What is Avalonia?
Avalonia is a powerful framework that enables developers to create cross-platform applications using .NET. It uses its own rendering engine to draw UI controls, ensuring consistent appearance and behavior across different platforms such as Windows, macOS, Linux, Android, iOS, and WebAssembly. This means developers can share their UI code and maintain a unified look and feel across different target platforms.
The Permissiveness and Convenience of the MIT License
The MIT License is a concise and permissive open-source software license. It allows users to freely use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the software. Users must include the copyright notice and permission notice in all copies or substantial portions of the software. The MIT License imposes very few restrictions on users, essentially granting them a high degree of freedom. It is suitable for various open-source projects, encourages code sharing and reuse, and promotes the rapid development of software technology.
Both Dotnet and Avalonia are under the MIT License, with the relevant code repositories:
- Dotnet: https://github.com/microsoft/dotnet
- Avalonia: https://github.com/AvaloniaUI/Avalonia
Semi.Avalonia and Ursa.Avalonia
(I) Semi.Avalonia - The Enchanting Realization of Theme Style
Semi.Avalonia is an exquisite presentation of the Semi Design theme style under the Avalonia UI framework, open-sourced under the MIT License. It brings a unique visual style to applications, like a beautiful painting, adding rich color and texture to the user interface.

Its repository address: https://github.com/irihitech/Semi.Avalonia
(II) Ursa.Avalonia - The Innovative Power of Custom Controls
Paired with the Ursa.Avalonia custom control library, also under the MIT License, it becomes even more powerful. Together, they create new visual and functional experiences for developers, as if opening a door to endless possibilities on the development journey.

Repository address: https://github.com/irihitech/Ursa.Avalonia
Performance in the Field of Xinchuang and Domestic Operating Systems
It is worth mentioning that these two libraries perform excellently in the field of Xinchuang and domestic operating systems. They have completed compatibility mutual certification with Loongson 3A6000 and LoongArch™, which is an important achievement in promoting autonomous and controllable domestic technologies.
The following information is quoted from the WeChat public account [Yihong Technology] article dated August 2nd, "Ursa and Semi Officially Complete LoongArch Compatibility Mutual Certification":
The two Avalonia control sets, BigBear Ursa and Semi, have completed compatibility mutual certification with Loongson 3A6000 and LoongArch™. This important milestone marks new progress in advancing autonomous and controllable domestic technologies.

Screenshots of Some Controls
Although each control has its own characteristics, they all showcase unique charm. Here are a few simple screenshots to give you a glimpse:
Overview of the Semi.Avalonia theme library:

Overview of the Ursa.Avalonia custom control library:

Practical Case Sharing
The webmaster's company project uses these controls, though it is inconvenient to show screenshots. However, you can refer to the tool CodeWF.Toolbox written by the webmaster using Avalonia UI with this theme and control library:
Repository: https://github.com/dotnet9/CodeWF.Toolbox
This utility uses Avalonia + Prism 8 modular development, with the file structure after AOT publishing:

It features both light and dark themes, creating different visual atmospheres:
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It also implements internationalization functionality, providing a convenient experience for global users:

Additionally, it includes practical JSON beautification and YAML to JSON conversion tools, shown in the following images:
JSON Beautification Tool

YAML to JSON Tool

Usage Experience Sharing
- Official Documentation
- Semi Documentation: https://docs.irihi.tech/semi
- Ursa Documentation: https://docs.irihi.tech/ursa/
- Reading Source Code
First, clone the control repository (the address is given above), and search based on the Readme and Demo run results. For example, if you find the Warning effect of the Button impressive:

Open the repository using VS Code or Visual Studio:

- Expand Semi.Avalonia.Demo
- Find the Pages directory and open ButtonDemo.axaml
- Locate the desired style based on interface keywords like Solid, Warning
In this way, you can easily master these excellent controls, adding efficiency and charm to your development work. I hope this article provides useful guidance and inspiration for your exploration of Avalonia open-source control libraries, helping you create even more amazing applications on your development journey.

