Exploring Flutter Desktop: Developing a Cross-Platform Desktop App

Flutter, originally designed for mobile development, has expanded to support desktop platforms, offering developers the ability to create cross-platform desktop applications. In this article, I will share my experience developing a desktop app using Flutter, highlighting the differences from mobile development and some of the challenges I faced along the way.

Getting Started with Flutter Desktop

Setting up Flutter for desktop development requires a few steps beyond the typical mobile setup. Flutter currently supports macOS, Windows, and Linux, and you need to enable desktop support before starting:

flutter config --enable-windows-desktop
flutter config --enable-macos-desktop
flutter config --enable-linux-desktop

After enabling desktop support, you can create a new Flutter project or update an existing one to run on desktop platforms. The development process largely follows the same flow as building a mobile app, but there are several key differences that I noticed.

One of the things I found exciting about working with Flutter for desktop was the ability to use the same codebase across multiple platforms while tweaking specific parts of the app to adapt to desktop features. Flutter’s flexibility in accommodating different platforms made this process smoother, and the initial setup only required a few modifications to make it desktop-ready.

Key Differences Between Desktop and Mobile Development

1. Input Methods
2. One of the primary differences is the way users interact with the application. Desktop apps typically rely on keyboard and mouse input rather than touch. Flutter’s default widget library is optimized for mobile gestures, but desktop development requires ensuring that your UI responds well to mouse clicks, hovers, and keyboard shortcuts.
3. In a mobile environment, you would primarily handle gestures like taps and swipes. However, in desktop applications, you need to consider additional input methods such as right-click context menus, mouse hover states, and keyboard navigation. Designing for these input methods ensures a seamless user experience that feels native to desktop users.

Example: Adding hover effects to buttons is crucial for desktop applications.

MouseRegion( 
  onEnter: (_) => setState(() => isHovered = true), 
  onExit: (_) => setState(() => isHovered = false),
   child: Container(     padding: EdgeInsets.all(16), 
    color: isHovered ? Colors.blueAccent : Colors.blue,
     child: Text('Hover Me', style: TextStyle(color: Colors.white)), 
  ), 
);

1. Additionally, keyboard shortcuts are an important aspect of desktop applications. Using the Shortcuts and Actions widgets in Flutter, I was able to create custom keyboard shortcuts that improved user experience by allowing quick access to various app functions.
2. Window Management
3. Desktop applications have resizable windows, which means that your app must be responsive to different window sizes. Unlike mobile devices where the screen size is fixed, users can resize a desktop app window to various dimensions, sometimes making it very narrow or very wide.
4. To handle this, I used Flutter’s LayoutBuilder and MediaQuery to make the UI responsive based on the available window size. Desktop users may also have multiple monitors with varying resolutions, making it essential to adapt the UI accordingly.

Example:

LayoutBuilder(   
builder: (context, constraints) {   
  if (constraints.maxWidth > 800) {  
     return WideScreenLayout();    
 } else {    
   return NarrowScreenLayout();    
 }  
 },
 );

Supporting window resizing also involves managing the dynamic arrangement of UI elements. I found that using widgets like Flexible and Expanded helped create a fluid layout that could adapt to various window sizes seamlessly, ensuring a consistent user experience.

Platform-Specific Features

1. Desktop applications often require platform-specific features like system tray integration, native menus, or custom window controls. While Flutter provides some basic cross-platform functionality, I found myself relying on plugins to achieve a more native desktop experience.
2. For example, I used the bitsdojo_window package to control the window's appearance and behavior, such as adding a custom title bar or handling window drag functionality. Another key feature I implemented was system tray support, which allowed my application to run in the background and be accessed from the system tray, a feature often expected in desktop applications.

Example: Adding custom window controls.

import 'package:bitsdojo_window/bitsdojo_window.dart'; 
 @override
 Widget build(BuildContext context) {
   return WindowTitleBarBox(  
   child: Row(    
   children: [  
       Expanded(child: MoveWindow()), 
        MinimizeWindowButton(),    
     MaximizeWindowButton(),   
      CloseWindowButton(),   
    ], 
    ),
   );
 }

Adding these customizations ensured that the desktop application felt more integrated with the host operating system, providing a more polished user experience.

Challenges Faced During Development

1. Lack of Desktop-Specific Widgets
2. Flutter’s widget set is still primarily optimized for mobile applications. During development, I realized that many of the built-in widgets were not optimized for desktop interactions. For instance, ListView scrolling with a mouse wheel or the lack of default context menus made it necessary to either create custom solutions or look for community-supported plugins.
3. Another challenge was implementing right-click context menus, which are a common feature in desktop apps. I used PopupMenuButton as a workaround, but it required additional customization to achieve the expected desktop behavior.
4. Solution: I used the scrollable_positioned_list package to create a better scrolling experience for desktop users and implemented custom context menus using PopupMenuButton. In some cases, I also had to create custom widgets to bridge the gap between mobile-centric Flutter widgets and desktop-specific functionality.

Handling Different Screen Sizes and Resolutions

1. On mobile, developers can use fixed sizes for certain UI elements because the screen size is relatively consistent across devices. On desktop, however, screens can vary greatly, and users can resize the app window at any time. To deal with this, I made extensive use of Flutter’s responsive design tools, like LayoutBuilder, Expanded, and Flexible.
2. Additionally, handling ultra-wide monitors and high DPI screens required careful planning. I leveraged MediaQuery to detect screen density and adjusted font sizes and element padding accordingly to ensure that the app looked good on both standard and high-resolution displays.

Limited Plugin Support

1. While Flutter has a vast library of plugins for mobile development, desktop plugin support is still growing. Some plugins I commonly used for mobile were either not available or lacked full support for desktop, which led to finding workarounds or building custom platform-specific code.
2. For instance, integrating file picker functionality on desktop was different compared to mobile. I used the file_selector package, which provides a unified API for choosing files on all supported platforms. However, some desktop-specific features, like multi-file selection, required extra effort to implement.

Example: Picking a file on desktop.

import 'package:file_selector/file_selector.dart'; 

 Future<void> pickFile() async { 
  final XFile? file = await openFile(acceptedTypeGroups:
 [     XTypeGroup(label: 'images', extensions: ['jpg', 'png']) 
  ]); 
  if (file != null) {   
  print('Selected file: ${file.path}'); 
  } }

Benefits of Flutter for Desktop

1. Single Codebase: One of the biggest advantages of using Flutter for desktop development is that you can use a single codebase for mobile, web, and desktop. This drastically reduces development time and makes maintaining consistency across platforms easier. Code reusability is one of the strongest reasons to consider Flutter for cross-platform development, as it allows for easier updates and feature parity across all supported platforms.
2. Hot Reload: Just like with mobile development, Flutter’s hot reload feature is a huge productivity boost when building desktop apps. It allowed me to iterate quickly and test changes instantly, which was especially helpful during the UI tweaking phase. Being able to see changes in real-time reduced the friction often associated with desktop development and made the development cycle much faster.
3. UI Consistency: Flutter’s rendering engine ensures that the UI looks consistent across different desktop platforms. This helps in maintaining a uniform user experience, which is crucial for cross-platform apps. The consistency provided by Flutter’s widgets means that users will have the same visual experience whether they are using the app on macOS, Windows, or Linux.
4. Access to Native Features: Using plugins and platform channels, Flutter allows you to access native features that are specific to the operating system. This means you can still implement platform-specific functionality without compromising the cross-platform nature of your app.

Conclusion

Developing a desktop application using Flutter was an exciting journey that allowed me to expand my skills beyond mobile development. While there are challenges such as adapting mobile-centric widgets for desktop use, handling different input methods, and dealing with limited plugin support, the benefits of using a single codebase and Flutter’s powerful UI toolkit outweigh the drawbacks. With continued improvements and growing community support, Flutter is becoming a viable option for building beautiful cross-platform desktop applications.

If you’re already familiar with Flutter for mobile, transitioning to desktop development is a natural next step. Just be prepared to address platform-specific challenges and embrace the differences in user interaction models that come with desktop environments. The experience of adapting your Flutter skills to desktop will broaden your understanding of cross-platform development and open new possibilities for creating applications that reach a wider audience.

With more plugins and better support for desktop features being developed regularly, Flutter is quickly becoming a go-to solution for developers who need to create applications that run seamlessly across multiple platforms, including mobile, web, and desktop. As the ecosystem matures, I expect Flutter’s desktop capabilities to grow stronger, making it an even more attractive choice for developers looking to build high-quality, cross-platform applications with a single codebase.

Originally published on Medium on November 16, 2024.