[Android] ScrollView events are not triggered when manually calling scrollTo

Description

When having a ScrollView with onMomentumX events, these event will not be triggered on Android if the scroll was triggered by a manual scrollTo call.

I expected the events to be triggered on both platforms, but they were only triggered on iOS.

Reproduction

Here is a small demo app to reproduce the issue on rnplay: https://rnplay.org/apps/aPVzIg

The app has a state change (in this case, the width of the container) triggered by the ScrollView’s onMomentumScrollEnd event, and a timeout to manually call scrollTo after 2,000ms.

When running the sample on iOS, the state change will be triggered automatically after 2 seconds due to the onMomentumScrollEndevent being triggered post scrollTo.

When running the sample on Android, the state change will not be triggered automatically after 2 seconds (even though the scrollTo call could be seen to have been executed as the offset of the ScrollView changes).

When manually scrolling the view on Android, the event is being called as expected.

Additional Information

• React Native version: 0.33
• Platform: Android

[tdekoning]

This is still an issue in RN 0.51

[tbarsbay]

Any chance we could re-open this? I’m still experiencing it on RN 0.48, Android 7.1 on a Nexus 6.

In particular, I’m using a FlatList which triggers onMomentumScrollEnd when I swipe between items but not when I call scrollToIndex on Android. But if I call scrollToIndex on iOS, it correctly calls onMomentumScrollEnd.