Using Flutter for Desktop Development

Flutter, Google’s UI toolkit, is primarily known for building cross-platform mobile applications. However, Flutter also supports building applications for the web, desktop (Windows, macOS, Linux), and embedded devices from a single codebase. This makes Flutter a versatile tool for developers aiming to target multiple platforms efficiently. This blog post will focus on Using Flutter for Desktop Development.

What is Flutter Desktop Development?

Flutter desktop development refers to the use of the Flutter framework to create applications that run on desktop operating systems like Windows, macOS, and Linux. This allows developers to write code once and deploy it on both mobile and desktop platforms, reducing development time and ensuring a consistent user experience.

Why Use Flutter for Desktop Development?

• Cross-Platform: Write code once and deploy it to multiple desktop platforms.
• Fast Development: Flutter’s hot-reload feature accelerates the development process.
• Rich UI: Create beautiful, responsive user interfaces with Flutter’s rich set of widgets.
• Performance: Flutter apps are performant thanks to its Skia rendering engine.
• Community and Support: Growing community and excellent documentation from Google.

Setting Up Flutter for Desktop Development

Before you start developing desktop apps with Flutter, you need to set up your environment correctly.

Step 1: Install Flutter

If you haven’t already, download and install the Flutter SDK from the official Flutter website (https://flutter.dev/docs/get-started/install). Follow the instructions specific to your operating system.

Step 2: Enable Desktop Support

Enable desktop support for your Flutter installation. Open a terminal and run the following command:

flutter config --enable-desktop

For specific platform support, you can use:

• Windows: flutter config --enable-windows-desktop
• macOS: flutter config --enable-macos-desktop
• Linux: flutter config --enable-linux-desktop

Step 3: Verify Flutter Installation

Run the following command to ensure that Flutter is correctly set up:

flutter doctor

This command checks your environment and shows any dependencies you might be missing.

Creating a New Flutter Desktop Application

To create a new Flutter desktop application, follow these steps:

Step 1: Create a New Project

Use the Flutter CLI to create a new project. Open your terminal and run:

flutter create my_desktop_app

This command creates a new Flutter project named my_desktop_app.

Step 2: Navigate to the Project Directory

cd my_desktop_app

Step 3: Run the Application

To run the application on your desktop, use the following command:

flutter run -d windows # For Windows
flutter run -d macos   # For macOS
flutter run -d linux   # For Linux

This command compiles and runs your Flutter application on your selected desktop platform.

Developing Your Flutter Desktop Application

Now that you have set up and run your Flutter desktop application, let’s dive into some development aspects.

UI Design and Widgets

Flutter provides a rich set of customizable widgets for creating beautiful user interfaces. Most widgets that work on mobile will also work on desktop, making the transition smooth. However, keep in mind that desktop applications might have different UI expectations than mobile apps.

Example:

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Desktop App',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Desktop Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Hello, Desktop!',
              style: TextStyle(fontSize: 24),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: () {
                print('Button Pressed!');
              },
              child: Text('Press Me'),
            ),
          ],
        ),
      ),
    );
  }
}

Platform-Specific Code

Sometimes, you might need to write platform-specific code to access certain desktop features. Flutter provides platform channels for this purpose.

Example:

Let’s say you want to access the native window size. You can use a MethodChannel to communicate with the native code.

Dart Code:

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

class PlatformService {
  static const platform = const MethodChannel('my_desktop_app/platform');

  Future<String> getOperatingSystem() async {
    String os;
    try {
      final String result = await platform.invokeMethod('getOperatingSystem');
      os = 'Operating system: $result';
    } on PlatformException catch (e) {
      os = "Failed to get operating system: '${e.message}'.";
    }
    return os;
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String _operatingSystem = 'Unknown operating system';

  @override
  void initState() {
    super.initState();
    _getOperatingSystem();
  }

  Future<void> _getOperatingSystem() async {
    String os = await PlatformService().getOperatingSystem();
    setState(() {
      _operatingSystem = os;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Platform Channel Demo'),
      ),
      body: Center(
        child: Text(_operatingSystem),
      ),
    );
  }
}

Native Code (Example in C++ for Windows):

// windows/runner/flutter_window.cpp

#include <flutter_windows.h>
#include <iostream>

void FlutterWindow::RegisterPlugins(flutter::PluginRegistry* registry) {
  // Register other plugins here
  RegisterMethodChannelPlugin(registry);
}

// RegisterMethodChannelPlugin implementation
#include <flutter/method_channel.h>
#include <flutter/plugin_registrar_windows.h>
#include <windows.h>

namespace {

class MethodChannelPlugin : public flutter::Plugin {
 public:
  static void RegisterWithRegistrar(flutter::PluginRegistrarWindows* registrar) {
    auto channel =
        std::make_unique<flutter::MethodChannel<flutter::EncodableValue>>(
            registrar->messenger(), "my_desktop_app/platform",
            &flutter::StandardMethodCodec::GetInstance());

    auto plugin = std::make_unique<MethodChannelPlugin>();

    channel->SetMethodCallHandler(
        [plugin_pointer = plugin.get()](
            const flutter::MethodCall<flutter::EncodableValue>& method_call,
            std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
          if (method_call.method_name().compare("getOperatingSystem") == 0) {
            // Get Windows version
            OSVERSIONINFOEX osvi;
            ZeroMemory(&osvi, sizeof(OSVERSIONINFOEX));
            osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);

            GetVersionEx((OSVERSIONINFO *)&osvi);

            std::ostringstream os_version_stream;
            os_version_stream << "Windows " << osvi.dwMajorVersion << "."
                              <Success(flutter::EncodableValue(os_version));
          } else {
            result->NotImplemented();
          }
        });

    registrar->AddPlugin(std::move(plugin));
  }

 private:
  MethodChannelPlugin() {}
  ~MethodChannelPlugin() {}
};

void RegisterMethodChannelPlugin(flutter::PluginRegistry* registry) {
  flutter::PluginRegistrarWindows* plugin_registrar =
      flutter::PluginRegistrarManager::GetInstance()->GetRegistrar<
          flutter::PluginRegistrarWindows>(registry);
  MethodChannelPlugin::RegisterWithRegistrar(plugin_registrar);
}

}  // namespace

Responsive Layout

Desktop applications often need to adapt to different window sizes and resolutions. Use Flutter’s flexible layout widgets, such as Flexible, Expanded, and LayoutBuilder, to create responsive UIs.

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Responsive Flutter App',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Responsive Demo'),
        ),
        body: LayoutBuilder(
          builder: (BuildContext context, BoxConstraints constraints) {
            if (constraints.maxWidth > 600) {
              return WideLayout();
            } else {
              return NarrowLayout();
            }
          },
        ),
      ),
    );
  }
}

class WideLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Expanded(
            child: Container(
              color: Colors.red,
              height: 200,
              child: Center(child: Text('Red Box', style: TextStyle(color: Colors.white))),
            ),
          ),
          Expanded(
            child: Container(
              color: Colors.green,
              height: 200,
              child: Center(child: Text('Green Box', style: TextStyle(color: Colors.white))),
            ),
          ),
        ],
      ),
    );
  }
}

class NarrowLayout extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Expanded(
            child: Container(
              color: Colors.red,
              child: Center(child: Text('Red Box', style: TextStyle(color: Colors.white))),
            ),
          ),
          Expanded(
            child: Container(
              color: Colors.green,
              child: Center(child: Text('Green Box', style: TextStyle(color: Colors.white))),
            ),
          ),
        ],
      ),
    );
  }
}

Deployment and Packaging

Once your desktop application is ready, you can package it for distribution. Flutter provides tools for creating executables for each desktop platform.

To build your app for a specific platform, use the following commands:

flutter build windows  # For Windows
flutter build macos    # For macOS
flutter build linux    # For Linux

These commands generate the necessary files and executables that you can distribute to your users.

Conclusion

Flutter offers a compelling solution for developing desktop applications that can be deployed across Windows, macOS, and Linux from a single codebase. With its rich set of widgets, hot-reload feature, and support for platform-specific code, Flutter simplifies the development process while providing a native-like experience for desktop users. Using Flutter for Desktop Development enables developers to reach a broader audience with less effort, making it a valuable tool in today’s cross-platform development landscape.