- From: Erik Dahlstrom <ed@opera.com>
- Date: Thu, 22 Dec 2011 22:36:10 +0100
- To: "public-svg-wg@w3.org" <public-svg-wg@w3.org>
Minutes:
http://www.w3.org/2011/12/22-svg-minutes.html
and as text below:
[1]W3C
[1] http://www.w3.org/
- DRAFT -
SVG Working Group Teleconference
22 Dec 2011
[2]Agenda
[2]
http://lists.w3.org/Archives/Public/public-svg-wg/2011OctDec/0109.html
See also: [3]IRC log
[3] http://www.w3.org/2011/12/22-svg-irc
Attendees
Present
+61.2.980.5.aaaa, heycam, [IPcaller], +33.9.53.77.aabb, ed,
cyril, Tav
Regrets
Chair
Cameron
Scribe
ed
Contents
* [4]Topics
1. [5]mesh gradients
2. [6]SVG2 requirements
* [7]Summary of Action Items
_________________________________________________________
<trackbot> Date: 22 December 2011
<cyril> yes, don't tell me I woke up early for nothing :)
<scribe> scribeNick: ed
mesh gradients
<Tav> [8]http://tavmjong.free.fr/SVG/MESH/Mesh_Boundaries.html
[8] http://tavmjong.free.fr/SVG/MESH/Mesh_Boundaries.html
TB: i've been looking at cyril's comments on the problems with mesh
gradients
... as can be seen in the examples in the link above, there are
discontinuity in the gradient
... scroll down, and you can see the same problem for linear
gradients too
... look at where the red line breaks
<cyril> mach banding effect I think
TB: probably the brain is geared towards finding discontinuities
CM: where there's a bend in the line, it looks brigther
<cyril> [9]http://en.wikipedia.org/wiki/Mach_banding
[9] http://en.wikipedia.org/wiki/Mach_banding
CC: not sure it's this exactly, but it's related
TB: with mesh gradients you have the control points along the sides,
that not only control the shape but also the spread
... next figure shows the same discontinuities as for the linear
gradients but with mesh gradients
... i've moved the control points in the figure with the purple
curve, giving a smoother look
... if you change the controlpoints you change two things at once,
both shape and color
... the mesh in this case is still a rectangle
CC: would be nice to show the controlpoints in the example, for
understanding it better
TB: will add that
... now in "Understanding Coons Patches"
... shows controlpoints, and what you get
... if you move controlpoints further you get discontinuities
... you can never have a derivative of 0 at the edge of a patch
CC: what if you put the controlpoint in horizontal?
TB: can't do that
... they're in colorspace
... 1/3 of the way up and 1/3 of the way down
... it's not a controlpoint for the mesh, it's for the color
CM: are you illustrating the rate of the change?
TB: something like that yes
CM: so the color moves quicker at the start of the curve
TB: i've plotted what happens when you move the controlpoints
CC: are you using the same controlpoints for the upper and lower
parts of the curve
TB: yes
CC: you use linear interpolation since you have two colors, you'd
have bilinear if you had one color in each corner
TB: just illustrating that it's possible to reduce the effect
... once you move the controlpoint outside the mesh it overlaps
itself
... if you introduce a tensor
... you could change the the way the colors inside the mesh are
distributed
... doesn't affect the edges
... i've looked at the cairo code and it exploits this to compute
the gradient, divides the patch from top to bottom using the tensor
points so that you have a series of bezier curves taht are no wider
than a pixel
... and then it draws each bezier curve in turn
CC: illustrator doesn't use coons patches
... probably tensor product patches with tensor derivatives
... with bicubic interpolation
TB: what they show in illustration...
... is shown as one patch but is actually many patches
... the boundaries don't correspond to the object, but to the edges
to the mesh
... some examples have rough shapes that can't be described by a
simple bezier
CM: clipping is another trick
TB: when we discussed it previously there was a request to use the
mesh as a clip or by itself
CC: but then tehre would be a problem with the stroke
... not sure if we decided to do it as a paintserver or not
TB: anyway, that's the state atm
CM: does messing with the controlpoints help for eliminating the
disconts?
TB: a bit
... by adding extra patches it's possible to smooth it out
CC: i've experimented with corel draw, looks like they do something
very similar to illustrator
CM: could the subdivision of patches be useful to define in the
document?
... could we describe this simply, and would we want to enable that
by an attribute for example?
CC: i think they're approximating, not sure there's a single way to
do this
... depends on quality etc
TB: leaning towards letting the author handle it
... if you have a regular gradient you owuld not use meshes, or they
would subdivide
... i'm going to read the paper cyril linked to again
CC: let's discuss this at the F2F
... coons patches are fine and you can do good things with them, but
there are limitations, and authoring tools solve them atm, but we
may want to introduce something like that in the future
TB: we might want to smooth out linear gradients too
... using catmull-rom curves
SVG2 requirements
<cyril>
[10]http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#F
ree_audio.2Fvideo_codec_requirements
[10]
http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#Free_audio.2Fvideo_codec_requirements
<cyril>
[11]http://mpeg.chiariglione.org/meetings/geneva11-1/geneva_press.ht
m
[11] http://mpeg.chiariglione.org/meetings/geneva11-1/geneva_press.htm
CC: this is from MPEG
... one track for MPEG1, since patents are phasing out
... other option is AVC standard but with a baseline where patent
holders agree to make it free
... that's not yet decided
... there are big interests, political and economical
CM: what's your sense of these two possible ways forward?
CC: first option is clear in terms of patent conflicts
... if there were other patents they would have been claimed before
... thing is it won't be good quality
... building on mpeg1 is unclear, due to patents
... other option H264 / AVC one, it would be compatible with most
exisitng codecs
... but it's a big question for the stakeholders
TB: what does google support in their browser?
CC: on pc it's different from on android
... think they're talking about dropping 264 on pc, and android
TB: what's the fallback?
CC: webm
... but the licensing isn't clear either
... mpeg issued a call for patents covering webm, and got responses
(3 digits)
CM: the responses will be published yes?
CC: i think so, next year maybe
CM: in terms of requirements i don't think we should be reuqiring
codecs at this point
<cyril> [12]http://www.webm-ccl.org/
[12] http://www.webm-ccl.org/
CM: it's something that should be done for the whole web platform
CC: apple and microsoft are missing from the webm licensing members
list
<cyril> SVG WG supports the goal, including for the whole web
platform, but it does not seem feasible at the moment
RESOLUTION: SVG WG supports the goal, including for the whole web
platform, but it does not seem feasible at the moment
<heycam>
[13]http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#T
ooltip_element
[13]
http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#Tooltip_element
CM: next tooltip elements
... this has come up before
... i've never really been satisfied with the tooltips in tiny so
far
... not clear to me what's a good solution
... he wants a way to generate tooltips
TB: doesn't browsers differ today with what's displayed as a
tooltip, <title> or xlink:title
CM: yes I think you're right TB
... html is a bit different because it has a title attribute
... i think our title element has a broader meaning than @title in
html
... people are used to what it does in html
... i think we should look into the issue for svg2
... agree with DOH that using metadata with role isn't the right way
to do this
CC: maybe a should req?
<Tav>
[14]http://tavmjong.free.fr/SVG/PROGRESSBAR/SteamEngineProgressBar_S
tandAlone.svg
[14]
http://tavmjong.free.fr/SVG/PROGRESSBAR/SteamEngineProgressBar_StandAlone.svg
<heycam> SVG 1.1 also says "Alternate presentations are possible,
both visual and aural, which display the ‘desc’ and ‘title’ elements
but do not display ‘path’ elements or other graphics elements. This
is readily achieved by using a different (perhaps user) style
sheet."
CM: the document has both <title> and <desc> duplicating the content
ED: don't think any of the browser display <desc> as a tooltip
CM: think we can improve on the requirements for tooltips, to align
with html implementation
... so that they're shown under the same circumstances
... we can investigate more when we look into the issue
RESOLUTION: SVG2 will have stronger requirements for when to display
tooltips
<heycam>
[15]http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#H
it-testing_on_image_alpha
[15]
http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#Hit-testing_on_image_alpha
CM: this was discussed in an FXTF meeting IIRC
... perhaps more generic, with images and fill
ED: probably the proposal from zynga, with masks for mouse events
CC: we could discuss this with alex at the F2F
<scribe> ACTION: ED to summarize the discussions about hittesting
with alpha from the FX list [recorded in
[16]http://www.w3.org/2011/12/22-svg-minutes.html#action01]
<trackbot> Created ACTION-3190 - Summarize the discussions about
hittesting with alpha from the FX list [on Erik Dahlström - due
2011-12-29].
<heycam>
[17]http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#A
nchor_events_.28anchorActivated.2C_anchorTargeted.29
[17]
http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#Anchor_events_.28anchorActivated.2C_anchorTargeted.29
CM: doug is requesting an event for when the link changes
... html already has the hashchanged events
CC: this should be part of the harmonization with html, right?
CM: not sure if we said before if we decided on document level
events and such
... think we should consider all the documentwide events
... in html, and make them apply to svg
... where it makes sense
<cyril> "SVG 2 will have HTML document wide events (including
hashchange) apply to SVG documents when they make sense"
RESOLUTION: SVG 2 will consider adding HTML document wide events
(including hashchange) in SVG documents where they make sense
<heycam>
[18]http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#C
onsider_adding_drag_and_drop_functionality
[18]
http://www.w3.org/Graphics/SVG/WG/wiki/SVG2_Requirements_Input#Consider_adding_drag_and_drop_functionality
CM: DND in html5 is dragsources and dragtargets, and getting things
from other applications
... not with moving elements around
... we should try to get the html5 dnd functionality
... not sure about the dnd for moving things in the document
... probably better to focus on improving the DOM apis for getting
the mouse cursor in the variious cooridnate systems, to ease moving
things around that way
ED: aligning with html5 on this sounds good to me
<heycam>
[19]http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.
html#dnd
[19]
http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#dnd
ED: and improving the DOM apis too
<scribe> ACTION: CM to investigate how html5 drag&drop could be used
in svg [recorded in
[20]http://www.w3.org/2011/12/22-svg-minutes.html#action02]
<trackbot> Sorry, amibiguous username (more than one match) - CM
<trackbot> Try using a different identifier, such as family name or
username (eg. charles, cmccorma)
<scribe> ACTION: heycam to investigate how html5 drag&drop could be
used in svg [recorded in
[21]http://www.w3.org/2011/12/22-svg-minutes.html#action03]
<trackbot> Created ACTION-3191 - Investigate how html5 drag&drop
could be used in svg [on Cameron McCormack - due 2011-12-29].
<scribe> ACTION: heycam to investigate what document wide events
would make sense to apply to svg documents too [recorded in
[22]http://www.w3.org/2011/12/22-svg-minutes.html#action04]
<trackbot> Created ACTION-3192 - Investigate what document wide
events would make sense to apply to svg documents too [on Cameron
McCormack - due 2011-12-29].
RESOLUTION: SVG2 may require drag&drop functionality, and we'll
investigate html5's functionality for that
trackbot, end telcon
Summary of Action Items
[NEW] ACTION: CM to investigate how html5 drag&drop could be used in
svg [recorded in
[23]http://www.w3.org/2011/12/22-svg-minutes.html#action02]
[NEW] ACTION: ED to summarize the discussions about hittesting with
alpha from the FX list [recorded in
[24]http://www.w3.org/2011/12/22-svg-minutes.html#action01]
[NEW] ACTION: heycam to investigate how html5 drag&drop could be
used in svg [recorded in
[25]http://www.w3.org/2011/12/22-svg-minutes.html#action03]
[NEW] ACTION: heycam to investigate what document wide events would
make sense to apply to svg documents too [recorded in
[26]http://www.w3.org/2011/12/22-svg-minutes.html#action04]
[End of minutes]
_________________________________________________________
Minutes formatted by David Booth's [27]scribe.perl version 1.136
([28]CVS log)
$Date: 2011/12/22 21:33:12 $
_________________________________________________________
[27] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
[28] http://dev.w3.org/cvsweb/2002/scribe/
Scribe.perl diagnostic output
[Delete this section before finalizing the minutes.]
This is scribe.perl Revision: 1.136 of Date: 2011/05/12 12:01:43
Check for newer version at [29]http://dev.w3.org/cvsweb/~checkout~/2002
/scribe/
[29] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/
Guessing input format: RRSAgent_Text_Format (score 1.00)
Found ScribeNick: ed
Inferring Scribes: ed
Default Present: +61.2.980.5.aaaa, heycam, [IPcaller], +33.9.53.77.aabb
, ed, cyril, Tav
Present: +61.2.980.5.aaaa heycam [IPcaller] +33.9.53.77.aabb ed cyril T
av
Agenda: [30]http://lists.w3.org/Archives/Public/public-svg-wg/2011OctDe
c/0109.html
Found Date: 22 Dec 2011
Guessing minutes URL: [31]http://www.w3.org/2011/12/22-svg-minutes.html
People with action items: cm ed heycam
[30]
http://lists.w3.org/Archives/Public/public-svg-wg/2011OctDec/0109.html
[31] http://www.w3.org/2011/12/22-svg-minutes.html
End of [32]scribe.perl diagnostic output]
[32] http://dev.w3.org/cvsweb/~checkout~/2002/scribe/scribedoc.htm
--
Erik Dahlstrom, Core Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group
Personal blog: http://my.opera.com/macdev_ed
Received on Thursday, 22 December 2011 21:36:29 UTC