fix: Reset offset to 0 on swipe end to prevent indicator jump

[AlexCernik]

Summary

When swiping between tabs, especially in React Native's New Architecture or on some devices, the offset value may retain a small negative or positive value (e.g. -0.02) even after the swipe ends. This causes a visual glitch where the indicator briefly "jumps" backward before settling on the correct tab.

This PR resets offset to 0 when pageScrollState becomes "idle", ensuring that the final position is stable and that the indicator aligns correctly with the selected tab.

Changes

• Added offset.setValue(0); to onPageScrollStateChanged when state is 'idle'

Why

To prevent the tab indicator from jumping slightly backward after swiping, improving visual consistency. #12493

Notes

This fix has no functional side effects and only affects the visual animation when the swipe ends.

Tested on:

• React Native 0.79.4
• Fabric enabled
• Android

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[satya164]

Thanks for the PR @AlexCernik

This seems like a bug in react-native-pager-view. Can you open a bug report there?

I'd rather not add a workaround and get the actual bug fixed instead.

[santhosh-umapathi-wikifolio]

And the change does not fix the problem, still it occurs. also some flickers on the tab indicator on tab press

[tom-richtr]

I can confirm that the bug is still present even with the proposed changes.
However I can confirm that refactoring to reanimated could fix the behaviour
See the changes mentioned in
#12646
https://github.com/hoangtrunnam/react-navigation/tree/merge_dev

[AlexCernik]

To test the fix, update react-native-tab-view/lib/module/PagerViewAdapter.js with the proposed solution.

[scole-rbi]

To test the fix, update react-native-tab-view/lib/module/PagerViewAdapter.js with the proposed solution.

• offset.setValue(0) fix from this PR significantly reduces indicator jump

• some residual stutter remains but the indicator no longer misaligns after settling.

• also found that removing the start CSS property from TabBarIndicator (which conflicts with the animated translateX during re-renders) further improves the result when combined with this fix

Note: the issue is reproducible on slow swipes too -- it's amplified by heavy screen content

• confirmed with minimal test app (same libraries, lightweight content) that jank does not appear, and that with a fully custom React.memo-blocked tab bar that the issue persists -- proving it originates in the native onPageScroll offset pipeline, not tab bar rendering

Tested: RN 0.81.5, Fabric, Android, Expo SDK 54, react-native-tab-view 4.3.0, react-native-pager-view 6.9.1

[troZee]

It has been fixed here https://github.com/callstack/react-native-pager-view/releases/tag/v8.0.1