Add multi-window sample

LICENSE

@@ -0,0 +1,25 @@
+Copyright 2014 The Flutter Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google Inc. nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

@@ -1,16 +1,9 @@
-# windows_c_multi_window
+# Windows multi-window sample
 
-A new Flutter project.
+This repository contains an experimental Flutter Windows app that launches
+multiple windows. This sample requires
+[Flutter's `master` channel](https://docs.flutter.dev/release/upgrade#changing-channels).
 
-## Getting Started
-
-This project is a starting point for a Flutter application.
-
-A few resources to get you started if this is your first Flutter project:
-
-- [Lab: Write your first Flutter app](https://docs.flutter.dev/get-started/codelab)
-- [Cookbook: Useful Flutter samples](https://docs.flutter.dev/cookbook)
-
-For help getting started with Flutter development, view the
-[online documentation](https://docs.flutter.dev/), which offers tutorials,
-samples, guidance on mobile development, and a full API reference.
+This sample is aspirational, may not actually work, may be outdated, and/or have
+other issues. This sample links against experimental Flutter Windows APIs that
+may break at any time. DO NOT DEPEND ON ANYTHING IN THIS REPOSITORY.

lib/main.dart

@@ -1,53 +1,35 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
 import 'package:flutter/material.dart';
+import 'src/widgets.dart';
 
 void main() {
-  runApp(const MyApp());
+  runWidget(MultiViewApp(
+    viewBuilder: (BuildContext context) => const Counter(),
+  ));
 }
 
-class MyApp extends StatelessWidget {
-  const MyApp({super.key});
+class Counter extends StatelessWidget {
+  const Counter({super.key});
 
-  // This widget is the root of your application.
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       title: 'Flutter Demo',
       theme: ThemeData(
-        // This is the theme of your application.
-        //
-        // TRY THIS: Try running your application with "flutter run". You'll see
-        // the application has a purple toolbar. Then, without quitting the app,
-        // try changing the seedColor in the colorScheme below to Colors.green
-        // and then invoke "hot reload" (save your changes or press the "hot
-        // reload" button in a Flutter-supported IDE, or press "r" if you used
-        // the command line to start the app).
-        //
-        // Notice that the counter didn't reset back to zero; the application
-        // state is not lost during the reload. To reset the state, use hot
-        // restart instead.
-        //
-        // This works for code too, not just values: Most code changes can be
-        // tested with just a hot reload.
         colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
         useMaterial3: true,
       ),
-      home: const MyHomePage(title: 'Flutter Demo Home Page'),
+      home: MyHomePage(title: 'Counter View ${View.of(context).viewId}'),
     );
   }
 }
 
 class MyHomePage extends StatefulWidget {
   const MyHomePage({super.key, required this.title});
 
-  // This widget is the home page of your application. It is stateful, meaning
-  // that it has a State object (defined below) that contains fields that affect
-  // how it looks.
-
-  // This class is the configuration for the state. It holds the values (in this
-  // case the title) provided by the parent (in this case the App widget) and
-  // used by the build method of the State. Fields in a Widget subclass are
-  // always marked "final".
-
   final String title;
 
   @override
@@ -59,50 +41,19 @@ class _MyHomePageState extends State<MyHomePage> {
 
   void _incrementCounter() {
     setState(() {
-      // This call to setState tells the Flutter framework that something has
-      // changed in this State, which causes it to rerun the build method below
-      // so that the display can reflect the updated values. If we changed
-      // _counter without calling setState(), then the build method would not be
-      // called again, and so nothing would appear to happen.
       _counter++;
     });
   }
 
   @override
   Widget build(BuildContext context) {
-    // This method is rerun every time setState is called, for instance as done
-    // by the _incrementCounter method above.
-    //
-    // The Flutter framework has been optimized to make rerunning build methods
-    // fast, so that you can just rebuild anything that needs updating rather
-    // than having to individually change instances of widgets.
     return Scaffold(
       appBar: AppBar(
-        // TRY THIS: Try changing the color here to a specific color (to
-        // Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
-        // change color while the other colors stay the same.
         backgroundColor: Theme.of(context).colorScheme.inversePrimary,
-        // Here we take the value from the MyHomePage object that was created by
-        // the App.build method, and use it to set our appbar title.
         title: Text(widget.title),
       ),
       body: Center(
-        // Center is a layout widget. It takes a single child and positions it
-        // in the middle of the parent.
         child: Column(
-          // Column is also a layout widget. It takes a list of children and
-          // arranges them vertically. By default, it sizes itself to fit its
-          // children horizontally, and tries to be as tall as its parent.
-          //
-          // Column has various properties to control how it sizes itself and
-          // how it positions its children. Here we use mainAxisAlignment to
-          // center the children vertically; the main axis here is the vertical
-          // axis because Columns are vertical (the cross axis would be
-          // horizontal).
-          //
-          // TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
-          // action in the IDE, or press "p" in the console), to see the
-          // wireframe for each widget.
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
             const Text(
@@ -119,7 +70,7 @@ class _MyHomePageState extends State<MyHomePage> {
         onPressed: _incrementCounter,
         tooltip: 'Increment',
         child: const Icon(Icons.add),
-      ), // This trailing comma makes auto-formatting nicer for build methods.
+      ),
     );
   }
 }

lib/src/widgets.dart

@@ -0,0 +1,73 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:ui' show FlutterView;
+
+import 'package:flutter/widgets.dart';
+
+/// Calls [viewBuilder] for every view added to the app to obtain the widget to
+/// render into that view. The current view can be looked up with [View.of].
+class MultiViewApp extends StatefulWidget {
+  const MultiViewApp({super.key, required this.viewBuilder});
+
+  final WidgetBuilder viewBuilder;
+
+  @override
+  State<MultiViewApp> createState() => _MultiViewAppState();
+}
+
+class _MultiViewAppState extends State<MultiViewApp> with WidgetsBindingObserver {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addObserver(this);
+    _updateViews();
+  }
+
+  @override
+  void didUpdateWidget(MultiViewApp oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    // Need to re-evaluate the viewBuilder callback for all views.
+    _views.clear();
+    _updateViews();
+  }
+
+  @override
+  void didChangeMetrics() {
+    _updateViews();
+  }
+
+  Map<Object, Widget> _views = <Object, Widget>{};
+
+  void _updateViews() {
+    final Map<Object, Widget> newViews = <Object, Widget>{};
+    for (final FlutterView view in WidgetsBinding.instance.platformDispatcher.views) {
+      final Widget viewWidget = _views[view.viewId] ?? _createViewWidget(view);
+      newViews[view.viewId] = viewWidget;
+    }
+    setState(() {
+      _views = newViews;
+    });
+  }
+
+  Widget _createViewWidget(FlutterView view) {
+    return View(
+      view: view,
+      child: Builder(
+        builder: widget.viewBuilder,
+      ),
+    );
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ViewCollection(views: _views.values.toList(growable: false));
+  }
+}

windows/runner/flutter_window.cpp

@@ -3,9 +3,10 @@
 #include <optional>
 
 #include "flutter/generated_plugin_registrant.h"
+#include "flutter_windows_internal.h"
 
-FlutterWindow::FlutterWindow(const flutter::DartProject& project)
-    : project_(project) {}
+FlutterWindow::FlutterWindow(FlutterDesktopEngineRef engine)
+  : engine_(engine) {}
 
 FlutterWindow::~FlutterWindow() {}
 
@@ -18,53 +19,52 @@ bool FlutterWindow::OnCreate() {
 
   // The size here must match the window dimensions to avoid unnecessary surface
   // creation / destruction in the startup path.
-  flutter_controller_ = std::make_unique<flutter::FlutterViewController>(
-      frame.right - frame.left, frame.bottom - frame.top, project_);
-  // Ensure that basic setup of the controller was successful.
-  if (!flutter_controller_->engine() || !flutter_controller_->view()) {
+  FlutterDesktopViewControllerProperties properties = {};
+  properties.width = frame.right - frame.left;
+  properties.height = frame.bottom - frame.top;
+
+  controller_ = FlutterDesktopEngineCreateViewController(engine_, &properties);
+  if (controller_ == nullptr) {
     return false;
   }
-  RegisterPlugins(flutter_controller_->engine());
-  SetChildContent(flutter_controller_->view()->GetNativeWindow());
-
-  flutter_controller_->engine()->SetNextFrameCallback([&]() {
-    this->Show();
-  });
-
-  // Flutter can complete the first frame before the "show window" callback is
-  // registered. The following call ensures a frame is pending to ensure the
-  // window is shown. It is a no-op if the first frame hasn't completed yet.
-  flutter_controller_->ForceRedraw();
 
+  FlutterDesktopViewRef view{ FlutterDesktopViewControllerGetView(controller_) };
+  SetChildContent(FlutterDesktopViewGetHWND(view));
   return true;
 }
 
 void FlutterWindow::OnDestroy() {
-  if (flutter_controller_) {
-    flutter_controller_ = nullptr;
+  if (controller_) {
+    FlutterDesktopViewControllerDestroy(controller_);
   }
 
   Win32Window::OnDestroy();
 }
 
 LRESULT
 FlutterWindow::MessageHandler(HWND hwnd, UINT const message,
-                              WPARAM const wparam,
-                              LPARAM const lparam) noexcept {
+  WPARAM const wparam,
+  LPARAM const lparam) noexcept {
   // Give Flutter, including plugins, an opportunity to handle window messages.
-  if (flutter_controller_) {
-    std::optional<LRESULT> result =
-        flutter_controller_->HandleTopLevelWindowProc(hwnd, message, wparam,
-                                                      lparam);
-    if (result) {
-      return *result;
+  if (controller_) {
+    LRESULT result;
+    bool handled = FlutterDesktopViewControllerHandleTopLevelWindowProc(
+      controller_,
+      hwnd,
+      message,
+      wparam,
+      lparam,
+      &result);
+
+    if (handled) {
+      return result;
     }
   }
 
   switch (message) {
-    case WM_FONTCHANGE:
-      flutter_controller_->engine()->ReloadSystemFonts();
-      break;
+  case WM_FONTCHANGE:
+    FlutterDesktopEngineReloadSystemFonts(engine_);
+    break;
   }
 
   return Win32Window::MessageHandler(hwnd, message, wparam, lparam);

windows/runner/flutter_window.h

@@ -1,18 +1,15 @@
 #ifndef RUNNER_FLUTTER_WINDOW_H_
 #define RUNNER_FLUTTER_WINDOW_H_
 
-#include <flutter/dart_project.h>
-#include <flutter/flutter_view_controller.h>
-
+#include <flutter_windows.h>
 #include <memory>
 
 #include "win32_window.h"
 
 // A window that does nothing but host a Flutter view.
 class FlutterWindow : public Win32Window {
  public:
-  // Creates a new FlutterWindow hosting a Flutter view running |project|.
-  explicit FlutterWindow(const flutter::DartProject& project);
+  explicit FlutterWindow(FlutterDesktopEngineRef engine);
   virtual ~FlutterWindow();
 
  protected:
@@ -23,11 +20,8 @@ class FlutterWindow : public Win32Window {
                          LPARAM const lparam) noexcept override;
 
  private:
-  // The project to run.
-  flutter::DartProject project_;
-
-  // The Flutter instance hosted by this window.
-  std::unique_ptr<flutter::FlutterViewController> flutter_controller_;
+   FlutterDesktopEngineRef engine_ = nullptr;
+   FlutterDesktopViewControllerRef controller_ = nullptr;
 };
 
 #endif  // RUNNER_FLUTTER_WINDOW_H_