How to make CircularProgressIndicator background transparent

Question

I am trying to show an CircularProgressIndicator in my login screen. When I enter username and password and click the login button I need to show a CircularProgressIndicator at the center of screen with the login screen still visible. I am able to show CircularProgressIndicator but it's covering the entire screen with white background. I want it to have a transparent background.

CircularProgressIndicator(
    modifier = Modifier
        .fillMaxSize()
        .wrapContentSize(Alignment.Center)
)

Answer 1

It seems that the CircularProgressIndicator has a white background because it is pushing away the content instead of displaying above it.

To show a CircularProgressIndicator above the LoginScreen, you can use Box Composables. Please try out the following code:

@Composable
fun LoadingScreen() {
    Box(
        modifier = Modifier.fillMaxWidth(),
        contentAlignment = Alignment.Center,
    ) {

        var isLoading by remember {
            mutableStateOf(true)
        }

        Column(
            verticalArrangement = Arrangement.spacedBy(12.dp)
        ) {
            TextField(value = "Username", onValueChange = {})
            TextField(value = "Password", onValueChange = {})
            Button(onClick = { /*TODO*/ }) {
                Text(text = "Login")
            }
        }
        if (isLoading) {
            // This Box Composable makes a light overlay, it is optional
            Box(
                modifier = Modifier.matchParentSize().background(Color.Gray.copy(alpha = 0.5f))
            )
            CircularProgressIndicator()
        }
    }
}

Output:

Answer 2

Create a new Composable ProgressOverlay like this:

@Composable
fun ProgressOverlay() {
    Box(
        modifier = Modifier
            .fillMaxSize()
            .clickable {  }
            .background(MaterialTheme.colorScheme.background.copy(alpha = 0.5f)),
        contentAlignment = Alignment.Center
    ) {
        CircularProgressIndicator()
    }
}

Then in you screen:

@Composable
fun MyLoginScreen() {
    Surface(
        modifier = Modifier
            .fillMaxSize()
    ) {
        //MyLoginScreenContent()
        
        ProgressOverlay()
    }
}

Note: The ProgressOverlay should be added at the end of the page content to always show above the other components.

I have also added an empty clickable in the ProgressOverlay so that the user can't interact with the rest of the UI while the circular progress indicator is shown.