Plumix

Flutter-inspired UI framework for .NET — build declarative, widget-based UIs in C# or F# with Flutter's Widget/Element/RenderObject architecture.

plumix.net · NuGet packages

Vision

• Keep Widget/Element/RenderObject architecture as close as practical to Flutter.
• Make rewriting controls from Flutter (Dart) to C# straightforward, with minimal conceptual translation.
• Reuse Avalonia mostly as platform infrastructure: app/window host, lifecycle, input plumbing, and drawing backend abstractions.
• Keep layout and paint behavior inside this framework's render layer.

Definition of Done

1. App UI is built with Flutter-like widgets and lifecycle primitives (StatefulWidget, State, SetState, reconciliation).
2. Render/layout/paint behavior is framework-owned (RenderObject/RenderBox/render pipeline), not Avalonia-control-driven UI logic.
3. Samples demonstrate real framework usage via widget host flow, not only low-level render demos.
4. Core primitives are stable and close enough to Flutter semantics for practical Dart-to-C# control porting.

Project Tracking

• Changelog: CHANGELOG.md
• Global implementation status and roadmap: docs/FRAMEWORK_PLAN.md
• AI-oriented context map and workflows: docs/ai/MODULE_INDEX.md
• Additional packages: Plumix.Packages

Example

C#

using Avalonia.Media;
using Plumix.Widgets;

namespace MyApp;

public sealed class MyApp : StatelessWidget
{
    public override Widget Build(BuildContext context)
    {
        return new Scaffold(
            body: new Center(
                child: new Column(
                    mainAxisAlignment: MainAxisAlignment.Center,
                    children:
                    [
                        new Text(
                            "Hello, Plumix!",
                            style: new TextStyle(fontSize: 32, fontWeight: FontWeight.Bold)
                        ),
                        new SizedBox(height: 16),
                        new Text("Flutter-like widgets, powered by .NET and Avalonia."),
                        new SizedBox(height: 24),
                        new ElevatedButton(
                            onPressed: () => { /* handle tap */ },
                            child: new Text("Get Started")
                        )
                    ]
                )
            )
        );
    }
}

F#

Plumix also ships first-class F# support: Plumix.FSharp provides Feliz-style Ui.* widget factories, and Plumix.Elmish hosts a standard Elmish (MVU) program as a widget — Plumix's own element reconciliation does the diffing, so there is no extra virtual-DOM layer.

open Elmish
open Plumix.Elmish
open Plumix.FSharp

type Model = { Count: int }
type Msg = Increment

let init () = { Count = 0 }, Cmd.none

let update msg model =
    match msg with
    | Increment -> { model with Count = model.Count + 1 }, Cmd.none

let view model dispatch =
    Ui.scaffold (
        appBar = Ui.appBar (titleText = "Hello, Plumix!"),
        body =
            Ui.center (
                Ui.column (
                    mainAxisAlignment = MainAxisAlignment.Center,
                    spacing = 12.0,
                    children = [
                        Ui.text ("Hello, Plumix!", fontSize = 32.0, fontWeight = FontWeight.Bold)
                        Ui.text "Flutter-like widgets, powered by .NET and Avalonia."
                        Ui.text (string model.Count, fontSize = 24.0)
                    ])),
        floatingActionButton =
            Ui.floatingActionButton (child = Ui.icon Icons.Add, onPressed = fun () -> dispatch Increment))

/// The MVU program as a plain Plumix widget — mount it anywhere in a widget tree.
let app () : Widget =
    Program.mkProgram init update view |> Program.toWidget

Prefer classic Flutter style? StatefulWidget/SetState work from F# too — see src/Sample/Plumix.FSharpSample for both variants side by side.

Contributing

Plumix is developed AI-first: code contributions are expected to be produced with a frontier coding agent (Claude Opus 4.8, GPT-5.5, or newer). Bug reports and discussions are welcome from everyone. See CONTRIBUTING.md for the workflow, commands, and PR checklist.

Looking for something to work on? docs/CUPERTINO_TODO.md lists the Cupertino widgets that still need porting — pick one, claim it, and send a PR.