1586055 - feComponentTransfer filters that are promoted as WebRender filters don't render beyond their input, even when they should

Status: VERIFIED FIXED

(Core :: Graphics: WebRender, defect, P3)

Description

[Markus Stange [:mstange]]

Attachment: testcase

This testcase should render a 200x200 square of green. When run with WebRender, it only renders a 100x100 square of green.

feComponentTransfer can render outside of its input if it maps alpha = 0 to alpha > 0.

Comment 1

[Connor Brewster [:cbrewster]]

WebRender doesn't keep track of filter regions specified on the svg filter element at all and instead uses the size of the content being filtered plus some inflation factors for effects like blur. To get around this, we currently apply a clip to the filter result, but this only works if the filter region is smaller than the size of the content to be filtered. In this case the filter region is larger than the contents being filtered, so incorrect results are produced.

final clip: https://searchfox.org/mozilla-central/rev/01d1011ca4a460f751da030d455d35c267c3e210/layout/svg/nsFilterInstance.cpp#367

I believe that this will be fixed once filter-primitive subregion support is added (1573657) as the filter primitive subregions should already take the filter region into account.

I've been a bit busy, but I am hoping to continue work on filter-primitive subregions soon. If this becomes higher priority, feel free to snag it.

Comment 2

[Glenn Watson [:gw]]

ahale, something to add to your list of things to consider as part of the SVG filter work.

Comment 3

[Ashley Hale [:ahale]]

Added to the WR SVG filters bug for tracking, currently lower priority than the SVG filter support overhaul but let me know if people want this urgently.

Comment 4

[Ashley Hale [:ahale]]

Confirmed this will be fixed by https://phabricator.services.mozilla.com/D174208 when I get it to land

Comment 5

[Ashley Hale [:ahale]]

Closing as this was fixed as part of enabling gfx.webrender.svg-filter-effects.

Comment 6

[Ardelean Oana, Desktop Test Engineering [:oardelean]]

Reproducible on Firefox 131.0 on Windows 10.
Issue is verified as fixed on Firefox 132.0b2 and Firefox Nightly 133.0a1 on Windows 10, Ubuntu 22, macOS 14.