Minutes, SVG WG Leipzig F2F 2014 minutes, day 1



as text:


       [1] http://www.w3.org/

                                - DRAFT -

                          SVG WG London F2F 2014

22 Aug 2014


       [2] http://www.w3.org/Graphics/SVG/WG/wiki/F2F/London_2014/Agenda

    See also: [3]IRC log

       [3] http://www.w3.org/2014/08/22-svg-irc


           Chris, Erik, Cameron, Doug, Nikos, Jet, Jonathan, Brian,
           Razvan, Dirk, Rossen, Rik, Tav


           birtles, Nikos


      * [4]Topics
          1. [5]Agenda review
          2. [6]The topic index
          3. [7]Putting SVG 2 spec on GitHub
          4. [8]marker, symbol: refX and refY shorthand anchor
             points: 'top left' 'center center', etc.
          5. [9]variable stroke width
          6. [10]New SVG DOM
      * [11]Summary of Action Items

Agenda review

    <birtles> scribenick: birtles

    <scribe> scribe: birtles

    ed: one suggestion was to split up the spec editing over all
    the days
    ... e.g. one hour per day for editing instead of a full day

    shepazu: just a suggestion, e.g. 4-5pm

    heycam: maybe not the end of the day
    ... just after/before lunch?

    shepazu: after lunch is fine

    (shuffling of PM agenda to put spec editing after lunch)

    ed: any other topics missing from agenda?

    krit: I'd like to give a progress report about CSS layout
    ... and discuss fill/stroke properties
    ... any day other than today is fine

    Tav: I'd like to get some review on my talk for the conference
    if there's time at the end

    (conference = graphical web conference)

    ed: no one calling in?

    heycam: I don't think so

The topic index


      [12] https://www.w3.org/Graphics/SVG/WG/wiki/Topics

    heycam: one problem we seem to have is that we easily lose
    track of previous discussion about topics
    ... we type up our minutes, send them to the ml, tracker picks
    up issues/actions but apart from that there's no
    indexing/tracking of topics
    ... often you want to find out the latest on an issue and you
    have to trawl through the ml
    ... so I wrote a couple of scripts to manage links to
    discussions on particular topics
    ... they harvest mails sent to the mailing list
    ... the above link, links to pages from telcon minutes etc.


      [13] https://www.w3.org/Graphics/SVG/WG/wiki/Topic_database

    heycam: if you follow the first link ^
    ... that's where it's getting its information from
    ... I've only added a couple of topic lists just to give you an
    idea of the kind of format

    <scribe> ... new ones will automatically get added as we send
    out more minutes to the list

    UNKNOWN_SPEAKER: it extracts out the names of topics and
    ... since tracker doesn't do that for us

    krit: are resolutions also tracked?

    heycam: they're automatically added but they're not
    automatically copied to the topic page

    shepazu: is this a tool that you can make available to other

    heycam: it's on my github but there may be some SVG-specific

    krit: so we have to use the same topic every time?

    heycam: that is a problem but you can go back and edit the
    topic names
    ... the new minutes will get added automatically and then
    myself or someone else will adjust the titles so they coalesce

    nikos: I've got a similar record on our wiki if you want to use
    that data for historical records

    heycam: I could also run the script on old mails
    ... hopefully that's useful
    ... let me know if you have problems/suggestions

    shepazu: w3c is looking now at exposing group/spec data through
    an API
    ... so this might be another tool
    ... we're finally abandoning the RDF structures we use
    ... it's quite likely that this information would be useful..
    to be able to drill down into topics that a WG discussed
    ... for example we manually maintain a list of our
    ... there's no way for us right now to get all our
    specifications and their statuses

    krit: what
    ... what's the problem with that?

    shepazu: it's not nicely maintained, e.g. what WG is producing
    what specs etc.
    ... which revision each spec is etc.
    ... if there's any data you feel you want from w3c then let us

    krit: resolutions are really important

    shepazu: I think this is good, and if it's in a wiki that good
    ... can we edit to add notes?

    heycam: it expects a precise format the moment but I can adjust

    shepazu: we use various bots
    ... I've never been very happy with the way we handle minutes
    ... it might be worth fixing those bots

    heycam: that's something I've often wanted to do, have links to
    etherpads etc.

    krit: can we add it to svgwg.org as well?

    heycam: yes, of course

    nikos: it might be good to highlight which telcons have

    heycam: I have this infrastructure to munch emails from the
    list now

Putting SVG 2 spec on GitHub

    heycam: so Dirk asked about this recently...

    krit: other WGs are experimenting with this
    ... HTML is one of them
    ... it's helping others to contribute to the specification
    ... some developers would be interested in submitting PRs for
    ... I think we could accept PRs under the W3C license

    heycam: I put the WebIDL spec on github and have accepted a few
    ... but it was a bit unclear if PRs from non-w3c members was ok

    krit: you could put a license on the repo

    (discussion about how hard it is/isn't to learn GitHub)

    heycam: one thing is that the mercurial repo does automatic
    building of the spec when you push changes
    ... would that work with github?

    ed: you can do that with git

    ChrisL: with git or github?

    ed: because we have our own server, we can use that

    (discussion about how we could set up automatic building with

    krit: the CSS testsuite runs some scripts on every push



    ed: using webhooks we can trigger actions from github

    heycam: if someone's willing to do the work for that I don't
    see a problem

    krit: I don't have the experience yet to do that

    ChrisL: who was pushing for that?

    heycam: I think Anne was looking to make some changes

    ChrisL: is he ok to pushes changes under W3C license?

    shepazu: it's not just about him, a lot of people are doing
    this and seeing good results

    ed: would we also push to the w3c mercurial repo?

    shepazu: I'd prefer to just push to the github

    (general agreement)

    jwatt: so we'd dump the w3c repo?

    shepazu: MikeSmith has some experience with doing this

    ChrisL: are we moving all the specs for this WG?

    shepazu: yes, I think so

    ed: on a related note, I noticed that web-platform-tests is on
    github and I suggest we drop the svg2-test repository and
    switch to web-platform-tests

    RESOLUTION: We will move SVG WG's specs from the W3C mercurial
    server to Github

    Tav: are we going to use github exclusively or if we still need
    our own server

    ed: we'll still need our own server to run the build scripts
    since we can't run arbitrary scripts on github

    jwatt: but as for the WG members, they'd just be using github

    Tav: and I'd still be able to build it locally

    ed: yes, sure

    Tav: so all the tools are included too

    <scribe> ACTION: Doug to talk to Mike Smith about migrating the
    SVG WG repository to Github [recorded in

    <trackbot> Created ACTION-3638 - Talk to mike smith about
    migrating the svg wg repository to github [on Doug Schepers -
    due 2014-08-29].

    ed: who's going to look at webhooks from github to get a ping
    when someone pushes
    ... so we can tell svgwg.org to rebuild the spec

    <scribe> ACTION: Dirk to actually perform the migration of SVG
    specs to Github in cooperation with Mike Smith [recorded in

    <trackbot> Created ACTION-3639 - Actually perform the migration
    of svg specs to github in cooperation with mike smith [on Dirk
    Schulze - due 2014-08-29].

    jwatt: we need to decide where it lives in github

    shepazu: Mike says he's happy to help and it all looks do-able

    <ed> [17]https://github.com/w3c/csswg-drafts

      [17] https://github.com/w3c/csswg-drafts

    ed: regarding tests, there's web-platform-tests

    <ed> [18]https://github.com/w3c/web-platform-tests

      [18] https://github.com/w3c/web-platform-tests

    ChrisL: regarding that, we previously decided we want to work
    with CSS WG's test infrastructure
    ... and their tools do lots of linking between specs
    ... but none of that's going to be on web-platform-tests

    <ed> there's also [19]https://github.com/w3c/csswg-test

      [19] https://github.com/w3c/csswg-test

    ChrisL: so we should choose wisely

    shepazu: the way that CSS has done things is idiosyncratic to
    the rest of the consortium
    ... I think we're probably better off aligning with the rest of
    the consortium
    ... I think there will be other tools built around

    heycam: the advantage of doing things in the CSS repository is
    that Peter Linss is very active, and works very hard to get
    things going right

    ChrisL: he is very active and we do do a lot of work together
    with the CSSWG

    heycam: it seems like the CSS tests are primarily reftests,
    where do their scripted tests run?

    ChrisL, krit: same repo

    krit: the JS tests can still have metadata

    birtles: the web-platform-tests can have a fair bit of metadata

    shepazu: from the perspective of web-platform org is that we're
    looking for something like icanuse.com
    ... MDN's equivalent is just a table that someone inputs
    ... but for webplatform.org we have scripts that do that
    automatically now
    ... caniuse is good but it's based on very few tests and we
    want to be more rigorous than that
    ... and have a clickable field where you can drill down to
    individual tests
    ... so you have a confidence score about how well a feature is

    ed: do we still want the svg2-tests repository or use one of
    the others?
    ... do we want a separate one?

    krit: shepherd doesn't care

    ChrisL: what you (shepazu) described about drilling down to
    individual tests sounds great
    ... but how far away is that

    shepazu: what we have now is a JSON structure that generates
    the tables
    ... so we can plug anything into those tables we want
    ... going from there to drilling down is probably a couple of
    weeks work
    ... it hasn't been a priority until now but it will be in the
    coming few months

    ChrisL: that's good for developers, but what about the WG who
    are looking for "how far are we from CR?" etc

    Tav: how can I put Inkscape's test results in?

    shepazu: I guess you would have to do it manually

    heycam: are you referring to the boxes in the CSS spec?

    krit: you'd have to ask Peter

    ChrisL: I think you'd have to fill in this data and pass a
    pointer... it's been asked before
    ... I think the answer is to mail Peter and ask

    shepazu: it sounds to me like people are leaning towards
    ... for webplatform.org we'd rather the data be all in one
    place and rather the CSS WG joined in what everyone else did

    krit: we can join these test repositories later
    ... i.e. go to CSS repo first and then merge to web platform

    birtles: can we go the other way?

    ChrisL: no

    Rozvan: what about tests which are only supported behind a
    ... we had this problem for crowdsourcing tests for CSS shapes
    ... users wouldn't know that they had to enable these flags so
    they'd report incorrect results

    shepazu: for webplatform.org we just want to get the results of
    tests (not create them or run them)

    birtles: I know we're doing some work to better integrate
    web-platform-tests into the Mozilla build system

    krit: we have that for the CSS repo as well

    heycam: we have some scripts for the CSS repo too

    shepazu: I'd like to avoid going to the mercurial of tests

    ed: what about user-submitted tests?
    ... do we want to decide a structure for that

    birtles: so TTWF normally submits tests to web-platform-tests?

    ed: yes

    ChrisL: but there are some tests in shepherd from TTWF

    heycam: at some point we need to convert our SVG 1.1 test suite
    to reftests etc. (i.e. automated tests)

    shepazu: that might be a good topic for TTWF

    (discussion about how to write reftests for things like paths)

    ed: another thing to consider about dropping svg2-tests is that
    it's not being pulled into blink's repo

    shepazu: at some point I'd like to add to the agenda discussion
    about using annotations in the SVG spec
    ... we should decide between the CSS test repo or

    heycam: I'd like to know if web-platform-tests supports


      [20] https://github.com/w3c/web-platform-tests/

    scribe: it would be good to use the structure from CSS for
    reftests and the boxes with test results

    shepazu: that's why I'd like to talk about annotations
    ... since we're planning on building that functionality
    ... if that kind of feature is useful, it will get added to

    ed: it doesn't seem like we're arriving at consensus over which
    repo to use

    ChrisL: I feel like I don't have enough information to decide

    Tav: I'd like to see a demonstration of both

    RESOLUTION: We will migrate tests from svg2-tests to either the
    CSS test repository or web-platform-tests (or both)

    (discussion about who to demonstrate the test repositories)

    (break 15mins)

    <heycam> ScribeNick: heycam

marker, symbol: refX and refY shorthand anchor points: 'top left'
'center center', etc.

    Tav: if you remember we decided to extend refX and refY to
    apply to symbols, like markers
    ... Andreas Neumann had requested that
    ... he's also now requested for us to consider adding
    shorthands: top, left, center
    ... because this is typically what people doing mapping stuff

    krit: center would be the bbox center?

    Tav: yes

    krit: do we support % on these attributes?

    Tav: don't know

    ed: they are length in SVG 1.1

    krit: which means it includes percentages
    ... what's it resolved against?

    ChrisL: so we could make left,center,right mean 0%,50%,100%
    ... that's the point of having a symbol rather than g, it has
    its own viewport

    krit: but no viewBox?

    ChrisL: yes

    Tav: right now it's the viewport that's being used

    krit: of the marker or the path?
    ... for refX and refY, is this % resolved against the viewport
    of the marker?

    Tav: yes
    ... I wasn't aware that % was already supported there

    <ChrisL> actually it does have a viewBox attribute

      [21] http://www.w3.org/TR/SVG/struct.html#SymbolElement

    heycam: if the %s mean what Andreas is requesting, then I would
    say just use the %s

    shepazu: this is what I wanted to roll these all up in one

    Tav: I was looking at that...
    ... these different elements differ enough in their uses that I
    think it would be hard?

    ChrisL: I think there is an advantage to having separate names
    for these things

    Tav: e.g. markers change depending on stroke-width, or not

    shepazu: that's sort of like a use? you can change some aspect
    of it, or not

    Tav: there's an attribute that controls whether it scales
    according to stroke width

    <ChrisL> advantage is you can optimise based on typical use eg
    caching patterns

    shepazu: if they haven't different behaviours, that's one
    thing, but if they have additional behaviours, I think we
    should try to do this
    ... consistency of the model, understandability
    ... bugs, etc. if you only have to do one different thing for
    this other use...

    Tav: I can try to find the work I did looking at this

    shepazu: maybe it doesn't make much sense for Inkscape but it
    does for the spec

    ChrisL: if we had a new DOM we could make all of these inherit
    from the one interface

    ed: your question is whether to allow the keywords?

    Tav: I didn't know percentages were already allowed

    ChrisL: so if we did support 'top left' it would be a shorthand
    for '0% 0%' etc.?

    Tav: it would be
    ... I'll ask what Andreas thinks about using the percentages

    ChrisL: one advantage to the shorthands is that CSS does that
    for thing like boxes, tiling of background images it has this
    center top syntax
    ... but it's just syntactic sugar
    ... the one thing to remember is to switch off the clipping
    ... otherwise you only get the first quadrant of your symbol
    ... don't understand why overflow isn't visible by default

    krit: so this is overflow: visible for symbol?

    shepazu: by default

    ChrisL: the only downside I can think of is if they have hidden
    things in the other quadrants
    ... I suggest we do that and have authoring guideliness to
    define symbol around (0,0) to make your life easier

    Tav: Andreas pointed out that in mapping you often have
    different anchor points
    ... a tower would be aligned to the center bottom, for example

    RESOLUTION: symbol will be overflow:visible by default by the
    UA style sheet in SVG 2

    <scribe> ACTION: Chris to add |symbol { overflow: visible; }|
    to the UA style sheet and add authoring suggestion to say to
    design symbols around (0,0) [recorded in

    <trackbot> Created ACTION-3640 - Add |symbol { overflow:
    visible; }| to the ua style sheet and add authoring suggestion
    to say to design symbols around (0,0) [on Chris Lilley - due

    ed: what about the keywords?
    ... transform-origin has these

    Tav: that's where I got the names frmo
    ... it might be useful if that's how it's done in CSS already

    ed: I think it's fine to add that

    heycam: I would prefer not adding the keywords

    ed: do you see refX/refY becoming presentation attribtues in
    the future?

    krit: to x and y maybe

    Tav: I don't think they need to be presentation attributes

    krit: I think for authors it's more important to have the basic
    shape geometry attribtues as properties

    nikos: I don't see any need to add the keywords; I think the
    meaning of the percentages are clear

    shepazu: no strong feeling

    krit: I don't think we should add the keywords

    Tav: ok I'll get back to Andreas with that

    <scribe> ACTION: Tav to get back to Andreas about refX/refY
    top/left/etc. [recorded in

    <trackbot> Created ACTION-3641 - Get back to andreas about
    refx/refy top/left/etc. [on Tavmjong Bah - due 2014-08-29].

    krit: for overflow:visible I thought we were talking about
    marker, not symbol

    ChrisL: I think we should do it for both

    ACTION-3640: Actually this should remove the existing UA style
    rule to set |overflow: hidden|

    <trackbot> Notes added to ACTION-3640 Add |symbol { overflow:
    visible; }| to the ua style sheet and add authoring suggestion
    to say to design symbols around (0,0).

    krit: did IE make overflow:visible by default on root <svg> of
    inline SVG?

    Rossen_: it made the most sense

    ed: it's what people would expect

    Rossen_: I'd expect it to be visible for foreignObject too

    ed: per spec that would be hidden since it's a
    viewport-establishing element


      [24] https://svgwg.org/svg2-draft/masking.html#OverflowProperty

    ed: so I would prefer to drop the last bullet point in that

    krit: I would worry about the inner SVG becoming
    ... otoh I'm surprised that inline root SVG is not breaking
    anything for IE

    ed: I think people are told to workaround it by putting
    ... the less special handling for overflow in SVG the better

    krit: that's a benefit, but I'm just noting that people are
    using inline SVG and I'm not sure if that new behaviour would
    be better
    ... maybe we can make this change and see implementation

    ed: pattern too?

    heycam: no I think that would break things

    <ed> The initial value for ‘overflow’ as defined in
    [CSS21-overflow] is 'visible', and this applies also to the
    rootmost ‘svg’ element; however, for child elements of an SVG
    document, SVG's user agent style sheet overrides this initial
    value and sets the ‘overflow’ property on elements that
    establish new viewports (e.g., ‘svg’ elements), ‘pattern’
    elements and ‘marker’ elements to the value hidden.

    <ed> (this is the last bulletpoint in the link I pasted above)

    ed: so pattern would remain
    ... but viewport establishing elements would all go to
    ... overflow doesn't apply to mask

    krit: mask default has this 10% margin region
    ... this has changed in the masking specification to be auto
    ... so it's effectively overflow:visible

    RESOLUTION: All viewport-establishing elements will be
    overflow:visible by default, except for root <svg> of SVG whole

    ACTION-3640: Plus more, check the minutes here.

    <trackbot> Notes added to ACTION-3640 Add |symbol { overflow:
    visible; }| to the ua style sheet and add authoring suggestion
    to say to design symbols around (0,0).

variable stroke width

    birtles: last time I put forward the proposals for syntax



    birtles: the next action coming out was to make a polyfill
    ... I did the part that does the parsing, but I didn't do the
    part which actually draws the stroke
    ... I don't have the time to do that
    ... so if anyone wants to see the feature progress, it needs
    your help to do that

    shepazu: I've done a lot of that stuff in the past

    ChrisL: did you try and it was complicated? or that's just
    where you stopped


      [26] https://rawgit.com/birtles/curvy/master/index.html

    birtles: I haven't updated the syntax for what we discussed in
    ... if you look at the wiki page, the property is now called
    ... but in the prototype here it's called stroke-widths
    ... so it's not up to date with the proposal

    shepazu: I see it supports inner and outer

    birtles: asymmetric stroke yes

    shepazu: how does it interpolate between the points?

    birtles: we were going to try different ways with the prototype

    ChrisL: would be a good option for Catmull-Rom
    ... the wikipedia page mentions a few different forms of
    Catmull-Rom, some of which are more well behaved than others
    ... i.e. doesn't produce cusps/loops

    Tav: inkscape has something similar implemented

    <scribe> ACTION: Tav to ask Inkscape vsw implementor to add
    Catmull-Rom interpolation to see what it's like [recorded in

    <trackbot> Created ACTION-3642 - Ask inkscape vsw implementor
    to add catmull-rom interpolation to see what it's like [on
    Tavmjong Bah - due 2014-08-29].

    cabanier: there's an Adobe guy who probably would be eager to
    help with the prototype

    <scribe> ACTION: Rik to ask the Adobe guy about working on the
    vsw prototype [recorded in

    <trackbot> Created ACTION-3643 - Ask the adobe guy about
    working on the vsw prototype [on Rik Cabanier - due

    Tav: we have cubic bezier, linear, and spiro as interpolations
    in Inkscape
    ... shouldn't be that hard to add Catmull-Rom
    ... I think this isn't the harder part of the problem
    ... joins are harder

    krit: dashes too

    [discussion about various corner cases]

    m_spline Centripetal Catmull–Rom spline


    <ed> [work on actions until 3.15pm]

    <nikos> trackbot, close ACTION-3599

    <trackbot> Closed ACTION-3599.

    <nikos> trackbot, close ACTION-3168

    <trackbot> Closed ACTION-3168.

    <nikos> trackbot, close ACTION-3170

    <trackbot> Closed ACTION-3170.

    trackbot, close ACTION-3634

    <trackbot> Closed ACTION-3634.

    <ChrisL> action-3640?

    <trackbot> action-3640 -- Chris Lilley to Add |symbol {
    overflow: visible; }| to the ua style sheet and add authoring
    suggestion to say to design symbols around (0,0) -- due
    2014-08-29 -- OPEN


      [30] http://www.w3.org/Graphics/SVG/WG/track/actions/3640

    <ChrisL> <svg><star><star><star><star><star><description>OMG
    its full of stars</description></svg>

    <ChrisL> s/star>/star\//g

    <nikos> Scribe: Nikos

    <scribe> scribenick: nikos


    heycam: last time we discussed the DOM stuff, the discussion
    ended on the point where a couple of people weren't sure about
    going ahead in this direction
    ... so we decided to write a polyfill for experimentation
    ... the polyfill only works in recent FF with a certain pref on
    ... relies on web components, shadow trees, mutation events,
    and some other features
    ... I'll take you through some of the examples that are in the
    ... graphics element causes the new DOM interfaces to be put on
    ... I realised that to avoid breaking the pages that use the
    old one, we need some syntactic way to opt into the new stuff
    ... the best way seemed to be to have a different element name
    for the root
    ... so that existing content gets the old interfaces
    ... and new elements can go in html namespace

    krit: does polyfill create elements in the html namespace?

    heycam: the root graphics element gets a shadow tree. The whole
    tree gets cloned in the shadow tree with updated names and
    cases and so on
    ... and it watches for updates
    ... there are limitations - events, etc

    ed: if you were to have nested graphics elements this wouldn't
    work right?

    heycam: no. inner things are called viewport and outer are

    ed: foreignObject?

    heycam: I didn't do it
    ... I rely on html parsing and these elements go in html
    namespace. there are some tricky bits that require parser
    ... if we had foreignObject it would probably be a good chance
    to use a different name

    birtles: we are going to look at using svg elements in html
    without foreignObject on Monday

    shepazu: rather than be a new element, couldn't the flag be svg
    element without the ns?

    heycam: you don't put the ns already in inline svg in html

    shepazu: the key is that things are going in the html ns

    heycam: yep

    heycam shows some demos

    heycam: there are some options for lengths. There are some
    modes you can set to try different options
    ... I'm not sure which would be best
    ... in terms of the namespace. Because we're in html ns. If I
    want to create a new rectangle I can just use
    ... certain things get a lot shorter - interaction with
    attributes, creation of element

    shepazu: why can't we expose these methods on existing svg

    heycam: the names are already taken
    ... currently if you're interacting with a rect you use
    rect.x.baseVal.value = 100
    ... if you wanted rect.x = 100, that would work
    ... but rect.x == 100 wouldn't work
    ... it doesn't know you want x to be a number
    ... I have an example showing the different ways of exposing
    svg lengths - moving-rects-0.html
    ... this is using the existing dom
    ... creates 10 rectangles, initially diagonally down the page
    at 0em, 1em, etc
    ... then does an animation where a random amount is added each
    ... most concise way to set is via setAttribute
    ... jittering rectangles around means you need .x.baseVal.value
    to get to a number
    ... same example using strings. Creating the object and setting
    initial values is more concise and more familiar for html
    ... doing the numeric stuff is a problem because you need to
    convert to numeric values
    ... this is a limitation of reflecting lengths only as strings

    ChrisL: could it be reflected multiple ways?

    birtles: you can't overload the getter but you can for the

    heycam: reflecting as strings is one option, but there are a
    few other options
    ... next example the properties on assignment can take number
    or string, but when you get them out you always get the user
    unit out

    ChrisL: so when getting values all numbers are converted to a
    canonical unit?

    heycam: yes
    ... this is nicer than string only, but you can't use .x to get
    the string value
    ... final way you could do it is to have parallel accessors
    ... e.g. rect.x_px

    ChrisL: I don't like that as much as .x.px

    shepazu: chaining is a common pattern, I don't know if it's
    only with methods or if it would also be useful for properties

    <ChrisL> no, I was unclear. I don't like either x.px or x_px;
    prefer just .x returning a number

    heycam: not really relevant for properties

    krit: I was talking with Dmitry. He doesn't like this kind of
    ... where you set with one value and getter returns a different
    value because it's in a different unit

    heycam: I think that's a valid point and might be reason to
    pick another proposal over this one
    ... might be an author expectation that returned value is the
    same as the set value

    krit: Dmitry suggested something like x.getPixel()

    shepazu: that's also magical

    ChrisL: problem with returning strings is you have to parse
    them or have utility functions for dealing with them
    ... I think there's something in css where you can assign but
    the returned value is a canonical type
    ... why can't it be the same here?

    krit: not the same in css
    ... internally css uses a canonical type

    ChrisL: I think it will align down the road with css

    heycam: depends if css goes down the road where you assign one
    type and get another out
    ... but they might not go in that direction
    ... whatever they do, it would be good to follow the same

    birtles: I thought the long term plan was to use value objects

    heycam: don't think it's going to happen soon

    birtles: I don't want us to paint ourselves into a corner where
    we can't align

    krit: I'm not sure if it's magic, as far as I read the proposal
    from Tab it's pretty straight forward

    heycam: I don't see that happening soon

    krit: could svg wg push that forward?
    ... I added new section in SVG 2 with x, y presentation
    attributes. We could start working on om for css
    ... I have a fear with any new OM. it's svg specific

    heycam: it's not svg specific in terms of the pattern of
    interacting with objects
    ... the pattern of exposing all properties as types appropriate
    to the property

    ChrisL: people like that sort of thing

    heycam: think there's a lot of antipathy wrt to getAttribute
    and setAttribute

    krit: I support the part of making everything in html namespace
    ... don't support new graphics element
    ... it took 12 years for svg to be adopted. Now they have to
    learn something new

    ChrisL: we can't break all the existing scripts

    krit: if we decide to use new dom we can't

    ChrisL: only way to move forward is to introduce a new element
    with the new dom
    ... so you're arguing for breaking all scripting in svg with
    new dom?

    krit: I'm arguing that we shouldn't introduce new dom because
    we won't do it right this time
    ... like last two times
    ... i prefer to follow pattern of new CSS OM
    ... rather than creating new SVG model
    ... implementations won't support elements in two namespaces
    ... it's duplication of maintenance effort

    heycam: I don't think it'll be too much work
    ... will just be an extra line in tables
    ... I think this DOM thing is actually rather small
    ... mostly it's accessor things
    ... which html elements already have code for reflection of
    ... if we have string or length then that's a bit different
    than html but it's not too much extra
    ... plus a couple of methods for dealing with list type things
    ... so total code to support new DOM is not that big

    krit: for webkit it would be a major change because svg
    animation uses old dom
    ... and needs to be mapped to new dom as well

    ChrisL: I see your point that we need to consider implementer
    ... if we allow opting in and promote the new dom
    ... in a few years we can drop the old method
    ... and break content that hasn't updated

    krit: my point is that supporting new svg dom in the meantime
    with long term plan to go to css om
    ... means three things we have to maintain at once

    ChrisL: css om is 5-10 years away

    krit: new svg dom will be same time frame before it is in
    mainstream use

    ChrisL: don't agree

    krit: in this case you said we'd break a lot of content with
    svg dom, but the adoption of the new dom will be lower than you

    ChrisL: I think as soon as this is implemented people will want
    to use it - it's simpler, probably more performant, etc
    ... everyone hates the existing dom
    ... number one thing people want is the dom fixed

    krit: we are seeing most content comes from tools or scripts
    ... people aren't using svg dom

    shepazu: possibly because it's so crap
    ... the performance hit for marshalling is bad, this might fix
    it right?

    heycam: for lists it should
    ... I can show an example - transform-changes-1.html
    ... graphics element, 3 shapes, each has an initial transform
    and we're doing some script animations
    ... instead of having svg transform list and all the items in
    the list
    ... we have getTransformItems() which returns an array of
    ... each item in the array is a plain javascript object with
    ... it's not a live reflection of the thing
    ... you can push some new object onto the end of the array and
    it takes effect

    krit: that's pretty neat
    ... but it would just work on svg elements?

    heycam: the model I'm thinking of, for elements that have
    attributes, for each attribute there's some accessor method
    ... why couldn't we use that on a div
    ... ?
    ... if cssom had some nice list method like this (which it
    doesn't) then you could

    shepazu: why do you think it's important that it's a generic
    one rather than one that works with svg elements

    krit: it's important to have a unified model

    shepazu: in what way is this not similar to getting the href of
    an a element in html?
    ... I think there's a core difference between svg and html
    ... html is light on attributes and attributes don't have
    complex values
    ... I think this is about as close as you can get with how a
    html dom would work

    ed: looking at an attribute with a complex structure - say path
    - there's talk of adding path to css
    ... would this work similarly on path in css?

    heycam: I would want the same dictionary values to be used

    krit: with the SVG attribute has the least priority in the
    cascade, you would constantly override the values

    heycam: maybe that's an argument for not having accessors on

    krit: it's the same with svg attributes

    heycam: that's true

    krit: I do like this api more than what we have on svg
    ... but it should apply to everything that's transformable

    shepazu: for transform you have a point

    heycam: maybe it would have been better to show an example on

    jet: I was hoping to see the sprite model on svg
    ... what I'm seeing is svg is more machine generated
    ... lists would have many elements and iterating over isn't
    ... what I'm seeing is that you can't pick out a particular

    heycam: one step in making it faster is the 'willchange'
    ... in terms of the dom memory size issue, if you're not going
    to make modifications, it's been suggested to take a snapshot
    of the tree as a raster and throw away the tree
    ... it's kind of possible now with some work using Canvas

    shepazu: there's a problem with that technique because you lose
    quality if someone zooms or does anything similar
    ... though perhaps you could just reconstruct

    heycam: depends if you've thrown away the subtree

    birtles: you could use an image element with a data uri to
    generate a sprite and throw away the dom tree

    heycam: it's a bit like the original promise of use

    shepazu: and by having params you could optimise on what would
    change and what would not
    ... so you could decide what bits to throw away and what to
    ... I hadn't considered that aspect, but params along with
    variables could be used as an optimisation hint
    ... one of the interesting things about svg is that you don't
    just have a static image - you have something you can change
    ... that is an advantage over rasters

    jet: I'm not just talking about performance, but usage
    ... vast majority of svg isn't programmed
    ... so I'd like to be able to opt in to enabling programming on
    svg content

    shepazu: you could specify that on the graphics element

    jwatt: you could probably determine that programatically
    ... you'd need to take note of percentages and layout
    ... it's kind of the thing that you don't want an author to

    heycam: if it's inline svg markup you need to have the dom
    because changes could come from outside

    jet: programmable graphics is useful, but we're making
    assumptions about the dom that come from html
    ... which is mostly hand written, but svg is generated
    ... author just wants a scalable image, but it's slow because
    all the stuff going on under the hood to support the dom

    heycam: you can already make that decision as an author by
    placing the image in line or not
    ... if you're doing inline svg you've made the decision that
    the dom needs to stick around

    krit: if you scale the webpage, is there a performance
    difference between scaling an inline svg or an image svg?

    Rossen_: you will see differences if you use percentages

    krit: if percentages aren't use will images always be faster in

    Rossen_: yes
    ... which goes back to the point before about using the svg as
    an image

    krit: I'm not sure about WebKit, what's FF like?

    birtles: we have optimisations on img that will make it faster
    ... I think we've worked out a way to reduce the cost of the
    DOM if that's what you want

    krit: is there a cost on the dom other than memory?

    jwatt: for us there would be - e.g. hit testing on elements

    krit: for re-rendering only the render tree would be used (in

    heycam: back to the polyfill

    Rossen_: there was a css value proposal that Tab had - I liked
    that he hid all the properties behind a CSS object

    krit: that's the css om

    Rossen_: have you thought of applying the same approach here?

    heycam: I think we considered at one point doing something like
    giving different united access
    ... e.g. element.px.width

    Rossen_: I liked it all being behind css
    ... related to dirk talking about transform, it's clear which
    you're working with

    <Rossen_> link to Tab's proposal

      [31] http://www.xanthir.com/b4UD0

    ed: we are moving more svg properties to css om, there's less
    unique svg attributes (or objects) in the dom

    heycam: for everything that has an attribute on an element,
    there's a dot something that lets you access it
    ... for consistency with html there should be some way of doing

    krit: not sure if we need to be consistent with html at that

    heycam: I think that's a consistency that hasn't been broken in
    ... an author can always guess how to interact with an object

    ed: I'd rather break the existing dom, phase it out and upgrade
    what we have

    heycam: to achieve that new objects shouldn't have access to
    the old dom

    shepazu: I'm don't think there's too much content using the
    current dom

    heycam: we get bugs filed all the time when things change

    krit: there's lots of differences now between Blink and WebKit
    and we don't get many bugs filed on it

    shepazu: I'm skeptical that there's content using the specific
    part of the dom that we would break
    ... some content would break obviously, but is there a
    significant amount?

    heycam: didn't we do a search last time and we found that d3
    uses some

    krit: just transform, with a fallback

    shepazu: I think we talked last time about reaching out to
    those library authors and seeing how they feel

    birtles: it's all the sites that have installed it and aren't
    updating it

    ChrisL: I'd like to take up your point, get Dmitry's input for

    shepazu: that's not what I'm talking about. I'm talking about
    the proposal not having this new graphics element

    ed: are there any other ways of opting in?

    heycam: I couldn't think of any that are reasonable

    shepazu: I'm suggesting that we break backwards compatibility
    ... just say rather than maintain these two paths, just break

    krit: speaking for WebKit and Apple, we would do it

    jwatt: if you do it and get away with it I'd be happy to do it

    shepazu: put out a build and see if people complain

    krit: we can't break getPathLength, but we can break animval

    heycam: I agree that if it's possible to completely replace
    things then that's the best solution
    ... but I'm cautious about doing that

    shepazu: there will be content that breaks, old documentation
    that will no longer be applicable
    ... but I suspect most of that content is not content that is
    being used
    ... a lot of the content would be from the old days
    ... FF broke almost all SVG content when it insisted we include
    the ns in the svg root
    ... I think we should be aggressive and try to change it and
    see what people say

    ed: as long as there's an alternative to the functionality

    shepazu: you can do it with a shim

    ed: that would be difficult with animval

    heycam: 1. whether or not new accessors are what we want

    2. is backwards compat what we want?

    heycam: I still think we should have the nice accessors, but it
    means we can do it in stages

    shepazu: I would be happy with any of the suggestions rather
    than what we have now
    ... I couldn't decide on which one we want now

    ed: it should be possible to drop parts of the old svg e.g the
    SVGPathSeg* API

    heycam: what do you think about the dictionary things?

    krit: everything using dictionaries is more like coding today
    ... could we map svg namespace to html namespace?

    heycam: that's a big dom core change but ....

    ed: we had some hacks in presto to let you do that
    (document.createElement("rect") got you an SVGRectElement if
    the document had an <svg> root)

    heycam: could hack html parser now to put svg elements into
    html namespace
    ... and rely on not inspecting the namespace

    krit: we got bug reports on that - about inheritance of objects
    ... right now is the best time to change svg this way

    <jwatt> Some modern HTML5 elements that have added numerical
    DOM properties:







    shepazu: right now people are using svg like an image, in the
    next few years people will be using it more like something you
    can program

    <jwatt> (so precedent for heycam's proposal)

    heycam: I think we have to provide a nice scripted interface.
    Don't think it's good to require people to use libraries

    jwatt: dirk was saying he didn't like having numerical
    properties - there's precedent for doing that in html5

    heycam: I think we have a path to the next step now
    ... if we can rip the band aid off then that's good
    ... we would still need to work out the details regarding
    namespace stuff
    ... if we're not using a new root element name

    shepazu: I wonder if this is something we should talk about at
    graphical web?
    ... on the panel thing

    heycam: for a couple of the changes here, can you change href
    and classname to a string?

    shepazu: you should also allow href without the xlink

    krit: we also need to talk about image vs img

    heycam: that was one of the wrinkles with this
    ... any way we go about it it's going to require changes to
    ... maybe we should allow img
    ... we are already switching to object-fit and object-position
    ... so to summarise the plan:
    ... 1. can we just remove the existing svg dom? dirk will try
    ... 2. if so, various parts of this proposal don't need to be
    done because we don't need to opt in
    ... we should give people whatever nicer options we can as soon
    as possible, but it doesn't have to be all at the same time
    ... 3. if it fails then we re-evaluate

    krit: WebKit only releases every year
    ... need to talk to someone else for Blink

    ed: I think as long as there's use counter data then it might
    be possible

    krit: introduce a compile or runtime flag

    heycam: decision about switching that flag?

    krit: easy on nightly

    ed: we can do it in parallel

    heycam: dirk, how close are you to being convinced to doing
    something like this if the plan fails?

    krit: my main concern was having a new graphics element that
    forces people to the new svg

    heycam: we didn't talk about lower casing all attributes

    shepazu: it might be advantageous for Blink and WebKit if you
    could point to this conversation and say this is what the svg
    wg is interested in doing to gather data

    jwatt: we should clarify that we're not removing the entire svg
    ... someone should come up with a list

    shepazu: we could give an example - say everything that is
    reflecting something

    RESOLUTION: We will remove SVG DOM attribute accessors pending
    web compatibility checks

    <jwatt> all IDL attributes of type SVGAnimated*

    ACTIONS: Erik to add run time flag to disable parts of SVG DOM
    in Blink

    <scribe> ACTION: Dirk to add compile time flag to disable parts
    of SVG DOM in WebKit [recorded in

    <trackbot> Created ACTION-3644 - Add compile time flag to
    disable parts of svg dom in webkit [on Dirk Schulze - due

    krit: I'd be interested in whether MS would remove the DOM if
    others did?

    Rossen_: likely would
    ... would be in favour of better accessors

    heycam: dirk your biggest concern is graphics element?

    krit: yes, duplicating code paths

    heycam: if we can't do removing and I can come up with another
    method of opting in without root graphics element would you be

    krit: yes

    heycam: I'm not sure there is another way but I could think
    about it

    ed: the point is to make existing svg elements inherit from

    heycam: yes

    shepazu: image element isn't as big a worry as a element as far
    as conflicts go

    krit: it's not used very much
    ... we'd have to discuss with html community
    ... most of html community would be happy if we move to html
    ... not sure they realise the cost though

    heycam: I wonder if we're at a point where we decide that we
    want to put things in the html namespace?

    krit: I think we should

    shepazu: I'm in favour of it

    ed: I'd like it if possible

    heycam: I propose that we work towards having all svg elements
    in the html namespace

    krit: do we need changes to the content model if we do that?
    ... e.g. circle having nested elements?

    heycam: don't think changes would be needed

    shepazu: think it would lead to changes but they're not

    heycam: I don't want to change the structure of elements

    krit: if we decide this is the direction we want to go. we can
    devote next f2f to resolving the issues

    Rossen_: moving to a namespace free world would be awesome

    RESOLUTION: We want better accessor methods for list type
    things. e.g. return array of plain javascript values
    ... All SVG elements should be moved to html namespace pending
    further discussion about details of doing that

    heycam: in my proposal I said that you can put things in html
    namespace or no namespace
    ... with the aim that if you're writing xml by hand you can
    leave off the xmlns
    ... seemed like the nicest thing to do

Summary of Action Items

    [NEW] ACTION: Chris to add |symbol { overflow: visible; }| to
    the UA style sheet and add authoring suggestion to say to
    design symbols around (0,0) [recorded in
    [NEW] ACTION: Dirk to actually perform the migration of SVG
    specs to Github in cooperation with Mike Smith [recorded in
    [NEW] ACTION: Dirk to add compile time flag to disable parts of
    SVG DOM in WebKit [recorded in
    [NEW] ACTION: Doug to talk to Mike Smith about migrating the
    SVG WG repository to Github [recorded in
    [NEW] ACTION: Rik to ask the Adobe guy about working on the vsw
    prototype [recorded in
    [NEW] ACTION: Tav to ask Inkscape vsw implementor to add
    Catmull-Rom interpolation to see what it's like [recorded in
    [NEW] ACTION: Tav to get back to Andreas about refX/refY
    top/left/etc. [recorded in

    [End of minutes]

     Minutes formatted by David Booth's [43]scribe.perl version
     1.138 ([44]CVS log)
     $Date: 2014-08-22 16:47:57 $

      [43] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
      [44] http://dev.w3.org/cvsweb/2002/scribe/

Scribe.perl diagnostic output

    [Delete this section before finalizing the minutes.]
This is scribe.perl Revision: 1.138  of Date: 2013-04-25 13:59:11
Check for newer version at [45]http://dev.w3.org/cvsweb/~checkout~/2002/

      [45] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/

Guessing input format: RRSAgent_Text_Format (score 1.00)

WARNING: Bad s/// command: s/star>/star\//g
Succeeded: s/ css the attribute/ the SVG attribute/
Succeeded: s/elements/attributes (or objects)/
Succeeded: s/rather than breaking existing dom/I'd rather break the exis
ting dom/
Succeeded: s/drop parts of the old svg/drop parts of the old svg e.g the
  SVGPathSeg* API/
Succeeded: s/presto to let you do that/presto to let you do that (docume
nt.createElement("rect") got you an SVGRectElement if the document had a
n <svg> root)/
Found ScribeNick: birtles
Found Scribe: birtles
Inferring ScribeNick: birtles
Found ScribeNick: heycam
Found Scribe: Nikos
Inferring ScribeNick: nikos
Found ScribeNick: nikos
Scribes: birtles, Nikos
ScribeNicks: birtles, heycam, nikos
Present: Chris Erik Cameron Doug Nikos Jet Jonathan Brian Razvan Dirk Ro
ssen Rik Tav
Agenda: [46]http://www.w3.org/Graphics/SVG/WG/wiki/F2F/London_2014/Agend
Got date from IRC log name: 22 Aug 2014
Guessing minutes URL: [47]http://www.w3.org/2014/08/22-svg-minutes.html
People with action items: chris dirk doug rik tav

      [46] http://www.w3.org/Graphics/SVG/WG/wiki/F2F/London_2014/Agenda
      [47] http://www.w3.org/2014/08/22-svg-minutes.html

    [End of [48]scribe.perl diagnostic output]

      [48] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm

Erik Dahlstrom, Web Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group

Received on Friday, 22 August 2014 16:49:53 UTC