Add support for onDettached onAttach UnityWidget

Author: Ortes

android/src/main/kotlin/com/xraph/plugin/flutter_unity_widget/FlutterUnityWidgetController.kt

@@ -345,7 +345,20 @@ class FlutterUnityWidgetController(
         // add unity to view
         UnityPlayerUtils.addUnityViewToGroup(view)
         UnityPlayerUtils.focus()
+
         attached = true
+
+        if (UnityPlayerUtils.controllers.size >= 2) {
+            for (controller in UnityPlayerUtils.controllers.subList(0, UnityPlayerUtils.controllers.size - 1)) {
+                if (controller.attached) {
+                    controller.detach()
+                }
+            }
+        }
+
+        Handler(Looper.getMainLooper()).post {
+            methodChannel.invokeMethod("events#onViewAttached", null)
+        }
     }
 
     // DO NOT CHANGE THIS FUNCTION
@@ -384,5 +397,12 @@ class FlutterUnityWidgetController(
         Choreographer.getInstance()
                 .postFrameCallback { f.run() }
     }
+
+    private fun detach() {
+        Handler(Looper.getMainLooper()).post {
+            methodChannel.invokeMethod("events#onViewDetached", null)
+        }
+        attached = false
+    }
     //#endregion
 }

lib/src/facade_widget.dart

@@ -16,6 +16,8 @@ class UnityWidget extends StatefulWidget {
     this.unloadOnDispose = false,
     this.printSetupLog = true,
     this.onUnityUnloaded,
+    this.onUnityAttached,
+    this.onUnityDetached,
     this.gestureRecognizers,
     this.placeholder,
     this.useAndroidViewSurface = false,
@@ -38,6 +40,12 @@ class UnityWidget extends StatefulWidget {
   ///Event fires when the [UnityWidget] unity player gets unloaded.
   final UnityUnloadCallback? onUnityUnloaded;
 
+  ///Event fires when Unity player is attached to the widget
+  final UnityAttachedCallback? onUnityAttached;
+
+  ///Event fires when Unity player is attached to the widget
+  final UnityDetachedCallback? onUnityDetached;
+
   final Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers;
 
   /// Set to true to force unity to fullscreen

lib/src/helpers/events.dart

@@ -34,3 +34,11 @@ class UnityCreatedEvent extends UnityEvent<void> {
 class UnityMessageEvent extends UnityEvent<dynamic> {
   UnityMessageEvent(int unityId, dynamic value) : super(unityId, value);
 }
+
+class UnityAttachedEvent extends UnityEvent<void> {
+  UnityAttachedEvent(int unityId, void value) : super(unityId, value);
+}
+
+class UnityDetachedEvent extends UnityEvent<void> {
+  UnityDetachedEvent(int unityId, void value) : super(unityId, value);
+}

lib/src/helpers/misc.dart

@@ -25,3 +25,7 @@ typedef void UnityMessageCallback(dynamic handler);
 typedef void UnitySceneChangeCallback(SceneLoaded? message);
 
 typedef void UnityUnloadCallback();
+
+typedef void UnityAttachedCallback();
+
+typedef void UnityDetachedCallback();

lib/src/io/device_method.dart

@@ -95,6 +95,12 @@ class MethodChannelUnityWidget extends UnityWidgetPlatform {
       case "events#onUnityCreated":
         _unityStreamController.add(UnityCreatedEvent(unityId, call.arguments));
         break;
+      case "events#onViewAttached":
+        _unityStreamController.add(UnityAttachedEvent(unityId, call.arguments));
+        break;
+      case "events#onViewDetached":
+        _unityStreamController.add(UnityDetachedEvent(unityId, call.arguments));
+        break;
       default:
         throw UnimplementedError("Unimplemented ${call.method} method");
     }
@@ -145,6 +151,16 @@ class MethodChannelUnityWidget extends UnityWidgetPlatform {
     return _events(unityId).whereType<UnitySceneLoadedEvent>();
   }
 
+  @override
+  Stream<UnityAttachedEvent> onUnityAttached({required int unityId}) {
+    return _events(unityId).whereType<UnityAttachedEvent>();
+  }
+
+  @override
+  Stream<UnityDetachedEvent> onUnityDetached({required int unityId}) {
+    return _events(unityId).whereType<UnityDetachedEvent>();
+  }
+
   @override
   Widget buildViewWithTextDirection(
     int creationId,

lib/src/io/mobile_unity_widget_controller.dart

@@ -18,7 +18,9 @@ class MobileUnityWidgetController extends UnityWidgetController {
   /// used for cancel the subscription
   StreamSubscription? _onUnityMessageSub,
       _onUnitySceneLoadedSub,
-      _onUnityUnloadedSub;
+      _onUnityUnloadedSub,
+      _onUnityAttachedSub,
+      _onUnityDetachedSub;
 
   MobileUnityWidgetController._(this._unityWidgetState,
       {required this.unityId}) {
@@ -30,11 +32,12 @@ class MobileUnityWidgetController extends UnityWidgetController {
   /// in [UnityWidget.onUnityCreated] callback.
   static Future<MobileUnityWidgetController> init(
       int id, MobileUnityWidgetState unityWidgetState) async {
-    await UnityWidgetPlatform.instance.init(id);
-    return MobileUnityWidgetController._(
+    final controller = MobileUnityWidgetController._(
       unityWidgetState,
       unityId: id,
     );
+    await UnityWidgetPlatform.instance.init(id);
+    return controller;
   }
 
   @visibleForTesting
@@ -66,6 +69,22 @@ class MobileUnityWidgetController extends UnityWidgetController {
           .onUnityUnloaded(unityId: unityId)
           .listen((_) => _unityWidgetState.widget.onUnityUnloaded!());
     }
+
+    if (_unityWidgetState.widget.onUnityAttached != null) {
+      _onUnityAttachedSub = UnityWidgetPlatform.instance
+          .onUnityAttached(unityId: unityId)
+          .listen((_) {
+        _unityWidgetState.widget.onUnityAttached!();
+      });
+    }
+
+    if (_unityWidgetState.widget.onUnityDetached != null) {
+      _onUnityDetachedSub = UnityWidgetPlatform.instance
+          .onUnityDetached(unityId: unityId)
+          .listen((_) {
+        _unityWidgetState.widget.onUnityDetached!();
+      });
+    }
   }
 
   /// Checks to see if unity player is ready to be used
@@ -200,10 +219,14 @@ class MobileUnityWidgetController extends UnityWidgetController {
     _onUnityMessageSub?.cancel();
     _onUnitySceneLoadedSub?.cancel();
     _onUnityUnloadedSub?.cancel();
+    _onUnityAttachedSub?.cancel();
+    _onUnityDetachedSub?.cancel();
 
     _onUnityMessageSub = null;
     _onUnitySceneLoadedSub = null;
     _onUnityUnloadedSub = null;
+    _onUnityAttachedSub = null;
+    _onUnityDetachedSub = null;
   }
 
   void dispose() {

lib/src/io/unity_widget.dart

@@ -61,6 +61,8 @@ class UnityWidget extends StatefulWidget {
     this.unloadOnDispose = false,
     this.printSetupLog = true,
     this.onUnityUnloaded,
+    this.onUnityAttached,
+    this.onUnityDetached,
     this.gestureRecognizers,
     this.placeholder,
     this.useAndroidViewSurface = false,
@@ -87,6 +89,12 @@ class UnityWidget extends StatefulWidget {
   ///Event fires when the [UnityWidget] unity player gets unloaded.
   final UnityUnloadCallback? onUnityUnloaded;
 
+  ///Event fires when Unity player is attached to the widget
+  final UnityAttachedCallback? onUnityAttached;
+
+  ///Event fires when Unity player is detached to the widget
+  final UnityDetachedCallback? onUnityDetached;
+
   final Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers;
 
   /// Set to true to force unity to fullscreen
@@ -192,6 +200,9 @@ class _UnityWidgetState extends State<UnityWidget> {
     _controller = controller;
     widget.onUnityCreated(controller);
 
+    // if (widget.onUnityAttached != null)
+    //   widget.onUnityAttached!();
+
     if (widget.printSetupLog) {
       log('*********************************************');
       log('** flutter unity controller setup complete **');

lib/src/io/unity_widget_platform.dart

@@ -107,6 +107,14 @@ abstract class UnityWidgetPlatform extends PlatformInterface {
     throw UnimplementedError('onUnitySceneLoaded() has not been implemented.');
   }
 
+  Stream<UnityAttachedEvent> onUnityAttached({required int unityId}) {
+    throw UnimplementedError('onUnityAttached() has not been implemented.');
+  }
+
+  Stream<UnityDetachedEvent> onUnityDetached({required int unityId}) {
+    throw UnimplementedError('onUnityDetached() has not been implemented.');
+  }
+
   /// Dispose of whatever resources the `unityId` is holding on to.
   void dispose({required int unityId}) {
     throw UnimplementedError('dispose() has not been implemented.');