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Re: [css-images][css-compositing] Blurring an elementís backdrop

From: Dirk Schulze <dschulze@adobe.com>
Date: Thu, 5 Dec 2013 22:26:51 -0800
To: Rik Cabanier <cabanier@gmail.com>
CC: Lea Verou <lea@verou.me>, Michael Mullany <michael@sencha.com>, Dean Jackson <dino@apple.com>, "public-fx@w3.org" <public-fx@w3.org>, www-style list <www-style@w3.org>, Stefan-Teodor Craciun <scraciun@adobe.com>
Message-ID: <20D0527E-671A-4E50-AABD-73E1B63C8CDF@adobe.com>

On Dec 6, 2013, at 5:42 AM, Rik Cabanier <cabanier@gmail.com> wrote:

> In going with Lea's comment that authors equate backdrop with blending, I propose the following new property:
> backdrop-blur: none | <length> 
> Length would be the parameter passed into the blur() filter [1]. 

This is extremely specific for exactly one use case. At least color matrix filters are common as well.

> Specifying this parameter in combination with mix-blend-mode[2], would blur the backdrop that is available during the blending step. Compositing would happen as usual.
> An alternate would be to extend mix-blend-mode so you can write the following:
> mix-blend-mode: screen blur(10px);

I would be more in favor for that. Although, it should have all filter functions as a list of filter functions.

> This can still be made compatible with future additions that target parts of an element.
> I'm in the process of creating an experimental windows-only build of firefox that implements.
> Thoughts?
> 1: http://www.w3.org/TR/filter-effects/#funcdef-blur
> 2: http://dev.w3.org/fxtf/compositing-1/#mix-blend-mode


> On Fri, Nov 29, 2013 at 7:51 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> On Thu, Nov 28, 2013 at 10:35 PM, Lea Verou <lea@verou.me> wrote:
> On Nov 29, 2013, at 12:45, Rik Cabanier <cabanier@gmail.com> wrote:
> > This might work.
> > My main concern is that it would overload mix-blend-mode too much since we're also hoping to repurpose it to blend different areas of an element. I'm unsure how we would reconcile that.
> > Do you have a suggestion?
> If the syntax for that is what was discussed in the FXTF a while ago, I donít see what the conflict would be. Care to elaborate? :)
> Looking 18 months (!) back on this thread, I proposed the following:
> mix-blend-mode: color-burn(blur(5px))
> Doing it this way will be confusing if we want to blend different elements, ie
> mix-blend-mode: background screen, border multiply, content overlay, element hue
> Now, each of those *could* theoretically blur the backdrop but that is not a strong use case.
> This syntax also gives the impression that your content/border/element has the effect applied as opposed to the backdrop.
> Also, as Michael mentioned, simply blurring will not give you the desired effect. You often want to soften the backdrop with a white color that's blended with soft light or screen. 
> He also mentions:
>  we need finer control of the blur opacity/falloff
> I'd prefer if we could create a new property that has nice defaults and if we can avoid writing filter chains in CSS.
Received on Friday, 6 December 2013 06:28:21 UTC

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