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[CSSWG] Minutes and Resolutions 2012-08-15 Wed PM III: Sticky Positioning, Animations, SciNot

From: fantasai <fantasai.lists@inkedblade.net>
Date: Wed, 29 Aug 2012 19:30:48 -0700
Message-ID: <503ED058.5080007@inkedblade.net>
To: "www-style@w3.org" <www-style@w3.org>
Sticky Positioning

   hober showed a demo of 'position: sticky'. Everyone agrees it's cool.


   - RESOLVED: Animations override all normal rules, but are overridden by
               all !important rules.
   - RESOLVED: Transitions happen last in the cascade
   - RESOLVED: Remove initAnimationEvent method
   - RESOLVED: Publish updated WD with those edits

Scientific Notation

   - RESOLVED: add scinot to CSS <number> using SVG syntax

====== Full minutes below ======

Sticky Positioning

   hober: I posted to www-style a proposal for adding a new position value
   hober: called 'sticky'
   hober: similar to relpos
   fantasai: It's like a combination of relpos and fixedpos that actually
   hober: It's in-flow like relpos
   hober: but the calculation of the offset is based on the intersection
          of the veiwport and the containing block
   hober: common use cases are, e.g. sidebar in a web page
   hober demonstrates
   * smfr perks up
   hober: This sort of thing is really common on the Web, using scroll
          events to emulate with JS
   hober: All just a single new position value
   hober: footer and header of table are always visible in viewport
   hober shows address book that works like iPhone address book headers
   plinss asks about a case of header and footer overlap
   hober: So I think it might be worth, in the longer term, adding a
          property for handling collisions
   hober: complicated if doing in multiple dimensions
   hober: by default would overlap
   hober: Looking for resolution to pursue the feature

   szilles: How does it behave for print?
   fantasai: would be same as relpos
   <dbaron> [5 conversations at once]
   glazou: I think it's not that easy to specify
   hober: I'll take an action to write a description
   szilles: If I don't have scrolling it doesn't move
   plinss: why not print on every page
   fantasai: Then you have the overlapping problem you have with fixed pos
             -- end up with tons of overlap.  If you want this effect when
             printing you need to make space for it.
   fantasai: That would be a different feature.

   glazou: If I can describe it this was included in the P language
   * fantasai thinks everything was in P language
   glazou: mechanism similar to pseudo-elements, you could select any
           element, such as viewport
   glazou: then had an element, and on that you could say "min-y: 0" inside
           the viewport
   glazou: meant element was always visible or invisible
   hober: Common design pattern, ppl emulate a lot with JS
   hober: But scrolling has gotten strange as time has gone on, so
          increasingly problematic
   <arronei> sticky, real world use case:
   <smfr> arronei: news.google.com sidebar

   Rossen: One question I have, new value is that the behavior is not
           applicable or useful for position: absolute
   hober: yes
   hober: Of all cases I've seen, makes more sense for in-flow positioning
          than out-of-flow. You want to leave space in flow for the item
   plinss: Suggest considering abspos version of this
   * smfr has never seen an abspos equivalent in the wild

   Bert: Seems you might want sticky differently in horizontal and vertical
   hober: Suppose you had a wide table, not so tall
   hober: you might want the column headers to stick the viewport, but if
          you scroll the table horizontally itself, you might want the row
          headers to stick within the viewport but not the scrolly
   hober: is it the nearest scrollable ancestor that you stick to?
   hober: do you have same decision in both dimensions?
   hober: worth thinking about
   plinss: Think proposal is for hober to write something up for css3-positioning
   plinss: would you co-edit?
   hober: either way
   <arronei> hober: add the proposal to http://wiki.csswg.org/spec/css3-positioning
   <Rossen> smfr, an example is running shopping cart totals positioned
            to left/right of forms

   glazou: Suppose green is the viewport
   glazou draws a big green box, left half has three black boxes stacked on
          top. Another black box below that, followed by red box, followed
          by blue box
   glazou: with collision could you get them to stack?
   overlap by default
   hober: I think overlapping by default is the right behavior here, could
          reuse collision later
   hober: also question of percentage values, at what distance do you start
   <smfr> stacking gets hard; you end up with a float-like algorithm
   <dbaron> I'm not convinced that reusing this same collision avoidance
            mechanism is the right thing.
   * fantasai notes yelp search results also uses stickypos


   <sylvaing> https://docs.google.com/spreadsheet/ccc?key=0Akz3Ts2PEQF2dE1fTHhJMlJBbnp6UmZNY2dzVHpEVGc
   sylvaing: This describes list of issues we had at last F2F
   sylvaing: some things fixed already
   sylvaing: hopefully reach LC at TPAC or before
   sylvaing: couple left over from Hamburg
   sylvaing: where in cascade do animations go?
   sylvaing: I believe dbaron described what Gecko was doing
   sylvaing: The emerging consensus was that transitions would happen
             at the very end
   sylvaing: you would go from current animation value to the transition end,
             but never really resolved on it
   <sylvaing> https://www.w3.org/Bugs/Public/show_bug.cgi?id=14713
   <sylvaing> http://lists.w3.org/Archives/Public/public-fx/2012AprJun/0107.html
   sylvaing: we discussed this part
   sylvaing: here's gecko's cascade
   sylvaing: we never resolved that
   sylvaing: I haven't checked recent webkit, but they used to have .. at
             the bottom
   sylvaing: in Gecko transitions are more important than animations
   dbaron: Except we would start a transition during an animation?
   <smfr> webkit still applies animations after everything else
   dbaron: starting a transition happens when we detect a computed value
           change that was not caused by an animation
   dbaron: the restyling operation..
   dbaron: The before and after styles are different in the no-animation case
   sylvaing: I'm trying to remember what's the difference...

   sylvaing: Other implementations don't let user !important and UA !important
             override animations. I think we do want that
   dbaron: I think we do want that.
   dbaron: Question is whether we want them under the other !important rules
   sylvaing: so any opinions?
   Florian: I remember having an opinion, but don't remember what it was

   fantasai: What are the options?
   sylvaing: Option A, animations are higher than UA and author !important rules
   sylvaing: Gecko allows them to override
   dbaron: Another option would be to put animations here, between author
           normal and author override
   fantasai: Where would scoped style fit in with that?
   dbaron: Author override and scoped would be a group
   dbaron: Question would be whether animations would go before the !important
           rules, or after them
   fantasai: So either animations would come right before all the !importants,
             or it would come right after all the author styles (including
   fantasai: I think having animations override user/UA !important rules
             is not a good idea
   glazou: I'm using them in BlueGryffon to prevent animations to run
   dbaron: Use case: user wants to override colors, but is fine with animations
           causing movement
   glazou: yes I think both User and Author !important should override
   RESOLVED: Animations are below user !important rules, not above them.
             [still discussing whether below or above author !important]

   dbaron explains why having transitions at the end of the cascade makes
          sense: the UA/user !important rules would prevent computed value
          changes that could trigger transitions
   sylvaing: so user rules could start them, but that's just about it
   RESOLVED: Transitions happen last in the cascade

   fantasai: So remaining question is whether author !important override
             animations or not
   RESOLVED: Animations override all normal rules, but are overridden by
             all !important rules.

   <sylvaing> https://www.w3.org/Bugs/Public/show_bug.cgi?id=14713
   sylvaing: snapshotting of values at the start of animation, action on
             smfr and dbaron on which properties snapshot or not
   sylvaing: talk about that yet?
   dbaron: not yet, no

   sylvaing: Raised by ...
   sylvaing: afaict not used
   dbaron: Yes, let's remove them
   RESOLVED: Remove initAnimationEvent method
   sylvaing: need to define a constructor

   <sylvaing> https://www.w3.org/Bugs/Public/show_bug.cgi?id=14781
   sylvaing: Spec doesn't specify starting frame / ending frame, spec
             defines generating them but doesn't define when ...
   dbaron: I believe we update it dynamically
   sylvaing: at some point you have your first frame, and others follow.
   dbaron: You're animating from that to some other point
   dbaron: if there's a style change that changes here, you're following
           this line instead of this line
   Florian: You put a transition for the adjustment being smooth?
   dbaron: Yes, maybe?
   sylvaing: I think we do it static at the moment. Think Webkit does too
   hober: Should be snapshotting after delay
   sylvaing: but compute first frame, last frame
   sylvaing: we didn't have a use case for dynamic case
   dbaron: My worry about dynamic case is mostly style changes that are
           nearly sequential
   dbaron: Because it'll expose when browsers coalesce things or not
   dbaron: Would like to minimize how much that's exposed
   sylvaing: Is that related to issue of which properties to snapshot?
   dbaron: testcases with a 5s delay are annoying
   dbaron: If I move the mouse into it while animating, it jumps to other
           position while animating
   sylvaing: Shouldn't this relate to general snapshotting issue?
   sylvaing: ok, think it's the same bug

   <smfr> https://www.w3.org/Bugs/Public/show_bug.cgi?id=15850
   sylvaing: I don't understand how you get an invalid rule here

   sylvaing: Have a few more edits, then ask for new WD
   RESOLVED: Publish updated WD with those edits
   sylvaing: Aiming for LC at TPAC or before

Scientific Notation

   TabAtkins: Required for SVG.
   dbaron: Unitless lengths and scientific notation are allowed in SVG attributes.
   * fantasai asks about CSS escapes in SVG
   TabAtkins: One use is to align with SVG
   TabAtkins: Other is it's useful in transformation matrices
   TabAtkins: Syntax spec already defines parsing for it, just have a
              flag for it to turn it on or off. So no additional work
              on the spec side.
   <dbaron> 8.574e-21parsec == 1px
   Florian: I will not object to scinot, but I'm not interested in it
   plinss: Any objections to adding scientific notation?
   Bert: Yes.
   Bert: I'm not happy with what we add, we don't have anything left for
         normal people.
   hober: Tab has two use cases
   hober: I don't consider them incredibly important, but they're reasonable.
   fantasai: I defer to dbaron.
   dbaron: I'm against it, but I'm not going to object.
   fantasai: That's my opinion.
   szilles: I'm not opposed, I'm not for
   alan: I think rationalizing things with SVG seems reasonable to do
   szilles: Useful, but not critical.
   Florian: which definition of scinot is this?
   Tab: Same as SVG. Number e integer
   Florian: How does this interact with minimum you're supposed to support
   TabAtkins: Turns into equivalent number
   dbaron: scinot is not valid in integers, only valid in numbers
   dbaron: Don't want to deal with scinot in integers
   TabAtkins quotes his spec text
   dbaron and TabAtkins discuss parsing problems and floats
   hober: Just force it to be a number
   * jdaggett maybe now is the right time to talk about priorities again...
   dbaron: Things that are integer are things we will represent using an
           integer rather than a floating type. Really don't want to
           encourage people to do exponents
   Florian: Since you don't care either way, when we're specifying precision
            of support, shouldn't require ... cancel out
   TabAtkins: So you're allowed to do truncation as you're parsing
   dbaron: SVG's integer type does not accept scinot
   <dbaron> http://www.w3.org/TR/SVG11/types.html#BasicDataTypes says
            <integer> doesn't take scientific notation and <number> does
   proposal: scinot for <number>, allow range-checking based on parse
             time as well as interpretation-time limits
   straw poll -> no consensus
   Straw poll again, more formally
   glazou: yes
   bert: no
   koji: abstain
   szilles: yes
   jdaggett: no
   glenn: yes
   hober: abstain abstain
   alan: yes
   fantasai: defer to dbaron
   tantek: defer to dbaron
   dbaron: no, but not objecting
   Tab: yes
   <smfr> yes
   Florian: abstain
   leif: why not, yes
   plinss: yes
   "Simon says"
   <smfr> :D
   Bert: Not really fair to ask every F2F until not enough around who disagree
   5 no, 8 yes
   RESOLVED: add scinot to CSS


   dbaron: Don't know what there is to discuss...
   tantek: Question is about going to FPWD
   dbaron: Think I'd rather not.
   <dbaron> with the ED as is

Meeting closed.
Received on Thursday, 30 August 2012 02:31:16 UTC

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