Bug 253606

Summary: [margin-trim] Trimmed block-start margins for boxes in a block container should be reflected in computed style
Product: WebKit Reporter: Sammy Gill <sgill26>
Component: CSSAssignee: Sammy Gill <sgill26>
Status: RESOLVED FIXED    
Severity: Normal CC: webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://github.com/web-platform-tests/wpt/pull/39705
Bug Depends on:    
Bug Blocks: 253454    

Description Sammy Gill 2023-03-08 14:34:45 PST
The web inspector shows the untrimmed margins for a box even if has been trimmed by the containing block's margin-trim property.
Comment 1 Radar WebKit Bug Importer 2023-03-08 14:35:02 PST
<rdar://problem/106452955>
Comment 2 Sammy Gill 2023-03-08 14:57:22 PST
Pull request: https://github.com/WebKit/WebKit/pull/11262
Comment 3 Sammy Gill 2023-04-11 15:06:24 PDT
Circling back to this after working on the flex and grid cases. I think we can achieve this by adding some extra information in layout state when a block container has block-start margin trim specified on it. 

We will check if this state is set as we recurse into the nested children and use it to determine if those nested children should trim also. The nested content will also need to take into consideration some other pieces of information, such as if its children's margins can collapse with its margin before (e.g. it does not have any border/padding)
Comment 4 Sammy Gill 2023-04-24 13:05:39 PDT
Pull request: https://github.com/WebKit/WebKit/pull/12884
Comment 5 Sammy Gill 2023-04-25 20:20:54 PDT
Submitted web-platform-tests pull request: https://github.com/web-platform-tests/wpt/pull/39705
Comment 6 EWS 2023-04-26 07:46:44 PDT
Committed 263412@main (99e30b0ca8f6): <https://commits.webkit.org/263412@main>

Reviewed commits have been landed. Closing PR #12884 and removing active labels.