Reanimated 4.4.0

Key changes

iOS CSS Core Animation

Reanimated 4.4.0 introduces a new platform-backed CSS animation engine on iOS that runs animations directly on Core Animation layers instead of going through the JS-driven update loop. It is hidden behind the IOS_CSS_CORE_ANIMATION static feature flag.

• feat: Wire CSSPlatformTransition with iOS platform implementation by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9325
• chore: Hide platform animations behind a feature flag by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9493

Animation Backend

A new Animation Backend has been integrated behind a feature flag, which will help greatly with the flow of updating the Shadow Tree in animations.

• Integrate Animation Backend behind a flag by @bartlomiejbloniarz in https://github.com/software-mansion/react-native-reanimated/pull/9279

New useTimestamp hook

A new useTimestamp hook exposes the current frame timestamp as a Shared Value that updates every frame with the time elapsed since the first frame, with an isActive flag to pause and resume updates.

• Adds useTimestamp hook by @ashfurrow in https://github.com/software-mansion/react-native-reanimated/pull/9162

Precompiled headers on Android

Reanimated's native build on Android now uses precompiled headers (ReanimatedPCH.h), significantly reducing C++ compile times for both fresh and incremental builds.

• Start using precompiled headers on Android by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9434

Other changes

• fix(Reanimated): Spring jitter by @piaskowyk in https://github.com/software-mansion/react-native-reanimated/pull/9463
• feat: emit ESM package json by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9481
• Add support for placeholderTextColor in synchronous props by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9409
• Add support for shadowColor in synchronous props by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9411
• Add support for shadowOffset in synchronous props by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9412
• Add support for outlineColor, outlineOffset and outlineWidth in synchronous props by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9417
• Add support for borderBlockColor, borderBlockStartColor and borderBlockEndColor in synchronous props by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9418
• Unify synchronous props logic between platforms by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9381
• Preallocate and reuse synchronous props buffers on Android by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9425
• fix(Reanimated): laggy LA outside of Animation Backend by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9431
• feat: CSSPlatformAnimation abstraction by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9278
• feat: CSSPlatformTransition abstraction by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9324
• chore: Rename EXPERIMENTAL_PLATFORM_CSS_ANIMATIONS to IOS_CSS_CORE_ANIMATION by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9506
• fix(Reanimated): RCTModernEventEmmitter for older RN by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9181
• chore(Reanimated): post release 4.3.0 by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9182
• Add check for conflicting feature flags by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9174
• Store ShadowNodeFamily instead of ShadowNode in UpdatesRegistry by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9156
• Store ShadowNodeFamily::Shared instead of ShadowNodeFamily * in PropsMap and ChildrenMap by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9184
• Remove useInterpolateConfig function and InterpolateConfig and ColorSpace types by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9150
• Bump React Native to 0.85.0-rc.6 by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9193
• Update doNotStrip to keepDebugSymbols by @wisniewskij in https://github.com/software-mansion/react-native-reanimated/pull/8636
• Migrated packages/react-native-reanimated java->kotlin by @tshmieldev in https://github.com/software-mansion/react-native-reanimated/pull/9163
• removed JSCallInvokerResolver.kt by @tshmieldev in https://github.com/software-mansion/react-native-reanimated/pull/9198
• chore: Bump RN to 0.85.0 stable by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9233
• fix: animation cancellation race condition by @Nodonisko in https://github.com/software-mansion/react-native-reanimated/pull/9235
• fix: animation cancellation race condition missing code by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9242
• Change UI runtime slow animations invocation pattern by @tshmieldev in https://github.com/software-mansion/react-native-reanimated/pull/9205
• chore: Remove no longer used StaticPropsRegistry methods and props by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9226
• chore: Remove unused css code by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9227
• fix: Incorrect CSS props reverting on CSS transition detach by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9220
• feat: Strict TS types in LA withInitialValues method by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9232
• fix: Freeze example crash and different timings by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9247
• feat: Add support for separate transform props in LA initial values config by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9237
• refactor: decouple raf and events by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9244
• feat(Reanimated): Export NativeEventsManager by @j-piasecki in https://github.com/software-mansion/react-native-reanimated/pull/8655
• feat: adds withTargetValues modifier to default layout animations by @PiotrWszolek in https://github.com/software-mansion/react-native-reanimated/pull/8848
• chore(Reanimated): jest tests for useFrameCallback by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9255
• docs: Remove withInitialValues for layout transitions by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9258
• fix: Remove withInitialValues and withTargetValues from layout transitions by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9259
• feat: Update initial value of shared value by @pranko17 in https://github.com/software-mansion/react-native-reanimated/pull/8782
• chore(Reanimated): add lint step to disallow worklets includes by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9262
• docs: Add new types of initial values in layout animation configs by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9257
• docs: Add withTargetValues to Layout Animations docs by @PiotrWszolek in https://github.com/software-mansion/react-native-reanimated/pull/9168
• fix: Fix handling falsy values in jestUtils getCurrentStyle by @edkimmel in https://github.com/software-mansion/react-native-reanimated/pull/7494
• fix: Unistyles flattening regression in 4.3.0 by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9284
• fix(Reanimated): not flushing updates without mapper runs by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9270
• fix(Reanimated): useScrollOffset on renderScrollComponent by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9286
• chore: Extract CSS loop to the separate OperationsLoop class by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9285
• Chore(Reanimated): reanimatedmoduleproxy refactor by @tshmieldev in https://github.com/software-mansion/react-native-reanimated/pull/9342
• fix(Reanimated): registries race conditions by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9323
• Remove checks for new arch enabled by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9311
• feat: Add short-circuit for scheduleOnUI called from the UI thread on Android by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9343
• feat: Add LoopOperation interface and operation-based scheduling primitives by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9346
• docs: remove outdated "Debugging worklets" guide by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9355
• Use REACT_NATIVE_VERSION_MINOR provided by React Native instead of custom definition by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/8412
• fix: Attempt to fix EXC_BAD_ACCESS in ReanimatedModuleProxy::performOperations during AnimationFrameBatchinator::flush by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9308
• Remove legacy CDP debugger setup via HermesExecutorRuntimeAdapter by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9356
• chore(Reanimated): remove maybeRequestRender dead code by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9357
• Remove linking ReactAndroid::hermestooling prefab by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9360
• fix(Reanimated): remove unnecessary locks by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9361
• Remove unused MessageQueueThread by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9329
• Remove RuntimeInitialization.md by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9362
• docs: add versions for Expo SDK 55 and 56 by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9341
• Remove special handling of react-native-tvos in podspecs by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9365
• Remove JSC runtime support by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9364
• Extract synchronous props serialization and parsing logic to separate files by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9368
• Improve error handling in synchronous props logic on Android by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9379
• fix: ReJest beforeEach blocks by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9363
• Remove _IS_FABRIC variable by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9375
• Add missing @DoNotStrip annotations by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9372
• chore: add include Matcher and cleanup runtime tests by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9384
• fix: Dedupe native keyframes registration across same-content rules by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9389
• refactor: Divide CSS Transition settings form diffs by @wisniewskij in https://github.com/software-mansion/react-native-reanimated/pull/9340
• Move SynchronousPropsBufferSerializer into #ifdef ANDROID by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9395
• Refactor synchronous props commands definition and lookup by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9396
• fix: Conflict with global expo type overrides by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9394
• Use pushInt and pushDouble helper functions in synchronous props serializer by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9397
• chore: Simplify AnimatedStyle types by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9400
• fix: runtime tests wrongly mocking console on UI Runtime by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9405
• chore: fix runtime tests formatting by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9404
• fix: Opaque colors support in SVG CSS animations by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9421
• fix(Reanimated): retain iOS module proxy explicitly by @bartlomiejbloniarz in https://github.com/software-mansion/react-native-reanimated/pull/9414
• fix: runtime tests ANR when initializing describe blocks by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9413
• fix: CSS animatedProps in SVG not passed in initial render by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9419
• fix: animatedProps should take precedence over inline props by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9422
• Replace std::stof with std::stod in synchronous props logic by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9424
• Synchronous props handling cleanup by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9423
• fix: add mutex lock in LayoutAnimationsManager::transferSharedConfig by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9429
• chore(Reanimated): remove onRender dead code by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9430
• docs: update supported synchronous props in "Feature flags" page by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9439
• Add constexpr in feature flag check in synchronous props buffer preallocation on Android by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9440
• Remove bridgeless check on iOS by @tomekzaw in https://github.com/software-mansion/react-native-reanimated/pull/9459
• fix: forward ref through Animated.FlatList under React 19 by @elliottkember in https://github.com/software-mansion/react-native-reanimated/pull/9466
• feat: OperationsLoop for simpler css animations and transitions updates by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9248
• chore: Cleaner CSS animation/transition lifecycle by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9487
• feat: Convert css easing configs to the intermediate config format instead of function by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9273
• fix: Centralize the usage of locks, fix potential race conditions by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9489
• feat: CSS AnimationStyleInterpolatorFactory allowing interpolated properties subset modification by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9276
• feat: CSSLoopAnimation abstraction for reanimated-loop updated CSS animation properties by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9277
• feat: CSSLoopTransition abstraction for reanimated-loop updated CSS animation properties by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9316
• chore: CSSTransition implementation cleanup by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9320
• chore: bump RN compatibility to 0.86 by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9496
• fix: Add missing locks by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9495
• fix: runtime tests in release by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9500
• chore: Remove EXPERIMENTAL_CSS_ANIMATIONS_FOR_SVG_COMPONENTS feature flag by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9501
• chore: Add missing EXPERIMENTAL\_PLATFORM\_CSS\_ANIMATIONS flag in a few places by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9502
• fix: Fix build issues after #9325 by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9504
• fix: Stop CA animations from leaking onto recycled layers by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9508
• fix: Convert CSS Core Animation beginTime to layer-local clock by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9507
• chore: Reintroduce EXPERIMENTAL_CSS_ANIMATIONS_FOR_SVG_COMPONENTS with default true by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9510
• docs: Add IOS_CSS_CORE_ANIMATION feature flag to docs by @MatiPl01 in https://github.com/software-mansion/react-native-reanimated/pull/9505
• release(Reanimated): 4.4.0 by @tjzel in https://github.com/software-mansion/react-native-reanimated/pull/9514

New Contributors

• @PiotrWszolek made their first contribution in https://github.com/software-mansion/react-native-reanimated/pull/8848
• @pranko17 made their first contribution in https://github.com/software-mansion/react-native-reanimated/pull/8782
• @edkimmel made their first contribution in https://github.com/software-mansion/react-native-reanimated/pull/7494
• @ashfurrow made their first contribution in https://github.com/software-mansion/react-native-reanimated/pull/9162
• @elliottkember made their first contribution in https://github.com/software-mansion/react-native-reanimated/pull/9466

Full Changelog: https://github.com/software-mansion/react-native-reanimated/compare/4.3.1...4.4.0