feat: implement window manager events

Author: okwasniewski

packages/react-native/Libraries/SwiftExtensions/RCTMainWindow.swift

@@ -21,6 +21,10 @@ public struct RCTMainWindow: Scene {
   var moduleName: String
   var initialProps: RCTRootViewRepresentable.InitialPropsType
   var onOpenURLCallback: ((URL) -> ())?
+  let windowId: String = "0"
+  
+  @Environment(\.scenePhase) private var scenePhase
+  
 
   public init(moduleName: String, initialProps: RCTRootViewRepresentable.InitialPropsType = nil) {
     self.moduleName = moduleName
@@ -31,13 +35,27 @@ public struct RCTMainWindow: Scene {
     WindowGroup {
       RCTRootViewRepresentable(moduleName: moduleName, initialProps: initialProps)
         .modifier(WindowHandlingModifier())
+        .onChange(of: scenePhase, { _, newValue in
+          postWindowStateNotification(windowId: windowId, state: newValue)
+        })
         .onOpenURL(perform: { url in
           onOpenURLCallback?(url)
         })
     }
   }
 }
 
+public func postWindowStateNotification(windowId: String, state: SwiftUI.ScenePhase) {
+  NotificationCenter.default.post(
+    name: NSNotification.Name(rawValue: "RCTWindowStateDidChange"),
+    object: nil,
+    userInfo: [
+      "windowId": windowId,
+      "state": "\(state)"
+    ]
+  )
+}
+
 extension RCTMainWindow {
   public func onOpenURL(perform action: @escaping (URL) -> ()) -> some Scene {
     var scene = self

packages/react-native/Libraries/SwiftExtensions/RCTWindow.swift

@@ -13,6 +13,8 @@ public struct RCTWindow : Scene {
   var id: String
   var sceneData: RCTSceneData?
   var moduleName: String
+  @Environment(\.scenePhase) private var scenePhase
+
 
   public init(id: String, moduleName: String, sceneData: RCTSceneData?) {
     self.id = id
@@ -25,6 +27,9 @@ public struct RCTWindow : Scene {
       Group {
         if let sceneData {
           RCTRootViewRepresentable(moduleName: moduleName, initialProps: sceneData.props)
+            .onChange(of: scenePhase) { _, newValue in
+              postWindowStateNotification(windowId: id, state: newValue)
+            }
         }
       }
       .onAppear {

packages/react-native/Libraries/WindowManager/RCTWindowManager.h

@@ -1,6 +1,7 @@
 #import <Foundation/Foundation.h>
 #import <React/RCTBridgeModule.h>
+#import <React/RCTEventEmitter.h>
 
-@interface RCTWindowManager : NSObject <RCTBridgeModule>
+@interface RCTWindowManager : RCTEventEmitter
 
 @end

packages/react-native/Libraries/WindowManager/RCTWindowManager.mm

@@ -10,14 +10,36 @@
 static NSString *const RCTOpenWindow = @"RCTOpenWindow";
 static NSString *const RCTDismissWindow = @"RCTDismissWindow";
 static NSString *const RCTUpdateWindow = @"RCTUpdateWindow";
+static NSString *const RCTWindowStateDidChangeEvent = @"windowStateDidChange";
 
-@interface RCTWindowManager () <NativeWindowManagerSpec>
+static NSString *const RCTWindowStateDidChange = @"RCTWindowStateDidChange";
+
+@interface RCTWindowManager () <NativeWindowManagerSpec> {
+  BOOL _hasAnyListeners;
+}
 @end
 
 @implementation RCTWindowManager
 
 RCT_EXPORT_MODULE(WindowManager)
 
+- (void)initialize {
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(handleWindowStateChanges:)
+                                               name:RCTWindowStateDidChange
+                                             object:nil];
+}
+
+-(void)startObserving
+{
+  _hasAnyListeners = YES;
+}
+
+- (void)stopObserving
+{
+  _hasAnyListeners = NO;
+}
+
 RCT_EXPORT_METHOD(openWindow
                   : (NSString *)windowId userInfo
                   : (NSDictionary *)userInfo resolve
@@ -68,6 +90,17 @@ @implementation RCTWindowManager
   });
 }
 
+- (void) handleWindowStateChanges:(NSNotification *)notification {
+  
+  if (_hasAnyListeners) {
+   [self sendEventWithName:RCTWindowStateDidChangeEvent body:notification.userInfo];
+  }
+}
+
+- (NSArray<NSString *> *)supportedEvents {
+  return @[RCTWindowStateDidChangeEvent];
+}
+
 - (facebook::react::ModuleConstants<JS::NativeWindowManager::Constants::Builder>)constantsToExport {
   return [self getConstants];
 }
@@ -87,4 +120,13 @@ @implementation RCTWindowManager
   return std::make_shared<facebook::react::NativeWindowManagerSpecJSI>(params);
 }
 
++ (BOOL)requiresMainQueueSetup {
+  return YES;
+}
+
+- (dispatch_queue_t)methodQueue
+{
+  return dispatch_get_main_queue();
+}
+
 @end

packages/react-native/Libraries/WindowManager/WindowManager.d.ts

@@ -1,8 +1,18 @@
+import {NativeEventSubscription} from '../EventEmitter/RCTNativeAppEventEmitter';
+
+type WindowManagerEvents = 'windowStateDidChange';
+
+type WindowState = {
+  windowId: string;
+  state: 'active' | 'inactive' | 'background';
+};
+
 export interface WindowStatic {
   id: String;
   open (props?: Object): Promise<void>;
   update (props: Object): Promise<void>;
   close (): Promise<void>;
+  addEventListener (type: WindowManagerEvents, handler: (info: WindowState) => void): NativeEventSubscription;
 }
 
 export interface WindowManagerStatic {

packages/react-native/Libraries/WindowManager/WindowManager.js

@@ -1,29 +1,54 @@
 /**
  * @format
- * @flow strict
+ * @flow strict-local
  * @jsdoc
  */
 
+import NativeEventEmitter from '../EventEmitter/NativeEventEmitter';
+import Platform from '../Utilities/Platform';
+import {type EventSubscription} from '../vendor/emitter/EventEmitter';
 import NativeWindowManager from './NativeWindowManager';
 
-const WindowManager = {
-  getWindow: function (id: string): Window {
+export type WindowStateValues = 'inactive' | 'background' | 'active';
+
+type WindowManagerEventDefinitions = {
+  windowStateDidChange: [{state: WindowStateValues, windowId: string}],
+};
+
+let emitter: ?NativeEventEmitter<WindowManagerEventDefinitions>;
+
+if (NativeWindowManager != null) {
+  emitter = new NativeEventEmitter<WindowManagerEventDefinitions>(
+    Platform.OS !== 'ios' ? null : NativeWindowManager,
+  );
+}
+
+class WindowManager {
+  static getWindow = function (id: string): Window {
     return new Window(id);
-  },
+  };
+
+  static addEventListener<K: $Keys<WindowManagerEventDefinitions>>(
+    type: K,
+    handler: (...$ElementType<WindowManagerEventDefinitions, K>) => void,
+  ): ?EventSubscription {
+    return emitter?.addListener(type, handler);
+  }
 
   // $FlowIgnore[unsafe-getters-setters]
-  get supportsMultipleScenes(): boolean {
+  static get supportsMultipleScenes(): boolean {
     if (NativeWindowManager == null) {
       return false;
     }
 
     const nativeConstants = NativeWindowManager.getConstants();
     return nativeConstants.supportsMultipleScenes || false;
-  },
-};
+  }
+}
 
 class Window {
   id: string;
+  isOpen: boolean = false;
 
   constructor(id: string) {
     this.id = id;

packages/react-native/src/private/specs/visionos_modules/NativeWindowManager.js

@@ -19,6 +19,10 @@ export interface Spec extends TurboModule {
   // $FlowIgnore[unclear-type]
   +updateWindow: (windowId: string, userInfo: Object) => Promise<void>;
   +closeWindow: (windowId: string) => Promise<void>;
+
+  // RCTEventEmitter
+  +addListener: (eventName: string) => void;
+  +removeListeners: (count: number) => void;
 }
 
 export default (TurboModuleRegistry.get<Spec>('WindowManager'): ?Spec);

packages/rn-tester/js/examples/XR/XRExample.js

@@ -19,6 +19,17 @@ const secondWindow = WindowManager.getWindow('SecondWindow');
 const OpenXRSession = () => {
   const [isOpen, setIsOpen] = React.useState(false);
 
+  React.useEffect(() => {
+    const listener = WindowManager.addEventListener(
+      'windowStateDidChange',
+      data => {
+        console.log('Window state changed to:', data);
+      },
+    );
+    return () => {
+      listener?.remove();
+    };
+  }, []);
   const openXRSession = async () => {
     try {
       if (!WindowManager.supportsMultipleScenes) {