MewUI

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😺 MewUI is a cross-platform and lightweight, code-first .NET GUI framework aimed at NativeAOT.

🧪 Experimental Prototype

[!IMPORTANT]
This project is a proof-of-concept prototype for validating ideas and exploring design directions.
As it evolves toward v1.0, APIs, internal architecture, and runtime behavior may change significantly.
Backward compatibility is not guaranteed at this stage.

🤖 AI-Assisted Development

[!NOTE] This project was developed using an AI prompt–driven workflow.
Design and implementation were performed through iterative prompting without direct manual code edits,
with each step reviewed and refined by the developer.

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🚀 Try It Out

No clone. No download. No project setup.
You can run MewUI immediately with a single command on Windows, Linux or macOS. (.NET 10 SDK required)

[!TIP] This is the quickest way to try MewUI without going through the usual repository and project setup steps.

curl -sL https://raw.githubusercontent.com/aprillz/MewUI/refs/heads/main/samples/FBASample/fba_gallery.cs -o - | dotnet run -

[!WARNING] This command downloads and executes code directly from GitHub.

Video

https://github.com/user-attachments/assets/fc2d6ad8-3317-4784-a6e5-a00c68e9ed3b

Screenshots

| Light | Dark | |---|---| | | |

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✨ Highlights

• 📦 NativeAOT + trimming first
• 🪶 Lightweight by design (small EXE, low memory footprint, fast first frame)
• 🧩 Fluent C# markup (no XAML)

🚀 Quickstart

• NuGet: https://www.nuget.org/packages/Aprillz.MewUI/

  • Aprillz.MewUI is a metapackage that bundles Core, all platform hosts, and all rendering backends.
  • Platform-specific packages are also available: Aprillz.MewUI.Windows, .Linux, .MacOS
  • Install: dotnet add package Aprillz.MewUI
  • See: Installation & Packages

• Single-file app (VS Code friendly)

  • See: samples/FBASample/fba_calculator.cs

  • Minimal header (without AOT/Trim options):

    #:sdk Microsoft.NET.Sdk
    #:property OutputType=Exe
    #:property TargetFramework=net10.0
    
    #:package Aprillz.MewUI@0.10.3
    
    // ...
    

• Run: dotnet run your_app.cs

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🧪 C# Markup at a Glance

• Sample source: https://github.com/aprillz/MewUI/blob/main/samples/MewUI.Sample/Program.cs

   var window = new Window()
       .Title("Hello MewUI")
       .Size(520, 360)
       .Padding(12)
       .Content(
           new StackPanel()
               .Spacing(8)
               .Children(
                   new Label()
                       .Text("Hello, Aprillz.MewUI")
                       .FontSize(18)
                       .Bold(),
                   new Button()
                       .Content("Quit")
                       .OnClick(() => Application.Quit())
               )
       );
  
   Application.Run(window);
  

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🎯 Concept

MewUI is a code-first GUI framework with four priorities:

• NativeAOT + trimming friendliness
• Small footprint, fast startup, low memory usage
• Fluent C# markup for building UI trees (no XAML)
• AOT-friendly binding

Non-goals (by design):

• WPF-style animations, visual effects, or heavy composition pipelines
• A large, “kitchen-sink” control catalog (keep the surface area small and predictable)
• Complex path-based data binding
• Full XAML/WPF compatibility or designer-first workflows

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✂️ NativeAOT / Trim

• The library aims to be trimming-safe by default (explicit code paths, no reflection-based binding).
• Windows interop uses source-generated P/Invoke (LibraryImport) for NativeAOT compatibility.
• On Linux, building with NativeAOT requires the AOT workload in addition to the regular .NET SDK (e.g. install dotnet-sdk-aot-10.0).
• If you introduce new interop or dynamic features, verify with the trimmed publish profile above.

To check output size locally:

• Publish: dotnet publish .\samples\MewUI.Gallery\MewUI.Gallery.csproj -c Release -p:PublishProfile=win-x64-trimmed
• Inspect: .artifacts\publish\MewUI.Gallery\win-x64-trimmed\

Reference (Aprillz.MewUI.Gallery.exe @v0.10.0)

• win-x64: ~3,545 KB
• osx-arm64: ~2,664 KB
• linux-arm64: ~3939 KB

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🔗 State & Binding (AOT-friendly)

Bindings are explicit and delegate-based (no reflection):

using Aprillz.MewUI.Binding;
using Aprillz.MewUI.Controls;

var percent = new ObservableValue<double>(
    initialValue: 0.25,
    coerce: v => Math.Clamp(v, 0, 1));

var slider = new Slider()
            .BindValue(percent);
var label  = new Label()
            .BindText(percent, v => $"Percent ({v:P0})");

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🧱 Controls / Panels

Controls (Implemented):

• Button
• Label, Image
• TextBox, MultiLineTextBox
• CheckBox, RadioButton, ToggleSwitch
• ComboBox, ListBox, TreeView, GridView
• Slider, ProgressBar, NumericUpDown
• TabControl, GroupBox
• MenuBar, ContextMenu, ToolTip (in-window popups)
• ScrollViewer
• Window, DispatcherTimer

Panels:

• Grid (rows/columns with Auto, *, pixel)
• StackPanel (horizontal/vertical)
• DockPanel (dock edges + last-child fill)
• UniformGrid (equal cells)
• WrapPanel (wrap + item size)
• SplitPanel (drag splitter)

All panels except SplitPanel support Spacing.

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🎨 Theme

MewUI uses a Theme object (colors + metrics) and ThemeManager to control defaults and runtime changes.

• Configure defaults before Application.Run(...) via ThemeManager.Default*
• Change at runtime via Application.Current.SetTheme(...) / Application.Current.SetAccent(...)

See: docs/Theme.md

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🖌️ Rendering Backends

Rendering is abstracted through:

• IGraphicsFactory / IGraphicsContext

Backends:

| Backend | Platform | Package | |---------|----------|---------| | Direct2D | Windows | Aprillz.MewUI.Backend.Direct2D | | GDI | Windows | Aprillz.MewUI.Backend.Gdi | | MewVG | Windows | Aprillz.MewUI.Backend.MewVG.Win32 | | MewVG | Linux/X11 | Aprillz.MewUI.Backend.MewVG.X11 | | MewVG | macOS | Aprillz.MewUI.Backend.MewVG.MacOS |

MewVG is a managed port of NanoVG, using OpenGL on Windows/Linux and Metal on macOS.

Backends are registered by the referenced backend packages (Trim/AOT-friendly). In app code you typically either:

• call *Backend.Register() before Application.Run(...), or
• use the builder chain: Application.Create().Use...().Run(...)

When using a metapackage (e.g., Aprillz.MewUI.Windows), you can select a single backend at publish time with -p:MewUIBackend=Direct2D. See Installation & Packages for details.

🪟 Platform Abstraction

Windowing and the message loop are abstracted behind a platform layer.

Currently implemented:

• Windows (Aprillz.MewUI.Platform.Win32)
• Linux/X11 (Aprillz.MewUI.Platform.X11)
• macOS (Aprillz.MewUI.Platform.MacOS)

Linux dialogs dependency

On Linux, MessageBox and file dialogs are currently implemented via external tools:

• zenity (GNOME/GTK)
• kdialog (KDE)

If neither is available in PATH, MewUI throws: PlatformNotSupportedException: No supported Linux dialog tool found (zenity/kdialog).

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📄Docs

• Installation & Packages
• C# Markup
• Binding
• Items and Templates
• Theme
• Application Lifecycle
• Layout
• RenderLoop
• Hot Reload
• Custom Controls

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🧭 Roadmap (TODO)

Platforms

• [ ] Linux/Wayland
• [x] macOS

Tooling

• [x] Hot Reload
• [ ] Design-time preview