809493 - Div contents leak out when scrolling nested div on some frames

Status: RESOLVED FIXED

(Core :: Graphics: Layers, defect)

Description

[Benoit Girard (:BenWa)]

STR:
1) Open layout/reftests/scrolling/opacity-mixed-scrolling-2.html on mobile
2) Pan the div slowly, sometimes the frame will stop with the contents leaking outside the bounds.

Comment 1

[Benoit Girard (:BenWa)]

Most likely related: On this page I also see the that the opacity varies as you pan the page and scroll the div.

Comment 2

[Benoit Girard (:BenWa)]

Note that these failures aren't caused by progressive painting but the artifacts are different with tiling.

Comment 3

[Benoit Girard (:BenWa)]

(In reply to Benoit Girard (:BenWa) from comment #1)
> Most likely related: On this page I also see the that the opacity varies as
> you pan the page and scroll the div.

This looks like a state change. I can reproduce this reliably using:

0) Enable tile borders (optional).
1) Scroll the div (the div will get it's own layers and tile border).
2) Scroll the page such that the background comes into view.
3) If the div layer is still active and the background is into view the opacity will change.

Comment 4

[Benoit Girard (:BenWa)]

Attachment: Part 1: Fix opacity

Comment 5

[Benoit Girard (:BenWa)]

Attachment: patch

Correct blend equation this time.

Comment 6

[Benoit Girard (:BenWa)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/f8989ca9a3c6

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/f8989ca9a3c6