feat: add option to subscribe to overlay status: overlay showing or o…

…verlay closed

android/src/main/java/flutter/overlay/window/flutter_overlay_window/CachedMessageChannels.java

@@ -1,11 +1,11 @@
 package flutter.overlay.window.flutter_overlay_window;
 
 import androidx.annotation.Nullable;
-import io.flutter.plugin.common.BasicMessageChannel;
+import io.flutter.plugin.common.MethodChannel;
 
 public abstract class CachedMessageChannels {
     @Nullable
-    public static BasicMessageChannel<Object> mainAppMessageChannel;
+    public static MethodChannel mainAppMessageChannel;
     @Nullable
-    public static BasicMessageChannel<Object> overlayMessageChannel;
+    public static MethodChannel overlayMessageChannel;
 }

android/src/main/java/flutter/overlay/window/flutter_overlay_window/FlutterOverlayWindowPlugin.java

@@ -21,8 +21,7 @@
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.embedding.engine.plugins.activity.ActivityAware;
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
-import io.flutter.plugin.common.BasicMessageChannel;
-import io.flutter.plugin.common.JSONMessageCodec;
+import io.flutter.plugin.common.JSONMethodCodec;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
@@ -165,37 +164,37 @@ private void registerMessageChannel(boolean isMainAppEngine) {
     private void unregisterMessageChannel(boolean isMainAppEngine) {
         if(isMainAppEngine) {
             if (CachedMessageChannels.mainAppMessageChannel == null) return;
-            CachedMessageChannels.mainAppMessageChannel.setMessageHandler(null);
+            CachedMessageChannels.mainAppMessageChannel.setMethodCallHandler(null);
             CachedMessageChannels.mainAppMessageChannel = null;
         } else {
             if(CachedMessageChannels.overlayMessageChannel == null) return;
-            CachedMessageChannels.overlayMessageChannel.setMessageHandler(null);
+            CachedMessageChannels.overlayMessageChannel.setMethodCallHandler(null);
             CachedMessageChannels.overlayMessageChannel = null;
         }
     }
 
     private void registerOverlayMessageChannel(io.flutter.plugin.common.BinaryMessenger overlyEngineBinaryMessenger) {
-        BasicMessageChannel<Object> overlayMessageChannel = new BasicMessageChannel<>(overlyEngineBinaryMessenger, OverlayConstants.MESSENGER_TAG, JSONMessageCodec.INSTANCE);
-        overlayMessageChannel.setMessageHandler((message, reply) -> {
+        MethodChannel overlayMessageChannel = new MethodChannel(overlyEngineBinaryMessenger, OverlayConstants.MESSENGER_TAG, JSONMethodCodec.INSTANCE);
+        overlayMessageChannel.setMethodCallHandler((call, result) -> {
             if (CachedMessageChannels.mainAppMessageChannel == null) {
-                reply.reply(false);
+                result.success(false);
                 return;
             }
-            CachedMessageChannels.mainAppMessageChannel.send(message);
-            reply.reply(true);
+            CachedMessageChannels.mainAppMessageChannel.invokeMethod("message", call.arguments);
+            result.success(true);
         });
         CachedMessageChannels.overlayMessageChannel = overlayMessageChannel;
     }
 
     private void registerMainAppMessageChannel(io.flutter.plugin.common.BinaryMessenger mainAppEngineBinaryMessenger) {
-        BasicMessageChannel<Object> mainAppMessageChannel = new BasicMessageChannel<>(mainAppEngineBinaryMessenger, OverlayConstants.MESSENGER_TAG, JSONMessageCodec.INSTANCE);
-        mainAppMessageChannel.setMessageHandler((message, reply) -> {
+        MethodChannel mainAppMessageChannel = new MethodChannel(mainAppEngineBinaryMessenger, OverlayConstants.MESSENGER_TAG, JSONMethodCodec.INSTANCE);
+        mainAppMessageChannel.setMethodCallHandler((call, result) -> {
             if (CachedMessageChannels.overlayMessageChannel == null) {
-                reply.reply(false);
+                result.success(false);
                 return;
             }
-            CachedMessageChannels.overlayMessageChannel.send(message);
-            reply.reply(true);
+            CachedMessageChannels.overlayMessageChannel.invokeMethod("message", call.arguments);
+            result.success(true);
         });
         CachedMessageChannels.mainAppMessageChannel = mainAppMessageChannel;
     }

android/src/main/java/flutter/overlay/window/flutter_overlay_window/OverlayService.java

@@ -82,6 +82,7 @@ public void onDestroy() {
             flutterView.detachFromFlutterEngine();
             flutterView = null;
         }
+        OverlayStatusEmitter.emitIsShowing(false);
         NotificationManager notificationManager = (NotificationManager) getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE);
         notificationManager.cancel(OverlayConstants.NOTIFICATION_ID);
     }
@@ -153,6 +154,7 @@ public int onStartCommand(Intent intent, int flags, int startId) {
         params.gravity = WindowSetup.gravity;
         flutterView.setOnTouchListener(this);
         windowManager.addView(flutterView, params);
+        OverlayStatusEmitter.emitIsShowing(true);
         return START_STICKY;
     }
 

android/src/main/java/flutter/overlay/window/flutter_overlay_window/OverlayStatusEmitter.java

@@ -0,0 +1,16 @@
+package flutter.overlay.window.flutter_overlay_window;
+
+public abstract class OverlayStatusEmitter {
+    static private final String methodName = "isShowingOverlay";
+    static private boolean lastEmittedStatus;
+    static void emitIsShowing(boolean isShowing) {
+        if(isShowing == lastEmittedStatus) return;
+        lastEmittedStatus = isShowing;
+        if(CachedMessageChannels.mainAppMessageChannel != null) {
+            CachedMessageChannels.mainAppMessageChannel.invokeMethod(methodName, isShowing);
+        }
+        if(CachedMessageChannels.overlayMessageChannel != null) {
+            CachedMessageChannels.overlayMessageChannel.invokeMethod(methodName, isShowing);
+        }
+    }
+}

lib/src/overlay_window.dart

@@ -1,20 +1,19 @@
 import 'dart:async';
 import 'dart:developer';
 
-import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_overlay_window/src/overlay_config.dart';
 
 class FlutterOverlayWindow {
   FlutterOverlayWindow._();
 
-  static final StreamController _controller = StreamController.broadcast();
-  static const MethodChannel _channel =
-      MethodChannel("x-slayer/overlay_channel");
-  static const MethodChannel _overlayChannel =
-      MethodChannel("x-slayer/overlay");
-  static const BasicMessageChannel _overlayMessageChannel =
-      BasicMessageChannel("x-slayer/overlay_messenger", JSONMessageCodec());
+  static final _controller = StreamController<dynamic>.broadcast();
+  static final _controllerOverlayStatus = StreamController<bool>.broadcast();
+
+  static const _channel = MethodChannel("x-slayer/overlay_channel");
+  static const _overlayChannel = MethodChannel("x-slayer/overlay");
+  static const _overlayMessageChannel =
+      MethodChannel("x-slayer/overlay_messenger", JSONMethodCodec());
 
   /// Open overLay content
   ///
@@ -93,19 +92,29 @@ class FlutterOverlayWindow {
   ///
   /// Returns `true` if the [data] was sent successfully, otherwise `false`.
   static Future<bool> shareData(dynamic data) async {
-    final isSent = await _overlayMessageChannel.send(data);
+    final isSent = await _overlayMessageChannel.invokeMethod('', data);
     return isSent as bool;
   }
 
   /// Streams message shared between overlay and main app
   static Stream<dynamic> get overlayListener {
-    _overlayMessageChannel.setMessageHandler((message) async {
-      _controller.add(message);
-      return message;
-    });
+    _registerOverlayMessageHandler();
     return _controller.stream;
   }
 
+  /// Overlay status stream.
+  ///
+  /// Emit `true` when overlay is showing, and `false` when overlay is closed.
+  ///
+  /// Emit value only once for every state change.
+  ///
+  /// Doesn't emit a change when the overlay is already showing and [showOverlay] is called,
+  /// as in this case the overlay will almost immediately reopen.
+  static Stream<bool> get overlayStatusListener {
+    _registerOverlayMessageHandler();
+    return _controllerOverlayStatus.stream;
+  }
+
   /// Update the overlay flag while the overlay in action
   static Future<bool?> updateFlag(OverlayFlag flag) async {
     final bool? _res = await _overlayChannel
@@ -131,6 +140,19 @@ class FlutterOverlayWindow {
     return _res ?? false;
   }
 
+  static void _registerOverlayMessageHandler() {
+    _overlayMessageChannel.setMethodCallHandler((call) async {
+      switch (call.method) {
+        case 'isShowingOverlay':
+          _controllerOverlayStatus.add(call.arguments as bool);
+          break;
+        case 'message':
+          _controller.add(call.arguments);
+          break;
+      }
+    });
+  }
+
   /// Dispose overlay stream.
   ///
   /// Once disposed, only a complete restart of the application will re-initialize the listener.