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Janic Duplessis
3ed4bf9046
Summary: The logic to constrain the last spacer size is incorrect in some cases where the spacer is the last spacer, but not the last section in the list. For more context, the role of spacer constraining is explained in this comment: ``` // Without getItemLayout, we limit our tail spacer to the _highestMeasuredFrameIndex to // prevent the user for hyperscrolling into un-measured area because otherwise content will // likely jump around as it renders in above the viewport. ``` For example it is incorrect in the case where we have: ITEMS SPACER ITEMS In this case the spacer is not actually the tail spacer so the constraining is incorrectly appied. This causes issues mainly when using `maintainVisibleContentPosition` since it will cause it to scroll to an incorrect position and then cause the view that was supposed to stay visible to be virtualized away. ## Changelog: [GENERAL] [FIXED] - Fix last spacer constrain logic in VirtualizedList Pull Request resolved: https://github.com/facebook/react-native/pull/41846 Test Plan: Tested using https://gist.github.com/janicduplessis/b67d1fafc08ef848378263208ab93d4c in RN tester, before the change content will jump on first click on add items. Tested using the same example and setting initial posts to 1000, then we can see our content view size is still constrained properly (see scrolling indicator as reference). Reviewed By: yungsters Differential Revision: D51964500 Pulled By: NickGerleman fbshipit-source-id: 4465aa5a36c95466aef6571314973c1e2c9a0f2c
@react-native/virtualized-lists
Installation
yarn add @react-native/virtualized-lists
Note: We're using yarn to install deps. Feel free to change commands to use npm 3+ and npx if you like
Testing
To run the tests in this package, run the following commands from the React Native root folder:
yarnto install the dependencies. You just need to run this onceyarn jest packages/virtualized-lists.