CSS View Transitions - Nested View Transition Groups

[vmpstr]

こんにちは TAG-さん!

I'm requesting a TAG review of CSS View Transition - Nested View Transition Groups.

View transitions work by generating a pseudo-element tree representing groups of the captured old state & the live new state of a transition. In its current form, the generated tree is "flat" - the original hierarchy in the DOM is lost, and all the captured groups are siblings under a single ::view-transition pseudo-element.

Instead of a flat tree, the author can nest ::view-transition-group pseudo-elements within each other. This is done with a new property, view-transition-group, which when applied on an element with a view-transition-name, defines whether the generated ::view-transition-group gets nested in one of its containers, or it would nest its own participating descendants.

• Explainer¹: https://github.com/WICG/view-transitions/blob/main/nested-explainer.md
• Specification: https://www.w3.org/TR/css-view-transitions-2/#view-transition-group-prop
• WPT Tests: https://wpt.fyi/results/css/css-view-transitions/nested?label=master&label=experimental&aligned
• User research: N/A
• Security and Privacy self-review²: N/A
• GitHub repo: https://github.com/w3c/csswg-drafts/
• Primary contacts:
  • @vmpstr (Google, Author)
  • @noamr (Google, Author)
• Organization/project driving the specification: Google
• Multi-stakeholder support³:
  • Chromium comments: N/A
  • Mozilla comments: CSS View Transitions - Nested View Transition Groups mozilla/standards-positions#1183
  • WebKit comments: CSS View Transitions - Nested View Transition Groups WebKit/standards-positions#466
• Status/issue trackers for implementations⁴: https://chromestatus.com/feature/5162799714795520

Further details:

• I have reviewed the TAG's Web Platform Design Principles
• Previous early design review, if any: N/A
• Relevant time constraints or deadlines: N/A
• The group where the work on this specification is currently being done: CSSWG
• The group where standardization of this work is intended to be done (if different from the current group):
• Major unresolved issues with or opposition to this specification: N/A
• This work is being funded by: Google