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Path length of a rounded rect in SVGT 1.2 conformance tests

From: Kalle Raita <kraita@nvidia.com>
Date: Tue, 8 Jan 2008 15:23:17 +0100
Message-ID: <85DD8D3F1695004A8A9A5AC16CE584BE048F548A@deemmail01.nvidia.com>
To: <www-svg@w3.org>
It seems to me that the SVGT 1.2 beta conformance tests assume that for
a rounded rectangle path length compution starts from point (x+rx,y),
whereas the specification would indicate point (x,y+ry). In 
"9.2 The 'rect' element", the specification says:
A 'rect' <http://www.w3.org/TR/SVGMobile12/shapes.html#RectElement>
element, taking its rounded corners into account, must be rendered in a
way that produces the same result as if the following path
<http://www.w3.org/TR/SVGMobile12/paths.html>  were specified instead:
(Note: all coordinate and length values are first converted into user
space coordinates according to Units
<http://www.w3.org/TR/SVGMobile12/coords.html#Units> .)

*	perform an absolute moveto
operation to location (x,y+ry), where x and y are the values of the 
'rect' <http://www.w3.org/TR/SVGMobile12/shapes.html#RectElement>
element's x
and y
attribute converted to user space, and rx and ry are the effective
values of the rx
and ry
attributes converted to user space
*	perform an absolute elliptical arc operation to coordinate
(x+rx,y), where the effective values for the rx
and ry
attributes on the 'rect'
<http://www.w3.org/TR/SVGMobile12/shapes.html#RectElement>  element
converted to user space are used as the rx and ry attributes on the
elliptical arc command, respectively, the x-axis-rotation is set to
zero, the large-arc-flag is set to zero, and the sweep-flag is set to
*	perform an absolute horizontal lineto
operation to location (x+width-rx,y), where width is the 'rect'
<http://www.w3.org/TR/SVGMobile12/shapes.html#RectElement>  element's 
attribute converted to user space
*	...

As I interpret this, the path begins at point (x, y+ry). This is most
prominently visible in test case shapes-rect-03-t, where the line
(apprently) signifying the start of the path is after the first rounded
corner, not before.
I've included a SVG file that tries to demonstrate this. There are two
rounded rectangles. One on the left is constructed with separate paths
for each segment and they are made visible one-by-one. Rectangle on the
right is created with <rect> element and it has an animated
stroke-dasharray, which draws only the segment that appeared on the left
hand rectangle. In the first frame the on-dash is at the beginning of
the path. The subsequent frames the dash array begins with 0 on-dash and
increasingly long off-dash followed by on-dash that marks the current
This is relevant at least for test cases paint-stroke-202-t and
Any insights into this issue appreciated.
  - Kalle Raita

Kalle Raita 
NVIDIA Corporation 
Tel. +358 40 723 1441 
http://eu.nvidia.com <http://eu.nvidia.com/>  


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Received on Tuesday, 8 January 2008 14:24:11 UTC

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