*Contact emails*
[email protected]

*Explainer*
*No information provided*

*Specification*
https://drafts.csswg.org/scroll-animations-1/#valdef-animation-timeline-range-scroll

*Summary*
This feature expands the set of named ranges of view timelines, adding a
"scroll" range. The Scroll-Driven Animations API introduced ViewTimelines
along with named ranges which refer to portions of a ViewTimeline that
define an animation's range[1]. However, all the named ranges provided were
restricted to the portion of the ViewTimeline where its subject is visible.
It is useful for authors to be able to refer to the full extent of the
scroll container underlying the timeline. This feature facilitates this by
adding a named range of "scroll" to the existing set ("entry", "exit",
"cover", "contain").

[1]
https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/animation-range

*Blink component*
Blink>Animation
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EAnimation%22>

*Web Feature ID*
Missing feature

*Motivation*
A scroll-driven animation's range[1] can be described in terms of the
(named) ranges of a ViewTimeline, i.e. "cover", "contain", "entry", "exit."
This allows authors to tie the progress of the animation directly to the
the position of the ViewTimeline's subject within the scroll container
underlying the ViewTimeline.

However, ViewTimelines are, by default, constrained to the portion of the
underlying scroll container within which the subject is (wholly or
partially) visible, i.e. the "cover" range, i.e. { rangeStart: cover 0%,
rangeEnd: cover 100%}. This means that an author has no way, for example,
to refer to a range that starts when the subject is visible but ends at the
end of the scrolling container (rather than when then subject stops being
visible). They could opt for a hack like { rangeStart: cover 0%, rangeEnd:
cover 10000%}, having attempted to manually calculate rangeEnd. Similarly,
to set rangeStart, to the start of the scroll container they'd need to
compute some negative percentage or px offset.

With a named range of "scroll", the author would write "scroll 0%" or
"scroll 100%" instead of manually-calculated values.

[1]
https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/animation-range

*Initial public proposal*
https://github.com/w3c/csswg-drafts/issues/9367#issuecomment-1854280461

*TAG review*
We think this should be covered by the TAG review[1] for scroll-driven
animations as it extended the API introduced in that feature by one
keyword.

[1] https://github.com/w3ctag/design-reviews/issues/828

*TAG review status*
Pending

*Risks*


*Interoperability and Compatibility*
*No information provided*

*Gecko*: No signal

*WebKit*: No signal

*Web developers*: No signals

*Other signals*:

*WebView application risks*

Does this intent deprecate or change behavior of existing APIs, such that
it has potentially high risk for Android WebView-based applications?
*No information provided*


*Debuggability*
*No information provided*

*Will this feature be supported on all six Blink platforms (Windows, Mac,
Linux, ChromeOS, Android, and Android WebView)?*
Yes

*Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
Yes
https://wpt.fyi/results/scroll-animations/view-timelines?label=master&label=experimental&aligned&q=view-timeline-get-current-time-range-name.tentative.html

https://wpt.fyi/results/scroll-animations/css/view-timeline-range-animation.html?label=master&label=experimental&aligned&q=view-timeline-range-animation.html

https://wpt.fyi/results/scroll-animations/view-timelines/view-timeline-get-set-range.html?label=master&label=experimental&aligned&q=view-timeline-get-set-range.html

*Flag name on about://flags*
*No information provided*

*Finch feature name*
*No information provided*

*Non-finch justification*
*No information provided*

*Rollout plan*
Will ship enabled for all users

*Requires code in //chrome?*
False

*Tracking bug*
https://crbug.com/41483848

*Estimated milestones*
Shipping on desktop 146
Shipping on Android 146
Shipping on WebView 146

*Anticipated spec changes*

Open questions about a feature may be a source of future web compat or
interop issues. Please list open issues (e.g. links to known github issues
in the project for the feature specification) whose resolution may
introduce web compat/interop risk (e.g., changing to naming or structure of
the API in a non-backward-compatible way).
*No information provided*

*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/6522328437620736?gate=6481153257242624

This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.

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