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Re: Comments on rotationAngle

From: Arthur Barstow <art.barstow@nokia.com>
Date: Fri, 01 Apr 2011 15:16:58 -0400
Message-ID: <4D9624AA.2070109@nokia.com>
To: ext Matt Brubeck <mbrubeck@mozilla.com>
CC: public-webevents@w3.org
On Apr/1/2011 1:10 PM, ext Matt Brubeck wrote:
> 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 sure.
>
> 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?

In the absence of other info, I would favor consistency with CSS and SVG.

-AB
Received on Friday, 1 April 2011 19:17:33 GMT

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