W3C home > Mailing lists > Public > www-style@w3.org > February 2012

Re: [css3-images] Referencing <svg> element directly with element()

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 27 Feb 2012 16:16:04 -0800
Message-ID: <CAAWBYDAhaH2KH1YEsqdKZ7jpgAcwfVBWQppfAtOp=nr-LZ+SFA@mail.gmail.com>
To: Boris Zbarsky <bzbarsky@mit.edu>
Cc: www-style@w3.org
On Fri, Feb 24, 2012 at 1:32 PM, Boris Zbarsky <bzbarsky@mit.edu> wrote:
> On 2/24/12 4:04 PM, Tab Atkins Jr. wrote:
>> Hm, why do you say that?  Inheritance is well-defined even if it's not
>> in the document
>
> But rule application is not.
>
> Specifically, if you have a disconnected document fragment, which rules
> should be applying to the elements in it?  Should inline styles be applying?
>  None of that stuff is really defined anywhere.
>
> getComputedStyle sort of makes up something, but it involves applying
> applying rules across documents and whatnot.  It's also not really all that
> workable in the face of dynamic changes.
>
>
>> Rendering an SVG paint server shouldn't require any information gained
>> from being in a displayed document, either.
>
>
> SVG assumes that styles can be computed in a sane way for all elements.
>
> Other specs don't define such sane ways of computing styles, yet.
>
> Maybe they should....  There are a lot of details to work out, though
> (scoped stylesheets in disconnected fragments; how should those work?).

For now, I've deleted the previous totally unnecessary paragraph about
cutting off inheritance, and added the following to the Paint Sources
section:

"""
Because paint sources have an intrinsic appearance, it's not necessary
for the element providing them to be in a document - for example, one
can simply create an element with JavaScript and directly assign it to
the CSSElementMap in HTML. However, some paint sources (such as an SVG
<pattern>) depend on style information for their appearance, and it's
currently largely undefined how styling information is assigned to an
element fragment that's not part of a document. (For example, does the
fragment receive styles from the active document? What if it has its
own <style> or <link rel=stylesheet> in it?) This specification
explicitly does not define how such a fragment is styled; it is
expected that CSS will define it in sufficient detail in the future.

For now, it is recommended that such fragments be inserted into a
document before being referenced. For example, a <pattern> element may
be placed into a ‘display:none’ <svg> element's <defs> element within
a document; this has no rendering or layout effects on the document,
but the style inheritance is well-defined.
"""

I'm not totally happy about leaving this undefined, but this spec
*really* isn't the place to define it, and I'm not happy with simply
disallowing this case in the spec, since there are definitely cases
where there isn't any ambiguity.  For example, a disconnected
<pattern> that used nothing but attributes for styling would work just
fine.

Is this acceptable?

~TJ
Received on Tuesday, 28 February 2012 00:16:51 GMT

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