coroutines/org.gtkkn.coroutines/GtkDispatcher

GtkDispatcher

Provides a dispatcher for GTK's main loop.

Work dispatched via this dispatcher is guaranteed to be executed on GTK's main/UI thread.

Note: To use Dispatchers.Main with GTK, you need to inject GtkDispatcher as the main dispatcher. This can be done using internal APIs:

@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
Dispatchers.setMain(GtkDispatcher)

A feature request for a stable API to set the main dispatcher is being tracked here: Kotlin Coroutines Issue #4286.

Bootstrapping Example

When starting a GTK application, you need to initialize the GTK environment on a dedicated thread and set up the main dispatcher. Here's a simplified example:

fun main() = runBlocking {
    // Bootstrap GTK on a dedicated thread
    val gtkMainThread = newSingleThreadContext("GTK-Main")

    // Inject GtkDispatcher as the Main dispatcher
    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
    Dispatchers.setMain(GtkDispatcher)

    // Start the GTK application
    withContext(gtkMainThread) {
        // Initialize GTK application and start the main loop
        val application = Application("com.example.myapp", ApplicationFlags.DEFAULT_FLAGS)
        application.onActivate {
            // Launch coroutines on the GTK main dispatcher
            CoroutineScope(Dispatchers.Main).launch {
                // Your UI code here
            }
        }
        application.onShutdown {
            GtkDispatcher.cancel()
            gtkMainThread.cancel()
    }
        application.run()
    }
}

In this example:

We create a dedicated thread (gtkMainThread) for bootstrapping GTK.
Inject GtkDispatcher as Dispatchers.Main to ensure coroutines use the GTK main loop.
Use withContext(gtkMainThread) to initialize GTK on the dedicated thread.
Launch coroutines using Dispatchers.Main for UI interactions.