ComponentActivity

ComponentActivity provides lower-level building blocks for composing higher-level activity components. It keeps that foundation small so components can work together without a deep activity hierarchy or strong coupling.

Its exposed helpers let you add an existing view, initialize view-tree owners, refresh a menu after a state change, and enable edge-to-edge display.

Use it when…

Use ComponentActivity when you are composing activity components and need these content, menu, or display helpers.

How it behaves

ComponentActivity is an open, main-actor-isolated subclass of Activity. The inherited Activity.onCreate calls body() and then buildUI() when it builds the content.

All four helpers log and return when the activity context is missing. addContentView also returns immediately if the supplied view has no underlying instance. enableEdgeToEdge returns with a debug log if the AndroidX edge-to-edge class cannot be loaded.

Examples

Display a ready message

import Droid

final class ReadyActivity: ComponentActivity {
    override var body: BodyBuilder.Result {
        TextView("Ready")
    }
}

Install existing content

This function accepts a view and layout params that already exist. Initialize the view-tree owners before adding the content so inflation and attach listeners see the owners already present.

@MainActor
func installContent(
    in activity: ComponentActivity,
    view: View,
    layoutParams: LayoutParams
) {
    activity.initializeViewTreeOwners()
    activity.addContentView(view, layoutParams)
}

Methods

addContentView

Adds an existing view with the supplied layout params through the underlying activity call. The view must have an underlying instance; otherwise the call returns without adding it.

@MainActor
func addContent(to activity: ComponentActivity, view: View, layoutParams: LayoutParams) {
    activity.addContentView(view, layoutParams)
}

initializeViewTreeOwners()

Sets view-tree owners before content is set. Call it before installing content, as in the example above.

@MainActor
func prepareContent(in activity: ComponentActivity) {
    activity.initializeViewTreeOwners()
}

invalidateMenu()

Invalidates the menu so its displayed state matches its current internal state. Call it after a menu state change, such as removing or disabling an item in response to a user event.

@MainActor
func menuStateDidChange(in activity: ComponentActivity) {
    activity.invalidateMenu()
}

enableEdgeToEdge()

Enables edge-to-edge display for the activity. If androidx/activity/EdgeToEdge cannot be loaded, the call logs a debug message and returns.

@MainActor
func enableEdgeToEdgeDisplay(in activity: ComponentActivity) {
    activity.enableEdgeToEdge()
}