PrimaryTabRow

Composable Component

Primary tabs are placed at the top of the content pane under a top app bar. They display the main content destinations. Fixed tabs display all tabs in a set simultaneously. They are best for switching between related content quickly, such as between transportation methods in a map. To navigate between fixed tabs, tap an individual tab, or swipe left or right in the content area.

Common

@Composable
fun PrimaryTabRow(
    selectedTabIndex: Int,
    modifier: Modifier = Modifier,
    containerColor: Color = TabRowDefaults.primaryContainerColor,
    contentColor: Color = TabRowDefaults.primaryContentColor,
    indicator: @Composable TabIndicatorScope.() -> Unit = {
        TabRowDefaults.PrimaryIndicator(
            modifier = Modifier.tabIndicatorOffset(selectedTabIndex, matchContentSize = true),
            width = Dp.Unspecified,
        )
    },
    divider: @Composable () -> Unit = @Composable { HorizontalDivider() },
    tabs: @Composable () -> Unit,
)

Parameters


selectedTabIndex	the index of the currently selected tab
modifier	the `Modifier` to be applied to this tab row
containerColor	the color used for the background of this tab row. Use `Color.Transparent` to have no color.
contentColor	the preferred color for content inside this tab row. Defaults to either the matching content color for `containerColor`, or to the current `LocalContentColor` if `containerColor` is not a color from the theme.
indicator	the indicator that represents which tab is currently selected. By default this will be a `TabRowDefaults.PrimaryIndicator`, using a `TabRowDefaults.tabIndicatorOffset` modifier to animate its position.
divider	the divider displayed at the bottom of the tab row. This provides a layer of separation between the tab row and the content displayed underneath.
tabs	the tabs inside this tab row. Typically this will be multiple `Tab`s. Each element inside this lambda will be measured and placed evenly across the row, each taking up equal space.

Code Examples

PrimaryTextTabs

@Preview
@Composable
@OptIn(ExperimentalMaterial3Api::class)
fun PrimaryTextTabs() {
    var state by remember { mutableStateOf(0) }
    val titles = listOf("Tab 1", "Tab 2", "Tab 3 with lots of text")
    Column {
        PrimaryTabRow(selectedTabIndex = state) {
            titles.forEachIndexed { index, title ->
                Tab(
                    selected = state == index,
                    onClick = { state = index },
                    text = { Text(text = title, maxLines = 2, overflow = TextOverflow.Ellipsis) },
                )
            }
        }
        Text(
            modifier = Modifier.align(Alignment.CenterHorizontally),
            text = "Primary tab ${state + 1} selected",
            style = MaterialTheme.typography.bodyLarge,
        )
    }
}

FancyTabs

@Preview
@Composable
@OptIn(ExperimentalMaterial3Api::class)
fun FancyTabs() {
    var state by remember { mutableStateOf(0) }
    val titles = listOf("Tab 1", "Tab 2", "Tab 3")
    Column {
        SecondaryTabRow(selectedTabIndex = state) {
            titles.forEachIndexed { index, title ->
                FancyTab(title = title, onClick = { state = index }, selected = (index == state))
            }
        }
        Text(
            modifier = Modifier.align(Alignment.CenterHorizontally),
            text = "Fancy tab ${state + 1} selected",
            style = MaterialTheme.typography.bodyLarge,
        )
    }
}

FancyTab

@Composable
fun FancyTab(title: String, onClick: () -> Unit, selected: Boolean) {
    Tab(selected, onClick) {
        Column(
            Modifier.padding(10.dp).height(50.dp).fillMaxWidth(),
            verticalArrangement = Arrangement.SpaceBetween,
        ) {
            Box(
                Modifier.size(10.dp)
                    .align(Alignment.CenterHorizontally)
                    .background(
                        color =
                            if (selected) MaterialTheme.colorScheme.primary
                            else MaterialTheme.colorScheme.background
                    )
            )
            Text(
                text = title,
                style = MaterialTheme.typography.bodyLarge,
                modifier = Modifier.align(Alignment.CenterHorizontally),
            )
        }
    }
}

FancyIndicator

@Composable
fun FancyIndicator(color: Color, modifier: Modifier = Modifier) {
    // Draws a rounded rectangular with border around the Tab, with a 5.dp padding from the edges
    // Color is passed in as a parameter [color]
    Box(
        modifier
            .padding(5.dp)
            .fillMaxSize()
            .border(BorderStroke(2.dp, color), RoundedCornerShape(5.dp))
    )
}

FancyIndicatorTabs

@Preview
@Composable
@OptIn(ExperimentalMaterial3Api::class)
fun FancyIndicatorTabs() {
    var state by remember { mutableStateOf(0) }
    val titles = listOf("Tab 1", "Tab 2", "Tab 3")
    Column {
        SecondaryTabRow(
            selectedTabIndex = state,
            indicator = {
                FancyIndicator(
                    MaterialTheme.colorScheme.primary,
                    Modifier.tabIndicatorOffset(state),
                )
            },
        ) {
            titles.forEachIndexed { index, title ->
                Tab(selected = state == index, onClick = { state = index }, text = { Text(title) })
            }
        }
        Text(
            modifier = Modifier.align(Alignment.CenterHorizontally),
            text = "Fancy indicator tab ${state + 1} selected",
            style = MaterialTheme.typography.bodyLarge,
        )
    }
}

FancyAnimatedIndicatorWithModifier

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun TabIndicatorScope.FancyAnimatedIndicatorWithModifier(index: Int) {
    val colors =
        listOf(
            MaterialTheme.colorScheme.primary,
            MaterialTheme.colorScheme.secondary,
            MaterialTheme.colorScheme.tertiary,
        )
    var startAnimatable by remember { mutableStateOf<Animatable<Dp, AnimationVector1D>?>(null) }
    var endAnimatable by remember { mutableStateOf<Animatable<Dp, AnimationVector1D>?>(null) }
    val coroutineScope = rememberCoroutineScope()
    val indicatorColor: Color by animateColorAsState(colors[index % colors.size], label = "")
    Box(
        Modifier.tabIndicatorLayout {
                measurable: Measurable,
                constraints: Constraints,
                tabPositions: List<TabPosition> ->
                val newStart = tabPositions[index].left
                val newEnd = tabPositions[index].right
                val startAnim =
                    startAnimatable
                        ?: Animatable(newStart, Dp.VectorConverter).also { startAnimatable = it }
                val endAnim =
                    endAnimatable
                        ?: Animatable(newEnd, Dp.VectorConverter).also { endAnimatable = it }
                if (endAnim.targetValue != newEnd) {
                    coroutineScope.launch {
                        endAnim.animateTo(
                            newEnd,
                            animationSpec =
                                if (endAnim.targetValue < newEnd) {
                                    spring(dampingRatio = 1f, stiffness = 1000f)
                                } else {
                                    spring(dampingRatio = 1f, stiffness = 50f)
                                },
                        )
                    }
                }
                if (startAnim.targetValue != newStart) {
                    coroutineScope.launch {
                        startAnim.animateTo(
                            newStart,
                            animationSpec =
                                // Handle directionality here, if we are moving to the right, we
                                // want the right side of the indicator to move faster, if we are
                                // moving to the left, we want the left side to move faster.
                                if (startAnim.targetValue < newStart) {
                                    spring(dampingRatio = 1f, stiffness = 50f)
                                } else {
                                    spring(dampingRatio = 1f, stiffness = 1000f)
                                },
                        )
                    }
                }
                val indicatorEnd = endAnim.value.roundToPx()
                val indicatorStart = startAnim.value.roundToPx()
                // Apply an offset from the start to correctly position the indicator around the tab
                val placeable =
                    measurable.measure(
                        constraints.copy(
                            maxWidth = indicatorEnd - indicatorStart,
                            minWidth = indicatorEnd - indicatorStart,
                        )
                    )
                layout(constraints.maxWidth, constraints.maxHeight) {
                    placeable.place(indicatorStart, 0)
                }
            }
            .padding(5.dp)
            .fillMaxSize()
            .drawWithContent {
                drawRoundRect(
                    color = indicatorColor,
                    cornerRadius = CornerRadius(5.dp.toPx()),
                    style = Stroke(width = 2.dp.toPx()),
                )
            }
    )
}

FancyIndicatorContainerTabs

@Preview
@Composable
@OptIn(ExperimentalMaterial3Api::class)
fun FancyIndicatorContainerTabs() {
    var state by remember { mutableStateOf(0) }
    val titles = listOf("Tab 1", "Tab 2", "Tab 3")
    Column {
        SecondaryTabRow(
            selectedTabIndex = state,
            indicator = { FancyAnimatedIndicatorWithModifier(state) },
        ) {
            titles.forEachIndexed { index, title ->
                Tab(selected = state == index, onClick = { state = index }, text = { Text(title) })
            }
        }
        Text(
            modifier = Modifier.align(Alignment.CenterHorizontally),
            text = "Fancy transition tab ${state + 1} selected",
            style = MaterialTheme.typography.bodyLarge,
        )
    }
}