Make auto_scroll follow in-place content growth#6637
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auto_scroll only scrolled to the end from ScrollableControl.build(), so it followed added children but not content that grows *in place* (e.g. text streamed into an existing child) — that never rebuilds the scrollable. - Add a ScrollMetricsNotification listener that re-pins to the end whenever the scroll extent grows, even without a rebuild. - Track the user's position; suspend pinning while they've scrolled away from the end and resume when they return. - Add an auto_scroll_animation property (duration + curve) to control the scroll; defaults to the historical 1s ease, set duration 0 for an instant jump.
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Problem
auto_scrollonly scrolls to the end from insideScrollableControl.build(). That fires when the scrollable rebuilds — e.g. a child is added — but not when existing content grows in place, such as text streamed into an existing child. So an auto-scrolling chat/log follows new messages but falls behind while a single message grows.Changes
packages/flet/lib/src/controls/scrollable_control.dart:NotificationListener<ScrollMetricsNotification>that re-pins to the end whenever the scroll extent grows, even when this widget doesn't rebuild.ScrollControllerlistener, 40px threshold): pinning pauses while the user has scrolled away from the end and resumes when they scroll back — so it never yanks a user who scrolled up to read history.auto_scroll_animationproperty (duration + curve). Defaults to the historical 1sease; set a duration of0for an instant jump (nice for fast, token-by-token streaming).sdk/python/packages/flet/src/flet/controls/scrollable_control.py:auto_scroll_animation: Optional[AnimationValue]property and update theauto_scrolldocs.Notes
auto_scroll=Trueusers keep the 1s ease behavior and additionally gain in-place-growth following.flutter analyzeon the changed control: no issues.Summary by Sourcery
Enhance scrollable controls so auto-scroll stays pinned to the end while content grows in place and remains user-friendly when the user scrolls away.
New Features:
Documentation: