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ISSUE-2284 (primitivesubregion_application): Clarify how the primitive subregion affects the filter input and outputs for all filter primitives [SVG Filters 1.2]

From: SVG Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Wed, 24 Jun 2009 14:39:17 +0000 (GMT)
To: public-svg-wg@w3.org
Message-Id: <20090624143917.604B4C6DB9@barney.w3.org>

ISSUE-2284 (primitivesubregion_application): Clarify how the primitive subregion affects the filter input and outputs for all filter primitives [SVG Filters 1.2]

http://www.w3.org/Graphics/SVG/WG/track/issues/2284

Raised by: Erik Dahlström
On product: SVG Filters 1.2

It's not fully clear in the spec how the filter primitive subregion affects filter inputs and outputs.

E.g for feOffset, when there's an 'x','y' offset in its primitive subregion as well as a 'dx','dy' offset, in which order should they be applied? Does the primitive subregion only affect the filter output, or is the input 'restricted/clipped' to this region as well? 

Example:
<feOffset in="SourceGraphic" x="50" y="50" width="200" height="200" dx="50" dy="50"/>

Now, the sourcegraphic has it's origin at (0,0) and has width,height (100,100). How should the filter primitive be applied, possible results:
a) move image (dx,dy) -> apply primsubregion -> output (looks like the input has been translated 50,50 and is not clipped)
b) apply subregion -> move image (dx,dy) -> output (looks like the input has been clipped and translated)

For feDisplacementMap, another question is how the primitive region restriction fits into the displacement equation, and how the cases where the input image and the displacement map are of different size are supposed to be handled.

[1] Related examples: http://www.tapper-ware.net/2009/05/perspective-texture-with-6-lines-of-svg.html
Received on Wednesday, 24 June 2009 14:39:26 GMT

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