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PullToRefreshBox

[PullToRefreshBox] is a container that expects a scrollable layout as content and adds gesture support for manually refreshing when the user swipes downward at the beginning of the content. By default, it uses [PullToRefreshDefaults.Indicator] as the refresh indicator.

Last updated:

Installation

dependencies {
   implementation("androidx.compose.material3:material3:1.3.0-beta03")
}

Overloads

@ExperimentalMaterial3Api
@Composable
fun PullToRefreshBox(
    isRefreshing: Boolean,
    onRefresh: () -> Unit,
    modifier: Modifier = Modifier,
    state: PullToRefreshState = rememberPullToRefreshState(),
    contentAlignment: Alignment = Alignment.TopStart,
    indicator: @Composable BoxScope.() -> Unit = {
        Indicator(
            modifier = Modifier.align(Alignment.TopCenter),
            isRefreshing = isRefreshing,
            state = state
        )
    },
    content: @Composable BoxScope.() -> Unit
)

Parameters

namedescription
isRefreshingwhether a refresh is occurring
onRefreshcallback invoked when the user gesture crosses the threshold, thereby requesting a refresh.
modifierthe [Modifier] to be applied to this container
statethe state that keeps track of distance pulled
contentAlignmentThe default alignment inside the Box.
indicatorthe indicator that will be drawn on top of the content when the user begins a pull or a refresh is occurring
contentthe content of the pull refresh container, typically a scrollable layout such as [LazyColumn] or a layout using [Modifier.verticalScroll]

Code Examples

PullToRefreshSample

@OptIn(ExperimentalMaterial3Api::class
@Preview
@Composable
@Sampled
fun PullToRefreshSample() {
    var itemCount by remember { mutableIntStateOf(15) }
    var isRefreshing by remember { mutableStateOf(false) }
    val state = rememberPullToRefreshState()
    val coroutineScope = rememberCoroutineScope()
    val onRefresh: () -> Unit = {
        isRefreshing = true
        coroutineScope.launch {
            delay(1500)
            itemCount += 5
            isRefreshing = false
        }
    }

    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text("Title") },
                // Provide an accessible alternative to trigger refresh.
                actions = {
                    IconButton(onClick = onRefresh) {
                        Icon(Icons.Filled.Refresh, "Trigger Refresh")
                    }
                }
            )
        }
    ) {
        PullToRefreshBox(
            modifier = Modifier.padding(it),
            state = state,
            isRefreshing = isRefreshing,
            onRefresh = onRefresh,
        ) {
            LazyColumn(Modifier.fillMaxSize()) {
                items(itemCount) { ListItem({ Text(text = "Item ${itemCount - it}") }) }
            }
        }
    }
}

PullToRefreshViewModelSample

@OptIn(ExperimentalMaterial3Api::class
@Sampled
@Preview
@Composable
fun PullToRefreshViewModelSample() {
    val viewModel = remember {
        object : ViewModel() {
            private val refreshRequests = Channel<Unit>(1)
            var isRefreshing by mutableStateOf(false)
                private set

            var itemCount by mutableStateOf(15)
                private set

            init {
                viewModelScope.launch {
                    for (r in refreshRequests) {
                        isRefreshing = true
                        try {
                            itemCount += 5
                            delay(1000) // simulate doing real work
                        } finally {
                            isRefreshing = false
                        }
                    }
                }
            }

            fun refresh() {
                refreshRequests.trySend(Unit)
            }
        }
    }

    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text("Title") },
                // Provide an accessible alternative to trigger refresh.
                actions = {
                    IconButton(
                        enabled = !viewModel.isRefreshing,
                        onClick = { viewModel.refresh() }
                    ) {
                        Icon(Icons.Filled.Refresh, "Trigger Refresh")
                    }
                }
            )
        }
    ) {
        PullToRefreshBox(
            modifier = Modifier.padding(it),
            isRefreshing = viewModel.isRefreshing,
            onRefresh = { viewModel.refresh() }
        ) {
            LazyColumn(Modifier.fillMaxSize()) {
                if (!viewModel.isRefreshing) {
                    items(viewModel.itemCount) {
                        ListItem({ Text(text = "Item ${viewModel.itemCount - it}") })
                    }
                }
            }
        }
    }
}

PullToRefreshSampleCustomState

@OptIn(ExperimentalMaterial3Api::class
@Preview
@Composable
@Sampled
fun PullToRefreshSampleCustomState() {
    var itemCount by remember { mutableIntStateOf(15) }
    var isRefreshing by remember { mutableStateOf(false) }
    val coroutineScope = rememberCoroutineScope()
    val onRefresh: () -> Unit = {
        isRefreshing = true
        coroutineScope.launch {
            // fetch something
            delay(1500)
            itemCount += 5
            isRefreshing = false
        }
    }

    val state = remember {
        object : PullToRefreshState {
            private val anim = Animatable(0f, Float.VectorConverter)

            override val distanceFraction
                get() = anim.value

            override suspend fun animateToThreshold() {
                anim.animateTo(1f, spring(dampingRatio = Spring.DampingRatioHighBouncy))
            }

            override suspend fun animateToHidden() {
                anim.animateTo(0f)
            }

            override suspend fun snapTo(targetValue: Float) {
                anim.snapTo(targetValue)
            }
        }
    }

    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text("TopAppBar") },
                // Provide an accessible alternative to trigger refresh.
                actions = {
                    IconButton(onClick = onRefresh) {
                        Icon(Icons.Filled.Refresh, "Trigger Refresh")
                    }
                }
            )
        }
    ) {
        PullToRefreshBox(
            modifier = Modifier.padding(it),
            isRefreshing = isRefreshing,
            onRefresh = onRefresh,
            state = state
        ) {
            LazyColumn(Modifier.fillMaxSize()) {
                if (!isRefreshing) {
                    items(itemCount) { ListItem({ Text(text = "Item ${itemCount - it}") }) }
                }
            }
        }
    }
}

PullToRefreshScalingSample

@Preview
@Composable
@Sampled
@OptIn(ExperimentalMaterial3Api::class
fun PullToRefreshScalingSample() {
    var itemCount by remember { mutableStateOf(15) }
    var isRefreshing by remember { mutableStateOf(false) }
    val state = rememberPullToRefreshState()
    val coroutineScope = rememberCoroutineScope()
    val onRefresh: () -> Unit = {
        isRefreshing = true
        coroutineScope.launch {
            // fetch something
            delay(1500)
            itemCount += 5
            isRefreshing = false
        }
    }

    val scaleFraction = {
        if (isRefreshing) 1f
        else LinearOutSlowInEasing.transform(state.distanceFraction).coerceIn(0f, 1f)
    }

    Scaffold(
        modifier =
            Modifier.pullToRefresh(
                state = state,
                isRefreshing = isRefreshing,
                onRefresh = onRefresh
            ),
        topBar = {
            TopAppBar(
                title = { Text("TopAppBar") },
                // Provide an accessible alternative to trigger refresh.
                actions = {
                    IconButton(onClick = onRefresh) {
                        Icon(Icons.Filled.Refresh, "Trigger Refresh")
                    }
                }
            )
        }
    ) {
        Box(Modifier.padding(it)) {
            LazyColumn(Modifier.fillMaxSize()) {
                if (!isRefreshing) {
                    items(itemCount) { ListItem({ Text(text = "Item ${itemCount - it}") }) }
                }
            }
            Box(
                Modifier.align(Alignment.TopCenter).graphicsLayer {
                    scaleX = scaleFraction()
                    scaleY = scaleFraction()
                }
            ) {
                PullToRefreshDefaults.Indicator(state = state, isRefreshing = isRefreshing)
            }
        }
    }
}