Closed Bug 1704478 Opened 3 years ago Closed 3 years ago

Incorrect clipping on MDN mix-blend-mode example


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




89 Branch
Tracking Status
firefox-esr78 --- unaffected
firefox87 --- unaffected
firefox88 --- verified
firefox89 --- verified


(Reporter: jnicol, Assigned: gw)




(Keywords: regression)


(2 files)

Attached image mix-blend-bug.png

Visit and make the browser window narrow enough that the example becomes scrollable. Then drag the example's scrollbar downwards. The images move up the page and remain visible even when they should be clipped by the scrollable frame's bounds.

Mozregression shows this is regressed by bug 1684781

Set release status flags based on info from the regressing bug 1684781

Severity: -- → S4
Flags: needinfo?(gwatson)
Priority: -- → P3
Blocks: gfx-triage
Assignee: nobody → gwatson
Flags: needinfo?(gwatson)

Is this more likely to affect Mobile where a narrow viewport is the norm?

Yes, I initially noticed it browsing the page on my phone

Jim, are we sure this should be P3/S4 then? I'm wondering if this is used widely enough that it'd be an RC respin driver this week.

Flags: needinfo?(jmathies)
Flags: in-testsuite?

When a root level blend container matches the criteria to be optimized
from a stacking context to a tile cache, we need to ensure that if
the source stacking context had any valid clips, they are propagated
to the shared clips applied by the tile cache.

Pushed by
Ensure clips are applied to root level blend containers. r=gfx-reviewers,lsalzman

Please nominate this for release approval when you get a chance. Not sure it's enough to drive an RC respin, but it might still make a good ride-along for a dot release.

Flags: needinfo?(jmathies)
Flags: needinfo?(gwatson)
Flags: in-testsuite?
Flags: in-testsuite+
Closed: 3 years ago
Resolution: --- → FIXED
Target Milestone: --- → 89 Branch

Comment on attachment 9215683 [details]
Bug 1704478 - Ensure clips are applied to root level blend containers.

Beta/Release Uplift Approval Request

  • User impact if declined: Mix-blend containers that exist inside a nested scroll frame but no other stacking context containers (e.g. clips / filters / transforms) may render outside that nested scroll frame in some cases. (ryanvm suggested nominating this as a release approval).
  • Is this code covered by automated tests?: Yes
  • Has the fix been verified in Nightly?: Yes
  • Needs manual test from QE?: Yes
  • If yes, steps to reproduce: Per bug report.
  • List of other uplifts needed: None
  • Risk to taking this patch: Low
  • Why is the change risky/not risky? (and alternatives if risky): It's a small patch, only affects mix-blend containers, so it should be relatively low risk.
  • String changes made/needed:
Flags: needinfo?(gwatson)
Attachment #9215683 - Flags: approval-mozilla-release?
Flags: qe-verify+
QA Whiteboard: [qa-triaged]

Comment on attachment 9215683 [details]
Bug 1704478 - Ensure clips are applied to root level blend containers.

Approved for 88.0rc2, thanks.

Attachment #9215683 - Flags: approval-mozilla-release? → approval-mozilla-release+

This issue is Verified as fixed on Windows 10, Mac Osx and Ubuntu in our latest Firefox 88.0rc2 as well as our latest nightly build 89.0a1 (2021-04-15).

QA Whiteboard: [qa-triaged]
Flags: qe-verify+

Verified as fixed on the Firefox RC 88.1.1 with Google Pixel 4 XL (11), Samsung Galaxy S7 (7).

No longer blocks: gfx-triage
Has Regression Range: --- → yes
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