1024126 - Add a danger zone to SharedFrameMetricsHelper::AboutToCheckerboard()

Status: RESOLVED FIXED

(Core :: Graphics: Layers, defect)

Description

[Kartikaya Gupta (email:[e-mail])]

As mentioned at https://bugzilla.mozilla.org/show_bug.cgi?id=1006579#c5 and https://bugzilla.mozilla.org/show_bug.cgi?id=1021248#c9, the AboutToCheckerboard function is really an IsCheckerboarding function at the moment. We should expand the currently-visible rect from the compositor (making sure to still clamp it to page bounds and so on) by a "danger zone" (see the equivalent Fennec code in DisplayPortCalculator.java).

Note that making this change will mean we drop into low-res painting more frequently that we do now, which may or may not be a good thing.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

This bug should also replace the Inflate added in https://hg.mozilla.org/integration/mozilla-inbound/rev/a73ed980626f with something like FuzzyContains to deal with rounding error better. I think half an app unit would probably make for a good epsilon for the fuzzy compare.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Attachment: Patch

Needs a bit more testing.

Comment 3

[Chris Lord [:cwiiis]]

Comment on attachment 8444705 [details] [diff] [review]
Patch

Review of attachment 8444705 [details] [diff] [review]:
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Nice :) We should try at some point to find good default values for those prefs - but really, we need to decide on that per device spec...

Comment 4

[Kartikaya Gupta (email:[e-mail])]

https://hg.mozilla.org/integration/mozilla-inbound/rev/c6a7886cde25

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/c6a7886cde25

Comment 6

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8444705 [details] [diff] [review]
Patch

[Approval Request Comment]
Bug caused by (feature/regressing bug #): enabling progressive painting
User impact if declined: occasionally we could get stuck in a state where part of the content isn't painted, due to rounding errors.
Testing completed (on m-c, etc.): locally, on m-c
Risk to taking this patch (and alternatives if risky): fairly low risk. affects b2g only. might want to bake a few more days before uplifting to ensure this doesn't break anything.
String or IDL/UUID changes made by this patch: none

Comment 7

[Sylvestre Ledru [:Sylvestre]]

Comment on attachment 8444705 [details] [diff] [review]
Patch

Baked enough. Approving.

Comment 8

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/1d16403e76a5