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[Bug 10799] drawImage/pattern filters underspecified

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Date: Tue, 07 Dec 2010 22:16:11 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1PQ5pT-000877-Nr@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=10799

--- Comment #15 from Philip Taylor <excors@gmail.com> 2010-12-07 22:16:11 UTC ---
By "in the area of the repetitions", I meant the area where the previous
paragraph says the pattern will be painted (anchored in a certain point and
repeated in certain directions). Outside that area, the pattern won't be
painted at all - it's only inside the area that the wrapping filter is used. So
no-repeat patterns and drawImage will both draw a single copy of the image with
sharp edges when scaled up, but will filter differently when computing the
pixels just inside the edges.

An alternative way to see it is that the pattern is always based on an
infinitely-repeating-in-both-directions image, with filtering applied to that,
and then the repeat-x/y/no-repeat setting is cropping the resulting image in
one or both directions. This is similar to how drawImage takes the entire input
image, filters that, and then crops to the specified source rectangle, rather
than cropping before filtering. So I think it's logically justifiable in that
way.

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Received on Tuesday, 7 December 2010 22:16:13 UTC

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