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Xui

Xui is a native .NET UI application framework built around a Canvas-based 2D drawing API.

It targets Windows, macOS, iOS, Android, and Browser from a single C# codebase — compiled ahead-of-time with the .NET AoT compiler, with no reflection at runtime.

What Xui is

  • A thin, high-performance rendering layer over each platform's native 2D API (Direct2D, CoreGraphics, Canvas).
  • A layout engine with a View tree that drives measure, arrange, and render passes.
  • A cross-platform input model unified over pointer, keyboard, and scroll events.
  • A testable architecture — the abstract layer has no platform dependencies and can be driven by an SVG renderer in unit tests.

What Xui is not

  • Not XAML. There are no XML templates or data-binding pipelines.
  • Not Blazor. There is no DOM, no JavaScript interop, no HTML.
  • Not WinUI, MAUI, or Avalonia. No shared control library built on platform controls.
  • Not a game engine. Though the Canvas API is similar to HTML5 Canvas, the layout system is designed for app UIs.

Key design choices

Abstract / Actual split. The core framework (Xui.Core) has zero platform dependencies. Platform runtimes (Xui.Runtime.Windows, Xui.Runtime.macOS, …) implement the actual interfaces. This makes the entire UI layer unit-testable without a GPU.

No boxing on the hot path. Fill styles (LinearGradient, ImagePattern) are ref struct values passed directly to the context methods — never boxed through an interface.

Service chain instead of static globals. Views request platform services (IImage, ITextMeasureContext) through IServiceProvider walking up the view tree to the window, then to the platform runtime. No statics, no singletons in the core.

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