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Re: Updated filters specification

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 29 Apr 2011 16:19:05 +1200
Message-ID: <BANLkTi=f6ymKhreFwTXZRyt=XKoerF4rWw@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: Erik Dahlstrom <ed@opera.com>, Dean Jackson <dino@apple.com>, Dirk Schulze <vbs85@gmx.de>, public-fx@w3.org, Anthony Grasso <anthony.grasso@cisra.canon.com.au>
On Fri, Apr 29, 2011 at 6:11 AM, Rik Cabanier <cabanier@gmail.com> wrote:

> can you show me an example where this is used?
> As was stated before in this thread, the effect of 'enable-background'
> could be emulated by just rearranging the content.
>
> "filtering" 2 images together really sounds like blending to me and as such
> should go into the blending spec. If that spec is not able to produce this
> effect (and you believe that this is a required feature) then the future CSS
> compositing specification should address it.
>

<filter id="blurBackground">
  <feGaussianBlur in="BackgroundImage" stdDeviation="4"/>
  <feComposite in="SourceImage"/>
</filter>
... lots of HTML content ...
  <div style="position:fixed; filter:url(#blurBackground)">...</div>

The background behind the <div> is blurred and the contents of the div are
drawn on top. You do not want to have to rearrange the content to get this
effect. I suppose you could address this in the compositing specification by
adding a special 'composite-background-blur' property, or something like
that, but how about this variant:

<filter id="rippleBackground">
  <feDisplacementMap in="BackgroundImage" in2="ripples.png"/>
  <feComposite in="SourceImage"/>
</filter>

This would apply a ripple effect to the background before drawing the div on
top, Hopefully we don't want to have that sort of effect in the compositing
spec.

Rob
-- 
"Now the Bereans were of more noble character than the Thessalonians, for
they received the message with great eagerness and examined the Scriptures
every day to see if what Paul said was true." [Acts 17:11]
Received on Friday, 29 April 2011 04:19:33 GMT

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