# WinUI 3 — Modern Native UI Framework for Windows Apps

> Build polished Windows desktop applications using Microsoft's latest native UI framework with Fluent Design, XAML, and the Windows App SDK.

## Install

Save as a script file and run:

# WinUI 3 — Modern Native UI Framework for Windows Apps

## Quick Use
```bash
# Requires Visual Studio 2022 with Windows App SDK workload
dotnet new winui3 -n MyWinUIApp
cd MyWinUIApp
dotnet build
dotnet run
```

## Introduction
WinUI 3 is Microsoft's native UI framework for building modern Windows desktop and UWP applications. It provides the full Fluent Design System, XAML markup, and a comprehensive control library as part of the Windows App SDK, decoupled from the OS update cycle so developers can ship the latest UI components regardless of the user's Windows version.

## What WinUI 3 Does
- Provides the official Fluent Design control library for Windows desktop applications
- Ships as a NuGet package via the Windows App SDK, independent of Windows OS releases
- Supports XAML markup and C#/C++ for building rich, accessible user interfaces
- Includes modern input handling with touch, pen, mouse, and keyboard support
- Renders UI using DirectComposition and Direct2D for smooth 60fps animations

## Architecture Overview
WinUI 3 is the UI layer of the Windows App SDK (formerly Project Reunion). It sits on top of the Windows composition engine, using DirectComposition for GPU-accelerated rendering and XAML Islands for hosting modern controls. The framework decouples UI components from the OS by shipping as a redistributable package. Applications reference WinUI via NuGet, and the runtime resolves to the installed Windows App SDK version on the target machine.

## Self-Hosting & Configuration
- Install Visual Studio 2022 with the Windows App SDK / WinUI workload or use the .NET CLI with WinUI templates
- Create a project using `dotnet new winui3` or the Visual Studio project wizard
- Add controls via XAML markup or C# code-behind using the `Microsoft.UI.Xaml` namespace
- Package for distribution using MSIX for Store deployment or unpackaged for sideloading
- Customize Fluent theming through resource dictionaries and the `Application.Resources` section

## Key Features
- Complete Fluent Design System with Mica, Acrylic, rounded corners, and smooth animations out of the box
- Rich control library: NavigationView, TreeView, InfoBar, BreadcrumbBar, and 60+ controls
- Hot Reload for XAML and C# during debugging for rapid UI iteration
- Accessibility built in with UI Automation, high contrast themes, and screen reader support
- Decoupled from OS releases so apps can use latest controls on older Windows 10 versions

## Comparison with Similar Tools
- **WPF** — Mature Windows UI framework; WinUI 3 is its successor with Fluent Design and modern rendering
- **UWP** — Sandboxed app model with WinUI 2; WinUI 3 removes sandbox restrictions for desktop apps
- **Avalonia** — Cross-platform .NET UI; WinUI 3 is Windows-only but offers deeper OS integration and official Fluent Design
- **Electron** — Web-tech desktop apps; WinUI 3 is native with lower memory usage and OS-native look and feel
- **MAUI** — Cross-platform .NET framework that uses WinUI 3 on Windows but adds iOS/Android/macOS targets

## FAQ
**Q: Does WinUI 3 work on Windows 10?**
A: Yes. WinUI 3 supports Windows 10 version 1809 (build 17763) and later through the Windows App SDK.

**Q: Can I migrate an existing WPF application to WinUI 3?**
A: WinUI 3 XAML is similar but not identical to WPF XAML. Microsoft provides migration guidance and XAML Islands for incremental adoption.

**Q: Is WinUI 3 open source?**
A: Yes. The WinUI library (microsoft-ui-xaml) is open source under the MIT license on GitHub.

**Q: Can I use WinUI 3 with C++ instead of C#?**
A: Yes. WinUI 3 supports both C# and C++/WinRT for application development.

## Sources
- https://github.com/microsoft/microsoft-ui-xaml
- https://learn.microsoft.com/en-us/windows/apps/winui/winui3/

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Source: https://tokrepo.com/en/workflows/asset-3f30933f
Author: Script Depot