Can you remind me what the current behavior is without the remembered scroll offset? I am wondering if there's any scenario where changing this could break existing anchor pos usage.
> Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)? > No Any reason this can't ship on all platforms? -- Dan From: Morten Stenshorne <msten...@chromium.org> Sent: Tuesday, March 4, 2025 11:41 PM To: blink-dev <blink-dev@chromium.org> Subject: [EXTERNAL] [blink-dev] Intent to Ship: CSS anchor positioning remembered scroll offset Contact emails msten...@chromium.org<mailto:msten...@chromium.org> Explainer None Specification https://drafts.csswg.org/css-anchor-position-1/#scroll Summary Add support for the concept of "remembered scroll offset" - see https://drafts.csswg.org/css-anchor-position-1/#scroll When a positioned element has a default anchor, and is tethered to this anchor at one edge, and against the original containing block at the other edge, the scroll offset will be taken into account when it comes to sizing the element. This way a developer can use all visible space (using `position-area`) for the anchored element when the document is scrolled at a given scroll offset. In order to avoid layout (resizing the element) every time the document is scrolled (which is undesired behavior, and also bad for performance), what will be used is a so-called "remembered scroll offset", rather than always using the current scroll offset. The remembered scroll offset is updated at a so-called "anchor recalculation point", which is either: - When the positioned element is initially displayed - When a different position option (`position-try-fallbacks`) is chosen Blink component Blink>Layout<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ELayout%22> TAG review None TAG review status Pending Risks Interoperability and Compatibility Anchor positioning isn't shipping in any other engine yet. Gecko: Positive (https://github.com/mozilla/standards-positions/issues/794) Anchor positioning not implemented in Firefox. WebKit: Support (https://github.com/WebKit/standards-positions/issues/167) Anchor positioning not implemented in Safari. 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? None Debuggability None Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)? No 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/css/css-anchor-position?label=master&label=experimental&aligned https://wpt.fyi/results/css/css-anchor-position/position-area-scrolling-005.html?label=master&label=experimental&aligned Flag name on about://flags Finch feature name CSSAnchorRememberedScrollOffset Requires code in //chrome? False Tracking bug https://issues.chromium.org/issues/373874012 Estimated milestones Shipping on desktop 135 Shipping on Android 135 Shipping on WebView 135 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). None Link to entry on the Chrome Platform Status https://chromestatus.com/feature/4710507824807936?gate=5315183922380800 Links to previous Intent discussions Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKWZFm5%3D2_bAxBDiD%3DzDaxbZOx7SZiZvEc5tmwCkUfTxevkphw%40mail.gmail.com This intent message was generated by Chrome Platform Status<https://chromestatus.com/>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org<mailto:blink-dev+unsubscr...@chromium.org>. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKWZFm6f2VOKrnSMcMCsDak41x-mij1LkDGVpYshEn9jBE7Tmw%40mail.gmail.com<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKWZFm6f2VOKrnSMcMCsDak41x-mij1LkDGVpYshEn9jBE7Tmw%40mail.gmail.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CH4PR00MB232981664E2B5B5EDF3897EEC5CA2%40CH4PR00MB2329.namprd00.prod.outlook.com.
