android LazyColum位于另一个LazyColum内部的水平寻呼机- Jetpack组合

hl0ma9xz  于 2023-01-28  发布在  Android
关注(0)|答案(2)|浏览(118)

我想要一个类似于TikToks个人资料屏幕的效果。上面是ProfilPictureusername,下面是stickyHeaderTabRowPostsDraftsLikesFavorites),以下为带4个屏幕的HorizontalPagerPostsDraftsLikesFavorites),这些屏幕中的每一个都包含一个列表。
如果我在Compose中构建这个,就会崩溃,因为我不能将两个LazyColums嵌套在一起。
下面是我尝试做的事情的一个简短版本:

val tabList = listOf("Posts", "Drafts", "Likes", "Favorites")
val pagerState: PagerState = rememberPagerState(initialPage = 0)
val coroutineScope = rememberCoroutineScope()

LazyColumn(modifier = Modifier.fillMaxSize()) {
    item {
        Box(
            modifier = Modifier
                .fillMaxWidth()
                .height(50.dp),
            contentAlignment = Alignment.Center
        ) {
            //Profile Header (Picture, Username, Followers, etc)
            Text(text = "Profile Picture")
        }
    }

    stickyHeader {
        TabRow(
            modifier = Modifier.fillMaxWidth(),
            backgroundColor = Color.Black,
            contentColor = Color.White,
            selectedTabIndex = pagerState.currentPage,
            indicator = { tabPositions ->
                TabRowDefaults.Indicator(
                    Modifier.pagerTabIndicatorOffset(pagerState, tabPositions)
                )
            }
        ) {
            // Add tabs for all of our pages
            tabList.forEachIndexed { index, title ->
                Tab(
                    text = { Text(title) },
                    selected = pagerState.currentPage == index,
                    onClick = {
                        coroutineScope.launch {
                            pagerState.animateScrollToPage(index)
                        }
                    },
                )
            }
        }
    }
    item {
        HorizontalPager(
            state = pagerState,
            count = tabList.size
        ) { page: Int ->
            when (page) {
                0 -> PostsList()
                1 -> DraftsList()
                2 -> LikesList()
                else -> FavoritesList()
            }
        }
    }
}

而在PostList()的内部组成例如是:

@Composable
fun PostList(){
    LazyColumn() {
        items(50){ index ->
            Button(onClick = { /*TODO*/ },
                modifier = Modifier.fillMaxWidth()) {
                Text(text = "Button $index")
            }
        }
    }
}

这是我得到的崩溃:

Vertically scrollable component was measured with an infinity maximum height constraints, which is disallowed. One of the common reasons is nesting layouts like LazyColumn and Column(Modifier.verticalScroll()). If you want to add a header before the list of items please add a header as a separate item() before the main items() inside the LazyColumn scope. There are could be other reasons for this to happen: your ComposeView was added into a LinearLayout with some weight, you applied Modifier.wrapContentSize(unbounded = true) or wrote a custom layout. Please try to remove the source of infinite constraints in the hierarchy above the scrolling container.

**编辑:**给LazyColumn一个固定的高度可以防止应用崩溃,但这不是一个令人满意的解决方案。当HorizontalPager中的4个列表大小不同时,会出现奇怪和错误的行为,看起来不对劲。我尝试的另一件事是使用FlowRow而不是LazyColumn,这似乎也有效并修复了崩溃,但在这里我也得到了一个奇怪的行为,HorizontalPager中的列表同时同步滚动,这不是我想要的。

HorizontalPager是什么使这项任务如此困难,没有它根本不是一个问题。
下面是测试项目:https://github.com/DaFaack/TikTokScrollBehaviourCompose
这就是当我给予LazyColumn一个2500.dp的固定高度时的样子,只有这样大的高度才能提供所需的滚动行为。这里的缺点是,即使列表是空的,它也有2500的高度,这会导致糟糕的用户体验,因为它允许用户在列表是空的情况下滚动

ndh0cuux

ndh0cuux1#

在这种情况下,在外层使用可滚动的Row而不是LazyColumn更容易。
这应该能达到你的目的:

package com.fujigames.nestedscrolltest

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
import androidx.compose.ui.input.nestedscroll.NestedScrollSource
import androidx.compose.ui.input.nestedscroll.nestedScroll
import androidx.compose.ui.unit.dp
import com.fujigames.nestedscrolltest.ui.theme.NestedScrollTestTheme
import com.google.accompanist.flowlayout.FlowRow
import com.google.accompanist.pager.ExperimentalPagerApi
import com.google.accompanist.pager.HorizontalPager
import com.google.accompanist.pager.pagerTabIndicatorOffset
import com.google.accompanist.pager.rememberPagerState
import kotlinx.coroutines.launch

class MainActivity : ComponentActivity() {
    @OptIn(ExperimentalPagerApi::class)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            NestedScrollTestTheme {
                BoxWithConstraints {
                    val screenHeight = maxHeight
                    val scrollState = rememberScrollState()
                    Column(
                        modifier = Modifier
                            .fillMaxSize()
                            .verticalScroll(state = scrollState)
                    ) {
                        Box(
                            modifier = Modifier
                                .height(200.dp)
                                .fillMaxWidth()
                                .background(Color.LightGray), contentAlignment = Alignment.Center
                        ) {
                            Text(text = "HEADER")
                        }

                        Column(modifier = Modifier.height(screenHeight)) {
                            val tabList = listOf("Tab1", "Tab2")
                            val pagerState = rememberPagerState(initialPage = 0)
                            val coroutineScope = rememberCoroutineScope()

                            TabRow(
                                modifier = Modifier.fillMaxWidth(),
                                backgroundColor = Color.White,
                                contentColor = Color.Black,
                                selectedTabIndex = pagerState.currentPage,
                                // Override the indicator, using the provided pagerTabIndicatorOffset modifier
                                indicator = { tabPositions ->
                                    TabRowDefaults.Indicator(
                                        Modifier.pagerTabIndicatorOffset(pagerState, tabPositions)
                                    )
                                }
                            ) {
                                tabList.forEachIndexed { index, title ->
                                    Tab(
                                        text = { Text(title) },
                                        selected = pagerState.currentPage == index,
                                        onClick = {
                                            coroutineScope.launch {
                                                pagerState.animateScrollToPage(index)
                                            }
                                        },
                                    )
                                }
                            }

                            HorizontalPager(
                                state = pagerState,
                                count = tabList.size,
                                modifier = Modifier
                                    .fillMaxHeight()
                                    .nestedScroll(remember {
                                        object : NestedScrollConnection {
                                            override fun onPreScroll(
                                                available: Offset,
                                                source: NestedScrollSource
                                            ): Offset {
                                                return if (available.y > 0) Offset.Zero else Offset(
                                                    x = 0f,
                                                    y = -scrollState.dispatchRawDelta(-available.y)
                                                )
                                            }
                                        }
                                    })
                            ) { page: Int ->
                                when (page) {
                                    0 -> ListLazyColumn(50)
                                    1 -> ListFlowRow(5)
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

@Composable
fun ListLazyColumn(items: Int) {
    LazyColumn(modifier = Modifier.fillMaxSize()) {
        items(items) { index ->
            Button(
                onClick = { /*TODO*/ },
                modifier = Modifier.fillMaxWidth()
            ) {
                Text(text = "Button $index")
            }
        }
    }
}

@Composable
fun ListFlowRow(items: Int) {
    FlowRow(modifier = Modifier.fillMaxSize()) {
        repeat(items) { index ->
            Button(
                onClick = { /*TODO*/ },
                modifier = Modifier.fillMaxWidth()
            ) {
                Text(text = "Button $index")
            }
        }

    }
}
eufgjt7s

eufgjt7s2#

使用Material3简单实现该行为
1.转到build.gradle并导入伴奏者寻呼机:

implementation "com.google.accompanist:accompanist-pager:0.28.0"

1.使用PagerStateCoroutineScopeScrollBehaviorTabRowHorizontalPager创建分页器屏幕,您可以使用TopAppBarDefaults提供的不同scrolBehaviors或实现您自定义的ScrollBehavior

@OptIn(ExperimentalPagerApi::class, ExperimentalMaterial3Api::class)
@Composable
fun PagerScreen() {
    // Tabs for pager
    val tabData = listOf(
        "Tab 1",
        "Tab 2",
    )

    // Pager state
    val pagerState = rememberPagerState()

    // Coroutine scope for scroll pager
    val coroutineScope = rememberCoroutineScope()

    // Scroll behavior for TopAppBar
    val scrollBehavior = TopAppBarDefaults.exitUntilCollapsedScrollBehavior(rememberTopAppBarState())

    Scaffold(
        topBar = {
            TopAppBar(
                scrollBehavior = scrollBehavior,
                title = {
                    Text(text = "Top app bar")
                },
                colors = TopAppBarDefaults.centerAlignedTopAppBarColors(
                    scrolledContainerColor = MaterialTheme.colorScheme.surface
                ),
            )
        },
        content = { innerPadding ->
            Column(
                modifier = Modifier
                    .padding(innerPadding)
                    .fillMaxSize(),
                content = {
                    TabRow(
                        selectedTabIndex = pagerState.currentPage,
                        tabs = {
                            tabData.forEachIndexed { index, title ->
                                Tab(
                                    text = { Text(title) },
                                    selected = pagerState.currentPage == index,
                                    onClick = {
                                        coroutineScope.launch {
                                            pagerState.animateScrollToPage(index)
                                        }
                                    },
                                )
                            }
                        }
                    )

                    HorizontalPager(
                        modifier = Modifier.fillMaxSize(),
                        count = tabData.size,
                        state = pagerState,
                    ) { tabId ->
                        when (tabId) {
                            0 -> Tab1(scrollBehavior = scrollBehavior)
                            1 -> Tab2(scrollBehavior = scrollBehavior)
                        }
                    }
                }
            )
        }
    )
}

1.为HorizontalPager创建选项卡:

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun Tab1(scrollBehavior: TopAppBarScrollBehavior) {
    // List items
    val listItems = listOf(
        "test 1 tab 1",
        "test 2 tab 1",
        "test 3 tab 1",
        "test 4 tab 1",
        "test 5 tab 1",
        "test 6 tab 1",
        "test 7 tab 1",
        "test 8 tab 1",
        "test 9 tab 1",
        "test 10 tab 1",
        "test 11 tab 1",
        "test 12 tab 1",
    )

    val listState = rememberLazyListState()

    LazyColumn(
        modifier = Modifier
            .fillMaxWidth()
            .nestedScroll(scrollBehavior.nestedScrollConnection),
        state = listState,
        contentPadding = PaddingValues(8.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp),
        content = {
            items(items = listItems) { item ->
                Card(
                    modifier = Modifier
                        .height(80.dp)
                        .fillMaxWidth(),

                    content = { Text(text = item) }
                )
            }
        }
    )
}

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun Tab2(scrollBehavior: TopAppBarScrollBehavior) {
    // List items
    val listItems = listOf(
        "test 1 tab 2",
        "test 2 tab 2",
        "test 3 tab 2",
        "test 4 tab 2",
        "test 5 tab 2",
        "test 6 tab 2",
        "test 7 tab 2",
        "test 8 tab 2",
        "test 9 tab 2",
        "test 10 tab 2",
        "test 11 tab 2",
        "test 12 tab 2",
    )

    val listState = rememberLazyListState()

    LazyColumn(
        modifier = Modifier
            .fillMaxWidth()
            .nestedScroll(scrollBehavior.nestedScrollConnection),
        state = listState,
        contentPadding = PaddingValues(8.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp),
        content = {
            items(items = listItems) { item ->
                Card(
                    modifier = Modifier
                        .height(80.dp)
                        .fillMaxWidth(),

                    content = { Text(text = item) }
                )
            }
        }
    )
}

完整代码:

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.lazy.rememberLazyListState
import androidx.compose.material3.*
import androidx.compose.runtime.Composable
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.ui.Modifier
import androidx.compose.ui.input.nestedscroll.nestedScroll
import androidx.compose.ui.unit.dp
import com.andreirozov.pager.ui.theme.PagerTheme
import com.google.accompanist.pager.ExperimentalPagerApi
import com.google.accompanist.pager.HorizontalPager
import com.google.accompanist.pager.rememberPagerState
import kotlinx.coroutines.launch

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            PagerTheme {
                Surface(modifier = Modifier.fillMaxSize()) {
                    PagerScreen()
                }

            }
        }
    }
}

@OptIn(ExperimentalPagerApi::class, ExperimentalMaterial3Api::class)
@Composable
fun PagerScreen() {
    // Tabs for pager
    val tabData = listOf(
        "Tab 1",
        "Tab 2",
    )

    // Pager state
    val pagerState = rememberPagerState()

    // Coroutine scope for scroll pager
    val coroutineScope = rememberCoroutineScope()

    // Scroll behavior for TopAppBar
    val scrollBehavior = TopAppBarDefaults.exitUntilCollapsedScrollBehavior(rememberTopAppBarState())

    Scaffold(
        topBar = {
            TopAppBar(
                scrollBehavior = scrollBehavior,
                title = {
                    Text(text = "Top app bar")
                },
                colors = TopAppBarDefaults.centerAlignedTopAppBarColors(
                    scrolledContainerColor = MaterialTheme.colorScheme.surface
                ),
            )
        },
        content = { innerPadding ->
            Column(
                modifier = Modifier
                    .padding(innerPadding)
                    .fillMaxSize(),
                content = {
                    TabRow(
                        selectedTabIndex = pagerState.currentPage,
                        tabs = {
                            tabData.forEachIndexed { index, title ->
                                Tab(
                                    text = { Text(title) },
                                    selected = pagerState.currentPage == index,
                                    onClick = {
                                        coroutineScope.launch {
                                            pagerState.animateScrollToPage(index)
                                        }
                                    },
                                )
                            }
                        }
                    )

                    HorizontalPager(
                        modifier = Modifier.fillMaxSize(),
                        count = tabData.size,
                        state = pagerState,
                    ) { tabId ->
                        when (tabId) {
                            0 -> Tab1(scrollBehavior = scrollBehavior)
                            1 -> Tab2(scrollBehavior = scrollBehavior)
                        }
                    }
                }
            )
        }
    )
}

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun Tab1(scrollBehavior: TopAppBarScrollBehavior) {
    // List items
    val listItems = listOf(
        "test 1 tab 1",
        "test 2 tab 1",
        "test 3 tab 1",
        "test 4 tab 1",
        "test 5 tab 1",
        "test 6 tab 1",
        "test 7 tab 1",
        "test 8 tab 1",
        "test 9 tab 1",
        "test 10 tab 1",
        "test 11 tab 1",
        "test 12 tab 1",
    )

    val listState = rememberLazyListState()

    LazyColumn(
        modifier = Modifier
            .fillMaxWidth()
            .nestedScroll(scrollBehavior.nestedScrollConnection),
        state = listState,
        contentPadding = PaddingValues(8.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp),
        content = {
            items(items = listItems) { item ->
                Card(
                    modifier = Modifier
                        .height(80.dp)
                        .fillMaxWidth(),

                    content = { Text(text = item) }
                )
            }
        }
    )
}

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun Tab2(scrollBehavior: TopAppBarScrollBehavior) {
    // List items
    val listItems = listOf(
        "test 1 tab 2",
        "test 2 tab 2",
        "test 3 tab 2",
        "test 4 tab 2",
        "test 5 tab 2",
        "test 6 tab 2",
        "test 7 tab 2",
        "test 8 tab 2",
        "test 9 tab 2",
        "test 10 tab 2",
        "test 11 tab 2",
        "test 12 tab 2",
    )

    val listState = rememberLazyListState()

    LazyColumn(
        modifier = Modifier
            .fillMaxWidth()
            .nestedScroll(scrollBehavior.nestedScrollConnection),
        state = listState,
        contentPadding = PaddingValues(8.dp),
        verticalArrangement = Arrangement.spacedBy(8.dp),
        content = {
            items(items = listItems) { item ->
                Card(
                    modifier = Modifier
                        .height(80.dp)
                        .fillMaxWidth(),

                    content = { Text(text = item) }
                )
            }
        }
    )
}

结果:

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