androidx.compose.material3.windowsizeclass

@ExperimentalMaterial3WindowSizeClassApi
@Composable
fun calculateWindowSizeClass(activity: Activity): WindowSizeClass

import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.material3.windowsizeclass.WindowWidthSizeClass
import androidx.compose.material3.windowsizeclass.calculateWindowSizeClass

class MyActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            // Calculate the window size class for the activity's current window. If the window
            // size changes, for example when the device is rotated, the value returned by
            // calculateSizeClass will also change.
            val windowSizeClass = calculateWindowSizeClass(this)
            // Perform logic on the window size class to decide whether to use a nav rail.
            val useNavRail = windowSizeClass.widthSizeClass > WindowWidthSizeClass.Compact

            // MyScreen knows nothing about window size classes, and performs logic based on a
            // Boolean flag.
            MyScreen(useNavRail = useNavRail)
        }
    }
}