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Re: [SVGMobile12] Comments: Coordinate Systems, Transformations and Units

From: T Rowley <tor@cs.brown.edu>
Date: Fri, 11 Nov 2005 14:53:03 -0600
Message-ID: <437504AF.8090004@cs.brown.edu>
To: Chris Lilley <chris@w3.org>
Cc: www-svg@w3.org

On 11/11/05 2:01 PM, Chris Lilley wrote:
>>"UR = User Rotate (currentRotate on SVGSVGElement)"
>>Where does this come from?  The closest thing to it, pan and zoom 
>>(13.7), doesn't mention rotation.
> True, although nor does it disallow it. Most user agents do not expose
> user rotation in the UI, but some do, so the equations cover that case
> as well. Its simply set to zero for those implementations that do not
> allow it.

So you're going to enforce implementation of magnification and panning 
(13.7 paragraph 3), but not rotation?  Please specify either all must be 
supported, or make them all optional.  Also 13.7 should indicate that 
this user action modifies the SVGElement's 
current{Scale,Translate,Rotate}.  Currently the only hint in the SVG 
specification that these two things are linked is the description of the 
  "scroll" and "zoom" events.  Another thing - shouldn't there be a 
"rotate" event to match?

>>Domain specific authoring notes (GIS) do not belong in the specification 
>>for a general purpose vector graphics format.
> Its just metadata. Furthermore, since there was scope for confusion how
> the two coordinate systems would be related, we felt that this
> description would be useful. And there are commercial services that use
> this.
> We added a note:
>   Note that the presence of this metadata does not affect the rendering
>   of the SVG in any way; it merely provides added semantic value for
>   applications that use of combine maps.

This resolution does not resolve the comment to my satisfaction.  What 
makes the GIS userbase so special that they get what's essentially a 
application note stuck in the official specification?  Let the various 
speciality users of SVG issue their own authoring recommendation 
documents, and let the SVG specification be just about SVG.
Received on Friday, 11 November 2005 20:54:21 UTC

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