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Add AccessibilityInfo.getContrastLevel and contrastLevelChanged on Android - #59181

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camilopires wants to merge 11 commits into
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camilopires:a11y/android-contrast-level
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Add AccessibilityInfo.getContrastLevel and contrastLevelChanged on Android#59181
camilopires wants to merge 11 commits into
react:mainfrom
camilopires:a11y/android-contrast-level

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@camilopires camilopires commented Oct 18, 2026

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Summary:

Android 14 (API 34) added a system contrast level (Settings → Accessibility → Color and motion → Contrast), from -1 to 1, read with UiModeManager.getContrast(). It is Android's equivalent of iOS Increase Contrast, which React Native already exposes as isDarkerSystemColorsEnabled(). The existing Android method, isHighTextContrastEnabled(), reads a different setting that only changes how text is drawn.

This adds AccessibilityInfo.getContrastLevel(): Promise<number> and a numeric contrastLevelChanged event, for Android only.

  • A ContrastChangeListener is registered while the app is resumed, and removed on pause and in invalidate().
  • The value is read again on resume, because registering doesn't report the current value.
  • The listener is created lazily, so older Android versions never load the API 34 interface.
  • On Android before 14 and on iOS, the method resolves to 0.
  • The TypeScript declarations add an addEventListener overload, because this event's payload is a number rather than a boolean.

RNTester gets a small example that shows the value and the last event's payload.

Discussion: react-native-community/discussions-and-proposals#1026

Changelog:

[ANDROID] [ADDED] - AccessibilityInfo.getContrastLevel() and contrastLevelChanged (Android 14+ contrast level)

Test Plan:

  • yarn jest packages/react-native/Libraries/Components/AccessibilityInfo: all tests pass
  • yarn flow-check: 0 errors
  • yarn lint: passes
  • yarn build-types --validate: API snapshot up to date
  • yarn test-generated-typescript and yarn test-typescript-legacy: pass
  • yarn format-check-kotlin: passes
  • RNTester builds: ./gradlew :packages:rn-tester:android:app:assembleDebug

RNTester on an Android 16 (API 36) emulator:

  • Getter: adb shell settings put secure contrast_level with 0, 0.5, 1.0 and -0.5 gave "Contrast level is 0." / "0.5." / "1." / "-0.5."
  • Events: Android recreates the activity when the contrast changes, so I logged the listener temporarily, locally and not in this PR. Setting 0.25, -0.75 and 0.0 logged contrastLevelChanged with exactly 0.25, -0.75 and 0, all in the same process.
  • Changed while in the background: set 0.75, then brought the app back. The row showed "Contrast level is 0.75."

RNTester on an Android 10 (API 29) emulator: "Contrast level is 0.", with no crashes across launch and resume.

@camilopires camilopires mentioned this pull request Oct 18, 2026
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Warning

JavaScript API change detected

This PR commits an update to ReactNativeApi.d.ts, indicating a change to React Native's public JavaScript API.

  • Please include a clear changelog message.
  • This change will be subject to additional review.

This change was flagged as: POTENTIALLY_BREAKING

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@meta-cla meta-cla Bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Oct 18, 2026
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@javache has imported this pull request. If you are a Meta employee, you can view this in D126038114.

@camilopires camilopires mentioned this pull request Oct 21, 2026
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camilopires and others added 3 commits October 24, 2026 00:52
@camilopires @claude
Add AccessibilityInfo.getContrastLevel and contrastLevelChanged on An…
bd397ed 
…droid

Android 14 (API 34) exposes the system contrast level, from -1 to 1, through
UiModeManager.getContrast(). It is the Android equivalent of Increase
Contrast on iOS; isHighTextContrastEnabled reads a different setting that
only changes how text is drawn. Register a ContrastChangeListener while the
app is resumed and read the value again on resume. Earlier versions and iOS
resolve to 0.

Adds Jest tests for the getter and the numeric event, and an RNTester
example that shows the value and the last event.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Update C++ API snapshots for getContrastLevel
4c86af4 
The Android NativeAccessibilityInfo spec's getContrastLevel now appears in
the generated spec, so it shows up in the Apple snapshots. Generated with
Doxygen 1.16.1 and Python 3.12, as in validate-cxx-api-snapshots.yml.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Test the Android contrast listener and events with Robolectric
93ae838 
Robolectric doesn't call contrast listeners, so on API 34 the test serves
a mock UiModeManager and calls the listener the module registers. It
checks that a change sends contrastLevelDidChange once (including a
negative level), resuming twice registers one listener, pausing and
invalidating remove it, and a change made while paused is sent on
resume. On API 33 it uses Robolectric's UiModeManager and checks the
level stays 0 with no event. Removing the listener registration makes
five of the seven tests fail.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires
camilopires force-pushed the a11y/android-contrast-level branch from 17016d3 to 93ae838 Compare October 24, 2026 00:08
@github-actions

github-actions Bot commented Oct 24, 2026 •
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Visual regression

No visual differences at 544a52180048.

android: no capture

camilopires and others added 7 commits October 24, 2026 14:40
@camilopires @claude
Use the contrast listener's value and tear it down on the UI thread
600567f 
The Android contrast listener now lives in a per-module
ContrastListenerApi34 helper, and the value Android passes to it is used
instead of being read again. Every path (start-up, resume, listener)
goes through one normaliser that maps NaN to 0 and clamps to -1..1.

invalidate() removes the lifecycle listener first, sets an invalidated
flag that resume and queued contrast callbacks check, and unregisters
the listener on the UI thread, posting when called from another thread.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Document getContrastLevel on iOS, older Android and missing native code
88d53b7 
The docs now say that iOS always resolves 0 and points to
isDarkerSystemColorsEnabled, that this is the closest Android
counterpart to Increase Contrast, that 0 also means Android before 14
or no UiModeManager, and that a missing native method rejects. The
d.ts event overload notes API 34.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Test that getContrastLevel rejects without the native module
55e8987 
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Show loading and errors in the RNTester contrast level row
381ff42 
The row shows 'loading' until the starting read finishes, and
'Unavailable: <message>' if it rejects. A starting read that finishes
after an event no longer overwrites the newer value.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Keep the last contrast level when Android reports NaN
8f2688c 
A NaN from the contrast listener or the read on resume no longer sends
contrastLevelChanged(0); the module keeps its last level and sends
nothing. NaN is still the standard contrast, 0, at construction, where
there is no earlier value. NaN and out-of-range values each warn once
on their own. invalidate() no longer posts the listener removal when
there is no listener, and its warning names the module.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Make the iOS contrastLevelChanged test fail if iOS subscribes
dadc980 
The test now emits both contrastLevelDidChange and contrastLevelChanged,
so mapping the event to either name on iOS would call the handler.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires @claude
Handle non-Error rejections in the RNTester contrast level row
544a521 
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@camilopires

camilopires commented Oct 24, 2026

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Pushed a few follow-ups from a review pass (no API changes):

  • The contrast level is clamped to -1…1 on every path. NaN maps to 0 only at start-up; after that, a NaN keeps the last good value instead of reporting standard contrast.
  • The listener now lives in a per-module @RequiresApi(UPSIDE_DOWN_CAKE) helper instead of an Any? field, uses the value the platform passes in, and is torn down on the UI thread in invalidate(), with queued callbacks ignored afterwards.
  • The docs say plainly that iOS always resolves 0 (use isDarkerSystemColorsEnabled there), and that a missing native module or method rejects.
  • Robolectric tests cover the listener, clamping, NaN, pause/resume and teardown (21 tests).

@camilopires @claude
Suppress BridgeReactContext deprecation in AccessibilityInfoModuleTest
d6b00f7 
CI compiles tests with -PenableWarningsAsErrors=true, and
BridgeReactContext is deprecated, so the test failed to compile there.
Suppress the deprecation for the file, as DeviceInfoModuleTest and the
other tests that use BridgeReactContext do.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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