react-native: [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

About this issue

Original URL
State: closed
Created 7 years ago
Reactions: 8
Comments: 18 (2 by maintainers)

Most upvoted comments

This is still an issue in RN 0.51

tdekoning on Dec 20, 2017

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.

tbarsbay on Sep 25, 2017

The issue is that onScroll or onMomentumScrollEnd does not trigger if scroll is triggered manually using scrollTo on Android.

For some reason setting animated: true in scrollTo seems to make it work.

superandrew213 on May 7, 2018

This still seems to be the case in 0.44. Would be really nice to have this same onMomentumScrollEnd hook for programmatic scrolls on Android. Is there any inherent reason why this behavior can’t be implemented for Android?

scottbrassfield on May 22, 2017

I have react-native in 0.40.0 version and I even don’t get onMomentumScrollEnd when I normally scroll… But only in Android, iOS works

lesniakania on Jan 21, 2017