Microsoft’s Project Reunion unifies old and new Windows apps
For years, Microsoft has tried to get developers to build Windows apps using its new Universal Windows Platform (UWP) rather than old-school Win32. At the online-only Build 2020 conference, the company unveiled Project Reunion, which aims to marry the two.
The old style still dominates the Windows app landscape, but UWP apps (as the name suggests) can easily be adapted to work not just on Windows computers, but also on Xbox consoles, the web, and even HoloLens. The downside is that they don’t work on the discontinued Windows 7 operating system, which doesn’t have an app store.
Project Reunion can also equip UWP apps with support for new input options such as touch and pen, in addition to mouse and keyboard. It allows coders to add swipe gestures that not only work on a Windows 10 touchscreen but also on an iPad.
Much of this cross-platform support comes from one of Project Reunion’s main components: WinUI 3, a UI framework that uses Fluent design controls and styles. Its predecessor was only available for UWP apps, but the new version also supports Win32 code. According to Microsoft, “WinUI 3 decouples the XAML, Composition, and Input layers from Windows 10.” In his Build demo, Kevin Gallo, Development Platform Manager at Microsoft, also showed off a nifty input box trick, where you can use mathematical operators and the app does the math for you. So if the form input is for square footage, you can just enter 12×21 and have the app calculate it.
Building a modern UWP app with Project Reunion (Image: Microsoft)
During Build 2017, I reported on the tools the company had produced to help convert Win32 apps to UWP apps. Reunion extends and expands on this initiative, adding Microsoft 365 Graph and WebView components as well as app compartmentalization through things like NuGet, a shared repository for .NET packages. Another current component of the Reunion Project is MSIXa modern application packaging tool.
WebView2 is now in preview, with the first stable release “approaching fast,” Gallo said. Not only does WebView2 allow you to access and display web content in your application, but also PDF files. As with WinUI 3, WebView2 is decoupled from Windows, meaning it doesn’t require a particular version of Windows. As you’d expect, WebView2 is powered by the new Edge browser built on Chromium code.
Microsoft’s Kevin Gallo showcases new coding tools at Build 2020 (Image: Microsoft)
The last current component of Project Reunion is Windows Virtual Desktop (WVD). According to Gallo, “WVD empowers remote work and education solutions for your Windows apps on iOS, Mac, Android, Linux and, of course, Windows.” It adapts WinUI programs to look native on those devices and can also take advantage of the tablet’s cameras and mic. WVD also benefits from the scalability of Azure, allowing you to add many users, while MSIX will allow for simplified deployment on these non-Windows platforms as well as Windows 10.
Interested developers can check out Project Reunion’s various pieces of code for themselves at its GitHub repository.
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