IRC log of svg on 2011-12-08

Timestamps are in UTC.

19:55:25 [RRSAgent]
RRSAgent has joined #svg
19:55:25 [RRSAgent]
logging to
19:55:27 [trackbot]
RRSAgent, make logs public
19:55:27 [Zakim]
Zakim has joined #svg
19:55:29 [trackbot]
Zakim, this will be GA_SVGWG
19:55:29 [Zakim]
I do not see a conference matching that name scheduled within the next hour, trackbot
19:55:30 [trackbot]
Meeting: SVG Working Group Teleconference
19:55:30 [trackbot]
Date: 08 December 2011
19:57:42 [shepazu]
19:59:00 [heycam]
19:59:29 [Tav]
20:00:09 [heycam]
Zakim, room for 8?
20:00:10 [Zakim]
ok, heycam; conference Team_(svg)20:00Z scheduled with code 26633 (CONF3) for 60 minutes until 2100Z
20:01:19 [Zakim]
Team_(svg)20:00Z has now started
20:01:21 [Zakim]
20:01:34 [ed]
Zakim, [IP is me
20:01:34 [Zakim]
+ed; got it
20:01:40 [Zakim]
20:01:41 [Zakim]
20:01:41 [Zakim]
20:01:45 [heycam]
Zakim, ??P4 is me
20:01:45 [Zakim]
+heycam; got it
20:02:36 [Zakim]
20:03:09 [heycam]
Chair: Cameron
20:03:13 [cyril]
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20:03:35 [cyril]
Zakim, what is the code?
20:03:35 [Zakim]
the conference code is 26633 (tel:+1.617.761.6200, cyril
20:03:45 [heycam]
20:03:54 [Zakim]
20:04:19 [cyril]
zakim, who is there?
20:04:19 [Zakim]
I don't understand your question, cyril.
20:04:25 [heycam]
Zakim, who is on the call?
20:04:25 [Zakim]
On the phone I see ed, heycam, Tav, cyril
20:04:31 [Zakim]
20:05:17 [ChrisL]
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20:06:11 [ChrisL]
zakim, code?
20:06:11 [Zakim]
the conference code is 26633 (tel:+1.617.761.6200, ChrisL
20:06:49 [Zakim]
20:07:16 [ChrisL]
zakim, who is here?
20:07:16 [Zakim]
On the phone I see ed, heycam, Tav, cyril, Doug_Schepers, ChrisL
20:07:29 [ChrisL]
scribenick: ChrisL
20:07:48 [ChrisL]
chair: heycam
20:07:56 [ChrisL]
topic: Sydney f2f
20:08:10 [ChrisL]
cc: updated wiki page, location is the novotel
20:08:21 [ChrisL]
20:08:56 [shepazu]
20:08:58 [ChrisL]
cc: room for 18 people and good connection, checking on vpn and when the room is open. Should be 8am to 7pm to give us flexibility
20:09:46 [heycam]
20:09:48 [ChrisL]
... tea, coffee, and lunch included. Three on-site restaurants. Booked weds-sat inclusive. Rate at the hotel for rooms, shortly
20:10:14 [ChrisL]
20:10:32 [ChrisL]
shepazu: conflicting audio wg meeting, might prevent me from attending
20:11:02 [ChrisL]
heycam: is this the w3c travel restriction?
20:11:51 [ChrisL]
shepazu:w3c nowadays does not like sending two staff contacts to a group. But this makes less sense if the staff contacts are active technicalcontributors rather than just process guardians
20:11:53 [stearns]
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20:12:07 [ChrisL]
shepazu: will sort out soon whether i can attend
20:12:22 [stearns]
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20:12:44 [ChrisL]
ChrisL: should be there, doctor permission, working on travel plans. responded to survey
20:13:05 [ChrisL]
cyril: nothing else i can think of - if there are questions please ask
20:13:26 [ChrisL]
... vegetarians and other dietary restrictions taken into account for lunch
20:14:06 [ChrisL]
topic: text metrics with display: none
20:14:07 [ChrisL]
20:14:08 [heycam]
20:14:50 [ChrisL]
heycam: brian birtles brought it up. Behaviour of svg dom text methods to get number of characters, extent, points along a line of text
20:15:04 [ericm]
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20:15:17 [ChrisL]
... and whether they count glyphs with display: none. In some cases the imps count characters in the dom
20:15:19 [ChrisL]
20:15:33 [ChrisL]
heycam: replied with my opinion
20:15:35 [shepazu]
20:15:35 [heycam]
20:15:36 [heycam]
20:15:58 [heycam]
CL: should be simple, we have definitions for what visibility:hidden and display:none means
20:16:13 [heycam]
… also we have a difference between characters in backing store and what's displayed
20:16:31 [heycam]
… everything that's display:none isn't in the render tree, which you must be doing if you're measuring the text, they're not there, they don't have a position
20:16:37 [heycam]
… that's separate from indexing into the characters
20:17:03 [Zakim]
20:17:06 [vhardy]
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20:17:07 [ChrisL]
heycam: agree it should be clear from the spec
20:17:23 [Zakim]
20:17:25 [heycam]
Zakim, ??p4 is me
20:17:25 [Zakim]
+heycam; got it
20:18:05 [ChrisL]
heycam: indexing should be based on characters in the backing store. Other imps dfo not count the display: none characters for indexing
20:18:06 [ed]
getNumberOfChars definition from 1.1SE [[ Returns the total number of characters available for rendering within the current element, which includes referenced characters from ‘tref’ reference, regardless of whether they will be rendered. ]]
20:18:41 [ChrisL]
... there is an issue of what to return if you ask about characters that are not rendered. need to decide on 0, or NaN or what
20:19:31 [ChrisL]
cyril: it can be hard to know if the font engine is only activated when displayingcharacters
20:19:58 [ChrisL]
heycam: can depend on glyph shapingand substitution. metrics only returned on characters that are displayed
20:20:16 [Zakim]
20:20:28 [ed]
20:20:47 [heycam]
Zakim, Oliver_Goldman is Vincent_Hardy
20:20:47 [Zakim]
+Vincent_Hardy; got it
20:21:16 [ChrisL]
ChrisL: I see erik posted about what 1.1se says
20:21:45 [ChrisL]
heycam: Its not inconsistent
20:22:31 [ChrisL]
ChrisL: But for the actual position along a path, it does depend on display: none
20:23:04 [ChrisL]
heycam: wondered about displaying the position where it *would* be
20:23:23 [ChrisL]
... but its not the right way as it depends on what that character is
20:23:37 [ChrisL]
... and you want to avoid the layout of the text
20:23:52 [ChrisL]
... so its better to throw an exception or return NaN
20:24:18 [ChrisL]
ChrisL: which is better, NaN or exceptions?
20:24:43 [ChrisL]
heycam: in the past we have not used NaN. Either is better than returning zero
20:25:46 [ChrisL]
ChrisL: exceptions can return information on why its not displayed - display: none or off the end of the path or clipped or whatever. more extensible also
20:25:54 [ChrisL]
heycam: true
20:26:31 [ChrisL]
ChrisL; Does the text need changes?
20:26:52 [ChrisL]
heycam: yes, display: none not handled. indexing is covered but could be clearer
20:27:15 [ChrisL]
ed: if its called on textPath, indexes are from start of path not start of element
20:28:10 [ChrisL]
ChrisL: so we have a rationale on how it should work, we now need to check the text, make changes, add examples and tests
20:28:44 [ed]
s/textPath, indexes are from start of path not start of element/textPath or tspan, indexes are from start of that element not the start of the <text> element/
20:29:04 [ChrisL]
... if these apply to 1.2SE should we add errata?
20:29:11 [ChrisL]
shepazu: no, a lot of work
20:29:18 [ChrisL]
ChrisL: yes, if it applies to 1.1
20:29:45 [ChrisL]
shepazu: remind people how long it took for 1.1se
20:29:59 [ChrisL]
heycam: mostly because it was a whole new edition, not justerrata
20:30:46 [ChrisL]
ChrisL: mainly the delay was getting implementations to pass
20:31:02 [ChrisL]
shepazu: fine to document errata for bugs
20:31:12 [ChrisL]
... want to avoid refactoring
20:32:49 [Zakim]
20:33:12 [Zakim]
20:33:12 [ChrisL]
ChrisL: (scribe missed)
20:33:14 [heycam]
Zakim, ??P0 is me
20:33:14 [Zakim]
+heycam; got it
20:33:57 [ChrisL]
heycam: for this particular issue its a sentence or two
20:34:18 [ChrisL]
... decide on case by case basis depending on effort needed to backport
20:35:07 [ChrisL]
action: cameron to propose wording changes and write tests for text metrics with display: none
20:35:07 [trackbot]
Created ACTION-3180 - Propose wording changes and write tests for text metrics with display: none [on Cameron McCormack - due 2011-12-15].
20:35:30 [ChrisL]
heycam: will reply on thread to update based on this discussion
20:35:46 [ChrisL]
topic: ignoring trailing semicolons
20:35:48 [heycam]
20:36:29 [ChrisL]
heycam; also from brian, this is for smil animation. some content on web uses semicolon termination rather than separation so the lest thing in the attr is a semicolon
20:36:55 [ChrisL]
... some implementations accept and ignore it, some consider it invalid. brian proposes to allow ignoring
20:36:57 [ChrisL]
20:37:03 [shepazu]
20:38:00 [ChrisL]
shepazu; recall this in 1.1 timeframe, i was on Dr Olaf's side and matching smil was important. Since changed opinion and think pragmatic choice is to be inconsistent to maximise compat with implementations and content
20:38:09 [ChrisL]
heycamq: my view also
20:38:47 [heycam]
CL: I want to distinguish ignoring a trailing semicolon and ignoring null values in the middle of a list
20:39:02 [heycam]
… dr olaf's point is that you can have null values and they can be meaningful, and we shouldn't disallow that
20:39:12 [heycam]
… if a null value at the end doesn't make a difference just ignoring it is a workable solution
20:40:02 [ChrisL]
heycam: proposal was just to allow a trailing semicolon and if you have a list of strings then you need an extra semicolon at the end to distinguish that case
20:40:37 [ChrisL]
shepazu: most real world cases are not expecting a trailing semicolon to be a null value
20:41:14 [ChrisL]
... most people dont understand the smil enough. common in aloop in script to just output semicolon always
20:41:24 [ChrisL]
... and also implementatins don't do that
20:41:59 [ChrisL]
heycam: much more common
20:42:36 [ChrisL]
... quirky part is requiring ;;; when you really do want a null last value
20:42:53 [ChrisL]
shepazu: wish we could search web to see the actual usage
20:43:09 [ChrisL]
ed: requiring an extra semicolon is not that bad
20:44:22 [ChrisL]
heycam: we shoud reuse smil unless we have a reason not to , but should not let it constrain us when we need to improve and clarify things
20:44:49 [ChrisL]
action: erik to reply on trailing semicolon thread
20:44:50 [trackbot]
Created ACTION-3181 - Reply on trailing semicolon thread [on Erik Dahlström - due 2011-12-15].
20:45:44 [Zakim]
20:45:50 [ChrisL]
topic: jltf draft review request
20:45:54 [heycam]
20:45:59 [heycam]
CL: I had a look at this
20:46:03 [heycam]
… I was familiar with the previous one
20:46:06 [heycam]
… they've added a new section
20:46:28 [Zakim]
20:46:32 [heycam]
… in terms of SVG, given that currently SVG doesn't understand how to do one line of text -- it doesn't do layout, or page layout -- and most of this is layout of formatted text on a page
20:46:36 [heycam]
… the affect on SVG is minimal
20:46:44 [heycam]
… it does have things about character classes, which might affect us
20:46:54 [heycam]
… so we neither violate it or prohibit it, it doesn't affect us
20:47:12 [heycam]
… as soon as we get wrapping text, 1.2T textArea or HTML text in a box
20:47:20 [heycam]
… there's nothing about ligature formation in there
20:47:28 [heycam]
… didn't see anything about :first-letter, which would affect us
20:47:39 [heycam]
… so from a quick pass looking at it, I don't think there's much impact on SVG directly
20:48:02 [ChrisL]
s/do one line/so more than one line/
20:48:18 [ChrisL]
heycam: little on layout requirements in figures
20:48:38 [Zakim]
20:48:40 [heycam]
CL: there is some information about figures, but it's mroe about layout of figures/captions in the document
20:48:42 [ChrisL]
ChrisL: yes, nothing on callouts in diagrams
20:49:26 [Zakim]
20:49:28 [heycam]
Zakim, [ is me
20:49:28 [Zakim]
+heycam; got it
20:49:34 [ChrisL]
ChrisL: wonder if this is missing because there is nothing there or because they didn't consider it
20:49:54 [ChrisL]
shepazu: its mainlky informed by traditional print media
20:50:40 [ChrisL]
... example, us uses a green check(tick) for ok and red cross fro wrong
20:50:50 [ChrisL]
in japan its a check for wrong and a circle for ok
20:51:38 [ChrisL]
... there are iconographic conventions that differ in japan. could be in their scope
20:52:07 [ChrisL]
ChrisL: we should reply asking them to cover this
20:52:28 [ChrisL]
shepazu; and we cn also say that we integrate the things that affect layout via css
20:52:56 [ChrisL]
action: chris respond to jlft review request
20:52:56 [trackbot]
Created ACTION-3182 - Respond to jlft review request [on Chris Lilley - due 2011-12-15].
20:53:32 [ChrisL]
topic: function based inputfor animation
20:53:34 [heycam]$c6355c40$52a014c0$@net
20:54:11 [ChrisL]
s/tfo/t fo/
20:54:42 [ChrisL]
heycam: this one we asked david for clarificationand he replied
20:55:12 [ChrisL]
... he wants animate motion but targetting the explicit attributes not the transform
20:55:27 [heycam]
s/the explicit/explicit/
20:55:52 [Zakim]
20:56:02 [heycam]
<animatePath xlink:href="#curve1" xattribute="cx" yattribute="cy"/>
20:56:03 [heycam]
<animatePath xlink:href="#curve2" xattribute="rx" yattribute="ry"/>
20:56:06 [ChrisL]
zakim, code?
20:56:06 [Zakim]
the conference code is 26633 (tel:+1.617.761.6200, ChrisL
20:56:42 [Zakim]
20:57:33 [ChrisL]
heycam: he wants to take x and y positions from the curves and apply them to particular attributes
20:57:55 [heycam]
CL: this reminds me of a comment we got a long time ago, whose profession was an animator
20:58:19 [heycam]
… they wanted smooth curves through things, and you couldn't do much without decomposing beziers into separate animations
20:58:26 [heycam]
… I'm wondering if this feature would let us do what he wanted
20:58:39 [heycam]
… he wanted to be able to animate any attribute as a smooth function, rather than giving a pointwise list of values and going dot to do
20:58:42 [heycam]
s/to do/to dot/
20:59:15 [ChrisL]
heycam: can get this if you animate with a list of values and use keysplines
20:59:49 [ChrisL]
... animate motion gives you an essy way to do (paced animation)
21:00:09 [heycam]
CL: if you use keySplines, that only gives you smoothness across a single pair of values, not curve continuity
21:00:22 [heycam]
… you would have to calculate it yourself
21:00:35 [heycam]
… and I'm not sure you can in all cases
21:01:09 [heycam]
… you're looking for tangent continuity where the pieces join
21:01:10 [ed]
note that some svg implementations allow keySpline values outside the 0..1 range
21:01:37 [heycam]
… we've already decided to include catmull rom curves, which give you curve continuity
21:02:28 [ChrisL]
ChrisL: yes its valuable for overshoot
21:02:44 [ChrisL]
heycam: yes for the controlpoints, not sure about the curves
21:03:08 [ChrisL]
ed: proposal is not much harder than what we already have, no new dependencies
21:03:20 [ChrisL]
... so this is not so hard to implement
21:03:39 [ChrisL]
... and if its useful then we could investigate more
21:04:20 [Zakim]
21:04:53 [heycam]
CM: I want to be slightly more convinced about use cases, but I can believe after this discussion that there are some
21:05:03 [heycam]
DS: can we say we'll look into variations on this theme for SVG2, without going in to too much detail?
21:05:19 [heycam]
CM: I think that's fine
21:05:22 [ed]
s/no new dependencies/it introduces no new element-to-element dependencies/
21:06:45 [heycam]
21:08:25 [ChrisL]
scribenick: ChrisL
21:09:41 [cyril]
RRSAgent, pointer please
21:09:41 [RRSAgent]
21:10:15 [ChrisL]
resolution: we will support path-based animations of pairs of attributes
21:11:48 [ChrisL]
action: erik to reply to david about function-based animation
21:11:49 [trackbot]
Created ACTION-3183 - Reply to david about function-based animation [on Erik Dahlström - due 2011-12-15].
21:12:47 [ChrisL]
cyril: are these restricted to animating attra on the same element
21:12:55 [ChrisL]
ChrisL: no
21:13:09 [cyril]
21:13:16 [ChrisL]
heycam: consistent with existing limitation as you can have two animations, one for x and one for y
21:13:57 [ChrisL]
topic: mesh gradients
21:14:06 [ChrisL]
21:14:08 [cyril]
21:14:38 [ChrisL]
cyril; reviewed this and was reading a paper explaining gradient mesh technologies
21:14:55 [ChrisL]
... played in inkscape and illustrator which behave differently
21:15:29 [ChrisL]
... illustrator shows four patches for editing, but they dont produce that rendering.
21:16:01 [ChrisL]
... because they use bilinear interpolation between vertices, not across patches
21:16:20 [ChrisL]
cyril: illustrator is generating hundreds of patches to give a smooth result
21:16:40 [ChrisL]
... this difference is confusing for people
21:17:21 [ChrisL]
cyril: in tav's example he uses degenerate meshes with coincident points, to loose the bilinear interpolation
21:17:36 [ChrisL]
tav: forgot how i had done it and ran into the same problem as you
21:18:23 [ChrisL]
cyril: wanted it to be clear that what we have now cannot make smooth gradients across patches. paper linked from my page describes another type with color derivatives at mesh points
21:19:20 [ChrisL]
... paper says that illustrator and corel draw estimate these derivatives based on a cubic interpolation of the color between two mesh vertices
21:20:06 [ChrisL]
cyril: so you have white and red, and you assume a cubic spline interpolation, use that as a derivative for the color
21:20:09 [ChrisL]
21:20:18 [shepazu]
21:21:08 [ChrisL]
cyril: want to propose changes to the requirements document, add to tensor product meshes to list of existing technologies
21:21:18 [ChrisL]
... and decide if we want those as well
21:21:18 [heycam]
21:21:40 [heycam]
CL: once you have multiple patches, sometimes you want a discontinuity
21:21:56 [heycam]
… if you think about it as a 2D curve, sometimes you want them to be continuous, sometimes a sharp change, sometimes discontiuous
21:22:04 [heycam]
… you tend to do that by duplicating control points
21:22:14 [heycam]
… first I agree we want smooth interpolation
21:22:19 [heycam]
… but you don't always want it
21:22:37 [heycam]
… at some extent we're comfortable adding this because cairo etc. supports it
21:22:47 [heycam]
… is there support in underlying libraries for these more complicated patches?
21:23:01 [heycam]
… or can you split them up programmatically so the author doesn't need to do it, and it doesn't need to be in the DOM?
21:23:25 [ChrisL]
cyril: agree we need both smooth and sharp interpolation
21:23:47 [ChrisL]
.. also agree its interesting to see what the underlying libraries have
21:24:24 [ChrisL]
tav: adobe pdf and postscript only support tensor, whichis coons with one additional control pooint
21:24:47 [ChrisL]
cyril: yes there is a difference between what illustrator supports and what pdf/ps support
21:25:25 [ChrisL]
tav: how often does this bite you? in black and white its obvious but when drawing natural objects how often do you meet this?
21:25:57 [ChrisL]
cyril: graphic designers want control over the transition, smooth to sharp
21:26:14 [ChrisL]
tav: can we rely on authoring software to generate this?
21:26:59 [heycam]
CL: it's not better if documents need to include many many small patches
21:27:00 [ChrisL]
cyril: not asking for the svg to be changed
21:28:34 [heycam]
CL: we're also adding catmull rom, perceptually linear colour spaces, those two things will help with smoother gradients
21:28:51 [heycam]
… if the coons patches are doing bilinear interpolation, can we just say that it uses bicubic? taking two patches into account?
21:28:58 [heycam]
… would that totally break what libraries have?
21:29:29 [ChrisL]
tav: libraries now create each patch separately
21:30:47 [ChrisL]
action: cyril to add Tensor-product patch meshes to the list of technologies in the requirements document
21:30:47 [trackbot]
Created ACTION-3184 - Add Tensor-product patch meshes to the list of technologies in the requirements document [on Cyril Concolato - due 2011-12-15].
21:31:43 [ChrisL]
heycam: smooth gradients are a should, if support mens native support in the language, we might decide not to based on library support
21:31:57 [ChrisL]
cyril: and possible fallback to authoring tools
21:32:09 [ChrisL]
cyril: wil ledit the rwquirements document
21:32:23 [ChrisL]
rrsagent, make minutes
21:32:23 [RRSAgent]
I have made the request to generate ChrisL
21:32:30 [Zakim]
21:32:31 [Zakim]
21:32:31 [Zakim]
21:32:35 [ChrisL]
zakim, list attendees
21:32:35 [Zakim]
21:32:36 [Zakim]
As of this point the attendees have been [IPcaller], ed, heycam, Tav, cyril, Doug_Schepers, ChrisL, Vincent_Hardy
21:32:39 [Zakim]
21:32:41 [Zakim]
21:32:42 [Zakim]
Team_(svg)20:00Z has ended
21:32:44 [Zakim]
Attendees were [IPcaller], ed, heycam, Tav, cyril, Doug_Schepers, ChrisL, Vincent_Hardy
21:32:45 [ChrisL]
meeting: SVG WG telcon
21:32:49 [ChrisL]
rrsagent, make minutes
21:32:49 [RRSAgent]
I have made the request to generate ChrisL