Re: Updated filters specification

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
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