Combining NestedScrollView with TabBarView has problems. #81619
Description
Hi! My post is related to this one.
So
1)If I use AutomaticKeepAliveMixin to keep the inner scrollers (and each of their children built by builder: methods), they are kept alive and when changing between the tabs, there are no lags in animation.
However, any scrolling of one of the inner scrollers also affects others and the individual scroll positions are not obeyed. Even though I use different PageStorageKey() for all of the scrollers, if AutomaticKeepAliveMixin is applied, scroll positions are problematic.
You can see this behavior here
2)If I don't apply AutomaticKeepAliveMixin to the inner scrollers, scroll positions have no issues and work as expected. However, this time, because each of the inner scrollers (and their respective children) is completely rebuilt whenever a tab change occurs.
When there are relatively fewer items inside inner scrollers (like 20-30 items per tab), TabBarView tab change animations are fluid and no issues. However, when after a user scrolls and fills lots of children into inner scrollers, then tab change becomes very laggy. This happens because the inner scrollers build from scratch.
You can see this behavior here
flutter doctor -v
[√] Flutter (Channel stable, 2.0.5, on Microsoft Windows [Version 10.0.18363.1500], locale en-US)
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