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Re: Comments on rotationAngle

From: Matt Brubeck <mbrubeck@mozilla.com>
Date: Fri, 01 Apr 2011 10:10:39 -0700
Message-ID: <4D96070F.4000103@mozilla.com>
To: public-webevents@w3.org
On 04/01/2011 09:56 AM, Matt Brubeck wrote:
> Oops! I was a math major, and assumed that *everybody* knew that
> positive angles are counter-clockwise:
> http://en.wikipedia.org/wiki/Angle#Positive_and_negative_angles
> But I see that other W3C specs are "backward," so I will change the
> Touch Events spec to match them. :)

To complicate matters, the InkML Candidate Recommendation defines pen 
rotation in counter-clockwise degrees around the origin.  So now I'm not 

InkML is more closely related, as it is defining the shape of a pen tip 
(including ellipses like the ones in the Touch Events spec). On the 
other hand, CSS 2D Transforms and SVG are more widespread, and are 
certain to be used alongside Touch Events.

I'm leaning toward the CSS/SVG convention, so authors won't need to flip 
angles around when translating touch areas into CSS or SVG rotations to 
draw them on the screen.  Any comments?
Received on Friday, 1 April 2011 17:11:15 UTC

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