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inconsistency about preserveAspectRatio for <image> element

From: Daniel Holbert <dholbert@mozilla.com>
Date: Mon, 11 Oct 2010 16:54:09 -0700
Message-ID: <4CB3A3A1.1040409@mozilla.com>
To: www-svg@w3.org
Hi www-svg,

I'm writing to request a modification to the SVG 1.1 spec, to clear up
an inconsistency.

The inconsistent sections are quoted at the bottom of this post.

The inconsistency is as follows:
 - The <image> documentation[1] says that the referenced SVG root node's
preserveAspectRatio attribute is "ignored".  It doesn't mention any
exceptions to this rule.
 - BUT, the preserveAspectRatio documentation[2] says that this
attribute might **not** be ignored -- in particular, if we have
  <image preserveAspectRatio="defer" ...>
then the root node's preserveAspectRatio value will be honored.

Please consider editing the <image> documentation to be less absolute
(and more consistent with the preserveAspectRatio documentation).

For example, the <image> documentation[1] could be modified to say
something like:
> When an ‘image’ element references an SVG image, the
> clip and overflow properties on the root element in the
> referenced SVG image are ignored.  The ‘preserveAspectRatio’
> attribute on the root element might also be ignored, depending
> on the value of the ‘image’ element's ‘preserveAspectRatio’
> attribute -- see the ‘preserveAspectRatio’ documentation
> for more details.

(I'm not sure if 'might' is the right word above -- sadly I'm not fluent
in spec-speak. :))

Thanks!
Daniel Holbert
Mozilla Corporation

[1] Section 5.7, on image:
> When an ‘image’ element references an SVG image the
>‘preserveAspectRatio’ attribute as well as the clip
> and overflow properties on the root element in the
> referenced SVG image are ignored
http://www.w3.org/TR/SVG11/struct.html#ImageElement

[2] Section 7.8, on preserveAspectRatio:
> If the value of ‘preserveAspectRatio’ on an ‘image’
> element starts with 'defer' then the value of the
> ‘preserveAspectRatio’ attribute on the referenced
> content if present should be used.
http://www.w3.org/TR/SVG11/coords.html#PreserveAspectRatioAttribute
Received on Monday, 11 October 2010 23:54:42 GMT

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