[CSSWG] Minutes San Francisco F2F 2019-02-27 Part I: Grid, CSS Sizing [css-grid] [css-sizing]

  These are the official CSSWG minutes.
  Unless you're correcting the minutes,
 Please respond by starting a new thread
   with an appropriate subject line.


  - RESOLVED: Change the specs so that the default scroll area
              includes paddings by default for Grid and Flexbox (Issue
              #3665: Include padding in scrollable overflow area)
  - The group had trouble visualizing Issue #3646 (Consider setting
      base sizes to growth limits when sizing under max-content
      constraint) and will spend some time with a whiteboard later on
      in the F2F.

CSS Sizing

  - RESOLVED: Use min-height: auto to solve problem of content
              overflowing aspect-ratio (Issue #3268: Rethinking how to
              prevent overflow in a container with an explicit aspect


Agenda: https://wiki.csswg.org/planning/sf-2019

  Rachel Andrew, Fronteers
  Rossen Atanassov, Microsoft
  Tab Atkins, Google
  Amelia Bellamy-Royds, Invited Expert
  Tantek Çelik, Mozilla
  Emilio Cobos, Mozilla
  Dave Cramer, Hachette Livre
  Elika Etemad, Invited Expert
  Jihye Hong, LGE
  Koji Ishii, Google
  Brian Kardell, JS Foundation (phone)
  Ian Kilpatrick, Google
  Rune Lillesveen, Google
  Chris Lilley, W3C (phone)
  Cameron McCormack, Mozilla
  Theresa O'Connor, Apeoplee
  François Remy, IDLAB
  Manuel Rego, Igalia
  Florian Rivoal, Invited Expert
  Hiroshi Sakakibara, BPS(Beyond Perspective Solutions)
  Jen Simmons, Mozilla
  Hyojin Song, LG Electronics
  Alan Stearns, Adobe
  Morten Stenshorne, Google
  Greg Whitworth, Microsoft
  Fuqiao Xue, W3C

Scribe: fremy


Include padding in scrollable overflow area
  github: https://github.com/w3c/csswg-drafts/issues/3665

  fantasai: This is a follow-up of last issue
  fantasai: where we resolved to take explicit tracks into account in
            the scroll area
  fantasai: but we had a tangent discussion about considering the

  fantasai: We have compat restrictions in the case of block
  fantasai: [missed the details of the compat case]
  fantasai: But we don't have such a compat issue for grid, so we can
            do this the way authors expect
  astearns: And we would be doing this for flexbox as well?
  fantasai: Yes
  fantasai: We already had people asking for this to be fixed for
  fantasai: and the closest we could do was to do this correctly when
            alignment properties have a non-default value

  dholbert: Doesn't chrome already do that in the block direction?
  fantasai: Yes, but we want to change the spec to require both axises
  <rego> example for flex and grid:

  dbaron: What are you proposing to include exactly?
  fantasai: Boxes that are in flow, and their border box, plus the
            entire grid, and the padding around all this should be
            included in the scrollable area
  dbaron: And what is the change?
  fantasai: Include the paddings
  florian: When the alignment is the default
  dbaron: But how about the margins?
  dbaron: I thought it wasn't interoperable
  dbaron: I would like the spec text to be very clear about what
          margins are included
  dbaron: For example, descendant margins, collapsing margins, and
          their interactions
  florian: But this is orthogonal to padding though
  dbaron: Yes, you're right, I just didn't know what was the change
          proposal about
  dbaron: I would be fine with any behavior, but would like the spec
          to be clear
  tantek: Do we have tests?
  fantasai: no, but I can make one
  <fantasai> testcase -
  <fantasai> In Firefox, there's only padding in the top/left
  <fantasai> In Chrome, you also have padding at the bottom
  <fantasai> Authors expect padding on all sides.
  <tantek> I see padding on all sides of the blue square in FF67

  Rossen: Sounds great, let's do it
  Rossen: Back when IE implemented this, we did it "right" be default
  Rossen: then got compat issues
  Rossen: but ideally we think this should be the default, so I
          support this change

  astearns: Where are we gonna write that?
  fantasai: In the same place as where the rules are today, but we can
            add a note to explain why block must be an exception

  jensimmons: I think for authors it's great that the new layout work
              properly, and then there is legacy
  jensimmons: It's great to clean cut from the past, if you rely on
              new things, you don't have to be aware of old legacy

  astearns: What about dbaron's concern that everything should be well
  fantasai: We should add all these details in the overflow spec
  fantasai: but the general behavior should be in the alignment spec,
            that only deals to in-flow content
  fantasai: But well, I agree, there will be changes in a couple of
            specs to achieve this result
  astearns: Grid and flexbox are probably gonna be released before
            overflow though
  astearns: so pulling it in would help get this to REC sooner
  florian: We can add a note in those specs, but in the end overflow
           is required for all modes, so it doesn't matter all that

  <tantek> fantasai, I see the same result in Safari and FF67. Blue
           square with padding all around it between it and black
  <rego> tantek: this is another example
  <tantek> rego, that example is inconsistent across FF67 (no
           scrollable padding bottom & right), and Safari (no
           scrollable padding right)

  astearns: any objection to this proposal?
  <fantasai> proposed resolution: include padding in scrollable
             overflow area, edits to grid/flexbox/alignment/overflow

  RESOLVED: Change the specs so that the default scroll area includes
             paddings by default for grid and flexbox

  tantek: Is there commitment to make the change in chrome?
  rego: Yes, we will make the change
  tantek: Cool
  <rego> at least we'll send the patch to Chromium and WebKit, if
         Apple doesn't agree with this I don't know

  Rossen: Just wanted to note that I had prior discussion on this
          topic, and one of the rules that some webkit engineers cared
          about was...
  Rossen: ... to minimize the amount of empty space you are scrolling
  Rossen: but for grid and flexbox, they are used as structure for
          other things, and it's important to preserve space because
          the space is part of the structure
  Rossen: So I don't think dropping padding there is an option that
          isn't weird
  Rossen: but we might want to give a chance to webkit folks to take a
  astearns: As for all resolutions, things can be reversed if needed
            but as far as I know, we have a webkit contributor here
            planning to make the change

Setting base sizes to growth limits under max-content constraint
  github: https://github.com/w3c/csswg-drafts/issues/3646

  oriol: There are two issues in there
  oriol: One is that when sizing a grid under max-content constraint
  oriol: when computing the space for item with intrinsic size
  oriol: we only consider the base size of tracks
  oriol: which can be smaller than the size of the track in the end
  oriol: So, maybe we should consider instead of the contribution of
         the item minus the track size
  oriol: consider the contribution of the item minus the growth limit
  oriol: (explains the example in the issue)
  oriol: When the growth limit of a track increases, we could increase
         to base size up to that growth limit
  oriol: This means that when you are using fit-content
  oriol: you need to do first min-content then max-content
  oriol: This is a lot of work
  oriol: but chromium isn't doing this all the time
  oriol: They perform a single layout track, and sets a base size of
         the tracks which is the min-content, and the growth-limit is
         the max-content
  oriol: which is ok if there are no spanning items, but if there are
         spanning items the result is wrong
  oriol: However, with my proposal, we wouldn't need to keep track of
         different base sizes for these two cases, and therefore we
         can always do only one single layout for fit-content
  oriol: (one single *extra* layout pass)
  * fantasai is wondering what's the relationship to

  astearns: Thanks oriol
  astearns: Some people in the room are reviewing this in a bit more
  astearns: Anyone has a response?
  astearns: Or should we continue this in the issue?
  rego: One question, are we sure that what the change is what authors
        would expect?
  rego: If it is, I think the change oriol proposed should get done,
        but maybe it isn't what authors expect, I'm not sure
  <bkardell> rego are you saying things would break?
  astearns: jensimmons? Do you have an opinion?
  jensimmons: Not yet
  Rossen: The issue is fairly new
  Rossen: maybe we need to take more time
  <tantek> TBH I can't visualize this. Any chance of projecting an
           example for things like this? E.g. before/after change?
  <bkardell> tantek, yes please
  <tantek> bkardell right?
  <bkardell> it sounds like a lot of people would appreciate that
  Rossen: maybe we can use whiteboards at lunch
  <florian> I am a little confused. Does that relate to
            https://github.com/w3c/csswg-drafts/issues/2356 ?
  fantasai: I'm in favor of that

  fantasai: With regard to the labels, I want to publish a new grid
  fantasai: So I'm classifying changes between big changes and minor
  fantasai: and I would want to first get to the changes that are just
  fantasai: and continue to work on bigger changes on a more relaxed

  rachelandrew: Is that just a performance issue?
  rego: Well, I mean, not entirely
  rego: but it would enable firefox to match both the spec and chrome,
        because in Chrome we don't follow the spec because it's both
        faster and easier not to follow it
  rego: With the proposed change, we could both update to this new text

  <tantek> (wants what Jen Simmons said minuted, but can't remember
           exactly to type it himself)
  <jensimmons> I said: Let’s figure this out. It should make sense for
               Authors. And we want to squash any interop problems…

CSS Sizing

Preventing overflow in a container with an explicit aspect ratio
  github: https://github.com/w3c/csswg-drafts/issues/3268

  fantasai: So jensimmons filed this issue about how we are going to
            handle a non-replaced element's aspect ratio
  fantasai: It's possible that the content might overflow the element
  fantasai: so do we want to make sure the aspect ratio is a rigid
            ratio, or just a minimum ratio?
  fantasai: There are multiple ways to do this
  fantasai: One would be to take advantage of min-height: auto to
            use min-content or aspect-ratio, but otherwise use only
            the aspect-ratio
  jensimmons: We talked about it before, if you have paragraph with a
              couple of words an an aspect ratio
  jensimmons: if the ratio allows for breathing room at the bottom,
              it's fine
  jensimmons: but if it's smaller because the paragraph has lots of
              words, then it's overflowing
  jensimmons: so we thought maybe the default behavior would to take
              min-content into account

  <fantasai> Florian's proposal to use min-height:
  fantasai: So, could we resolve and add this into the spec
  florian: min-content and max-content are the same in that direction
  florian: but if they wouldn't be in the future, which one would we
           want to use?
  florian: Right now, we don't have mechanism to tweak it but it might
           come later

  <dbaron> Was having min/max-aspect-ratio one of the options?
  dbaron: min-aspect-ratio/max-aspect-ratio
  dbaron: but width/height are defined in the other direction
  dbaron: (of priority?)
  fantasai: Yes, but you can apply the ratio in both directions,
            because we do it in the direction that is auto
  jensimmons: I don't know what min-aspect-ratio or max-aspect-ratio
              would mean, and I don't think we need a three-part
              aspect ratio system
  dbaron: But if you worry about sizing of height, I guess by then the
          width has been set
  dbaron: The idea I was thinking is that you might want an aspect
          ratio, but that could be taller or wider, you could use
  dbaron: Well, ok, maybe I got this backwards
  dbaron: so it's fair to say that min and max might be confusing in
          this case
  dbaron: but it's more expressive
  jensimmons: I don't think there is a use case for max-aspect ratio
  jensimmons: I think the desired behavior is that you set an aspect
              ratio, and if there's more content it grows bigger... or
              it overflows
  jensimmons: you want the aspect ratio to either be strict
  jensimmons: or allow for the box to grow
  jensimmons: It's not a minimum aspect ratio, it's the desired aspect
              ratio unless it gets overflowed
  jensimmons: I don't know what the use case is for a maximum aspect
  jensimmons: or a range of aspect ratios
  jensimmons: From authoring / film industry... doesn't make sense
  jensimmons: You want a particular target, or you let it slide
              because it's not a good idea (overflow)
  jensimmons: I'd rather do the 1st proposal not the 2nd, to summarize

Scribe: fremy & fantasai

  rachelandrew: Trying to think of a use case this doesn't solve.
                Would like something written up with an example, say
                to authors, "this is what we're thinking of doing,
                behaves like this. Can you think of any use case it
                doesn't solve?"
  rachelandrew: People are doing this all over the web, so have an
                idea of what they need
  rachelandrew: We could get this out there and see if it'll solve the
  florian: agree with jensimmons

  florian: The thing you brought up, dbaron, is what the proposal is
           trying to solve
  florian: Want to grow by default if too much content
  florian: min/max-aspect ratio is too confusing
  florian: and the first one gets most of what you want, and you can
           enforce strictly if you need
  jensimmons: 2 use cases most common
  jensimmons: 1 - video or empty decorative box
  jensimmons: not a video element video, but iframe or object or
  jensimmons: other use case is teaser cards or something like that
  jensimmons: Maybe you want them all squares
  jensimmons: but you don't want them to constrain height, because
              want to allow overflow
  jensimmons: Is anyone imagining a different class of use case?

  bkardell: I'm hesitant to even bring this up, because not sure it
            fits in conversation, but not that long ago I worked on a
            project that was CMS-oriented
  bkardell: It was very open to what authors could provide
  bkardell: There were maybe 2-3 different kinds of images with their
            own aspect ratios
  bkardell: There was some negotiation
  bkardell: wanting to deal with the actual aspect ratio was the issue
            we had there
  bkardell: but seems the opposite of what jen's talking about
  bkardell: might not be relevant...
  astearns: We're talking here to add an aspect ratio to non-replaced
  astearns: so behavior needs to be specified for when content can't
            match aspect ratio that was specified
  astearns: Images always can
  jensimmons: Images come in when you use object-fit: cover or contain
  jensimmons: and want to give a particular aspect ratio
  jensimmons: but that's about interaction of explicit and implicit
              aspect ratios

  fantasai: One of the benefits of the min-height: auto solution
  fantasai: is that we can easily turn off the grow behavior
  fantasai: for example when we have scrolling in place
  fantasai: which I think is what we want by default
  fantasai: This is what min-height: auto is for

  dholbert: One thing to think about is the thing with aspect-ratio is
            not itself scrollable
  dholbert: but it has a scrollable child
  dholbert: min-height: auto means be as tall as the thing inside the
            scrollable thing
  dholbert: because the scrollble content is one level below
  dholbert: Fixable by setting min-height: 0
  dholbert: but might be worth thinking about
  fantasai: Actually, that spec has a simple solution

  fantasai: The question is whether this is web-compatible
  fantasai: so we need to implement this and see in a canary build if
            that works
  cbiesinger: It's in the backlog, but only for width
  fantasai: Well, you said you could only do this for width, but
            eventually we would want to try both
  fantasai: but width is a good start

  florian: Maybe this is one place where in the block axis we have a
           difference between min-content/max-content... maybe not
  florian: max-content you expand all the content. min-content you
  Rossen: That's super weird
  Rossen: I think it is super weird. It is also a behavior that is
  Rossen: If we going to introduce something like this, let's not
          re-introduce max-width or something
  Rossen: Let's add another property
  florian: I did not mean the max-width property
  florian: I meant the max-content keyword
  florian: min-height: auto grows you beyond the auto height
  florian: If you specified min-height: max-content you would grow and
           min-height: min-content you would not
  jensimmons: We started there, but decided to use auto instead
  jensimmons: You'd get the same result

  florian: Thing I hadn't considered is what dholbert brought up, when
           it's the children of the thing with an aspect ratio that
           are scrollable
  florian: Do you want control over that?
  florian: ...
  jensimmons: My expectation is that if you assign an aspect ratio to
              a box and inside there's controllable content, then your
              desire is to keep that content at that aspect ratio
  jensimmons: and then the content scrolls
  jensimmons: That would be awesome
  jensimmons: The fact that children is scrolling, want the container
              to grow?
  fantasai: I think this is one of the big mistake we made, and I
            really want this fixed
  fantasai: I am afraid of the webcompat
  fantasai: so I can't make this change just by myself
  <fremy> +1 to what fantasai said
  fantasai: But authors shouldn't have to set weird height:0 etc hacks
            to work around this
  astearns: But this is orthogonal to this issue, right?
  fantasai: Yes
  <tantek> +1 on fantasai's proposal from an authoring perspective. I
           hope we can do it and maintain compat!

  <fantasai> proposal is to use min-height: auto to solve the problem
             of having the box grow past its aspect-ratio in order to
             accommodate content that would otherwise overflow

  jensimmons: [gives an example]
  jensimmons: If I have 400px wide box with 1:1 aspect ratio and
              content is 700px high
  jensimmons: min-height: auto computes to 700px, therefore wins over
              the height calculated by aspect ratio
  jensimmons: author can set min-height: 0 to get that content ignored
              in the sizing
  dholbert: For both axes?
  fantasai: I think so, but not if both are auto
  dholbert: (example about a very long word you can't break)

  AmeliaBR: object-fit?
  fantasai: This is about non-replaced elements, doesn't apply

  astearns: Objections to proposed resolution?

  RESOLVED: Use min-height: auto to solve problem of content
            overflowing aspect-ratio

Received on Thursday, 16 May 2019 22:55:34 UTC