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README.md

nativeapi for Go

Native desktop APIs for Go, backed by the libnativeapi C ABI through cgo. The generated API covers windows, views, menus, tray icons, displays, keyboard, dialogs, preferences and the other APIs currently exposed by the C ABI.

This is a source-checkout binding for macOS, Windows and Linux. It is not yet published as a standalone Go module: the headers and CMake build require the workspace's core/ submodule. No third-party Go dependencies are required.

Build

Requires Go 1.22+, cgo enabled, CMake 3.24+, and a C/C++ compiler. macOS needs Xcode command-line tools. Linux also needs GTK 3, X11 and XI development packages:

sudo apt-get install cmake pkg-config build-essential libgtk-3-dev libx11-dev libxi-dev

From the workspace root:

git submodule update --init core
cmake -S bindings/go -B bindings/go/build -DCMAKE_BUILD_TYPE=Release
cmake --build bindings/go/build --config Release --parallel
cd bindings/go
go test ./...

On Windows, build the native library with Visual Studio's CMake generator and use a MinGW-w64 C compiler for cgo (CC=gcc). Add bindings\go\build to PATH when running Go tests or examples so Windows can find nativeapi_go.dll. The Go-side C allocations are freed by the same C runtime that allocated them; native outputs are freed by the core. macOS and Linux embed the checkout's bindings/go/build location as an rpath. To distribute an application, ship the native shared library and configure its loader path for your installation.

Linux tests and window examples require a desktop session; in headless CI use xvfb-run -a go test ./... (install xvfb).

Usage

A local consumer uses this module path with a replacement pointing to the checkout:

require github.com/libnativeapi/nativeapi/bindings/go v0.0.0
replace github.com/libnativeapi/nativeapi/bindings/go => /path/to/nativeapi/bindings/go
package main

import (
	"fmt"
	. "github.com/libnativeapi/nativeapi/bindings/go"
	"runtime"
)

func main() {
	runtime.LockOSThread()
	Init()
	prefs, err := NewPreferencesWithScope("my-app")
	if err != nil {
		panic(err)
	}
	defer prefs.Release()
	if err := prefs.Set("theme", "dark"); err != nil {
		panic(err)
	}
	fmt.Println(prefs.Get("theme", "system"))
	if err := PollEvents(0); err != nil {
		panic(err)
	}
}

The examples use a dot import (. "github.com/libnativeapi/nativeapi/bindings/go") to call exported APIs without a package prefix.

The generated API follows Go's naming conventions:

  • Getters omit Get: window.Title(), prefs.Keys(), DisplayManager.All(). Lookup operations named Get keep that name, for example prefs.Get(key, fallback).
  • KeyboardAccelerator.String() implements fmt.Stringer. Initialisms use ID, URL, OS and UI, and parameters use lowerCamelCase.
  • Constructors return (*T, error). Overloads use concise names: NewShortcut(id, options), NewShortcutWithCallback(id, accelerator, callback), NewPreferencesWithScope(scope) and NewWindowFromNative(pointer).
  • Native singletons are exported values with methods, such as DisplayManager.All() and Application.Run(). Their implementation types are private, and the values hold no owned handles. Static methods on regular types remain package functions. Overloaded lookups name the key, such as ShortcutManager.GetByID(id) and ShortcutManager.GetByAccelerator(accelerator).
  • Fallible boolean operations return error: prefs.Set(key, value), window.Close() and menu.RemoveItem(item). Predicates including Contains, IsVisible, HasShadow and CanOpen keep returning bool.
  • Object factories and registration return (*T, error). Object getters keep returning *T, with nil for absence. The C ABI cannot distinguish absence from some getter failures; the binding does not invent an error cause.

Errors from native failures include the operation name and wrap ErrOperationFailed; errors.Is(err, ErrOperationFailed) recognizes them. ErrInvalidArgument covers binding-level validation, such as a nil listener callback or a negative event-poll timeout. Native boolean/handle failures do not carry a detailed cause in the C ABI, so the binding reports only the failure. Structured results, such as URLOpenResult, retain the native error code and message when the API provides them.

Enums have typed constants such as TitleBarStyleNormal. Default parameters remain explicit Go arguments. Optional strings use *string (nil means absent). Inherited views embed *View; pass label.View to root.AddSubview. Release() drops an owned reference, while Window.Close() closes the window.

Threads, events and ownership

Call runtime.LockOSThread from main or init, then Init on the main goroutine before other native APIs. Create, use and release native objects on that thread. Application.Run() / Application.RunWithWindow(window) runs the native loop. Use Dispatch(func() { ... }) to schedule UI work from other goroutines and check its returned error. Console tools can call PollEvents(timeout) on the main thread instead, where timeout is a time.Duration (for example 10*time.Millisecond). Do not call PollEvents inside an already running native event loop.

AddListener receives a Go function and returns (ListenerID, error). RemoveListener returns an error for an unknown listener ID. Callbacks run synchronously on the UI thread and should return quickly without panicking. Events have a Type discriminator, common fields and the fields for each variant; only the active variant's fields are populated. Remove listeners when done. Callback contexts are kept alive with runtime/cgo.Handle stored in C memory (see runtime/cgo.Handle) and released through the core's release hook, including failure and replacement paths. Reclamation may be deferred until the event loop is serviced.

Call Release for every successful reference returned by a constructor, getter, factory or object list. Getters return nil for invalid handles. List arrays are freed by the binding while ownership of their handles transfers to Go. Copies of a wrapper share release state; releasing one invalidates those copies. Release is safe to repeat and accepts nil receivers. There are no automatic object finalizers. Strings, lists, maps and value structs are copied into Go and native outputs are freed automatically. Event handle fields are borrowed until the callback returns; use EventRequest.Defer inside the callback to obtain an owned EventDecision when an asynchronous decision is needed.

Examples and generation

After building the shared library, run either example from its own directory:

cd examples/go_display_example
go run .
# Or: cd examples/go_window_example && go run .
# The window example also accepts --smoke for a self-closing runtime check.

From the workspace root:

./codegen bindings --lang go
./codegen check --lang go

The Go SDK (gofmt) is required when generating or checking Go output. nativeapi.gen.go and bridge.gen.h are generated from the same IR as every other binding; edit the generator or C++ headers, then regenerate. runtime.go, src/runtime.cpp and the build configuration are hand-written.

Contributing

Development happens in nativeapi, which holds every binding and the code generator and checks out the core library as a submodule:

git clone --recursive https://github.com/libnativeapi/nativeapi.git

Files marked AUTO-GENERATED. DO NOT EDIT. are generated from the C++ headers in nativeapi. To change the API, send a pull request there; maintainers regenerate the bindings.