Documentation
ArionUI is one engine that draws millions of records without creating a UI control for any of them. These pages cover getting it running, declaring what it shows, and how it is put together.
ArionUI is an early preview: version 0.1.0-preview.1, and the API still moves. The packages are on nuget.org; the open source is on GitHub. Everything below is written against the code, and every sample on these pages was compiled against it. Samples call a few helpers that stand for your own application — Log, Open, Save and the like.
Start here
git clone https://github.com/ArionUI/ArionUI
cd ArionUI
dotnet run --project samples/ArionUI.Sample.AvaloniaThat opens a window with a million generated orders. Click the Id or Amount header to sort, type into the filter row under the headers, drag a caption to reorder. Install and first grid takes it apart and puts a grid in your own window.
ArionUI Core is open source under Apache-2.0: the engine, the table, card and tree views, the Skia renderer and the Avalonia and WPF hosts. ArionUI Pro is a set of closed-source NuGet packages — grouping, pivot, charts, 3D charts, timeline, planning, conditional formatting, layout persistence and export. They are free of charge during the preview, also for commercial use, with no key and no watermark. Where a page shows something that needs a Pro package, it says which one.
What is in here
The chapters on the left follow the order in which a grid is built. In short:
- Install and first grid
- What you need, the packages for Avalonia and WPF, the WinForms host from source, and the smallest program that shows a working grid.
- Columns · Data sources · Views
- What the grid shows: columns declared once with their behaviour, the source that feeds them — lists, live collections, feeds, server queries, master-detail, trees — and the view that draws them as a table, cards, a tree or a pivot.
- The grid API
grid.Api, the one facade on every host: state, selection, editing, commands, events, filters, panes and presentation hooks.- Editing · Selection · Sorting and filtering · Keyboard and accessibility
- What the user does with it — editors, validation and undo; ranges and the clipboard; sort, filter row, value filters and search; every key, and the screen-reader layer.
- Localisation · Theming · MVVM · Hosting · Performance
- Texts and cultures (German by default), themes and style rules, bindable properties and commands, the three hosts and the GPU path, and what keeps a grid fast in your own code.
- Board · Styling · Controls · Control surface · Modernise an app
- Whole windows, in preview: the layout grid, style sheets with a cascade, the drawn controls, controls outside a grid on all three hosts, and a guide for putting a new UI on an existing WinForms or WPF application.
- Pro modules
- One page per package — grouping, pivot, charts, 3D charts, timeline, planning, conditional formatting, layout persistence, export — each with its install command and the call that switches it on, and the preview licence.
- Architecture · What it does not do yet · FAQ · Release notes
- How the layers are cut, the gaps written down rather than left to be discovered, the questions of the first hour, and what this version contains. Every type and member is in the API reference.
Why the row count does not matter
Most grids build a piece of the interface for every row and then work to keep up as rows pile in. ArionUI builds none of them: it draws the rows that fit on the screen and nothing else. Sorting and filtering are index projections over your list — SortFilterSource in front of it — so they reorder integers and never copy your data. Grouping and pivot, which are Pro packages, sit in the same chain.
| Frame cost while scrolling | 1,000 rows | 1,000,000 rows |
|---|---|---|
| Avalonia | 1.28 ms | 1.33 ms |
| WPF | 0.88 ms | 0.93 ms |
Median frame cost while scrolling with the mouse wheel, a 1400 × 900 grid on the GPU path, Intel laptop GPU (i7-11800H, UHD Graphics), best of three runs per host, measured on 3 October 2026 with the host benchmark of the development repository. Your data itself is yours: the grid holds an index over it, not a copy.
Licence
ArionUI Core is published under the Apache License 2.0, patent grant included. The source, the backlog and the open issues are on GitHub: github.com/ArionUI/ArionUI. ArionUI Pro is closed source and ships under a preview licence that is free of charge, including for commercial use; the licence text travels in each package.