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SOC-0028: Implement a Jetpack Compose Renderer for GTK 4 ​

Project size: 3 months

Estimated difficulty: Hard

  • Experience with Kotlin & Kotlin/Native
  • Familiarity with Jetpack Compose runtime and compiler plug‑ins
  • Knowledge of GTK 4, Libadwaita, and the GObject type system
  • Competence in C/C++ interop, memory management, and build tooling (Gradle, Meson)
  • Understanding of coroutine scheduling and UI main‑loop architectures
  • Comfort with Linux development environments and debugging native code

Description ​

Jetpack Compose for Desktop currently rasterises its widgets through Skia, so Linux applications miss out on GTK’s native look‑and‑feel, accessibility tree, and theming.

This project will create a Compose runtime renderer that maps composables directly to real GTK 4 / Libadwaita widgets via the gtk‑kn Kotlin/Native bindings.

Key tasks:

  1. Runtime glue Implement GtkNode, GtkWidgetApplier, and a custom MonotonicFrameClock that schedule recomposition on the GTK main thread.
  2. Widget wrappers Provide Compose‑style primitives (Text, Button, Column, Row, TextField, Image, Window) that delegate to their GTK/Adwaita counterparts while exposing the familiar Compose API.
  3. Tooling & distribution Publish the renderer to Maven Central, add a Gradle template for new projects, and supply documentation so developers can implementation("dev.compose:compose-gtk:★") and start coding immediately.

With this renderer, a Kotlin snippet like:

main.kt
kt
Window("Compose GTK") {
    Column {
        Text("Hello Libadwaita")
        Button("Click Me") { /* ... */ }
    }
}

will yield a fully native Adwaita window indistinguishable from a C/Vala application.

Expected Results ​

  • A production‑ready compose‑gtk library (JVM + native artifacts)
  • Core widget set with recomposition‑safe property updates
  • Frame‑stable performance (≥60 FPS) on sampled list scrolling and layout stress tests
  • Sample applications demonstrating state management, navigation, and theming with CSS
  • CLI/Gradle plugin that scaffolds new projects and bundles resources

Stretch Goals ​

  • Libadwaita adaptive widgets and dark‑mode synchronisation
  • Animation DSL backed by GTK frame clock
  • Hot‑reload development server for instant iterative feedback
  • IntelliJ/VS Code preview plug‑in showing live GTK renditions of composables