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Comments on rotationAngle

From: <Cathy.Chan@nokia.com>
Date: Tue, 29 Mar 2011 21:20:20 +0000
To: <public-webevents@w3.org>
Message-ID: <D66EA3180FEC4248B33155A2C7E6313B014E061B@008-AM1MPN1-015.mgdnok.nokia.com>
To clarify my comment on 2 representations of a touch area, here is an example. Let's say the touch area is an ellipse with major axis 50 and minor axis 10, and that the major axis is aligned with the X axis and the minor axis is aligned with the Y axis. The straightforward representation of this area is (radiusX=50, radiusY=10, rotationAngle=0deg), but it can also be represented as (radiusX=10, radiusY=50, rotationAngle=90deg). Similarly, if the area is rotated by 30deg counterclockwise, the new representation could be either (radiusX=50, radiusY=10, rotationAngle=30deg) or (radiusX=10, radiusY=50, rotationAngle=-60deg).

If we are to stick with the radiusX/Y definition we now have, the range of the rotationAngle should be (-45,45] to eliminate duplicate representations..

Alternatively, we can use a major/minor notation for the axis lengths, in which case the range of rotationAngle needs to be (-90,90] to cover all possibilities. (We can even continue to call the attributes radiusX/Y. We just need to change the definitions accordingly.)

On a separate note, we also need a default value for rotationAngle, as we do for radiusX/Y.

Regards, Cathy.

-----Original Message-----
From: public-webevents-request@w3.org [mailto:public-webevents-request@w3.org] On Behalf Of Barstow Art (Nokia-CIC/Boston)
Sent: Tuesday, March 29, 2011 12:22 PM
To: public-webevents@w3.org
Subject: Draft Minutes: 29 March 2011 call

The draft minutes from the March 29 voice conference are available at the following and copied below:



Issue-1 "Resolve touch area re. radius and angle"

    <Barstow>  AB: Issue 1 (
    [17]http://www.w3.org/2010/webevents/track/issues/1 ) is now in the
    Pending Review state. Matt included a proposed resolution in the
    issue and checked-in a fix "Updated the spec to include a
    rotationAngle attribute as suggested by Olli in ACTION-17:

      [17] http://www.w3.org/2010/webevents/track/issues/1
      [18] http://dvcs.w3.org/hg/webevents/rev/1ea45991d3e9

    <Barstow>  AB: is that about right Matt?

    <Barstow>  MB: yes

    <Barstow>  DS: would like a bit of an explanation

    <Barstow>  MB: I added a new property to Touch interface

    <Barstow>  ... called rotationAngle

    <Barstow>  ... it is angle in degrees from 90 to -90

    <Barstow>  ... describes ellipse

    <Barstow>  DS: sounds fine to me


      [19] http://dvcs.w3.org/hg/webevents/raw-file/tip/touchevents.html#attributes

    <Barstow>  OP: would be good to get feedback from the Canonical

    <Barstow>  ... I sent an email to the list but didn't a reply

    <Barstow>  DS: we should definitely ask for feedback from them

    <Barstow>  MB: one think I didn't do was to talk about things outside
    of the elliptical touch area

    <Barstow>  ... that is, I made the scope fairly limited

    <Barstow>  AB: do people want some time to review this?

    <Barstow>  CC: I have a question

    <Barstow>  ... the proposal is +90 to -90

    <Barstow>  ... that gives two different ways to represent the area

    <Barstow>  ... not sure if two representations of the area is a
    problem or not

    <Barstow>  MB: that's a good point

    <Barstow>  ... other specs talk about Major and Minor rather than
    RadiusX and RadiusY

    <Barstow>  ... I'd be happy to look at any change proposals

    <Barstow>  OP: SVG has areaX and areaY

    <Barstow>  ... using radiusX and radiusY to be consistent with SVG

    <Barstow>  DS: again, I don't think that SVG consistency here is that

    <Barstow>  OP: but consistency would be good

    <Barstow>  DS: don't think SVG compatibility here is that important

    <Barstow>  ... and SVG could change to be consistent with our spec

    <Barstow>  OP: really think we need feedback from Canonical

    <Barstow>  DS: re +/-90 degrees

    <Barstow>  ... how to detect rotation seems tricky

    <Barstow>  ... not clear what it is relevant to (point of ref)

    <Barstow>  [ Scribe missed comment by MB ... ]

    <Barstow>  DS: what if finger is offscreen and then orientation

    <Barstow>  ... does x, why change, does orientation change

    <Barstow>  MB: a lot of things change in that case

    <Barstow>  ... including rX and rY

    <Barstow>  DS: think we need to think about this

    <Barstow>  AB: my conclusion is we need some more time

    <Barstow>  ... do we want a fixed review period

    <Barstow>  ... and if no comments, Matt's proposal is accepted

    <Barstow>  DS: yes, think so; we don't need to be perfect with our
    early WDs

    <Barstow>  AB: I propose people send comments during the next week

    <Barstow>  ... and if no one raises any concerns with Matt's proposal
    we consider it accepted
Received on Tuesday, 29 March 2011 21:22:14 UTC

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