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Re: [filter-effects] @support condition for custom filters

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 11 Feb 2013 15:14:17 -0800
Message-ID: <CAAWBYDAd0-k43JbgiEpjPto+MTBGQhO4mSrbU=awvBuLQSKRdw@mail.gmail.com>
To: Dirk Schulze <dschulze@adobe.com>
Cc: www-style list <www-style@w3.org>
On Mon, Feb 11, 2013 at 3:05 PM, Dirk Schulze <dschulze@adobe.com> wrote:
> Hi all,
>
> The Filter Effects[1] specification defines the custom() filter function to extend the predefined filters by new, customized filters including CSS Shaders, but not limited to CSS Shaders. This was discussed and accepted by the SVG WG [2].
>
> Feature detection is important to support future extensions of the spec and test for the availability. I have an action from the SVG WG to ask for a new condition 'filter' on the @support rule. This filter descriptor can take different feature keywords. For CSS Shaders I would suggest 'webgl' because of the relation to WebGL. More feature keywords can be added by future versions of Filter Effects allowing other or future shading languages and parameterized SVG filters. The filter condition would look like in the following demonstration:
>
> @support filter: webgl {
>         @filter curl {
>                 src: url(vertex.vs), url(fragment.fs);
>                 geometry: grid(4,5);
>                 parameters: transform scale(2,2);
>         }
> }
>
> I would like to ask for feedback, concerns or suggestions.

Ah, this is why we allowed ourselves an extension point.

You can't do it with the syntax you've provided.  That asks if the
implementation supports a "filter: webgl" interface.  However, you can
define a function that asks for that particular support.  For example,
a filter-type() property could work:

@support (filter-type(webgl)) {
  @filter curl { ... }
}

~TJ
Received on Monday, 11 February 2013 23:15:03 GMT

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