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Re: Comments on rotationAngle

From: Matt Brubeck <mbrubeck@mozilla.com>
Date: Wed, 06 Apr 2011 10:42:06 -0700
Message-ID: <4D9CA5EE.3040802@mozilla.com>
To: Cathy.Chan@nokia.com
CC: public-webevents@w3.org
On 04/04/2011 11:48 AM, Cathy.Chan@nokia.com wrote:
> When I suggested adding a default value for rotationAngle, I was thinking about the value the device is to use when it is not able to provide a measured value for it. For example, for radiusX/Y, we already say "1 if no value is known. This attribute may not be available on all user agents or platforms." Thus, for rotationAngle, I would suggest "0 if no value is known. This attribute may not be available on all user agents or platforms. "

Agreed.  I made a small change in this direction.  I'm waiting for more 
feedback and results of other discussions before making any larger changes:
http://dvcs.w3.org/hg/webevents/rev/348e35a8557f

> Furthermore I'm not entirely convinced that it is necessary to mandate rotationAngle=0 when the touch area is a circle. Let's say I'm emulating a touch area which is a slanted ellipse, and radiusX shrinks from 40 to 10 while radiusY is constant at 20. It would be awkward to have to change rotationAngle from whatever value it was to 0 the moment that radiusX hits 20, and switch it back to the original value right after.
>
> I'd say rotationAngle *should* be 0 if the touch area is a circle, but other values should be acceptable as well. (After all the attribute doesn't actually have any effect when the area is a circle.)

I'm open to this argument.  The spec already requires some discontinuous 
jumps (when rotationAngle moves past 90 or 0), but these are not as 
"awkward" as the case you describe here.  Meanwhile, the benefit 
(guaranteeing a single correct value of rotationAngle) is not that great.

If we decide that we don't need to guarantee a unique value for 
rotationAngle, then I propose removing the rotationAngle=0 requirement 
for circular areas completely (rather than downgrading it to SHOULD).
Received on Wednesday, 6 April 2011 17:42:35 GMT

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