Generate nested scroll view#55239
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@Abbondanzo has exported this pull request. If you are a Meta employee, you can view the originating Diff in D90902079. |
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Summary: This diff adds the ability to experiment with using `NestedScrollView` instead of `ScrollView` as the parent class for `ReactScrollView` on Android. Since Java doesn't support multiple inheritance or conditional parent class selection, this is implemented using code generation: - A Python script (`generate-nested-scroll-view.py`) generates `ReactNestedScrollView.java` and `ReactNestedScrollViewManager.kt` from their respective source files - The generated files are identical to the originals except they extend `NestedScrollView` instead of `ScrollView` - A Buck genrule verifies the generated files stay in sync with source files at build time - The `useNestedScrollViewAndroid` feature flag controls which implementation is used at runtime This approach allows us to safely A/B test the NestedScrollView implementation without requiring JS changes, since both managers register with the same `REACT_CLASS` name (`"RCTScrollView"`). Changelog: [Internal] Differential Revision: D90902079
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If this lands, my PR from 2024: #44099 will be eligible for closing. |
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This pull request has been merged in 5e93036. |
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This pull request was successfully merged by @Abbondanzo in 5e93036 When will my fix make it into a release? | How to file a pick request? |
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…View (#1527) ## Problem With React Native's `useNestedScrollViewAndroid` feature flag (RN 0.85+, react/react-native#55239), `ScrollView` renders as `ReactNestedScrollView`, which extends `androidx.core.widget.NestedScrollView` (a `FrameLayout`) — not `android.widget.ScrollView`. `ClippingScrollViewDecoratorView.findScrollView` only matches `view is ScrollView`, so it returns null, `decorateScrollView()` silently no-ops, and `contentInsetBottom`/`contentInsetTop` are dropped entirely. In a `KeyboardChatScrollView` this means: list content hides behind the composer, and `blankSpace`/`extraContentPadding` have no effect on Android. ## Fix Match `NestedScrollView` as well, and pass the found view around as `ViewGroup`. Every member used by the decorator and the padding-scroll workaround (`clipToPadding`, `getChildAt`, `setPadding`, `scrollBy`, `scrollY`, `canScrollVertically`, `getLocationOnScreen`) lives on `ViewGroup`/`View`, and `NestedScrollView` extends its scroll range via bottom padding + `clipToPadding = false` exactly like `ScrollView`. `ReactNestedScrollView` itself is package-private, hence matching on the public androidx base class. ## Testing Verified in a chat app (RN 0.85.3, new arch, `useNestedScrollViewAndroid` enabled) via patch-package: composer inset, keyboard padding, and `blankSpace` all apply again; behavior with the flag disabled (plain `ScrollView`) is unchanged. 🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Summary:
This diff adds the ability to experiment with using
NestedScrollViewinstead ofScrollViewas the parent class forReactScrollViewon Android.Since Java doesn't support multiple inheritance or conditional parent class selection, this is implemented using code generation:
generate-nested-scroll-view.js) generatesReactNestedScrollView.javaandReactNestedScrollViewManager.ktfrom their respective source filesNestedScrollViewinstead ofScrollViewuseNestedScrollViewAndroidfeature flag controls which implementation is used at runtimeThis approach allows us to safely A/B test the NestedScrollView implementation without requiring JS changes, since both managers register with the same
REACT_CLASSname ("RCTScrollView").Changelog: [Internal]
Differential Revision: D90902079