Microsoft continually releases new tools and updates to its existing software to make it easier for developers to build Windows 10 apps. Now, the company has announced the Windows UI (WinUI) Library Preview for developers building apps for its Universal Windows Platform (UWP).
WinUI allows developers to access and use Fluent controls, styles, and other UWP XAML controls via NuGet packages. This release is important because previously, the UWP XAML app development framework was made available and updated only through the Windows and SDK rollout, which severely limited its potential.
Furthermore, other advantages of these NuGet packages is that they facilitate developers in building "version adaptive" apps, software that can target multiple releases of Windows 10 and is backward-compatible from Windows 10 version 1607 to the latest Insider builds.
WinUI's contents include Fluent Design components like Acrylic material and Reveal highlighting. It also features the TreeView control as a separate class, allowing for more freedom of use across different versions of Windows 10, as well as more features than the standard SDK. Furthermore, it contains new controls like MenuBar and CommandBarFlyout too. Lastly, it boasts the Microsoft.UI.Xaml.Core.Direct package, which is a standalone WinRT library, offering lower-level access to the XAML framework.
Microsoft is currently releasing WinUI packages as prerelease, however, future rollouts will also include RTM versions. The company says that:
The prerelease versions are fully functional for testing and evaluation purposes, but we recommend using the RTM versions for production apps.
Not all of the XAML platform is in WinUI. For future versions we’re evaluating moving more of the XAML platform to WinUI packages, and are also exploring options for moving our development process to an open source model on GitHub.