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Re: [web-animations] Fixing getAnimations()

From: Kevin Doughty <socallednonflipped@gmail.com>
Date: Sun, 29 Nov 2015 16:51:29 -0500
Message-ID: <CAAbwtRwcnDfkALPvy7AyBE+-EW9kkjv-qe_AyN90zAufiFOjeA@mail.gmail.com>
To: Rachel Nabors <rachelnabors@gmail.com>
Cc: Brian Birtles <bbirtles@mozilla.com>, "public-fx@w3.org" <public-fx@w3.org>, "www-style@w3.org" <www-style@w3.org>
I want to add that the problem with Apple’s Core Animation view animation
for AppKit is that there is no way to specify what name is used for
implicit animation (CSS transition behavior). Animations get added with a
name that is the same as the property being transitioned (in most cases).
This prevents multiple animations running concurrently on the same
property, and is what I want resolved. For additive transitions in Core
Animation, still, the only solution is to use method-swizzling (monkey
patching). I've suggested a naming property for Web-Animations, something
like “transition-naming” with values “exact”, “none”, and “increment”, but
I concede it is awkward. An alternate to allow multiple animations with the
same name, returned in an array, would be even worse.

On Sun, Nov 29, 2015 at 4:31 PM, Kevin Doughty <socallednonflipped@gmail.com
> wrote:

> Why is there a distinction between CSS transitionProperty and CSS
> animationName and script based animation id? Why are these three not one
> and the same? I do want a way to access all animations vs. a single keyed
> accessor. Something like getAnimations() and getAnimationNamed(). But how
> about you let getAnimations operate on a NodeList instead of creating
> parallel API (like the subtree boolean) to do the same tasks?
>
> document.querySelectorAll(...).getAnimations()
>
> If the user wants to recall animations they should give them a name. Too
> many conveniences make an API hard to grasp, when all one needs to do is
> loop through and filter.
>
> On Thu, Nov 26, 2015 at 1:38 AM, Rachel Nabors <rachelnabors@gmail.com>
> wrote:
>
>> I concur these are issues. I like the way your thinking is going.
>>
>>
>> [image: photo]
>> *Rachel Nabors*
>> Web Animation Engineer
>> w:rachelnabors.com
>> <http://twitter.com/rachelnabors>  <http://dribbble.com/rachelthegreat>
>> <http://plus.google.com/u/0/+RachelNabors>
>> <http://linkedin.com/in/rachelnabors>
>> ------------------------------
>>
>> Curator of Web Animation Weekly <http://www.webanimationweekly.com>
>>
>>
>>
>> On Wed, Nov 25, 2015 at 6:40 PM Brian Birtles <bbirtles@mozilla.com>
>> wrote:
>>
>>> Hi,
>>>
>>> Web Animations defines Animatable.getAnimations() (where Animatable is
>>> implemented by Element and a forthcoming PseudoElement interface) and I
>>> think we've agreed to add Document.getAnimations() as well.[1]
>>>
>>> I've found two problems with the first method which I'm going to call
>>> Element.getAnimations() for now since PseudoElement doesn't exist yet.
>>>
>>>
>>> PROBLEM 1. Element.getAnimations() doesn't work on a subtree
>>>
>>> Recently I was working on a presentation where I wanted to use script to
>>> restart all the animations in a particular slide, represented by a
>>> <section> element.
>>>
>>> What I really wanted to do was something like:
>>>
>>>    section.getAnimations().forEach(anim => anim.currentTime = 0);
>>>
>>> However, Element.getAnimations() doesn't return animations from its
>>> descendants (unlike querySelectorAll, getElementById, etc.).
>>>
>>> To further complicate things, Document.getAnimations() *does* return
>>> animations from its desendants (or will, once it is specced).
>>>
>>>
>>> PROBLEM 2. getAnimations() relies too much on the order in which
>>> animations are returned
>>>
>>> Whenever you see code using getAnimations(), it almost always looks like
>>> this:
>>>
>>>    var anim = elem.getAnimations()[0];
>>>
>>> That's really brittle. If some style is added that causes a transition
>>> to fire on elem, you may end up getting the wrong result.
>>>
>>> Of course, you can go through all the animations returned from
>>> getAnimations() and test their animationName/transitionProperty
>>> attributes and make sure you get the right object, but most people won't
>>> bother.
>>>
>>>
>>> PROPOSAL: Add some options to getAnimations()
>>>
>>> At a minimum, I think we need:
>>>
>>> * transitionProperty - used to filter by 'transitionProperty' which is
>>>    only set on CSS transitions
>>>
>>> * animationName - used to filter by 'animationName' which is only set on
>>>    CSS animations
>>>
>>> * id - used to filter by 'id' which may be set on script-generated
>>>    animations
>>>
>>> * subtree - true means to fetch animations from descendents too (based
>>>    on the Mutation Observer API)
>>>
>>> It's not obvious to me what the default value of subtree should be. I'd
>>> say 'false' except that would prevent using the same options object on
>>> Document.getAnimations(). Perhaps true? Given that most people will use
>>> this on leaf nodes anyway, maybe that would be ok?
>>>
>>> It's also not clear if we should only inspect the transitionProperty on
>>> CSSTransition objects, or if script-generated objects that define their
>>> own transitionProperty should be considered too. I guess they should.
>>> Likewise for animationName and CSS Animations.
>>>
>>> Some usage patterns are bogus, e.g. passing subtree:false to
>>> Document.getAnimations() or specifying both transitionProperty and
>>> animationName (except in rare cases where script added these
>>> properties), but maybe that's ok.
>>>
>>> Example usage:
>>>
>>>    // Get the animation I just added
>>>    elem.style.animation = 'move 3s';
>>>    var anim = elem.getAnimations({ animationName: 'move' })[0];
>>>
>>>    // Get all transform transitions in this section
>>>    section.classList.add('move-in');
>>>    var transitions =
>>>      section.getAnimations({ transitionProperty: 'transform' });
>>>
>>> As you can see in the first example, we still have the '[0]' thing
>>> there. It's more safe now since we're only dealing with CSS Animations
>>> named 'move', but you could still get the wrong result and it's also a
>>> bit of an eyesore and pain to type.
>>>
>>> I wonder if it's worth following the querySelector/querySelectorAll
>>> pattern and having a pair of functions: getAnimation/getAnimations?
>>>
>>> In the singular, if there were multiple matches on the same element
>>> you'd return the one with the highest composite order[2] since that's
>>> most likely to be the one that you want. If you had multiple matches
>>> within a subtree, I'm not sure: tree order or composite order.
>>>
>>> Possible future extensions:
>>>
>>> * Parameters to get only CSS transition or only CSS animations?
>>> * Parameters to get all animations that affect certain properties? e.g.
>>>    all animations that affect either the 'opacity' property or
>>>    'visibility' property.
>>>
>>> These can be easily implemented using Array.filter() so there's no
>>> urgency for these.
>>>
>>> What do you think?
>>>
>>> Brian
>>>
>>>
>>> [1] https://lists.w3.org/Archives/Public/public-fx/2015JulSep/0073.html
>>> [2] http://w3c.github.io/web-animations/#the-effect-stack
>>>
>>>
>
Received on Sunday, 29 November 2015 21:52:02 UTC

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