order of transform/motion animation application

Dirk, while reviewing the Safari/WebKit results, claims that
animate-elem-24-t is incorrect since it gets the relative order of
application of motion animation and the transform attribute the wrong
way around.

I made a little test:


Firefox and Opera move the rectangle to position A (motion applied after
rotate transform), while Batik and WebKit move it to position B (motion
applied before rotate transform).

This is what the spec has to say:

  The various (x,y) points of the shape provide a supplemental
  transformation matrix onto the CTM for the referenced object which
  causes a translation along the x- and y-axes of the current user
  coordinate system by the (x,y) values of the shape computed over time.
  Thus, the referenced object is translated over time by the offset of
  the motion path relative to the origin of the current user coordinate
  system. The supplemental transformation is applied on top of any
  transformations due to the target element's ‘transform’ attribute or
  any animations on that attribute due to ‘animateTransform’ elements on
  the target element.

This seems unclear to me.  When it talks about translating along the
axes of the user coordinate system, it sounds like it is describing
option A.  But then stating that the transformation is supplemental and
is applied on top of the transform makes it sound like option B.

Which is it?  (Either way, clarification with an example is needed.)

Cameron McCormack ≝ http://mcc.id.au/

Received on Tuesday, 1 February 2011 02:11:39 UTC