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Re: [web-anim] Web animations minutes, 31 October 2012

From: Shane Stephens <shans@google.com>
Date: Thu, 1 Nov 2012 09:15:44 +1100
Message-ID: <CAGTfzwTjAxpEtbUgb=1Z061QYS13uRJ5=n5YvGX6PHRCQDF-nQ@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: Brian Birtles <bbirtles@mozilla.com>, "public-fx@w3.org" <public-fx@w3.org>
Thanks for your response and explanation.

It's clear that the two should sit at separate cascade levels, to clarify
which wins in the case of an overlap. But it still isn't clear to me that
the cascade levels should be non-adjacent.

Is there a strong desire for transitions to sit as high in the cascade as
possible? What does it buy us? Would it be acceptable to put transitions
directly above animations, and below the user stylesheet?

The problem we are anticipating in Web Animations is that it will be
significantly more difficult to implement CSS Transitions and Animations
using Web Animations components if the contributions of these two types of
animation end up being influenced differently by user styles. Ideally we
would like to see all of CSS Transitions, CSS Animations and SVG Animations
acting in a unified manner on a web document to produce animated content.

Obviously if there are strong reasons for this difference then we just need
to cope, but absent a strong reason I think the desire within the FXTF to
unify SVG Animations with CSS Transitions and Animations forms a reasonably
strong reason to keep the cascade levels adjacent.


On Wed, Oct 31, 2012 at 9:56 PM, Tab Atkins Jr. <jackalmage@gmail.com>wrote:

> On Wed, Oct 31, 2012 at 6:33 AM, Brian Birtles <bbirtles@mozilla.com>
> wrote:
> > We don't currently distinguish between Animations and Transitions in Web
> > Animations.
> >
> > Action: Shane to discover why DB thinks this is important
> Several reasons.
> One, transitions are considered less disruptive than animations.  When
> people set values in a user stylesheet, it seems okay to still run
> transitions by default (people can always shut them down with a
> user-level "transition: none !important;" rule) - they're still
> respecting the user's desire, just over a non-instantaneous interval -
> so it's okay for magic-transition rules to sit at a higher cascade
> level than user!important rules.
> On the other hand, animations are more disruptive by default.  There
> is no connection between the animation and the user's own preferences
> - if they set "color: black !important;" in their user stylesheet, an
> animation can still make the text pulse red and yellow.  Thus, having
> user preferences override magic-animation rules by default seems like
> a good idea.  This means that magic-animation rules should either sit
> between author and author!important rules, or between author!important
> and user!important rules.  It doesn't matter too much which of those
> two are chosen - FF happens to take the first one.
> Two, having the two sit at separate cascade levels (even if they're
> adjacent) seems good to help resolve questions of "what wins when an
> element has both a transition and an animation" in an understandable
> manner.
> ~TJ
Received on Wednesday, 31 October 2012 22:16:11 UTC

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