Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Description • 10 years ago

There are some cases where we end up creating nsDisplayLayerEventRegions display items with no actual hit regions. We should discard these (or not create them to begin with). Sometimes I see scrollbar frames also seem to create event regions with z=2147483647 and no actual hit region.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 2 • 8 years ago

Comment on attachment 8759250 [details] [diff] [review]
Patch

I updated the patch per Matt and tn's comments. I left the deletion in the ProcessDisplayItems as well because there might be other empty event regions that sneak through from [1] or [2] and even though they won't have wrapper items like nsDisplayTransform it's still good to eliminate them. Try push at [3]

[1] http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsFrame.cpp?rev=bd393975aadd#2843
[2] http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsFrame.cpp?rev=bd393975aadd#2850
[3] https://treeherder.mozilla.org/#/jobs?repo=try&revision=222e62d6fd09

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 3 • 8 years ago

Review commit: https://reviewboard.mozilla.org/r/57586/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/57586/

	Markus Stange [:mstange]
	Comment 4 • 8 years ago

Comment on attachment 8759678 [details]
Bug 1108052 - Remove empty event regions display items because they only slow things down and can add extraneous layers.

https://reviewboard.mozilla.org/r/57586/#review54382

	Pulsebot
	Comment 5 • 8 years ago

Pushed by kgupta@mozilla.com:
https://hg.mozilla.org/integration/mozilla-inbound/rev/e2b1014ab075
Remove empty event regions display items because they only slow things down and can add extraneous layers. r=mstange

	Carsten Book [:Tomcat]
	Comment 6 • 8 years ago
bugherder

https://hg.mozilla.org/mozilla-central/rev/e2b1014ab075

	Kartikaya Gupta (email:kats@mozilla.staktrace.com) Assignee
	Comment 7 • 8 years ago

Comment on attachment 8759678 [details]
Bug 1108052 - Remove empty event regions display items because they only slow things down and can add extraneous layers.

Approval Request Comment
[Feature/regressing bug #]: APZ
[User impact if declined]: some animations might be slower than without APZ if they have a lot of visibility:hidden items that get layerized.
[Describe test coverage new/current, TreeHerder]: no automated tests, but see bug 1276713 for how this was uncovered
[Risks and why]: low risk, fairly straightforward optimization
[String/UUID change made/needed]: none

	Sylvestre Ledru [:Sylvestre]
	Comment 8 • 8 years ago

Comment on attachment 8759678 [details]
Bug 1108052 - Remove empty event regions display items because they only slow things down and can add extraneous layers.

ok, as it improves the perfs, let's take it. Should be in 48 beta 2

	Carsten Book [:Tomcat]
	Comment 9 • 8 years ago
bugherder uplift

https://hg.mozilla.org/releases/mozilla-beta/rev/11986e199445