From WPF to Avalonia: A Guide for .NET Developers Exploring Cross-Platform UI Frameworks

A comprehensive guide to introduce Avalonia, a cross-platform UI framework to .NET developers familiar with WPF. Comparing key features, exploring the transition process.

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Mike James

Introduction

As a .NET developer proficient in WPF (Windows Presentation Foundation), you've likely harnessed the power and flexibility of this robust UI framework to create beautiful and performant Windows applications. But in today's diverse computing landscape, the ability to develop cross-platform applications has become increasingly crucial as more and more people migrate away from using Windows. What if you could leverage your existing WPF skills to create stunning, cross-platform applications? Enter Avalonia, the next evolution in .NET UI development.

In this comprehensive guide, we'll explore how Avalonia empowers WPF developers to reuse their existing skills, compare key features, examine the transition process, and highlight the benefits of adopting Avalonia.

Understanding Avalonia: The Cross-Platform WPF v2

Avalonia is a powerful, open-source UI framework that brings the familiarity of WPF to the world of cross-platform development. If you're comfortable with WPF, you'll find yourself right at home with Avalonia. Let's delve into the key features that make Avalonia a natural progression for WPF developers:

XAML-based UI

Just like in WPF, you'll define your user interfaces using XAML in Avalonia. This declarative approach to UI design allows for a clear separation of concerns between design and business logic. The syntax is nearly identical, making the transition seamless for WPF developers. Here's a quick comparison:

As you can see, the syntax is almost identical, allowing you to transfer your existing experience with XAML development directly to Avalonia. 

Familiar Controls

Avalonia comes with a rich set of modern UI controls, providing a comprehensive toolkit for creating sophisticated and interactive user interfaces. These controls are designed to be familiar to WPF developers, easing the transition to cross-platform development. The framework offers a wide array of controls, from basic elements like buttons and text inputs to more complex controls such as data grids and tree views. This extensive collection ensures that developers can create feature-rich applications without the need for extensive third-party libraries. Moreover, Avalonia apps provide consistent behaviour and appearance across different operating systems. Below is a list of the most commonly used controls: 

These controls behave similarly to their WPF counterparts, allowing you to create complex UIs without having to learn an entirely new set of components. In many cases, you can simply copy and paste your WPF XAML into an Avalonia project, make a few changes and you’re ready to run. 

Data Binding

Data binding, a core feature of WPF, is fully supported in Avalonia. This powerful mechanism allows you to create dynamic, data-driven UIs with ease. Avalonia supports various binding modes, including:

  • OneWay
  • TwoWay
  • OneTime
  • OneWayToSource

Here's an example of data binding in Avalonia:

<TextBox Text="{Binding UserName}" />

This should look very familiar to WPF developers, as the syntax is identical.

MVVM Pattern

Avalonia fully embraces the Model-View-ViewModel (MVVM) pattern, a cornerstone of modern WPF development. This architectural pattern allows for clean separation of concerns, making your code more maintainable and testable. Our .NET templates come with ReactiveUI, but it's entirely optional, with many developers opting to use the newer MVVM Toolkit.  You’re not limited to just these two though, you can bring almost any MVVM library, or roll your own. 

Styles and Templates

Customising your UI with styles and control templates is a crucial aspect of both WPF and Avalonia development. Avalonia's styling is the most obvious departure from WPF. There are two ways to style controls in Avalonia, Styles and ControlTheme. A Style is a CSS-like style, which like CSS, use Selectors. Here's a simple example of a style in Avalonia:

Styles

ControlThemes are more like the traditional WPF-Styles, and are typically used to create themes for lookless controls. You can learn more about our styles in our documentation

From WPF UserControl to Avalonia

Creating custom controls is a common task in WPF development, and Avalonia makes this process just as straightforward. Let's compare the creation of a UserControl in both frameworks:

WPF vs Avalonia XAML

As you can see, the structure and syntax are nearly identical, with only minor differences in namespace declarations. This similarity extends to the code-behind files as well, making the transition from WPF to Avalonia UserControls almost effortless.

Why Choose Avalonia as Your WPF UI Framework Alternative?

Now that we've explored the similarities between WPF and Avalonia, let's examine the compelling reasons to consider Avalonia for your next project:

Cross-Platform Compatibility

Unlike WPF, which is Windows-only, Avalonia runs on Windows, macOS, and Linux, iOS, Android and the Web. This cross-platform capability allows you to reach a broader audience with a single codebase, saving time and resources in development and maintenance. 

Modern Architecture

Avalonia is built with modern .NET in mind, supporting .NET Core and .NET 5+. This modern foundation ensures better performance, improved security, and access to the latest .NET features and optimizations. For some context on how cutting edge Avalonia is, we were already testing on NET9 before NET8 had been released as stable. 

Active Development and Community Support

With a thriving community and regular updates, Avalonia is continuously improving and expanding its capabilities. Avalonia is a future-looking framework, with a roadmap that extends out to the next decade. This active ecosystem ensures that you'll have access to the latest features, bug fixes, and community-driven extensions.

Performance

Avalonia is designed to be lightweight and performant, even on lower-end devices such as embedded HMIs. This focus on efficiency makes it an excellent choice for applications that need to run smoothly across a wide range of hardware configurations. We view performance as a critical feature of the framework. We’re constantly working to ensure that Avalonia remains the most performant cross-platform UI technology available to .NET developers. 

Extensibility

Like WPF, Avalonia allows you to create custom controls and extend existing ones. This flexibility enables you to tailor the framework to your specific needs and create unique, branded experiences for your users. You can see jus a few of the community build custom controls on the Awesome Avalonia GitHub Repository.

Mobile Development

While WPF is limited to desktop applications, Avalonia supports mobile development for iOS and Android . We even have a proof-of-concept that enables using Avalonia without the Mono Runtime, which provides significant performance improvements! The ability to take your WPF skills to create truly cross-platform applications that run on desktop and mobile devices is a huge advantage for organisations looking for a WPF replacement. 

Transitioning from WPF to Avalonia: Best Practices

While the transition from WPF to Avalonia is relatively smooth, there are some best practices to keep in mind:

  1. Leverage Your XAML Knowledge: Your existing XAML skills will transfer well to Avalonia. Start by recreating familiar UI layouts and gradually explore Avalonia-specific features.
  2. Explore Avalonia-Specific Controls: While many controls are similar, Avalonia offers some unique controls like the NativeMenuBar for creating native-looking menus across platforms.
  3. Adapt to Styling Differences: While styling in Avalonia is similar to WPF, there are some differences. Spend time understanding Avalonia's styling system, particularly around selectors and pseudoclasses.
  4. Embrace Cross-Platform Design: When designing your UI, consider how it will look and function across different platforms. Avalonia provides tools to create adaptive layouts that work well on various operating systems.
  5. Utilise Avalonia's Documentation and Community Resources: Take advantage of Avalonia's comprehensive documentation and active community forums. These resources can be invaluable when transitioning from WPF.

Introducing Avalonia XPF: Bridging WPF and Avalonia

For developers deeply invested in WPF but looking to modernise their applications, Avalonia offers a solution: Avalonia XPF. This allows you to run your existing WPF applications on non-Windows platforms with little to no changes to your codebase.

Key benefits of Avalonia XPF include:

  1. Code Reuse: Leverage your existing WPF codebase on other platforms without a rewrite. This can save significant time and resources in the transition to cross-platform development.
  2. Optional Gradual Migration: Transition your application to full Avalonia at your own pace, bit by bit. This allows for a phased approach to modernisation, reducing risk and allowing for continuous delivery of features.
  3. Expanded Market: Reach macOS and Linux users without maintaining separate codebases. This can significantly increase your potential user base without a proportional increase in development effort.
  4. Future-Proofing: Prepare your application for a cross-platform future while preserving your current investment in WPF. This strategic approach ensures that your application remains relevant and accessible as the computing landscape evolves.
  5. Familiar Development Experience: Continue using your preferred WPF development tools and practices while still targeting new platforms. This smooth transition path helps maintain team productivity during the migration process.

How Avalonia XPF Works

Avalonia XPF acts as a compatibility layer between your WPF application and the Avalonia framework. It is a cross-platform fork of WPF, with the unmanaged composition engine of WPF replaced with Avalonia. 

This approach allows for a high degree of compatibility, including ensuring that your 3rd party dependencies will continue to work. 

If you’re interested in trying Avalonia XPF, then get in touch with us to start a trial. 

Conclusion: Embracing the Future of .NET UI Development

As we've explored in this comprehensive guide, Avalonia offers a compelling path forward for WPF developers looking to expand into cross-platform development. With its familiar XAML-based approach, rich set of controls, and powerful features like data binding and MVVM support, Avalonia provides a natural evolution for your WPF skills.

The benefits of adopting Avalonia are clear:

  • Reach a wider audience with cross-platform compatibility
  • Leverage your existing WPF knowledge and skills
  • Enjoy improved performance and modern architecture
  • Future-proof your applications for the evolving computing landscape

And with Avalonia XPF, the barrier to entry for cross-platform development has never been lower for WPF developers. You can begin your journey to cross-platform development while preserving your investment in existing WPF applications.

Whether you're looking to create new cross-platform applications from scratch or breathe new life into existing WPF projects, Avalonia provides a powerful, familiar framework for .NET developers. As the software development landscape continues to evolve, embracing cross-platform technologies like Avalonia will be crucial for staying competitive and meeting the diverse needs of modern users.

Ready to take your WPF skills cross-platform? Dive into Avalonia today and unlock a world of possibilities for your .NET applications. The future of UI development is here, and it's more accessible than ever for WPF developers like you.