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Re: [filter-effects] url() as pass-through on invalid reference?

From: Stephen White <senorblanco@chromium.org>
Date: Thu, 25 Jul 2013 08:13:58 -0400
Message-ID: <CAPeKFTiMLKufwtFNL3Gah8xvUnBGd_6+YD7Ao-Vtxun02_7p3g@mail.gmail.com>
To: Dirk Schulze <dschulze@adobe.com>
Cc: Boris Zbarsky <bzbarsky@mit.edu>, "www-style@w3.org" <www-style@w3.org>, "public-fx@w3.org" <public-fx@w3.org>
One related case is that even a valid filter with a url() could be pending
a network load. If we do a "best effort" render (render the valid parts of
the chain), then a mix of shorthand filters mixed with a url() filter, e.g.

filter: blur(4px) url(foo.svg#bar) contrast(0.5);

will render progressively. I.e., it'll render the blur and contrast, and
then re-render once the network fetch is done. This is likely how it works
in Chrome/Safari, but I'm not sure it's the best behaviour.


On Sun, Jul 14, 2013 at 10:20 AM, Dirk Schulze <dschulze@adobe.com> wrote:

> On Jul 12, 2013, at 2:31 PM, Boris Zbarsky <bzbarsky@MIT.EDU> wrote:
> > On 7/12/13 5:25 PM, Robert O'Callahan wrote:
> >> I feel pretty strongly that the SVG behavior is not appropriate. I think
> >> any sort of invalid 'filter' value, including a <filter> element with a
> >> child element of unknown type, should cause the filtered element to be
> >> rendered normally (i.e. 'filter' treated as 'none'). Otherwise I think
> >> introducing new <fe> SVG element types does not get useful fallback.
> >
> > OK, should that be raised as an issue on SVG, then?  I feel like we
> > should have consistency between the case when there is only one url() in
> > 'filter' and the case when there are multiple things including a url()
> I forgot to paste the link to the Filter Effects specification that allows
> multiple declarations on url() [1]. Sorry for that.
> 1) SVG 1.1 was not clear about what happens if the specified URL is not
> referencing an existing <filter> element. Implementations treat this case
> as if 'none' was specified.
> 2) For SVG 1.1: if one of the primitives is in an error state (which used
> to happen quite often in earlier versions of the spec.) then nothing gets
> rendered at all.
> I agree with you Boris that we should not treat both cases differently.
> However, I am more in favor of just not applying the filter then stop
> rendering of the filtered element entirely (suggestion from roc).
> With Filter Effects we have a new situation since we allow multiple filter
> functions or url()s. The reason why it changes the way to look at the topic
> is the following:
> A) Treat errors as "filter: none" and refuse the whole filter chain
> might be described similarly with
> B) Treat failing filter function as pass-through and still apply the other
> filter functions.
> Both, A) and B) just make a difference on applying multiple filter
> functions if we agree on the behavior of 1).
> Greetings,
> Dirk
> [1] http://dev.w3.org/fxtf/filters/#FilterProperty
> CCed public-fx again.
> >
> > -Boris
> >
Received on Thursday, 25 July 2013 12:14:25 UTC

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