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Re: Margins for filters?

From: Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
Date: Mon, 19 Apr 2010 12:37:42 +0200
Message-ID: <4BCC3276.6000606@hccnet.nl>
To: Erik Dahlstrom <ed@opera.com>
CC: robert@ocallahan.org, Dirk Schulze <vbs85@gmx.de>, www-svg@w3.org
Erik Dahlstrom wrote:
> On Mon, 19 Apr 2010 07:45:00 +0200, Robert O'Callahan 
> <robert@ocallahan.org> wrote:
>> I suggest we continue to allow filter primitive subregions to clip filter
>> primitives, but that we make the default filter primitive subregion 
>> (for all
>> filter primitives) be infinite so no clipping is performed.
> 
> What you are suggesting is to allow the filter primitive subregion to be 
> larger than the filter region, so calling it 'subregion' sounds wrong to 
> me (editorial, but still, if that change is made I'd like to call it 
> 'filter primitive region' instead).

Okay, so basically the idea currently on the table would be to more or 
less forget about the filter effects region and filterRes (and do the 
same for masks), but keep filter primitive "subregions"? With the twist 
that by default such a region would be infinite (conceptually). Have I 
got that right?

Something like that would indeed be nice. Although it might be good to 
change an implementation to actually do that first, to see how well it 
works in practice, and to evaluate the impact on existing images.

For backwards compatibility we probably still should respect the filter 
effects region if it is specified explicitly, but it might be reasonable 
to simply change the default to being infinite (like with subregions). 
Note that this does NOT mean that a renderer would be required to 
actually store an infinite output, as obviously any viewport will be 
finite and there are no IIR filter primitives (so to speak). So a 
renderer could in principe "simply" render the required parts.

Or, if an infinite filter effects region is deemed too problematic the 
default could be made "auto", instructing the renderer to use the 
required margins. These margins could be left upto the renderer in most 
cases (or given a minimum?), and for filters like feFlood they could be 
given very specific values.
Received on Monday, 19 April 2010 10:38:21 GMT

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