Add animatedDeferStartOfTimingAnimations feature flag

Summary:
Add the `animatedDeferStartOfTimingAnimations` common (native + JS) feature flag (default off). On its own this is a no-op; it gates deferring the start of native-driven timing animations to the first rendered frame, implemented in the following diffs.

The flag is defined as a `common` flag (not JS-only) so the same value can be read from both the JS Animated layer and the native C++ animation code. This diff includes all the generated accessors, regenerated via `yarn featureflags --update`: Kotlin (`ReactNativeFeatureFlags*.kt`), C++ (`ReactNativeFeatureFlags*.h`/`.cpp` and the JNI interop), the JS `ReactNativeFeatureFlags.js`, and the native module spec.

Changelog: [Internal]

Differential Revision: D106825629

Author: zeyap

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<86c797c19cc585b74714ca3aa75bbd6d>>
+ * @generated SignedSource<<5a3498ac81b47029c55d5ad60459b3a0>>
  */
 
 /**
@@ -36,6 +36,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun commonTestFlag(): Boolean = accessor.commonTestFlag()
 
+  /**
+   * When enabled, native timing animations defer their first frame and re-anchor timing to prevent skipping initial frames when the UI thread is busy with layout work.
+   */
+  @JvmStatic
+  public fun animatedDeferStartOfTimingAnimations(): Boolean = accessor.animatedDeferStartOfTimingAnimations()
+
   /**
    * Enable emitting of InteractionEntry live metrics to the debugger. Requires `enableBridgelessArchitecture`.
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<d71556cf1226fe6a41dd388568153d3a>>
+ * @generated SignedSource<<3b5c4a312ce0ef80fea3cd3bb733924c>>
  */
 
 /**
@@ -21,6 +21,7 @@ package com.facebook.react.internal.featureflags
 
 internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccessor {
   private var commonTestFlagCache: Boolean? = null
+  private var animatedDeferStartOfTimingAnimationsCache: Boolean? = null
   private var cdpInteractionMetricsEnabledCache: Boolean? = null
   private var cxxNativeAnimatedEnabledCache: Boolean? = null
   private var defaultTextToOverflowHiddenCache: Boolean? = null
@@ -117,6 +118,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun animatedDeferStartOfTimingAnimations(): Boolean {
+    var cached = animatedDeferStartOfTimingAnimationsCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.animatedDeferStartOfTimingAnimations()
+      animatedDeferStartOfTimingAnimationsCache = cached
+    }
+    return cached
+  }
+
   override fun cdpInteractionMetricsEnabled(): Boolean {
     var cached = cdpInteractionMetricsEnabledCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<2ee82b1e1dcae3ea10dbd92549d65a6c>>
+ * @generated SignedSource<<45cd25ae7e3e3d850e3c80fc0a433dd6>>
  */
 
 /**
@@ -30,6 +30,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun commonTestFlag(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun animatedDeferStartOfTimingAnimations(): Boolean
+
   @DoNotStrip @JvmStatic public external fun cdpInteractionMetricsEnabled(): Boolean
 
   @DoNotStrip @JvmStatic public external fun cxxNativeAnimatedEnabled(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<738a114e73ddb940fb14efd0dff79d1b>>
+ * @generated SignedSource<<53813a42017eb4b46774e6bb0c46185a>>
  */
 
 /**
@@ -25,6 +25,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun commonTestFlag(): Boolean = false
 
+  override fun animatedDeferStartOfTimingAnimations(): Boolean = false
+
   override fun cdpInteractionMetricsEnabled(): Boolean = false
 
   override fun cxxNativeAnimatedEnabled(): Boolean = false

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<d5b84c7e0c58f61d891e0dd63f61b4c0>>
+ * @generated SignedSource<<4ce8eccad029b1b8b8296ca4e5664d2a>>
  */
 
 /**
@@ -25,6 +25,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private val accessedFeatureFlags = mutableSetOf<String>()
 
   private var commonTestFlagCache: Boolean? = null
+  private var animatedDeferStartOfTimingAnimationsCache: Boolean? = null
   private var cdpInteractionMetricsEnabledCache: Boolean? = null
   private var cxxNativeAnimatedEnabledCache: Boolean? = null
   private var defaultTextToOverflowHiddenCache: Boolean? = null
@@ -122,6 +123,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun animatedDeferStartOfTimingAnimations(): Boolean {
+    var cached = animatedDeferStartOfTimingAnimationsCache
+    if (cached == null) {
+      cached = currentProvider.animatedDeferStartOfTimingAnimations()
+      accessedFeatureFlags.add("animatedDeferStartOfTimingAnimations")
+      animatedDeferStartOfTimingAnimationsCache = cached
+    }
+    return cached
+  }
+
   override fun cdpInteractionMetricsEnabled(): Boolean {
     var cached = cdpInteractionMetricsEnabledCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<a3dbeb4eec6efecc4fc355b15a984e58>>
+ * @generated SignedSource<<dccf6ee6d2603cac53e58d6c80640d3f>>
  */
 
 /**
@@ -25,6 +25,8 @@ import com.facebook.proguard.annotations.DoNotStrip
 public interface ReactNativeFeatureFlagsProvider {
   @DoNotStrip public fun commonTestFlag(): Boolean
 
+  @DoNotStrip public fun animatedDeferStartOfTimingAnimations(): Boolean
+
   @DoNotStrip public fun cdpInteractionMetricsEnabled(): Boolean
 
   @DoNotStrip public fun cxxNativeAnimatedEnabled(): Boolean

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<99f843dd0784f9fe372f943767e2033c>>
+ * @generated SignedSource<<e6b17f4548b88ccca9605165525c03b8>>
  */
 
 /**
@@ -45,6 +45,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool animatedDeferStartOfTimingAnimations() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("animatedDeferStartOfTimingAnimations");
+    return method(javaProvider_);
+  }
+
   bool cdpInteractionMetricsEnabled() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("cdpInteractionMetricsEnabled");
@@ -570,6 +576,11 @@ bool JReactNativeFeatureFlagsCxxInterop::commonTestFlag(
   return ReactNativeFeatureFlags::commonTestFlag();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::animatedDeferStartOfTimingAnimations(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::animatedDeferStartOfTimingAnimations();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::cdpInteractionMetricsEnabled(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::cdpInteractionMetricsEnabled();
@@ -1034,6 +1045,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "commonTestFlag",
         JReactNativeFeatureFlagsCxxInterop::commonTestFlag),
+      makeNativeMethod(
+        "animatedDeferStartOfTimingAnimations",
+        JReactNativeFeatureFlagsCxxInterop::animatedDeferStartOfTimingAnimations),
       makeNativeMethod(
         "cdpInteractionMetricsEnabled",
         JReactNativeFeatureFlagsCxxInterop::cdpInteractionMetricsEnabled),

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<05716b6ab8139bc31b962f9158acd6b6>>
+ * @generated SignedSource<<49ef70701e00d4f06c400157392405bd>>
  */
 
 /**
@@ -33,6 +33,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool commonTestFlag(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool animatedDeferStartOfTimingAnimations(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool cdpInteractionMetricsEnabled(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<dda96e26972d745fa18d802035194cf0>>
+ * @generated SignedSource<<bbd44d6cf4f8d004d502defb44d1fff1>>
  */
 
 /**
@@ -30,6 +30,10 @@ bool ReactNativeFeatureFlags::commonTestFlag() {
   return getAccessor().commonTestFlag();
 }
 
+bool ReactNativeFeatureFlags::animatedDeferStartOfTimingAnimations() {
+  return getAccessor().animatedDeferStartOfTimingAnimations();
+}
+
 bool ReactNativeFeatureFlags::cdpInteractionMetricsEnabled() {
   return getAccessor().cdpInteractionMetricsEnabled();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<dcb1e3ba662f28194124dc63879f4fde>>
+ * @generated SignedSource<<4c8925cb81d67439feb8f3c1e9690d36>>
  */
 
 /**
@@ -44,6 +44,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool commonTestFlag();
 
+  /**
+   * When enabled, native timing animations defer their first frame and re-anchor timing to prevent skipping initial frames when the UI thread is busy with layout work.
+   */
+  RN_EXPORT static bool animatedDeferStartOfTimingAnimations();
+
   /**
    * Enable emitting of InteractionEntry live metrics to the debugger. Requires `enableBridgelessArchitecture`.
    */