gtk-kn provides Kotlin/Native bindings for GTK, its dependencies, and additional GObject-based libraries. GTK is a
cross-platform GUI toolkit offering a complete set of widgets for building graphical applications. Kotlin/Native allows
Kotlin code to compile to native code across multiple platforms.
Note: This project is in development and not yet production-ready. Contributions are welcome!
A basic "Hello World" example that opens a window with a button and a signal handler:
private const val APP_ID = "org.gtkkn.samples.gtk.helloworld"
fun main() {
// Create a new application
val app = Application(APP_ID, ApplicationFlags.FLAGS_NONE)
// Connect to "activate" signal of `app`
app.onActivate {
// Create a button with label and margins
val button = Button()
button.setLabel("Click me!")
button.setMargins(12)
// Connect to "clicked" signal of `button`
button.onClicked {
// Set the label to "Hello World!" after the button has been clicked on
button.setLabel("Hello World!")
}
// Create a window and set the title
val window = ApplicationWindow(app)
window.setTitle("My GTK App")
window.setChild(button)
// Present window
window.present()
}
// Run the application
app.runApplication()
}For more details, see the Documentation and Examples.
Comprehensive documentation for gtk-kn is available at gtk-kn.org, with a mirror
at gtk-kn.github.io. If issues are found, please report them on the project’s GitLab
page.
If you’re interested in contributing, review our contributing guidelines and code of conduct before getting started.
We’re actively seeking contributors with experience in C, GTK, or GObject who are interested in supporting the gtk-kn
project. We’re particularly focused on enhancing features that require in-depth knowledge of GTK and GObject internals,
such as In/Out parameter handling and GPointer support.
If you’re skilled in these areas or simply enthusiastic about contributing to Kotlin/Native GTK bindings, we’d love to collaborate! Whether you can offer occasional insights or are interested in taking on specific tasks, your help is greatly appreciated.
Feel free to reach out via the GitLab issue tracker.
To build the project, follow the setup instructions here.
Documentation on deploying bindings to Maven local is available here.
The samples directory contains example applications demonstrating the GTK bindings in Kotlin/Native.
See the project board for our roadmap and progress updates.
The gir module contains a generator that parses GObject Introspection .gir files and generates Kotlin code in the
bindings modules. By default, bindings are generated for all supported libraries from .gir files in
/usr/share/gir-1.0/.
Run the generator with:
./gradlew gir:runTo clean generated bindings:
./gradlew cleanBindingsTo revert uncommitted changes to the generated bindings:
./gradlew revertBindingsModules under bindings/ house generated code for supported libraries. Generated code resides in
org.gtkkn.bindings.<library-name>, with additional support code in org.gtkkn.extensions.<library-name>.
Our focus is on Linux (CI tests every change on Arch Linux, Fedora, openSUSE Tumbleweed and the latest Ubuntu LTS). Other distributions should also work. Windows and macOS support are planned.
- GObject's classes are generated as Kotlin classes
- GObject's interfaces are generated as Kotlin interfaces
- Class and interface methods are generated as Kotlin methods on the Kotlin class/interface
- Where possible, class constructors are implemented as constructors on the Kotlin class
- Other constructors are generated as static factory functions on the companion object
- Signals on classes, interfaces and other types can be used through
on<SignalName>()methods on the Kotlin class - GObject class properties are generated as Kotlin properties
- GObject records (C structs) are generated as Kotlin classes
- GObject's enumerations are generated as Kotlin enum classes
- GObject bitfields are generated as Kotlin enum classes with additional support methods for using them as flags
- Standalone library functions are generated as methods in a Kotlin Object named after the library
- Methods using the GLib
GErrormechanism will return aResult<T>where the failure case throwable is of typeGlibException - Constructors using the GLib
GErrormechanism will throwGlibExeption GlibExceptionprovides access to the underlyingErrorwhich is a wrapper for theGErrorstruct- GLib error domains are generated as enum classes, so they can be used in exhaustive when statements
Currently, the generator does not handle versions and deprecation information. For this reason it is important to make
sure the gir files used for generating, and the installed system library versions used by cinterop (in /usr/include/)
are in sync.
While generating, the generator can encounter top-level types and functions it does not support yet. These are logged in
a skip file named <library-name>-skips.txt in the modules build folder.
When the generator encounters methods, properties or child types that it does not support, it will log these in a dedicated section in the KDoc for the containing type.
Automatic GObject reference counting and ownership management is on our roadmap.
User-defined subclassing for GObject and GtkWidget types is supported with basic features; more advanced functionality is planned.
A Gradle plugin is in development to support compiling resources, schemas, and packaging. Meson support for GNOME/GTK ecosystem integration is also planned.
The "kn" in gtk-kn stands for Kotlin/Native, chosen to align with similar projects like gtk-rs for Rust.
Reach us on Matrix or via the GitLab issue tracker.
This project is licensed under the GNU Lesser General Public License v2.1 (LGPLv2.1). However, different sections are licensed as follows:
- Documentation:
docs/- CC-BY-SA 4.0. - Samples:
samples/- MIT License.