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[fxtf-drafts] Pull Request: Clip backdrop root (input) image to border box of element

From: Mason Freed via GitHub <sysbot+gh@w3.org>
Date: Tue, 11 Jun 2019 17:01:45 +0000
To: public-fxtf-archive@w3.org
Message-ID: <pull_request.opened-287181329-1560272504-sysbot+gh@w3.org>
mfreed7 has just submitted a new pull request for https://github.com/w3c/fxtf-drafts:

== Clip backdrop root (input) image to border box of element ==
With this change, the spec is now explicit that the input image for the backdrop root image should be clipped to the border box of the element. Prior to this change, the spec was written such that the
entire backdrop image was to be used as the filter input. For filters that move pixels (e.g. blur), this
meant that neighboring content that is outside the bounds of the element would influence the filtered
content within the element's bounds.

This change is a good one for these reasons:
 - It agrees more closely with existing Webkit/Safari behavior.
 - It improves performance, by filtering fewer pixels in the
   case of pixel-moving filters.
 - Developers have been disappointed with the existing behavior
   of bringing in pixels from outside the bounds of the
   element, and have requested a way to turn this behavior off.
   See the discussion starting at [1].

See https://github.com/w3c/fxtf-drafts/pull/342
Received on Tuesday, 11 June 2019 17:01:47 UTC

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