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[csswg-drafts] User coordinate space statement breaks SVG

From: Simon Fraser via GitHub <sysbot+gh@w3.org>
Date: Thu, 12 Jan 2017 17:07:35 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-200424910-1484240854-sysbot+gh@w3.org>
smfr has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== User coordinate space statement breaks SVG ==
http://www.w3.org/mid/CAFDDJ7yhF7Qn28wVMqb7ra6N9Q=j74OTqHWpjLeYrH=LQwmd4A@mail.gmail.com

In the CSS transforms module, the section "User Coordinate space" has 
the
following statement:

In particular the patternUnits
> 
<http://www.w3.org/TR/2011/REC-SVG11-20110816/pservers.html#PatternElementPatternUnitsAttribute>
> , gradientUnits
> 
<http://www.w3.org/TR/2011/REC-SVG11-20110816/pservers.html#LinearGradientElementGradientUnitsAttribute>
>  and maskUnits
> 
<http://www.w3.org/TR/2011/REC-SVG11-20110816/masking.html#MaskElementMaskUnitsAttribute>
 attributes
> don’t affect the user coordinate system used for transformations 
[SVG11]
> <http://dev.w3.org/csswg/css-transforms-1/#biblio-svg11>.


Links:

   - last published working draft
   
http://www.w3.org/TR/2013/WD-css-transforms-1-20131126/#svg-user-coordinate-space
   - current editor's draft
   http://dev.w3.org/csswg/css-transforms-1/#svg-user-coordinate-space

Although the draft spec references SVG 1.1, this would be a *breaking
change* from current SVG behavior.  The SVG definition used for
gradientTransform and patternTransform is as follows:

 This additional transformation matrix is post-multiplied to (i.e.,
> inserted to the right of) any previously defined transformations, 
including
> the implicit transformation necessary to convert from object 
bounding box
> units <http://www.w3.org/TR/SVG11/coords.html#ObjectBoundingBox> to 
user
> space.

Links:
   -
   
http://www.w3.org/TR/SVG11/pservers.html#LinearGradientElementGradientTransformAttribute
   -
   
http://www.w3.org/TR/SVG11/pservers.html#PatternElementPatternTransformAttribute

Unless there is an overwhelming reason to change this, I would 
recommend
that the CSS transforms text be updated to state the transformation 
applies
in the user coordinate system in effect for the element's contents,*
including* any implicit transformations created by patternUnits,
gradientUnits, or maskUnits.

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/893 using your GitHub 
account
Received on Thursday, 12 January 2017 17:07:41 UTC

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