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Re: filter primitive subregion and feGaussianBlur

From: Robert O'Callahan <robert@ocallahan.org>
Date: Sat, 29 Jan 2011 22:45:11 +1300
Message-ID: <AANLkTimNSniDWJSwgQzEm4_+8gCJ4yWwEUTP3efLgs12@mail.gmail.com>
To: Erik Dahlstrom <ed@opera.com>
Cc: www-svg@w3.org
On Sat, Jan 29, 2011 at 4:03 AM, Erik Dahlstrom <ed@opera.com> wrote:

> This is a response to
> http://lists.w3.org/Archives/Public/www-svg/2008May/0013.html (tracked as
> ISSUE-2334).
>
>  "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.
> ]]
>

That sounds fine.


>
>  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.
> ]]
>

What does "periodic boundary conditions" mean?

Rob
-- 
"Now the Bereans were of more noble character than the Thessalonians, for
they received the message with great eagerness and examined the Scriptures
every day to see if what Paul said was true." [Acts 17:11]
Received on Saturday, 29 January 2011 09:45:44 GMT

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