0.
<dael> Rossen_: In other cases you'll have wrong behavior if you round trip to 0.
<dael> fantasai: Those cases are already auto.
<dael> Rossen_: Okay.
<dael> Rossen_: Anyone from FF that wants to chime in? Seems Gecko is the only one that may need to do work.
<dael> Rossen_: Objections?
<dael> Rossen_: I don't hear obj, but there isn't large representation from Gecko. If they have additional comments the issue is there.
<dael> tantek: Is the main argument round tripping?
<dael> fantasai: Main argument is to have a simplier rule for auto. If we were going back in time we'd have auto always go to auto and never 0 so in layout modes with another meaning it's consistant. For flex there's a complex set of conditions for when auto behaves as 0. only with overflow visible and main axis. Seems simplier to compute to auto.
<dael> Rossen_: We've added a whole bunch of magic into auto for flex. We don't want to expose parts of the magic sometimes. We just want it to be always auto.
<fantasai> dholbert: yeah
<dholbert> fantasai: OK, I don't have strong opinions then
<dael> Rossen_: tantek Anything else you want?
<dael> tantek: I'm trying to understand, but no reason to object. I see dholbert is checking.
<rego> dholbert, yep only about getComputedStyle()
<dholbert> fantasai: ...except I'd prefer to avoid introducing "this property's *computation* [as visible through inheritance etc] depends on that property's computed value on the same element" special cases
<dael> fantasai: Argument to compute to 0 is the author gets that result immediately when we can reliably get 0. Case to compute to auto is we can make it a simple rule. You could prob. argue in either direction.
<dael> Rossen_: I'm not hearing pushback.
<dael> Rossen_: Sounds like we have 3 impl shipping the proposed behavior.
<dael> Rossen_: I'm going to call for objections. Any objections?
<dael> RESOLVED: compute min-width/min-height: auto to auto
@dholbert

This comment has been minimized.

Contributor

dholbert commented Jan 31, 2018

[EDIT: the minutes & previous comment have now been clarified - thanks!]

I'm confused about the resolution here. The end of the minutes had this:

Rossen_: Sounds like we have 3 impl shipping the proposed behavior.
12:32 PM Rossen_: I'm going to call for objections. Any objections?
12:32 PM RESOLVED: compute min-width/min-height: auto to zero

I assume the 3 impl are Webkit/Blink/Edge, but according to #2230 (comment) , those 3 impls all compute min-width/min-height:auto to itself in both axes, which is not what the resolution said to do. Can someone clarify what the resolution was?

@tantek

This comment has been minimized.

Contributor

tantek commented Jan 31, 2018

Also please clarify whether this resolution is ONLY for grid and flex items, or has broader scope.

@fantasai

This comment has been minimized.

Contributor

fantasai commented Jan 31, 2018

Fixed the minutes, clearly they were wrong. Grid and flex items only; other things can be considered as separate issues on a case by case basis.

@tantek

This comment has been minimized.

Contributor

tantek commented Jan 31, 2018

From IRC:

Rossen_: RESOLVED: computed value of min width and min height is auto even if it's internally resolved to 0 for layout purposes

and yes for grid & flex items only, anything else file that separate

moz-v2v-gh pushed a commit to mozilla/gecko-dev that referenced this issue Feb 1, 2018

Bug 1434658: Simplify getComputedStyle behavior for "min-{width,heigh…
…t}:auto" to *always* return "auto" for flex/grid items, per CSSWG resolution. r=bradwerth

This change is in response to this CSSWG resolution:
"RESOLVED: compute min-width/min-height: auto to auto"
w3c/csswg-drafts#2230 (comment)
...which was later clarified as only being applicable to grid/flex items (in
both axes). Other layout modes may get further min-width/min-height
clarification, but for now we'll leave that behavior the same (returning 0 from
getComputedStyle).

MozReview-Commit-ID: 2wLYDAOj9I6

--HG--
extra : rebase_source : c5f384ef5ae906e20a6e10da20c39b0a5eb226eb

jasonLaster pushed a commit to jasonLaster/gecko-dev that referenced this issue Feb 2, 2018

Bug 1434658: Simplify getComputedStyle behavior for "min-{width,heigh…
…t}:auto" to *always* return "auto" for flex/grid items, per CSSWG resolution. r=bradwerth

This change is in response to this CSSWG resolution:
"RESOLVED: compute min-width/min-height: auto to auto"
w3c/csswg-drafts#2230 (comment)
...which was later clarified as only being applicable to grid/flex items (in
both axes). Other layout modes may get further min-width/min-height
clarification, but for now we'll leave that behavior the same (returning 0 from
getComputedStyle).

MozReview-Commit-ID: 2wLYDAOj9I6
@fantasai

This comment has been minimized.

Contributor

fantasai commented Feb 6, 2018

I believe this is fixed in the specs; please re-open if there is anything unclear about it in css-grid/css-flexbox/css-sizing!

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment