Transfer data from secondary to main display

android/src/main/kotlin/com/namit/presentation_displays/PresentationDisplay.kt

@@ -9,8 +9,11 @@ import android.view.ViewGroup
 import android.widget.FrameLayout
 import io.flutter.embedding.android.FlutterView
 import io.flutter.embedding.engine.FlutterEngineCache
+import io.flutter.plugin.common.MethodCall
+import io.flutter.plugin.common.MethodChannel
 
-class PresentationDisplay(context: Context, private val tag: String, display: Display) :
+
+class PresentationDisplay(context: Context, private val tag: String, display: Display,private val callBack: (tip: Any?) -> Unit) :
     Presentation(context, display) {
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -30,6 +33,15 @@ class PresentationDisplay(context: Context, private val tag: String, display: Di
         val flutterEngine = FlutterEngineCache.getInstance().get(tag)
         if (flutterEngine != null) {
             flutterView.attachToFlutterEngine(flutterEngine)
+
+            MethodChannel(
+                flutterEngine.dartExecutor.binaryMessenger,
+                "main_display_channel"
+            ).setMethodCallHandler { call, result ->
+                if (call?.method == "transferDataToMain") {
+                    callBack(call?.arguments);
+                }
+            }
         } else {
             Log.e("PresentationDisplay", "Can't find the FlutterEngine with cache name $tag")
         }

android/src/main/kotlin/com/namit/presentation_displays/PresentationDisplaysPlugin.kt

@@ -30,6 +30,7 @@ class PresentationDisplaysPlugin : FlutterPlugin, ActivityAware, MethodChannel.M
   private var flutterEngineChannel: MethodChannel? = null
   private var context: Context? = null
   private var presentation: PresentationDisplay? = null
+  private var flutterBinding: FlutterPlugin.FlutterPluginBinding? = null
 
   override fun onAttachedToEngine(
       @NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding
@@ -43,6 +44,7 @@ class PresentationDisplaysPlugin : FlutterPlugin, ActivityAware, MethodChannel.M
             DisplayManager
     val displayConnectedStreamHandler = DisplayConnectedStreamHandler(displayManager)
     eventChannel.setStreamHandler(displayConnectedStreamHandler)
+      flutterBinding = flutterPluginBinding
   }
 
   companion object {
@@ -72,6 +74,7 @@ class PresentationDisplaysPlugin : FlutterPlugin, ActivityAware, MethodChannel.M
 
   override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
     Log.i(TAG, "Channel: method: ${call.method} | arguments: ${call.arguments}")
+    val channelMainName: String = "main_display_channel"
     when (call.method) {
       "showPresentation" -> {
         try {
@@ -86,11 +89,21 @@ class PresentationDisplaysPlugin : FlutterPlugin, ActivityAware, MethodChannel.M
           val tag: String = obj.getString("routerName")
           val display = displayManager?.getDisplay(displayId)
           if (display != null) {
+              var dataToMainCallback: (Any?) -> Unit = {
+                      argument : Any? ->
+                  MethodChannel(
+                      flutterBinding!!.flutterEngine.dartExecutor.binaryMessenger,
+                      channelMainName
+                  ).invokeMethod(
+                      "dataToMain", argument
+                  )
+              }
+
             val flutterEngine = createFlutterEngine(tag)
             flutterEngine?.let {
               flutterEngineChannel =
                   MethodChannel(it.dartExecutor.binaryMessenger, "${viewTypeId}_engine")
-              presentation = context?.let { it1 -> PresentationDisplay(it1, tag, display) }
+              presentation = context?.let { it1 -> PresentationDisplay(it1, tag, display, dataToMainCallback) }
               Log.i(TAG, "presentation: $presentation")
               presentation?.show()
 

example/lib/main.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:presentation_displays/display.dart';
 import 'package:presentation_displays/displays_manager.dart';
+import 'package:presentation_displays/main_display.dart';
 import 'package:presentation_displays/secondary_display.dart';
 
 Route<dynamic> generateRoute(RouteSettings settings) {
@@ -96,6 +97,8 @@ class _DisplayManagerScreenState extends State<DisplayManagerScreen> {
   final TextEditingController _nameOfIndexController = TextEditingController();
   String _nameOfIndex = "";
 
+  dynamic dataFromMain;
+
   @override
   void initState() {
     displayManager.connectedDisplaysChangedStream?.listen(
@@ -108,23 +111,31 @@ class _DisplayManagerScreenState extends State<DisplayManagerScreen> {
 
   @override
   Widget build(BuildContext context) {
-    return Scaffold(
-      appBar: AppBar(
-        title: const Text('Plugin example app'),
-      ),
-      body: Center(
-        child: SingleChildScrollView(
-          child: Column(
-            mainAxisAlignment: MainAxisAlignment.center,
-            crossAxisAlignment: CrossAxisAlignment.center,
-            children: <Widget>[
-              _getDisplays(),
-              _showPresentation(),
-              _hidePresentation(),
-              _transferData(),
-              _getDisplayeById(),
-              _getDisplayByIndex(),
-            ],
+    return MainDisplay(
+      callback: (arguments) {
+        setState(() {
+          dataFromMain = arguments;
+        });
+      },
+      child: Scaffold(
+        appBar: AppBar(
+          title: const Text('Plugin example app'),
+        ),
+        body: Center(
+          child: SingleChildScrollView(
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.center,
+              crossAxisAlignment: CrossAxisAlignment.center,
+              children: <Widget>[
+                _getDisplays(),
+                _showPresentation(),
+                _hidePresentation(),
+                _transferData(),
+                _dataFromSecond(),
+                _getDisplayeById(),
+                _getDisplayByIndex(),
+              ],
+            ),
           ),
         ),
       ),
@@ -254,6 +265,20 @@ class _DisplayManagerScreenState extends State<DisplayManagerScreen> {
     );
   }
 
+  Widget _dataFromSecond() {
+    return Column(
+      mainAxisAlignment: MainAxisAlignment.center,
+      crossAxisAlignment: CrossAxisAlignment.center,
+      children: [
+        Padding(
+          padding: const EdgeInsets.all(8.0),
+          child: Text('Data from second: ${dataFromMain ?? '-'}'),
+        ),
+        const Divider(),
+      ],
+    );
+  }
+
   Widget _getDisplayeById() {
     return Column(
       mainAxisAlignment: MainAxisAlignment.center,
@@ -336,6 +361,10 @@ class SecondaryScreen extends StatefulWidget {
 
 class _SecondaryScreenState extends State<SecondaryScreen> {
   String value = "init";
+  DisplayManager displayManager = DisplayManager();
+
+  final TextEditingController _dataToTransferController =
+      TextEditingController();
 
   @override
   Widget build(BuildContext context) {
@@ -349,9 +378,51 @@ class _SecondaryScreenState extends State<SecondaryScreen> {
       child: Container(
         color: Colors.white,
         child: Center(
-          child: Text(value),
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: [_getTransferToMainButton(), _getDataFromMainText()],
+          ),
         ),
       ),
     ));
   }
+
+  Widget _getTransferToMainButton() {
+    return Column(
+      mainAxisAlignment: MainAxisAlignment.center,
+      crossAxisAlignment: CrossAxisAlignment.center,
+      children: [
+        Padding(
+          padding: const EdgeInsets.all(8.0),
+          child: TextField(
+            controller: _dataToTransferController,
+            decoration: const InputDecoration(
+              border: OutlineInputBorder(),
+              labelText: 'Data',
+            ),
+          ),
+        ),
+        Button(
+            title: "TransferDataToMain",
+            onPressed: () async {
+              displayManager.transferDataToMain(_dataToTransferController.text);
+            }),
+        const Divider(),
+      ],
+    );
+  }
+
+  Widget _getDataFromMainText() {
+    return Column(
+      mainAxisAlignment: MainAxisAlignment.center,
+      crossAxisAlignment: CrossAxisAlignment.center,
+      children: [
+        SizedBox(
+          height: 50,
+          child: Center(child: Text('Data from main: $value')),
+        ),
+        const Divider(),
+      ],
+    );
+  }
 }

lib/displays_manager.dart

@@ -5,12 +5,14 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:presentation_displays/display.dart';
+import 'package:presentation_displays/main_display.dart';
 import 'package:presentation_displays/secondary_display.dart';
 
 const _listDisplay = "listDisplay";
 const _showPresentation = "showPresentation";
 const _hidePresentation = "hidePresentation";
 const _transferDataToPresentation = "transferDataToPresentation";
+const _transferDataToMain = "transferDataToMain";
 
 /// Display category: secondary display.
 /// <p>
@@ -24,24 +26,28 @@ const _transferDataToPresentation = "transferDataToPresentation";
 /// [DisplayManager.getDisplays], [DisplayManager.getNameByDisplayId],
 /// [DisplayManager.getNameByIndex], [DisplayManager.showSecondaryDisplay],
 /// [DisplayManager.transferDataToPresentation], [DisplayManager.hideSecondaryDisplay]
+/// [DisplayManager.transferDataToMain]
 /// </p>
 ///
 /// [DisplayManager.getDisplays]
 ///
 const String DISPLAY_CATEGORY_PRESENTATION =
     "android.hardware.display.category.PRESENTATION";
 
-/// Provide you with the method for you to work with [SecondaryDisplay].
+/// Provide you with the method for you to work with [SecondaryDisplay] and [MainDisplay].
 class DisplayManager {
   final _displayMethodChannelId = "presentation_displays_plugin";
   final _displayEventChannelId = "presentation_displays_plugin_events";
+  final _mainChannel = "main_display_channel";
 
   late MethodChannel? _displayMethodChannel;
   late EventChannel? _displayEventChannel;
+  MethodChannel? _mainMethodChannel;
 
   DisplayManager() {
     _displayMethodChannel = MethodChannel(_displayMethodChannelId);
     _displayEventChannel = EventChannel(_displayEventChannelId);
+    _mainMethodChannel = MethodChannel(_mainChannel);
   }
 
   /// Gets all currently valid logical displays of the specified category.
@@ -202,4 +208,62 @@ class DisplayManager {
   Stream<int?>? get connectedDisplaysChangedStream {
     return _displayEventChannel?.receiveBroadcastStream().cast();
   }
+
+  /// Transfer data to a main display
+  /// <p>
+  /// Transfer data from secondary screen to a main display
+  /// Consider using [arguments] for cases where a particular run-time type is expected. Consider using String when that run-time type is Map or JSONObject.
+  /// </p>
+  /// <p>
+  /// Main Screen
+  ///
+  /// ```dart
+  /// class _MainScreenState extends State<MainScreen> {
+  ///   @override
+  ///   Widget build(BuildContext context) {
+  ///       return MainDisplay(
+  ///        callback: (argument) {
+  ///          Song.fromJson(argument)
+  ///       },
+  ///       child: Center()
+  ///     );
+  ///   }
+  /// }
+  /// ```
+  ///
+  /// ```
+  /// Secondary display
+  ///
+  /// ```dart
+  /// DisplayManager displayManager = DisplayManager();
+  /// ...
+  /// static Future<void> transferData(Song song) async {
+  ///   displayManager.transferDataToMain(<String, dynamic>{
+  ///         'id': song.id,
+  ///         'title': song.title,
+  ///         'artist': song.artist,
+  ///       });
+  /// }
+  /// ```
+  /// Class Song
+  ///
+  /// ```dart
+  /// class Song {
+  ///   Song(this.id, this.title, this.artist);
+  ///
+  ///   final String id;
+  ///   final String title;
+  ///   final String artist;
+  ///
+  ///   static Song fromJson(dynamic json) {
+  ///     return Song(json['id'], json['title'], json['artist']);
+  ///   }
+  /// }
+  /// ```
+  /// </p>
+  ///
+  /// return [Future<bool>] the value to determine whether or not the data has been transferred successfully
+  Future<bool?>? transferDataToMain(dynamic arguments) async {
+    return _mainMethodChannel?.invokeMethod(_transferDataToMain, arguments);
+  }
 }

lib/main_display.dart

@@ -0,0 +1,44 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:presentation_displays/displays_manager.dart';
+import 'package:presentation_displays/secondary_display.dart';
+
+/// This widget will wrap the main display, it will receive data transmitted from [DisplayManager].
+/// [MainDisplay.callback] instance of [ArgumentsCallback] to receive data transmitted from the [DisplayManager].
+/// [MainDisplay.child] child widget of main display
+class MainDisplay extends StatefulWidget {
+  const MainDisplay({Key? key, required this.callback, required this.child})
+      : super(key: key);
+
+  /// instance of [ArgumentsCallback] to receive data transmitted from the [DisplaysManager].
+  final ArgumentsCallback callback;
+
+  /// Your Flutter UI on Main Screen
+  final Widget child;
+
+  @override
+  _MainDisplayState createState() => _MainDisplayState();
+}
+
+class _MainDisplayState extends State<MainDisplay> {
+  final _mainChannel = "main_display_channel";
+  MethodChannel? _mainMethodChannel;
+
+  @override
+  void initState() {
+    _addListenerForMain(widget.callback);
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return widget.child;
+  }
+
+  _addListenerForMain(ArgumentsCallback function) {
+    _mainMethodChannel = MethodChannel(_mainChannel);
+    _mainMethodChannel?.setMethodCallHandler((call) async {
+      function(call.arguments);
+    });
+  }
+}