Add UiModeUtils.isDarkMode helper (#51925)

Summary:
This PR is part of the [edge-to-edge core implementation effort](https://github.com/facebook/react-native/pull/47554). It adds a helper to `ContextUtils`, called `isDarkMode` in order to be reused accross the Android codebase.

## Changelog:

- [Internal] [Added] - Add `UiModeUtils.isDarkMode` helper

Pull Request resolved: https://github.com/facebook/react-native/pull/51925

Test Plan:
<img width="300" alt="Screenshot 2025-06-10 at 17 50 19" src="https://github.com/user-attachments/assets/48795406-e852-486a-bae8-54507ad769ee" />

<img width="300" alt="Screenshot 2025-06-10 at 17 50 42" src="https://github.com/user-attachments/assets/0dbdece9-04f7-487b-ace8-4786c8da381d" />

Rollback Plan:

Reviewed By: cortinico

Differential Revision: D76352849

Pulled By: alanleedev

fbshipit-source-id: fbbc772d1dfa3e30e62a71a711de11b85cdec446

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/appearance/AppearanceModule.kt

@@ -8,13 +8,13 @@
 package com.facebook.react.modules.appearance
 
 import android.content.Context
-import android.content.res.Configuration
 import androidx.appcompat.app.AppCompatDelegate
 import com.facebook.fbreact.specs.NativeAppearanceSpec
 import com.facebook.react.bridge.ReactApplicationContext
 import com.facebook.react.bridge.UiThreadUtil
 import com.facebook.react.bridge.buildReadableMap
 import com.facebook.react.module.annotations.ReactModule
+import com.facebook.react.views.common.UiModeUtils
 
 /** Module that exposes the user's preferred color scheme. */
 @ReactModule(name = NativeAppearanceSpec.NAME)
@@ -41,13 +41,7 @@ constructor(
       return overrideColorScheme.getScheme()
     }
 
-    val currentNightMode =
-        context.resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK
-    return when (currentNightMode) {
-      Configuration.UI_MODE_NIGHT_NO -> "light"
-      Configuration.UI_MODE_NIGHT_YES -> "dark"
-      else -> "light"
-    }
+    return if (UiModeUtils.isDarkMode(context)) "dark" else "light"
   }
 
   public override fun getColorScheme(): String {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/common/UiModeUtils.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.views.common
+
+import android.content.Context
+import android.content.res.Configuration
+
+/** Utility object providing static methods for working with UI mode properties from Context. */
+internal object UiModeUtils {
+
+  /**
+   * Determines whether the current UI mode is dark mode
+   *
+   * @param context The context to check the UI mode from
+   * @return true if the current UI mode is dark mode, false otherwise
+   */
+  @JvmStatic
+  fun isDarkMode(context: Context): Boolean =
+      context.resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK ==
+          Configuration.UI_MODE_NIGHT_YES
+}

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/view/WindowUtil.kt

@@ -7,7 +7,6 @@
 
 package com.facebook.react.views.view
 
-import android.content.res.Configuration
 import android.graphics.Color
 import android.os.Build
 import android.view.Window
@@ -15,6 +14,7 @@ import android.view.WindowManager
 import androidx.core.view.ViewCompat
 import androidx.core.view.WindowCompat
 import androidx.core.view.WindowInsetsControllerCompat
+import com.facebook.react.views.common.UiModeUtils
 
 @Suppress("DEPRECATION")
 internal fun Window.setStatusBarTranslucency(isTranslucent: Boolean) {
@@ -71,9 +71,7 @@ internal fun Window.setSystemBarsTranslucency(isTranslucent: Boolean) {
   WindowCompat.setDecorFitsSystemWindows(this, !isTranslucent)
 
   if (isTranslucent) {
-    val isDarkMode =
-        context.resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK ==
-            Configuration.UI_MODE_NIGHT_YES
+    val isDarkMode = UiModeUtils.isDarkMode(context)
 
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
       isStatusBarContrastEnforced = false