1987965 - Trigger layout in ResizeObserver loop on scroll-based overflow

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, enhancement)

Description

[David Shin[:dshin]]

Scrolling may cause positioned element to overflow, which in turn may cause position-try-fallbacks.
(So this likely also depends on position-try-fallbacks being implemented)

Comment 1

[David Shin[:dshin]]

Bug 1962598 implements fallbacks at layout time.
So just need to force a layout if positioned rect + offset overflows its abs-cb and we have fallbacks to try.
(position-visibility hiding is at paint-time, so it won't force layout, but it's likely checked here)

Comment 2

[David Shin[:dshin]]

This will live around where bug 1987964 will touch. That bug is waiting on Oct 15 CSSWG breakout session for anchor-positioning.

Comment 3

[David Shin[:dshin]]

As per resolution, we'll be using the IntersectionObserver machinery but run it around the content-visibility time, confirming the same timing as bug 1987964.

content-visibility already runs IO during its evaluation

Comment 4

[Tiaan Louw [:tlouw]]

Attachment: WIP: Bug 1987965 - Trigger layout in ResizeObserver loop on scroll-based overflow r=emilio,dshin

Comment 5

[Emilio Cobos Álvarez [:emilio]]

Attachment: A test-case.

Comment 6

[Emilio Cobos Álvarez [:emilio]]

Attachment: WIP: Bug 1987965 - A WIP attempt to preserve the original fallback position.

Not sure we should do this, it's kinda gross.

Comment 7

[Emilio Cobos Álvarez [:emilio]]

Here's a try run with the last version of the patch that we worked on: https://treeherder.mozilla.org/jobs?repo=try&landoCommitID=165784

Comment 8

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1987965 - Trigger layout in ResizeObserver loop on scroll-based overflow r=dshin

Check whether positioned frames still fits their abs-cb and have any
fallbacks remaining, then trigger a layout.

Co-authored-by: David Shin <[e-mail]>
Co-authored-by: Emilio Cobos Álvarez <[e-mail]>

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/21742c0ed633
https://hg.mozilla.org/integration/autoland/rev/0be9da23ba3c
Trigger layout in ResizeObserver loop on scroll-based overflow r=dshin,layout-reviewers

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/41f47bef3f9a
https://hg.mozilla.org/integration/autoland/rev/9ef634821b84
Annotate some platform-dependent test expectations.

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/1b390c6ab147
https://hg.mozilla.org/integration/autoland/rev/c20fd9d863e5
fix lint failure

Comment 12

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/0be9da23ba3c
https://hg.mozilla.org/mozilla-central/rev/9ef634821b84
https://hg.mozilla.org/mozilla-central/rev/c20fd9d863e5