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Minutes: 3 April 2011 FXTF telcon

From: Doug Schepers <schepers@w3.org>
Date: Mon, 04 Apr 2011 18:54:22 -0400
Message-ID: <4D9A4C1E.6020908@w3.org>
To: "public-fx@w3.org" <public-fx@w3.org>

                    CSS-SVG Task Force Teleconference

04 Apr 2011



    See also: [3]IRC log

       [3] http://www.w3.org/2011/04/04-fx-irc


           smfr, +1.206.675.aaaa, Doug_Schepers, ed, +1.650.253.aabb,
           TabAtkins, ChrisL, anthony, hober




      * [4]Topics
          1. [5]CSS Animation synchronization
          2. [6]SVG/CSS 2d transforms - 'transform-origin'
          3. [7]Filter Effects status update
      * [8]Summary of Action Items

    <trackbot> Date: 04 April 2011

    <scribe> scribeNick: shepazu

CSS Animation synchronization



    ed: long thread, wondered what the status of the animation work is?

    smfr: Dean promised to publish a draft this week
    ... has an API for WebKit

    ed: does it do sync?

    smfr: I don't think so
    ... it's hard to do smooth frame synchronization starting one
    animation at the end of another
    ... hard to get seamless joins based on 'animationEnd' event

    ChrisL: so, you want a negative offset?

    smfr: I think it's better to use JS APIs, per Dean's spec

    cabanier: on mobile devices, JS overhead becomes tens of seconds

    TabAtkins: that's based on the traditional approach, not Dean's

    smfr: you would set it up using keyframes or such, not execute it
    directly (?)

    cabanier: on iPad, we have to skip frames on animations, how would
    you set this up?

    TabAtkins: [missed]

    cabanier: ok, I'll have to see it working

    TabAtkins: it's simple at the moment, but has clear directions for

    ed: does this solve Paul's concerns?

    cabanier: paul was asking about pausing and rewinding animations, or
    replacing them midway through
    ... we were more concerned about synchronization in a simple manner
    ... without setting it up in advance or keying off an animation
    event handler

    ed: ok, we will wait for Dean's spec before going further

SVG/CSS 2d transforms - 'transform-origin'



    anthony: been discussion on the list about how the transform
    attribute is going to be used in relation to CSS
    ... I thought we were going for an override, but the list discussion
    doesn't seem to agree
    ... ROC put up some options... I don't have personal preferences, I
    am just curious what others think we should do?



    anthony: the most pertinent point for this discussion is point 1:
    "Elements with SVG transform attributes must default to top-left as

    transform origin, but CSS transforms default to the center."

    anthony: not sure the spec reflects the group decision at this point

    ed: I think it does reflect this first point
    ... for backwards compatibility



    ed: 'transform-origin' property has an initial value of center
    (50%,50%) for CSS, and origin (0,0) for SVG

    <ed> initial value is auto

    <ed> but it maps to those

    anthony: seems like people are leaning toward roc's option 1a: "1a)
    Introduce a UA style rule that sets transform-origin to "top left"
    for all SVG elements."
    ... would this apply before or after the transform is applied?

    smfr: SVG or CSS transform?

    anthony: I thought we were doing a 1-1 mapping?

    smfr: not sure how they interact

    shepazu: do CSS transforms override or supplement SVG transforms?

    ChrisL: depends on if @transform is promoted to a CSS property

    <ChrisL> if its promoted toa property then a style rule overrides.
    if not,then they could be defined to combine. Depends what we want

    ed: I did an experimental implementation that did a post-multiply,
    and it seemed easy enough to use, but felt a bit strange not to have
    @transform as a presentation attribute

    <ChrisL> Not promoting transform to a property minimises the
    backwards compatibility issues and means the dom still works as it
    did before

    ed: didn't experiment much, but that was the easiest way

    anthony: what about animation?

    shepazu: still works for animating with CSS animations

    ChrisL: I think the simpler path is not promoting @transform to a
    property, and just define how they combine

    shepazu: I tend to agree, though ed's point is taken

    ed: yeah, that solves the DOM issues as well

    shepazu: my only concern would be for SVG UAs that don't support
    CSS, but I think those are dwindling

    anthony: would CSS transforms still apply to SVG

    ChrisL: yes, they would be separate sources of transformation, and
    you would simply post-multiply them

    Resolution: pending further discussion with other stakeholders, we
    will not define @transform as a presentation attribute

    <scribe> ACTION: anthony to reply to Roc's email with our suggested
    resolution [recorded in

    <trackbot> Created ACTION-28 - Reply to Roc's email with our
    suggested resolution [on Anthony Grasso - due 2011-04-11].

Filter Effects status update



    ChrisL: my impression is that CSS people want it to be very simple,
    and that adding borders, backgrounds, etc complicates it, so a
    better would be to add new 'in's to the SVG filter primitives
    ... simon had a counterproposal with separate names, but that raised
    the question of how they combined

    ed: I think I'm in favor of having additional filter input image
    keywords, and we could define them for the SVG case

    ChrisL: for instance, for things that don't use the CSS box model,
    you would just use transparent black for the border image (for

    ed: we already have 'backgroundImage', but could do it differently
    for HTML

    <scribe> ACTION: ed to add filter input image keywords for CSS and
    HTML [recorded in

    <trackbot> Created ACTION-29 - Add filter input image keywords for
    CSS and HTML [on Erik Dahlström - due 2011-04-11].

    ed: would like to have a list... background of element, border,
    content box...

    ChrisL: padding is always transparent...
    ... so, that's a good list
    ... start with simple ones, like solid and dotted border, and give
    it a dropshadow
    ... then experiment with 9-box, apply effects... string of pearls,
    celtic knot...
    ... take the alpha channel of the border image to produce a
    dropshadow, I think that would be compelling

    ed: I'll also try to combine SVG Compositing to filters.... haven't
    looked at it yet...

    <scribe> ACTION: ed to add normative reference to SVG Compositing in
    Filters, and merge them where it applies [recorded in

    <trackbot> Created ACTION-30 - Add normative reference to SVG
    Compositing in Filters, and merge them where it applies [on Erik
    Dahlström - due 2011-04-11].

    trackbot: end telcon

Summary of Action Items

    [NEW] ACTION: anthony to reply to Roc's email with our suggested
    resolution [recorded in
    [NEW] ACTION: ed to add filter input image keywords for CSS and HTML
    [recorded in
    [NEW] ACTION: ed to add normative reference to SVG Compositing in
    Filters, and merge them where it applies [recorded in
Received on Monday, 4 April 2011 22:54:28 UTC

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