Is there a compose equivalent to `android:keepScreenOn`?

# compose

[André Kindwall]

Is there a compose equivalent to android:keepScreenOn?

[knthmn]

You can get the activity from LocalContext, and use DisposableEffect() to create a composable that when in the composition tree, prevents the screen from being turned off.

@Composable
fun KeepScreenOn() {
    val activity = findFromContext<Activity>()!!
    val flag = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
    DisposableEffect(activity) {
        activity.window.addFlags(flag)
        onDispose {
            activity.window.clearFlags(flag)
        }
    }
}

@Composable
inline fun <reified T> findFromContext(): T? {
    var context = LocalContext.current
    while (context !is T) {
        context = (context as? ContextWrapper)?.baseContext ?: return null
    }
    return context
}

[André Kindwall]

Thanks! It works perfectly but I modified it a little bit

@Composable
fun KeepScreenOn(content: @Composable () -> Unit) {
    val window = LocalWindow.current

    DisposableEffect(window) {
        window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
        onDispose {
            window.clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON)
        }
    }

    content()
}

[Adam Powell]

You could skip the content parameter entirely and simply call this with no parameters somewhere in your UI, there's not much benefit in having other UI be child content of it. Since you're effectively modifying a root view parameter, you might also look for a way to stash a reference count with the root view, say in a view tag or something, so that you don't end up with strange results if there's more than one instance of this composable in your composition

[Chuck Stein]

@André Kindwall Is LocalWindow something you created yourself? I don't see it documented anywhere, but would love a way to access the window from a Composable!

[knthmn]

Pretty sure he created it himself. You can get Window from LocalContext.

[Chuck Stein]

@knthmn Does it require casting the Context as an Activity? Is that always guaranteed to be safe?

[knthmn]

Similar code is used by BackHandler for searching OnBackPressedDispatcherOwner from the context.
https://androidx.tech/artifacts/activity/activity-compose/1.3.0-alpha05-source/androidx/activity/compose/BackHandler.kt.html
https://androidx.tech/artifacts/activity/activity-compose/1.3.0-beta01-source/androidx/activity/compose/ActivityComposeUtils.kt.html

If you use your composables from a fragment you need to handle it separately.

[knthmn]

An alternative is to provide Window as a composition local