Relative relayouting

[irisjae]

Description

When the list enters a region with bad size estimates, scrolling becomes incredibly choppy, appearing to the user as if the list content is jumping around as the user scrolls.

Another issue is that the list is not able to maintain the visible content position when the provided data changes.

This patch implements a relative relayouting algorithm both in native and in RecyclerListView, and solves these problems. Here is a longer analysis of the problem and solution.

Hopefully, this mechanism can be part of FlashList.

Relevant issues:

• maintainVisibleContentPosition Not Working #547
• Scrolling up very choppy after using scrollToIndex #582
• initialRenderIndex makes content jump around when non deterministic Flipkart/recyclerlistview#241
• incorrect dimensions on first layout when using forceNonDeterministicRendering  Flipkart/recyclerlistview#195

Relevant PRs:

• [DF] feat(#547): add experimentalScrollPositionManagement support to FlashList #824

Reviewers’ hat-rack 🎩

• Accurate initialRenderIndex
• Accurate scroll methods
• Allows list to maintain position across data changes
• Allows list to not jump when estimated sizes are badly off
• Allows list to not jump when layouts before visible position change

Screenshots or videos (if needed)

Checklist

• I have added a changelog entry following the Keep a Changelog guidelines.

[zulfio]

Tested, it's working fine. It's not choppy when scrolling up.