Windows UI Library
User interface API, part of Windows Runtime
Windows UI Library (WinUI codenamed "Jupiter", and also known as UWP XAML and WinRT XAML) is a user interface API that is part of the Windows Runtime programming model that forms the backbone of Universal Windows Platform apps (formerly known as Metro-style or Immersive) for the Windows 8, Windows 8.1, Windows 10 and Windows Phone 8.1 operating systems. It enables declaring user interfaces using Extensible Application Markup Language (XAML) technology.
WinUI is one of the multiple UI frameworks provided built-in for the Windows Runtime; the others being HTML5 (e.g., via WinJS) and DirectX.
WinUI 2 is an extension library for UWP XAML containing controls and styling that match the Windows 11 design language. It is shipped through NuGet and is distinct from the UWP XAML framework, which provides the actual rendering engine; though, they may be treated as synonyms.
WinUI 3 decouples WinRT XAML from the operating system as a separate package to be updated quickly and make new features work on older versions of Windows. It is part of Windows App SDK (codenamed "Project Reunion"), a Microsoft effort to reconcile the Windows desktop (Win32) and the UWP low IL app model.
01Windows Phone
Up to Windows Phone 8.0 WinRT XAML was not supported and XAML applications were based on Silverlight XAML and deployed in XAP format.
In Windows Phone 8.1 WinRT XAML is available along with improved Windows Runtime support. This convergence between platforms enable Universal apps that can target both Windows 8.1 and Windows Phone 8.1 while sharing most of the code, including user interface. The Windows Phone 8.1 is still capable of running Silverlight XAML apps and new features and API were also added to this too (called Silverlight 8.1)
Sources and credits
This article is adapted from the Wikipedia article “Windows UI Library”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
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