What's new in WinUI 3.0?
Unlike WinUI 2.0 and the incremental versions that followed, WinUI 3.0 is a major update featuring more than new and improved controls and libraries to use with UWP and .NET 5 apps. In fact, the primary goal of WinUI 3.0 was not to add new controls and features beyond its current UWP counterparts. For version 3.0, the team has made WinUI a complete UI framework that can sit atop the UWP or Win32 application platforms.
Goodbye UWP?
So, what is happening to UWP? Will my UWP apps stop working?
As previously mentioned, the plan for the UWP UI libraries is to keep providing important security updates, but they will not receive any new features going forward. All new features and updates will be developed for WinUI. New WinUI projects will support all types of Windows UI client. For existing Win32 applications, developers can incrementally upgrade parts of an application to WinUI with the Xaml Islands interop control. New applications will be developed in WinUI with either .NET Core, written in C# or VB, or with native C++. These clients will sit on top of either the Win32 platform or UWP. This is all possible because WinUI is developed completely in C++.
Note
Some features discussed in this book will not be available in the first stable Release To Manufacturing (RTM) version of WinUI 3.0, coming in March 2021 with Project Reunion v0.5. XAML Islands will not be available and UWP clients will not be fully supported initially. For a full list of what is planned for the first stable release of WinUI 3.0, you can reference the team's roadmap on GitHub: https://github.com/microsoft/microsoft-ui-xaml/blob/master/docs/roadmap.md#winui-30-feature-roadmap.
The fact that WinUI is developed in C++ enables React Native for Windows client apps to interoperate with the WinUI platform. Between React Native and the Uno Platform, WinUI has some great cross-platform potential.
Let's look at this new app model in the following screenshot:
Figure 1.9 – The WinUI 3.0 app model
As you can see, there will be multiple paths available for developers to create apps for Windows PCs and tablet devices such as the dual-screen Surface Duo. Other Windows devices, such as Xbox and HoloLens, will need to follow the UWP app model under the WinUI layer.
New features for WinUI 3.0
Are there any new features in WinUI 3.0?
While it sounded like the team was so busy creating a UI framework to replace the UWP UI libraries, they did find some time to add a few new features. The major new control available in version 3.0 is the new WebView2 control based on the Microsoft Edge Chromium browser. Compatibility is also a feature. All XAML and Composition features available in the Spring 2019 Windows SDK will be backward-compatible, back to the Windows Creators update and later.
Project Reunion and WinUI
WinUI 3.0 is bringing UWP and Win32 application developers together on a single set of UI libraries, but that is only the beginning. At Microsoft's Build 2020 conference, the Windows team announced Project Reunion, a long-term plan for bringing all Windows developers together on a single platform. WinUI 3.0 is focused on the UI layer, while Project Reunion will encompass WinUI and the entire Windows developer platform. In 2021, Microsoft will release three versions of Project Reunion and WinUI 3.x, as follows:
- March 2021: The first Project Reunion release, version 0.5, will feature the first supported release of WinUI 3.
- May 2021: This Project Reunion version 0.8 will include several enhancements to WinUI 3.
- October 2021: This will be the Project Reunion 1.0 release, with more improvements to WinUI 3.
To read more about Project Reunion and to follow its progress, you can check out their GitHub repository at https://github.com/microsoft/ProjectReunion. Now, let's see how WinUI compares to other Windows development frameworks.
