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Re: Comments on rotationAngle

From: Matt Brubeck <mbrubeck@mozilla.com>
Date: Fri, 01 Apr 2011 09:56:20 -0700
Message-ID: <4D9603B4.80103@mozilla.com>
To: public-webevents@w3.org
I accidentally responded to Cathy off-list.  (I need to configure my 
mail reader to make this mistake harder to make.)  Our off-list messages 
are below, with her permission.

On 03/29/2011 02:20 PM, Cathy.Chan@nokia.com wrote:
 > 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..
 > On a separate note, we also need a default value for
 > rotationAngle, as we do for radiusX/Y.

I've changed the spec to address these comments:

rotationAngle now has a range of [0, 90), and a default value of 0. This 
should provide a unique valid representation for any touch area.  I 
think this should simplify testing and interop without any significant 
cost to implementers.

On 04/01/2011 09:35 AM, Cathy.Chan@nokia.com wrote:
 > Another question: is there any particular reason that rotationAngle
 > is positive in the *counter*-clockwise direction? As far as I can
 > tell, related specs (CSS transform, SVG and the Linux doc that led
 > to this issue) have positive angles in the clockwise direction. I
 > know we don't *have* to be consistent with everybody and all, but
 > consistency certainly makes life easier for the developer.

Oops!  I was a math major, and assumed that *everybody* knew that 
positive angles are counter-clockwise:

But I see that other W3C specs are "backward," so I will change the 
Touch Events spec to match them.  :)
Received on Friday, 1 April 2011 16:56:55 UTC

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