Closed Bug 1574100 Opened 3 months ago Closed 3 months ago

Assertion failure: aLayer.GetReferentId(), at APZCTreeManager.cpp:835


(Core :: Panning and Zooming, defect)

Not set



Tracking Status
firefox70 --- fixed


(Reporter: hiro, Assigned: botond)


(Blocks 1 open bug)



(3 files, 1 obsolete file)

I am less sure this is a fission specific issue or not.

Attaching file is a patch including a browser mochitest which causes this assertion.

I am going to post a backtrace for the assertion in the next comment.

Attached file backtrace

The patch I posted didn't include browser.ini file. Sorry for that.

Assignee: nobody → hikezoe.birchill
Attachment #9085688 - Attachment is obsolete: true
Assignee: hikezoe.birchill → nobody

The test times out for me, but it doesn't reproduce the assertion.

Correction: I can reproduce the assertion, if I run the test normally. (Before, I was running it with xvfb-run, that seems to interfere with this test somehow.)

I think I see what's happening: in cases where a RefLayer has multiple frame metrics, only the bottom LayerMetricsWrapper conceptually represents the ref layer for purposes of building the hit-testing tree. Accordingly, LayerMetricsWrapper should only return RefLayer properties if AtBottomLayer() is true.

This is done correctly in GetReferentId(), but not in GetEventRegionsOverride().

Assignee: nobody → botond

We only want the bottom LayerMetricsWrapper / WebRenderScrollDataWrapper to
be treated as a ref layer, and only ref layers have event regions overrides.

Pushed by
For RefLayers with multiple metrics, only expose the event regions override for the bottom one. r=tnikkel

(In reply to Hiroyuki Ikezoe (:hiro) from comment #0)

I am less sure this is a fission specific issue or not.

This is unlikely to affect non-Fission. While theoretically possible, it would require the browser UI to be scrollable, or something like that.

Thanks for the quick fix! Amazing!

Closed: 3 months ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla70
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