Example app broken on non-macOS platforms

[jmatth]

Description

Launching the app on non-macOS platforms results in immediate exceptions. I've so far tested on Windows and Chrome, but based on the exceptions I'm almost certain the same errors will occur on any platform other than macOS

Steps To Reproduce

1. Run the example app in this repo targeting a device other than macos.

Expected behavior

Example app should open and display the widgets gallery.

Actual behavior

An exception is immediately thrown. Since the exception is thrown in main before runApp is called, the app seemingly freezes with a blank screen without even displaying Flutter's red error screen in debug mode.

Screenshots

Windows

Chrome

Logs

Logs

Logs generated without --verbose since doing so adds a bunch of useless noise that pushes the comment length above Github's limit.

Launching lib\main.dart on Windows in debug mode...
Building Windows application...                                     6.6s
√  Built build\windows\runner\Debug\example.exe.
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: MissingPluginException(No implementation found for method initialize on channel macos_window_utils/window_manipulator)
#0      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:308:7)
<asynchronous suspension>
#1      WindowManipulator.initialize (package:macos_window_utils/window_manipulator.dart:38:5)
<asynchronous suspension>
#2      MacosWindowUtilsConfig.apply (package:macos_ui/src/macos_window_utils_config.dart:71:5)
<asynchronous suspension>
#3      _configureMacosWindowUtils (package:example/main.dart:19:3)
<asynchronous suspension>
#4      main (package:example/main.dart:23:3)
<asynchronous suspension>

Syncing files to device Windows...                                  72ms

Flutter run key commands.
r Hot reload. 
R Hot restart.
h List all available interactive commands.
d Detach (terminate "flutter run" but leave application running).
c Clear the screen
q Quit (terminate the application on the device).

A Dart VM Service on Windows is available at: http://127.0.0.1:54997/cCv-1HuzTj4=/
The Flutter DevTools debugger and profiler on Windows is available at: http://127.0.0.1:9103?uri=http://127.0.0.1:54997/cCv-1HuzTj4=/

Application finished.

Analyzing example...                                            
No issues found! (ran in 1.1s)

[!] Flutter (Channel stable, 3.10.5, on Microsoft Windows [Version 10.0.22621.1848], locale en-US)
    ΓÇó Flutter version 3.10.5 on channel stable at C:\Users\josh\fvm\versions\3.10.5
    ! Upstream repository C:\Users\josh\Projects\forks\flutter is not a standard remote.
      Set environment variable "FLUTTER_GIT_URL" to C:\Users\josh\Projects\forks\flutter to dismiss this error.
    ΓÇó Framework revision 796c8ef792 (8 days ago), 2023-06-13 15:51:02 -0700
    ΓÇó Engine revision 45f6e00911
    ΓÇó Dart version 3.0.5
    ΓÇó DevTools version 2.23.1
    ΓÇó If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks and upgrades.

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 33.0.2)
    ΓÇó Android SDK at C:\Users\josh\AppData\Local\Android\sdk
    ΓÇó Platform android-33, build-tools 33.0.2
    ΓÇó Java binary at: C:\Program Files\Common Files\Oracle\Java\javapath\java.exe
    ΓÇó Java version Java(TM) SE Runtime Environment (build 18.0.2.1+1-1)
    ΓÇó All Android licenses accepted.

[√] Chrome - develop for the web
    ΓÇó Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop for Windows (Visual Studio Community 2022 17.6.3)
    ΓÇó Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    ΓÇó Visual Studio Community 2022 version 17.6.33801.468
    ΓÇó Windows 10 SDK version 10.0.22621.0

[!] Android Studio (not installed)
    ΓÇó Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/windows#android-setup for detailed instructions).

[√] IntelliJ IDEA Community Edition (version 2022.2)
    ΓÇó IntelliJ at C:\Users\josh\AppData\Local\JetBrains\Toolbox\apps\IDEA-C\ch-0\222.4345.14
    ΓÇó Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    ΓÇó Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart

[√] VS Code (version 1.79.2)
    ΓÇó VS Code at C:\Users\josh\AppData\Local\Programs\Microsoft VS Code
    ΓÇó Flutter extension version 3.66.0

[√] Connected device (3 available)
    ΓÇó Windows (desktop) ΓÇó windows ΓÇó windows-x64    ΓÇó Microsoft Windows [Version 10.0.22621.1848]
    ΓÇó Chrome (web)      ΓÇó chrome  ΓÇó web-javascript ΓÇó Google Chrome 114.0.5735.134
    ΓÇó Edge (web)        ΓÇó edge    ΓÇó web-javascript ΓÇó Microsoft Edge 112.0.1722.64

[√] Network resources
    ΓÇó All expected network resources are available.

! Doctor found issues in 2 categories.

Further details

The initial exception comes from an unconditional call into macos_window_utils right at the top of main. Since that plugin understandably only supports macOS, this call throws. After fixing this the app is still broken due to an unconditional use of PlatformMenuBar, which is again only supported on macOS. Adding conditional logic to only execute this code on macOS allows the example app to run.

Edit: for web, an additional fix is needed to prevent accessing Platform.isMacOS in utils.dart.

[GroovinChip]

Been trying to make this work on web and I think this it be more trouble than its worth. We may need to make it clear that from 2.0 on, it is expected that macos_ui only be used on macOS.

[whiplashoo]

Indeed, I too believe that supporting only macOS (and providing a web playground for showcasing the components) would be optimal going forward.

[GroovinChip]

I've got it sort of working on web:

Theming is borked for some reason

EDIT: only dark theme is borked, light looks fine:

[GroovinChip]

Minimum reproducible sample using 2.0.0-beta.9:

import 'package:flutter/material.dart';
import 'package:macos_ui/macos_ui.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MacosApp(
      title: 'Flutter Demo',
      theme: MacosThemeData.light(),
      darkTheme: MacosThemeData.dark(),
      themeMode: ThemeMode.dark,
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return MacosWindow(
      child: MacosScaffold(
        children: [
          ContentArea(
            builder: (context, _) => const Center(child: Text('Content')),
          ),
        ],
      ),
    );
  }
}