android host color scheme listener

Author: intergalacticspacehighway

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/ReactInstanceManager.java

@@ -72,6 +72,7 @@
 import com.facebook.react.devsupport.interfaces.PackagerStatusCallback;
 import com.facebook.react.devsupport.interfaces.PausedInDebuggerOverlayManager;
 import com.facebook.react.devsupport.interfaces.RedBoxHandler;
+import com.facebook.react.fabric.FabricUIManager;
 import com.facebook.react.interfaces.TaskInterface;
 import com.facebook.react.internal.AndroidChoreographerProvider;
 import com.facebook.react.internal.ChoreographerProvider;
@@ -865,6 +866,11 @@ public void onConfigurationChanged(Context updatedContext, @Nullable Configurati
 
       if (appearanceModule != null) {
         appearanceModule.onConfigurationChanged(updatedContext);
+
+        UIManager uiManager = UIManagerHelper.getUIManager(currentReactContext, FABRIC);
+        if (uiManager instanceof FabricUIManager) {
+          ((FabricUIManager) uiManager).onColorSchemeChanged(appearanceModule.getColorScheme());
+        }
       }
     }
   }

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -439,6 +439,16 @@ public void stopSurface(final int surfaceID) {
     mBinding.stopSurface(surfaceID);
   }
 
+  /**
+   * Triggers re-resolution of conditional styles when the color scheme changes.
+   */
+  public void onColorSchemeChanged(String colorScheme) {
+    if (mBinding == null) {
+      return;
+    }
+    mBinding.onColorSchemeChanged("dark".equals(colorScheme));
+  }
+
   @Override
   public void initialize() {
     mEventDispatcher.addBatchEventDispatchedListener(mBatchEventDispatchedListener);

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManagerBinding.kt

@@ -79,6 +79,8 @@ internal class FabricUIManagerBinding : HybridClassBase() {
 
   external fun driveCxxAnimations()
 
+  external fun onColorSchemeChanged(isDark: Boolean)
+
   external fun driveAnimationBackend(frameTimeNanos: Long)
 
   external fun drainPreallocateViewsQueue()

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/runtime/ReactHostImpl.kt

@@ -68,6 +68,8 @@ import com.facebook.react.runtime.internal.bolts.TaskCompletionSource
 import com.facebook.react.turbomodule.core.interfaces.CallInvokerHolder
 import com.facebook.react.uimanager.DisplayMetricsHolder
 import com.facebook.react.uimanager.PixelUtil
+import com.facebook.react.uimanager.UIManagerHelper
+import com.facebook.react.uimanager.common.UIManagerType
 import com.facebook.react.uimanager.events.BlackHoleEventDispatcher
 import com.facebook.react.uimanager.events.EventDispatcher
 import com.facebook.react.views.imagehelper.ResourceDrawableIdHelper
@@ -745,6 +747,13 @@ public class ReactHostImpl(
 
       val appearanceModule = currentReactContext.getNativeModule(AppearanceModule::class.java)
       appearanceModule?.onConfigurationChanged(context)
+
+      // Initialize the color scheme for conditional styles (media query)
+      if (appearanceModule != null) {
+        (UIManagerHelper.getUIManager(currentReactContext, UIManagerType.FABRIC)
+                as? FabricUIManager)
+            ?.onColorSchemeChanged(appearanceModule.getColorScheme())
+      }
     }
   }
 

packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.cpp

@@ -61,6 +61,17 @@ void FabricUIManagerBinding::driveCxxAnimations() {
   scheduler->animationTick();
 }
 
+void FabricUIManagerBinding::onColorSchemeChanged(jboolean isDarkColorScheme) {
+  auto scheduler = getScheduler();
+  if (!scheduler) {
+    LOG(ERROR)
+        << "FabricUIManagerBinding::onColorSchemeChanged: scheduler disappeared";
+    return;
+  }
+  scheduler->onColorSchemeDidChange(
+      isDarkColorScheme ? ColorScheme::Dark : ColorScheme::Light);
+}
+
 void FabricUIManagerBinding::driveAnimationBackend(jlong frameTimeNanos) {
   if (!animationChoreographer_) {
     LOG(ERROR)
@@ -860,6 +871,8 @@ void FabricUIManagerBinding::registerNatives() {
           "setPixelDensity", FabricUIManagerBinding::setPixelDensity),
       makeNativeMethod(
           "driveCxxAnimations", FabricUIManagerBinding::driveCxxAnimations),
+      makeNativeMethod(
+          "onColorSchemeChanged", FabricUIManagerBinding::onColorSchemeChanged),
       makeNativeMethod(
           "driveAnimationBackend",
           FabricUIManagerBinding::driveAnimationBackend),

packages/react-native/ReactAndroid/src/main/jni/react/fabric/FabricUIManagerBinding.h

@@ -127,6 +127,8 @@ class FabricUIManagerBinding : public jni::HybridClass<FabricUIManagerBinding>,
 
   void driveCxxAnimations();
 
+  void onColorSchemeChanged(jboolean isDarkColorScheme);
+
   void driveAnimationBackend(jlong frameTimeNanos);
 
   void drainPreallocateViewsQueue();

packages/react-native/ReactCommon/react/renderer/core/ShadowNode.cpp

@@ -132,9 +132,6 @@ ShadowNode::ShadowNode(
     }
     propagateUncullableTraitsFromChildren();
   }
-  // Unconditional, unlike the uncullable trait: this node's own contribution
-  // is props-derived, and a clone may change props while keeping children
-  // (e.g. a media query patch), which flips the self bit.
   propagateStyleConditionsTrait();
 }