5 Avalonia Features That Make WPF Devs Jealous

For years, Windows Presentation Foundation (WPF) has been the go-to framework for building rich, desktop applications on Windows. Its powerful data binding, flexible styling, and mature ecosystem have made it a favorite among .NET developers. However, the development landscape is constantly evolving, Avalonia has emerged a strong contender, capturing the attention and, dare we say, a hint of envy from the WPF crowd.

Avalonia is an open-source, cross-platform UI framework that allows .NET developers to build beautiful and performant applications for Windows, macOS, Linux, WebAssembly, Android, and iOS, all from a single codebase. While WPF remains a strong choice for Windows-centric development, Avalonia boasts several features that address some of WPF's long-standing limitations and offer a more modern and versatile approach to UI development.

If you're a seasoned WPF developer, you might be wondering what all the fuss is about. Prepare to have your interest piqued as we delve into five Avalonia features that are likely to make you look over the fence with a touch of jealousy.

1. True Cross-Platform: Write Once, Run Everywhere (Seriously)

This is undoubtedly Avalonia's crown jewel and the most significant differentiator from WPF. While WPF is firmly rooted in the Windows ecosystem, Avalonia breaks free from these shackles, offering a truly cross-platform solution. Imagine crafting a stunning user interface and, with minimal platform-specific tweaks, deploying it seamlessly across Windows, macOS, and a variety of Linux distributions.

But Avalonia doesn't stop there. It extends its reach to the web through WebAssembly (WASM), enabling you to run your .NET desktop application directly in the browser. And if that wasn't enough, mobile support for Android and iOS is also a reality. This unparalleled level of platform support opens up a world of possibilities for .NET developers. You can now target a much broader audience without the need to maintain separate codebases or learn entirely new frameworks for each platform.

For WPF developers who have long wished for a way to bring their applications to other operating systems without a complete rewrite, Avalonia's cross-platform capabilities are a dream come true. The ability to share a vast majority of your UI code and business logic across diverse platforms is a massive productivity booster and a significant competitive advantage. Think of the reduced development time, streamlined maintenance, and the expanded market reach – it's enough to make any WPF developer consider a change of scenery.

2. A Styling System That Breathes Modernity

WPF's styling and templating system is undeniably powerful, but it can also be verbose and, at times, a bit cumbersome. Avalonia, on the other hand, introduces a more modern and flexible styling system that draws inspiration from the familiar and widely adopted Cascading Style Sheets (CSS).

This CSS-like approach brings several advantages. Firstly, it often leads to more concise and readable styling code. Selectors allow you to target controls based on their type, name, classes, and even their relationship to other controls in the visual tree. This makes it easier to apply styles consistently across your application and manage complex styling scenarios.

Let's look at a simple example: changing a Button's background color when the mouse hovers over it.
WPF:

<Style TargetType="Button">
    <Setter Property="Background" Value="LightGray"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}">
                    <ContentPresenter HorizontalAlignment="Center"
                                    VerticalAlignment="Center"/>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Style.Triggers>
        <Trigger Property="IsMouseOver" Value="True">
            <Setter Property="Background" Value="DarkGray"/>
        </Trigger>
    </Style.Triggers>
</Style>

Avalonia:

<Style Selector="Button">
    <Setter Property="Background" Value="LightGray"/>
</Style>

<Style Selector="Button:pointerover">
    <Setter Property="Background" Value="DarkGray"/>
</Style>

Notice how much more succinct the Avalonia version is. It leverages pseudo-classes like :pointerover (similar to CSS's :hover), eliminating the need for ControlTemplate and Style.Triggers for this common scenario.

This conciseness extends to conditional styling based on data. In WPF, you'd typically use DataTriggers, which can become quite verbose. Avalonia allows you to apply classes conditionally, leading to cleaner XAML.

WPF (DataTrigger):

<Style TargetType="TextBlock">
    <Setter Property="Foreground" Value="Black" />
    <Style.Triggers>
        <DataTrigger Binding="{Binding IsError}" Value="True">
            <Setter Property="Foreground" Value="Red" />
        </DataTrigger>
    </Style.Triggers>
</Style>

Avalonia (Conditional Class):

<Style Selector="TextBlock.error">
    <Setter Property="Foreground" Value="Red"/>
</Style>

<TextBlock Text="Something might be wrong"
           Classes.error="{Binding IsError}"

In the Avalonia example, we define a style for the .error class and then conditionally apply that class based on the IsError property. This approach feels more aligned with web development practices and often results in more maintainable styling code.

Furthermore, Avalonia's styling system offers features like hierarchical styling, where styles can inherit from one another, and attached properties, which allow you to extend the styling capabilities of existing controls without modifying their source code. This level of flexibility empowers developers to create truly unique and visually appealing user interfaces with greater ease.

For WPF developers who have sometimes found themselves wrestling with complex style definitions or wishing for a more intuitive way to apply and manage styles, Avalonia's modern and flexible styling system is a breath of fresh air. It offers a more streamlined and developer-friendly approach to UI customization, making it easier to achieve the desired look and feel for your applications.

3. Performance 🚀

WPF applications perform well on Windows, thanks to its reliance on DirectX for rendering. Avalonia, with its focus on running on low-powered devices, has been designed from the ground up with performance in mind across all its supported targets.

Avalonia employs a highly optimized rendering pipeline that leverages the power of the GPU for smooth and responsive user interfaces. It utilizes Skia, a 2D graphics library developed by Google, which is known for its high performance and cross-platform capabilities. This allows Avalonia applications to achieve excellent rendering performance, even on less powerful hardware and across different operating systems.

Furthermore, Avalonia's architecture is designed to be lightweight and efficient. It avoids many of the legacy dependencies and overhead that can sometimes bog down WPF applications. This focus on performance translates into a snappier user experience, faster startup times, and smoother animations, regardless of whether your application is running on a high-end Windows desktop or a resource-constrained Linux device.

For WPF developers who have encountered performance bottlenecks or struggled to achieve consistent performance across different Windows environments, Avalonia's commitment to cross-platform performance is a compelling proposition. The ability to deliver a smooth and responsive user experience across all supported platforms without a significant performance hit is a significant advantage in today's diverse technological landscape.

4. WebAssembly: Your .NET Desktop App in a Browser

This is a feature that truly pushes the boundaries of what's possible with a .NET UI framework. Avalonia's support for WebAssembly (WASM) allows you to take your existing .NET desktop application and run it directly within a web browser. This opens up a whole new realm of possibilities for application deployment and accessibility.

Imagine being able to share your complex, feature-rich .NET application with users simply by providing them with a URL. No installation required, no platform-specific considerations – just a seamless experience within their web browser. This is a game-changer for many scenarios, including:

• Internal Tools and Dashboards: Easily deploy internal applications to your team without worrying about individual installations or operating system compatibility.

• Demos and Trials: Provide potential customers with an interactive demonstration of your software directly on your website.

• Cloud-Based Applications: Build powerful, client-side applications that leverage the benefits of web deployment.

While there are other ways to build web applications with .NET, Avalonia's WASM support offers a unique advantage: it allows you to leverage your existing XAML and C# skills to build web experiences that have the look and feel of a desktop application. For WPF developers who have invested years in mastering these technologies, this is an incredibly attractive proposition. The ability to extend their existing expertise to the web without a steep learning curve is a significant productivity win. The setup involves targeting the netX.Y (where X.Y is your .NET version) and browser-wasm TFM (Target Framework Moniker) in your project file and including the necessary Avalonia packages. While a deep dive into the code is beyond this article, the ability to add browser-wasm to your project's TargetFrameworks and see your XAML-based UI run in a browser is a powerful motivator.

5. An Open-Source Heart and a Thriving Community

WPF, while part of the open-source .NET ecosystem, still has strong ties to Microsoft and its development processes. Avalonia, on the other hand, is a truly open-source project. This fosters a vibrant and active community of developers who are passionate about the framework and actively contribute to its development and improvement.

This open-source nature brings several benefits. Firstly, it means that Avalonia is constantly evolving and improving at a rapid pace. New features are added, bugs are fixed, and performance enhancements are made through the collaborative efforts of the community. This ensures that Avalonia stays up-to-date with the latest trends and technologies in UI development.

Secondly, the open-source community provides a valuable resource for developers. Whether you're looking for help with a specific problem, want to learn about best practices, or simply want to connect with other Avalonia developers, you'll find a welcoming and supportive community ready to assist you. This can be a significant advantage, especially when compared to the sometimes more formal and less accessible support channels for proprietary frameworks.

For WPF developers who appreciate the benefits of open-source software and enjoy being part of a collaborative community, Avalonia's open-source heart and thriving community are a major draw. The ability to contribute to the framework's development, learn from other developers, and be part of a passionate and engaged community can be a very rewarding experience.

Is It Time to Make the Switch?

WPF remains a powerful and relevant framework for building Windows desktop applications. However, as the demand for cross-platform solutions and modern UI experiences continues to grow, Avalonia presents a compelling alternative. Its true cross-platform capabilities, modern styling system, impressive performance, WebAssembly support, and vibrant open-source community offer a glimpse into the future of .NET UI development.

If you're a WPF developer who finds yourself increasingly constrained by the limitations of a Windows-only world or yearning for a more modern and flexible approach to UI development, it might be time to give Avalonia a closer look.

While "jealousy" might be a strong word, there's no denying that Avalonia offers some truly enticing features that are sure to capture the attention and perhaps even a touch of envy from even the most seasoned WPF veterans. So, why not explore what Avalonia has to offer? You might just find yourself falling in love with a new way to build beautiful and performant applications for every platform.