wip: able to create windows in the reference application again

Author: mattkae

examples/multi_window_ref_app/lib/app/main_window.dart

@@ -1,7 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:multi_window_ref_app/app/window_metadata_content.dart';
 
-import 'regular_window_content.dart';
 import 'window_settings.dart';
 import 'window_settings_dialog.dart';
 
@@ -74,7 +73,8 @@ class _MainWindowState extends State<MainWindow> {
                     listenable: _windowManagerModel,
                     builder: (BuildContext context, Widget? child) {
                       return _WindowCreatorCard(
-                          selectedWindow: _windowManagerModel.selected);
+                          selectedWindow: _windowManagerModel.selected,
+                          windowManagerModel: _windowManagerModel);
                     })
               ],
             ),
@@ -83,12 +83,29 @@ class _MainWindowState extends State<MainWindow> {
       ),
     );
 
+    return ViewAnchor(
+        view: ListenableBuilder(
+            listenable: _windowManagerModel,
+            builder: (BuildContext context, Widget? widget) {
+              return _ViewCollection(windowManagerModel: _windowManagerModel);
+            }),
+        child: widget);
+  }
+}
+
+class _ViewCollection extends StatelessWidget {
+  _ViewCollection({required this.windowManagerModel});
+
+  _WindowManagerModel windowManagerModel;
+
+  @override
+  Widget build(BuildContext context) {
     final List<Widget> childViews = <Widget>[];
-    for (final WindowMetadata childWindow in _windowManagerModel.windows) {
+    for (final WindowMetadata childWindow in windowManagerModel.windows) {
       childViews.add(WindowMetadataContent(childWindow: childWindow));
     }
 
-    return ViewAnchor(view: ViewCollection(views: childViews), child: widget);
+    return ViewCollection(views: childViews);
   }
 }
 
@@ -181,9 +198,11 @@ class _ActiveWindowsTable extends StatelessWidget {
 }
 
 class _WindowCreatorCard extends StatefulWidget {
-  const _WindowCreatorCard({required this.selectedWindow});
+  const _WindowCreatorCard(
+      {required this.selectedWindow, required this.windowManagerModel});
 
   final WindowMetadata? selectedWindow;
+  final _WindowManagerModel windowManagerModel;
 
   @override
   State<StatefulWidget> createState() => _WindowCreatorCardState();
@@ -216,7 +235,9 @@ class _WindowCreatorCardState extends State<_WindowCreatorCard> {
               children: [
                 OutlinedButton(
                   onPressed: () async {
-                    await createRegular(size: _settings.regularSize);
+                    final WindowMetadata metadata =
+                        await createRegular(size: _settings.regularSize);
+                    widget.windowManagerModel.add(metadata);
                   },
                   child: const Text('Regular'),
                 ),

packages/flutter/lib/src/widgets/window.dart

@@ -5,6 +5,7 @@
 import 'dart:ui' show FlutterView;
 
 import 'package:flutter/material.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
 
 /// Defines the type of a [Window]
@@ -81,27 +82,34 @@ class _RegularWindowState extends State<RegularWindow> {
   @override
   void initState() {
     super.initState();
-    final _WindowingAppContext? windowingAppContext =
-        _WindowingAppContext.of(context);
     widget._future.then((RegularWindowMetadata metadata) async {
-      assert(windowingAppContext != null);
-      _listener = _WindowListener(
-          viewId: metadata.view.viewId,
-          onChanged: (_WindowChangeProperties properties) {
-            if (widget.controller == null) {
-              return;
-            }
-
-            if (properties.size != null) {
-              widget.controller!._size = properties.size!;
-            }
-
-            if (properties.parentViewId != null) {
-              widget.controller!._parentViewId = properties.parentViewId;
-            }
-          },
-          onDestroyed: widget.onDestroyed);
-      windowingAppContext!.windowingApp._registerListener(_listener!);
+      if (widget.controller != null) {
+        widget.controller!._parentViewId = metadata.parentViewId;
+        widget.controller!._size = metadata.size;
+      }
+
+      SchedulerBinding.instance.addPostFrameCallback((_) async {
+        final _WindowingAppContext? windowingAppContext =
+            _WindowingAppContext.of(context);
+        assert(windowingAppContext != null);
+        _listener = _WindowListener(
+            viewId: metadata.view.viewId,
+            onChanged: (_WindowChangeProperties properties) {
+              if (widget.controller == null) {
+                return;
+              }
+
+              if (properties.size != null) {
+                widget.controller!._size = properties.size!;
+              }
+
+              if (properties.parentViewId != null) {
+                widget.controller!._parentViewId = properties.parentViewId;
+              }
+            },
+            onDestroyed: widget.onDestroyed);
+        windowingAppContext!.windowingApp._registerListener(_listener!);
+      });
     });
   }
 
@@ -123,7 +131,8 @@ class _RegularWindowState extends State<RegularWindow> {
         builder: (BuildContext context,
             AsyncSnapshot<RegularWindowMetadata> metadata) {
           if (!metadata.hasData) {
-            return Container();
+            final WidgetsBinding binding = WidgetsFlutterBinding.ensureInitialized();
+            return binding.wrapWithDefaultView(Container());
           }
 
           return View(
@@ -202,6 +211,7 @@ Future<RegularWindowMetadata> createRegular({required Size size}) async {
 Future<_WindowMetadata> _createWindow(
     {required Future<Map<Object?, Object?>> Function(MethodChannel channel)
         viewBuilder}) async {
+  WidgetsFlutterBinding.ensureInitialized();
   final Map<Object?, Object?> creationData =
       await viewBuilder(SystemChannels.windowing);
   final int viewId = creationData['viewId']! as int;
@@ -260,6 +270,7 @@ class _WindowListener {
 /// The current [Window] can be looked up with [WindowContext.of].
 class WindowingApp extends StatelessWidget {
   WindowingApp({super.key, required this.children}) {
+    WidgetsFlutterBinding.ensureInitialized();
     SystemChannels.windowing.setMethodCallHandler(_methodCallHandler);
   }