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Re: feImage image sizing

From: Erik Dahlström <ed@opera.com>
Date: Thu, 06 Mar 2008 11:42:24 +0100
To: robert@ocallahan.org, www-svg <www-svg@w3.org>
Message-ID: <op.t7lb0ynugqiacl@gnorps.palace.opera.no>

Hello Rob,

On Wed, 05 Mar 2008 09:17:43 +0100, Robert O'Callahan  
<robert@ocallahan.org> wrote:

> http://www.w3.org/TR/SVG/filters.html#feImage
>
> If the xlink:href references a stand-alone image resource such as a JPEG,
>> PNG or SVG file, then the image resource is rendered according to the
>> behavior of the  
>> 'image'<http://www.w3.org/TR/SVG/struct.html#ImageElement>element
>>
>
> For the <image> element, 'width' and 'height' are required attributes  
> that
> define the size of the viewport into which the image is rendered.  
> <feImage>
> doesn't have these attributes, so how should the image viewport be  
> sized? If
> the image viewport is supposed to be (0,0)-(100%,100%) of the user
> coordinate system established by the value of 'primitiveUnits' on the
> 'filter' element, I think the spec needs to be clarified to say so
> explicitly.

Actually, <feImage> have 'x', 'y', 'width' and 'height' attributes since  
those describe the filter primitive subregion[1]. Even if not specified on  
the <feImage>, these attributes take their defaults from the <filter>  
element so that the filter primitive subregion is always defined.

I don't think the behavior is undefined as the spec stands, but I agree  
that it could be clarified.

Cheers
/Erik

[1] http://www.w3.org/TR/SVG/filters.html#FilterPrimitiveSubRegion

-- 
Erik Dahlstrom, Core Technology Developer, Opera Software
Co-Chair, W3C SVG Working Group
Personal blog: http://my.opera.com/macdev_ed
Received on Thursday, 6 March 2008 10:42:48 GMT

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