Android: Scroll View Stretch Effect Inconsistency

Description

Tested on Android Pixel 9.

I am trying to understand an issue. I found some threads. #35424 and #47021. When I use a ScrollView with overScrollMode="always" and the content is smaller than the ScrollView the stretch effect does not show when I drag on a child view.. It works fine when I use a horizontal scroll.

I looked into Androids ScrollView code. It has a return in onInterceptTouchEvent:

// Don't try to intercept touch if we can't scroll anyway.
if (getScrollY() == 0 && !canScrollVertically(1)) {
    return false;
}

Is this a correct fix?

@Override
boolean canScrollVertically(int direction) {
    return super.canScrollVertically(direction)
    || (direction > 0. MScrollEnabled && getOverScrollMode() == OVER_SCROLL_ALWAYS);
}

If I set ALWAYS the view can give feedback. So reporting it as scrollable will fix the issue... Accessibility and nested-scroll parents will also see the view, as scrollable in that mode.

Steps to reproduce

Create a ScrollView with some text children:

<ScrollView style={{ height: 150 }} overScrollMode="always">
    <Text style={{ padding: 8 }}>Row one</Text>
    <Text style={{ padding: 8 }}>Row two</Text>
</ScrollView>

The difference:

• If I set the scroll to horizontal there is a visible Stretch effect no matter where I drag from.
• If I set it to vertical it does not work when I tap and drag from the Text.

React Native Version

React-native 0.85.3

Affected Platforms

Runtime - Android

Output of npx @react-native-community/cli info

System:
  OS: macOS 26.5.1
  CPU: (12) arm64 Apple M2 Pro
  Memory: 316.38 MB / 32.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 24.1.0
    path: /Users/davidmalesevic/.nvm/versions/node/v24.1.0/bin/node
  Yarn: Not Found
  npm:
    version: 11.7.0
    path: /Users/davidmalesevic/.nvm/versions/node/v24.1.0/bin/npm
  Watchman: Not Found
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.5
      - iOS 26.5
      - macOS 26.5
      - tvOS 26.5
      - visionOS 26.5
      - watchOS 26.5
  Android SDK: Not Found
IDEs:
  Android Studio: 2025.2 AI-252.28238.7.2523.14688667
  Xcode:
    version: 26.6/17F113
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.18
    path: /opt/homebrew/opt/openjdk@17/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 19.2.3
    wanted: 19.2.3
  react-native:
    installed: 0.85.3
    wanted: 0.85.3
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

Stacktrace or Logs

N/A

MANDATORY Reproducer

https://github.com/Alforofous/rn-vertical-stretch-repro

Screenshots and Videos

まず必須の reproducer を実行し、overScrollMode="always" を指定した場合の垂直 ScrollView と水平 ScrollView の動作を比較します。Android ScrollView の onInterceptTouchEvent と canScrollVertically のロジックを読み、その後 React Native ScrollView の統合を追跡します。child からドラッグすると垂直方向のストレッチ効果が発生し、アクセシビリティやネストされたスクロールに意図しない変更がないことが完了の条件です。