Bug 283846 – [css-contain-2] content skipped with `content-visibility: auto` should still be findable

• Status: RESOLVED
• Resolution: FIXED
• Component: CSS

[Nathan Knowler]

Created attachment 473400 [details]
Reduced test with some off-screen content skipped with `content-visibility: auto`.

Content skipped with `content-visibility: auto` should still be findable with find-in-page features and in Safari it’s not. I did confirm that content is still accessible in VoiceOver (e.g. if the skipped content includes a link, it’ll surface in the Web Rotor).

Latest draft spec (this is not a recent change): https://drafts.csswg.org/css-contain/#valdef-content-visibility-auto

macOS Version: 15.1.1 (24B2091)
Safari version 18.1.1 (20619.2.8.11.12)
Safari Tech Preview Release 208 (Safari 18.2, WebKit 20621.1.5.1)

[Radar WebKit Bug Importer]

<rdar://problem/141086607>

[Nathan Knowler]

Created attachment 474222 [details]
Reference video for matching content with a text fragment in Safari 18.3

I’m adding a video demonstration of how text fragment URLs relate to this bug in Safari 18.3. The behaviour is slightly different than find-in-page. The page scrolls to the location of the match. The matched text displays briefly, before disappearing. This means that content with `content-visibility: auto` that is within the viewport is still hidden.

[Tim Nguyen (:ntim)]

rdar://141237620

[Tim Nguyen (:ntim)]

Created attachment 474285 [details]
WIP TextIterator changes

My TextIterator changes should be correct, but I'm missing some other part of the puzzle that I can't seem to pinpoint atm.

[zalan]

Created attachment 474731 [details]
Patch

[zalan]

fullyClipsContents change is not quite right. I think what we need here is to run the forced layout without applying implicit size containment on c-v auto content so that c-v auto block containers don't get collapsed.

[zalan]

(as it is difficult to differentiate  actual collapsed containers from containers with zero height caused by applying (c-v a) size containment)

[zalan]

Created attachment 474757 [details]
Patch

[zalan]

Created attachment 474759 [details]
[fast-cq]Patch

[EWS]

Committed 292919@main (d1074e32ca2f): <https://commits.webkit.org/292919@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 474759 [details].

[zalan]

oops, forgot to submit the test. will do it in a bit.

[zalan]

(In reply to zalan from comment #11)
> oops, forgot to submit the test. will do it in a bit.

https://commits.webkit.org/292949@main