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[web-anim] Web animations minutes, 13 / 14 December 2012

From: Brian Birtles <bbirtles@mozilla.com>
Date: Fri, 14 Dec 2012 14:09:36 +0900
Message-ID: <50CAB490.9070206@mozilla.com>
To: "public-fx@w3.org" <public-fx@w3.org>
Web animations minutes, 13 / 14 December 2012

Etherpad: https://etherpad.mozilla.org/ep/pad/view/ro.JmTgOwIT-so/latest
Present: Steve Block, Shane Stephens, Douglas Stockwell, Brian Birtles

Agenda:

1. Status update
2. CSS WG resolutions review
3. PathAnimationEffect proposal
4. Events


1. STATUS UPDATE
================

Brian:
* Rename AnimationFunction -> AnimationEffect
* Make Animation.effect nullable
* GroupedAnimationEffect work
* Fix iterationStart behaviour
* Bug fixes (thanks Steve!)


2. CSS WG RESOLUTIONS REVIEW
=============================

http://lists.w3.org/Archives/Public/www-style/2012Dec/0188.html

- RESOLVED: Transitions defines the timing functions, Animations has 
normative dependency on Transitions for them.
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=14784

- RESOLVED: Animations only "run" (fire start events, etc) if they have 
at least one valid keyframe.
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=15251
Brian: I'd like to revisit this decision for the following reasons:
* There are valid use cases for an 'empty' animation that fires events 
such as  to simply to get the events and do appropriate actions 
(particularly when running off a global clock).
* If you later allow sequencing and such an animation is part of the 
sequence, you'd expect it to take time--why wouldn't it fire events too?
* It's useful to think of animations in two parts timing+animation. 
Events relate to timing. They should still fire regardless of whether 
there is an animation or not.

I (Brian) recently made Web Animations support having a 'null' animation 
function for these reasons. If CSS differs in this area it will confuse 
authors and complicate the mapping (since at the point where you remove 
a keyframe you'll also have to somehow disable or remove the 
corresponding Animation object(s)).

On further thought, this doesn't effect us too much since the CSS 
bindings would simply not generate an Animation when there are no keyframes.

 > Brian might get back to CSS WG about this

- RESOLVED: When an element changes from display:none to display: 
non-none, animations start immediately.
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=14785
Brian: not sure this has much effect on us? An issue for the CSS mapping?

- RESOLVED: An initially-paused animation is still started (fires start 
events, etc.)
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=14774
Brian: Not sure if we do this. I thought we resolved to do this but it 
doesn't look like the algorithms actually do this yet? i.e. if you pause 
before the start time it doesn't start?

 > Brian to look into this

- RESOLVED: Animations can be paused during their delay phase, which 
freezes the remaining delay to be applied after it unpauses.
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=14774
Brian: Pretty sure we do this.

- RESOLVED: animation-play-state is not in the shorthand on purpose
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=14787
Brian: doesn't effect us

- RESOLVED: animation-play-state has the same list behavior as the other 
animation properties, matching the length of animation-name.
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=14786
Brian: doesn't effect us

- RESOLVED: Look into "adjacent keyframes" for level 4, but not for the 
current level.
   https://www.w3.org/Bugs/Public/show_bug.cgi?id=20092
Brian: We already support this


3. PathAnimationEffect PROPOSAL
===============================

 > Currently tracking SVG fairly closely at this stage.

Still need to think about how to incorporate paced timing into the model 
and ordering of path animations vs regular transform animations from a 
compatibility point of view.


4. EVENTS
=========

Briefly discussed how we can unify CSS and SVG events. Possibility of 
delaying to v2.

One common use is:

   elem.animate({ opacity: '0%' }, 1).onend =
      function() { elem.parentNode.removeChild(elem); };

Disagreement about the criticality of events to the API.

 > Brian to spec it out and mark it as 'at risk'. We'll seek wider 
feedback later about how critical this is.


Next meeting: Mon Dec 17, 17:30 PST / Tues 18 Dec 12:30 AEDST / Tues 18 
Dec 10:30 JST @ https://etherpad.mozilla.org/JNHdgLfAYm

Past meetings: http://www.w3.org/Graphics/fx/wiki/Web_Animations/Meetings
Received on Friday, 14 December 2012 05:10:11 GMT

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