Scaffold
In Material Design, a scaffold is a fundamental structure that provides a standardized platform for complex user interfaces. It holds together different parts of the UI, such as app bars and floating action buttons, giving apps a coherent look and feel.
Example
The Scaffold
composable provides a straightforward API you can use to
quickly assemble your app's structure according to Material Design guidelines.
Scaffold
accepts several composables as parameters. Among these are the
following:
topBar
: The app bar across the top of the screen.bottomBar
: The app bar across the bottom of the screen.floatingActionButton
: A button that hovers over the bottom-right corner of the screen that you can use to expose key actions.
For more detailed examples on how you can implement both top and bottom app bars, see the app bars page.
You can also pass Scaffold
content as you would to other containers. It passes
an innerPadding
value to the content
lambda that you can then use in child
composables.
The following example provides a full example of how you might implement
Scaffold
. It contains a top app bar, bottom app bar, and a floating action
button that interacts with Scaffold
's internal state.
@Composable fun ScaffoldExample() { var presses by remember { mutableIntStateOf(0) } Scaffold( topBar = { TopAppBar( colors = topAppBarColors( containerColor = MaterialTheme.colorScheme.primaryContainer, titleContentColor = MaterialTheme.colorScheme.primary, ), title = { Text("Top app bar") } ) }, bottomBar = { BottomAppBar( containerColor = MaterialTheme.colorScheme.primaryContainer, contentColor = MaterialTheme.colorScheme.primary, ) { Text( modifier = Modifier .fillMaxWidth(), textAlign = TextAlign.Center, text = "Bottom app bar", ) } }, floatingActionButton = { FloatingActionButton( presses++ }) { Icon(Icons.Default.Add, contentDescription = "Add") } } ) { innerPadding -> Column( modifier = Modifier .padding(innerPadding), verticalArrangement = Arrangement.spacedBy(16.dp), ) { Text( modifier = Modifier.padding(8.dp), text = """ This is an example of a scaffold. It uses the Scaffold composable's parameters to create a screen with a simple top app bar, bottom app bar, and floating action button. It also contains some basic inner content, such as this text. You have pressed the floating action button $presses times. """.trimIndent(), ) } } }
This implementation appears as follows: