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Re: filter primitive subregion and feGaussianBlur

From: Erik Dahlstrom <ed@opera.com>
Date: Fri, 28 Jan 2011 16:03:57 +0100
To: "robert@ocallahan.org" <robert@ocallahan.org>
Cc: www-svg@w3.org
Message-ID: <op.vp0xgsn8geuyw5@localhost>
This is a response to  
http://lists.w3.org/Archives/Public/www-svg/2008May/0013.html (tracked as  

> "Restricts calculation" is a bit ambiguous. Does this mean:
> -- The implementation takes a snapshot of the input image, with the  
> geometry
> of the snapshot determined by the filter primitive subregion for the
> feGaussianBlur, and performs processing on that, treating the boundaries  
> of
> the snapshot as the boundary where boundary conditions are applied.
> or something else?

The spec has been updated [1] as agreed in [2] to say that:

   ‘x’, ‘y’, ‘width’ and ‘height’ act as a hard clip clipping rectangle on  
both the filter primitive's input image(s) and the filter primitive result.

> BTW the spec also says
>> If the input has infinite extent and is a tile, the filter is evaluated
> with periodic boundary conditions.
> I'm not sure what it means for the input to have infinite extent in this
> context, and I'm not sure what it means to be "a tile". Does it mean that
> the input is an feTile? Could this be more precisely defined?

Updated [3][4] to say:

If the input has infinite extent and is constant (e.g FillPaint where the  
fill is a solid color), this operation has no effect. If the input has  
infinite extent and the filter result is the input to an ‘feTile’, the  
filter is evaluated with periodic boundary conditions.

For completeness, could you please indicate whether these changes have
been made to your satisfication?


[2] http://lists.w3.org/Archives/Public/www-svg/2010Jul/0009.html

Erik Dahlstrom, Core Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group
Personal blog: http://my.opera.com/macdev_ed
Received on Friday, 28 January 2011 15:04:36 UTC

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