Adaptive

Prerequisites

The app must:

• Use Compose for all screens. If it's still using Fragments or Views, suggest using the XML to Compose skill to migrate those screens.
• Use Jetpack Navigation 3. If it doesn't, suggest the Navigation 3 skill to migrate the app.

Workflow to make an app adaptive

To make an app adaptive, follow these steps or a subset of them adapting to the task.

• Step 1: Verify current UI
• Step 2: Make the navigation bar adaptive
• Step 3: Add multi-pane layouts
• Step 4: Make vertical lists adaptive by changing the number of columns
• Step 5: Hide app bars when scrolling

Step 1. Verify current UI

Ensure that screenshot tests exist to verify the current UI on different form factors. If they don't exist, add the Compose Preview Screenshot Testing tool. Use the following annotation to create previews for all the major form factors. For example:

<br />

@Preview(name = "Phone", device = Devices.PHONE, showBackground = true)
@Preview(name = "Foldable", device = Devices.FOLDABLE, showBackground = true)
@Preview(name = "Tablet", device = Devices.TABLET, showBackground = true)
@Preview(name = "Desktop", device = Devices.DESKTOP, showBackground = true)
annotation class FormFactorPreviews

@PreviewTest
@FormFactorPreviews
@Composable
fun FeedScreenPreview() {
    SnippetsTheme {
        Box {
            Text("My Screen")
        }
    }
}
   

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Step 2. Make the navigation bar adaptive

Bottom navigation bars are optimized for touch input when the user is holding a phone in portrait mode. On larger screen hand-held devices, like tablets and unfolded foldables, the navigation area must be accessible from the edge of the screen (navigation rail).

If you need to provide more screen space for the content, hide the navigation area. Examples of this include:

• Hiding the navigation bar when the user scrolls down and showing it again when the user scrolls up. The assumption is that when the user is scrolling down, they are consuming content but when scrolling up they are trying to navigate away from that content.
• Hiding the navigation area when its content is distracting. For example, in camera previews or when displaying a full-screen photo.

When the detail screen is displayed full-screen on mobile, full-screen mode must be deactivated on larger screens.

Steps to migrate:

• Locate the existing navigation bar.
• Convert each item to a NavigationSuiteItem.
• Identify whether the navigation bar's visibility changes. For example, if it is wrapped with an AnimatedContent or AnimatedVisibility composable. If so, follow the guidance in the "Control navigation area visibility".
• Replace the container that held the navigation bar (often a Scaffold) with NavigationSuiteScaffold from the Material 3 adaptive layouts library.
• Supply the navigation items using the navigationItems parameter of NavigationSuiteScaffold.

Step 2.1. Control navigation area visibility

If the navigation bar's visibility changes - it is hidden under certain scenarios or on certain screens - this behavior must be maintained with the adaptive navigation area. This is done using NavigationSuiteScaffold's state parameter.

Steps to migrate:

• Identify the scenarios under which the navigation bar is hidden. This is usually done with a boolean variable for the visibility. Use isNavBarVisible or shouldShowNavBar as the variable name.
• Create an instance of NavigationSuiteScaffoldState using rememberNavigationSuiteScaffoldState() and pass it to NavigationSuiteScaffold.
• When the navigation area visibility changes, use a LaunchedEffect to call show or hide on the NavigationSuiteScaffoldState.

For example:

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// Pass this variable to any composable that needs to control the navigation area visibility
var isNavBarVisible by remember { mutableStateOf(true) }
val scaffoldVisibilityState = rememberNavigationSuiteScaffoldState()

NavigationSuiteScaffold(
    navigationSuiteItems = navItems,
    state = scaffoldVisibilityState
) {
    // Main content
}

LaunchedEffect(isNavBarVisible){
    if (isNavBarVisible) {
        scaffoldVisibilityState.show()
    } else {
        scaffoldVisibilityState.hide()
    }
}
   

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Step 3. Add multi-pane layouts using Navigation 3 Scenes

Analyze the codebase looking for related screens - tapping on something in one screen opens another screen that shows information related to the first. There are two canonical screen relationships: list-detail and supporting pane.

IMPORTANT: You must use the Navigation 3 SceneStrategy approach to implement multi-pane layouts. Do not use ListDetailPaneScaffold or SupportingPaneScaffold.

Step 3.1. List-detail

Identify the list and detail screens

List-detail layouts display a list of items (this is the list screen) and clicking on an item opens a new screen that shows more details about that item (the detail screen).

Typical usage includes productivity apps like email, notes, and messaging.

Unless requested explicitly, avoid this pattern when the detail content requires substantial screen space (e.g., images or media that benefits from a full-screen presentation).

Add a Material list-detail SceneStrategy

• Add the androidx.compose.material3.adaptive:adaptive-navigation3 library
• Create an androidx.compose.material3.adaptive.navigation3.ListDetailSceneStrategy using rememberListDetailSceneStrategy
• Pass the ListDetailSceneStrategy to NavDisplay using its sceneStrategies parameter

Use metadata to identify the list and detail screens

• Add metadata using entry(metadata = ...) or NavEntry(metadata = ...) to the list entry using ListDetailSceneStrategy.listPane(detailPlaceholder = { <placeholder composable> }).
• Use the detailPlaceholder parameter to add a placeholder on the detail screen when no list items are selected.
• Add metadata to the detail entry using ListDetailSceneStrategy.detailPane().

Important considerations

• When a detail screen displays its content full-screen on mobile (content fills the entire screen, bars or rails are hidden), full-screen mode must be deactivated if it's part of a list-detail layout.
• Detail screens must not show a back arrow when on a list-detail layout.

For a reference implementation, check the Nav3 Material List Detail recipe.

Step 3.2. Supporting pane

Identify supporting pane screens where a main screen displays a single item, and selecting it opens a "supporting screen" with more details. The supporting screen complements the main screen and is shown in a supporting pane.