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注册个人网站要多少钱,建设医院在哪里,山西城乡建设厅网站,wordpress设置邮件这一节主要了解一下Compose中的Pager#xff0c;在Jetpack Compose开发中#xff0c;Pager是用于实现滑动页面集合的核心组件#xff0c;支持水平#xff08;HorizontalPager#xff09;和垂直#xff08;VerticalPager#xff09;方向的滑动#xff0c;能够灵活管理页…这一节主要了解一下Compose中的Pager在Jetpack Compose开发中Pager是用于实现滑动页面集合的核心组件支持水平HorizontalPager和垂直VerticalPager方向的滑动能够灵活管理页面内容、状态和交互。简单总结:API:HorizontalPager/VerticalPager:核心组件分别实现横向 / 纵向翻页rememberPagerState:创建并记忆 Pager 状态包含当前页码、滑动偏移等PagerScope:页面作用域提供 pageOffset 等页面滑动状态参数PageSize:定义页面尺寸PagerSnapDistance:定义滑动后吸附到页面的距离场景:1 图片轮播 在电商、新闻等应用中顶部展示多张图片并自动轮播用户可手动滑动切换。2 引导页 应用首次启动时展示多页引导内容用户滑动浏览后进入主界面。3 分类标签页 顶部标签栏切换时下方内容同步滑动栗子:implementation(io.coil-kt:coil-compose:2.5.0)// 权限 uses-permission android:nameandroid.permission.INTERNET /import androidx.compose.runtime.Composable import androidx.compose.animation.core.animateFloatAsState import androidx.compose.foundation.Image import androidx.compose.foundation.background import androidx.compose.foundation.layout.Arrangement import androidx.compose.foundation.layout.Box import androidx.compose.foundation.layout.Column import androidx.compose.foundation.layout.Row import androidx.compose.foundation.layout.fillMaxSize import androidx.compose.foundation.layout.padding import androidx.compose.foundation.layout.size import androidx.compose.foundation.pager.HorizontalPager import androidx.compose.foundation.pager.PageSize import androidx.compose.foundation.pager.rememberPagerState import androidx.compose.foundation.shape.CircleShape import androidx.compose.material3.Button import androidx.compose.material3.MaterialTheme import androidx.compose.material3.Surface import androidx.compose.material3.Text import androidx.compose.runtime.LaunchedEffect import androidx.compose.runtime.getValue import androidx.compose.runtime.mutableStateOf import androidx.compose.runtime.remember import androidx.compose.runtime.rememberCoroutineScope import androidx.compose.runtime.setValue import androidx.compose.ui.Alignment import androidx.compose.ui.Modifier import androidx.compose.ui.draw.alpha import androidx.compose.ui.draw.scale import androidx.compose.ui.layout.ContentScale import androidx.compose.ui.unit.dp import androidx.compose.ui.unit.sp import coil.compose.rememberAsyncImagePainter import kotlinx.coroutines.delay import kotlinx.coroutines.launch data class PagerItem( val id: Int, val title: String, val imageUrl: String, val bgColor: androidx.compose.ui.graphics.Color ) fun Float.format(digits: Int): String %.${digits}f.format(this) Composable fun PagerDemo() { val pagerData listOf( PagerItem(1, 商品A, https://picsum.photos/800/400?random1, androidx.compose.ui.graphics.Color(0xFF6495ED)), PagerItem(2, 商品B, https://picsum.photos/800/400?random2, androidx.compose.ui.graphics.Color(0xFF90EE90)), PagerItem(3, 商品C, https://picsum.photos/800/400?random3, androidx.compose.ui.graphics.Color(0xFFFFB6C1)), PagerItem(4, 商品D, https://picsum.photos/800/400?random4, androidx.compose.ui.graphics.Color(0xFFFFD700)) ) Surface(modifier Modifier.fillMaxSize()) { val pagerState rememberPagerState( initialPage 0, pageCount { pagerData.size } ) val coroutineScope rememberCoroutineScope() var slideOffset by remember { mutableStateOf(0.0f) } LaunchedEffect(pagerState.currentPage, pagerState.currentPageOffsetFraction) { slideOffset pagerState.currentPage pagerState.currentPageOffsetFraction } Column( modifier Modifier.fillMaxSize(), horizontalAlignment Alignment.CenterHorizontally ) { Text( text 滑动进度${slideOffset.format(2)}, fontSize 16.sp, modifier Modifier.padding(16.dp) ) HorizontalPager( state pagerState, modifier Modifier .weight(1f) .padding(horizontal 20.dp), pageSize PageSize.Fill, pageSpacing 16.dp, contentPadding androidx.compose.foundation.layout.PaddingValues(horizontal 20.dp) ) { pageIndex - val item pagerData[pageIndex] val pageOffset pagerState.currentPageOffsetFraction val scale by animateFloatAsState( targetValue if (pageIndex pagerState.currentPage) 1f else 0.9f, label pageScale ) val alpha by animateFloatAsState( targetValue if (pageIndex pagerState.currentPage) 1f else 0.7f, label pageAlpha ) var isLoading by remember { mutableStateOf(true) } LaunchedEffect(pageIndex) { delay(300) isLoading false } Box( modifier Modifier .fillMaxSize() .scale(scale) .alpha(alpha) .background(item.bgColor, MaterialTheme.shapes.medium) .padding(16.dp), contentAlignment Alignment.Center ) { if (isLoading) { Text(text 加载中..., color androidx.compose.ui.graphics.Color.White) } else { Column( horizontalAlignment Alignment.CenterHorizontally ) { Image( painter rememberAsyncImagePainter(model item.imageUrl), contentDescription item.title, modifier Modifier .size(200.dp, 150.dp) .padding(bottom 16.dp), contentScale ContentScale.Crop ) Text( text item.title, fontSize 20.sp, color androidx.compose.ui.graphics.Color.White ) } } } } Column( modifier Modifier.padding(16.dp), horizontalAlignment Alignment.CenterHorizontally ) { Row( horizontalArrangement Arrangement.spacedBy(8.dp), modifier Modifier.padding(bottom 16.dp) ) { pagerData.forEachIndexed { index, _ - val isSelected index pagerState.currentPage Box( modifier Modifier .size(if (isSelected) 12.dp else 8.dp) .background( color if (isSelected) androidx.compose.ui.graphics.Color.Blue else androidx.compose.ui.graphics.Color.Gray, shape CircleShape ) ) } } Row( horizontalArrangement Arrangement.spacedBy(16.dp) ) { Button( onClick { coroutineScope.launch { if (pagerState.currentPage 0) { pagerState.animateScrollToPage(pagerState.currentPage - 1) } } }, enabled pagerState.currentPage 0 ) { Text(text 上一页) } Button( onClick { coroutineScope.launch { if (pagerState.currentPage pagerData.size - 1) { pagerState.animateScrollToPage(pagerState.currentPage 1) } } }, enabled pagerState.currentPage pagerData.size - 1 ) { Text(text 下一页) } } } } } }import androidx.compose.foundation.Image import androidx.compose.foundation.background import androidx.compose.foundation.layout.Box import androidx.compose.foundation.layout.fillMaxSize import androidx.compose.foundation.layout.padding import androidx.compose.foundation.pager.VerticalPager import androidx.compose.foundation.pager.rememberPagerState import androidx.compose.material3.Surface import androidx.compose.material3.Text import androidx.compose.runtime.Composable import androidx.compose.ui.Alignment import androidx.compose.ui.Modifier import androidx.compose.ui.graphics.Color import androidx.compose.ui.layout.ContentScale import androidx.compose.ui.unit.dp import androidx.compose.ui.unit.sp import coil.compose.rememberAsyncImagePainter Composable fun PagerDemo() { val imageUrls listOf( https://picsum.photos/800/1200?random1, https://picsum.photos/800/1200?random2, https://picsum.photos/800/1200?random3 ) val pagerState rememberPagerState( initialPage 0, pageCount { imageUrls.size } ) Surface(modifier Modifier.fillMaxSize()) { VerticalPager( state pagerState, modifier Modifier.fillMaxSize(), pageSize androidx.compose.foundation.pager.PageSize.Fill ) { pageIndex - Box( modifier Modifier.fillMaxSize(), contentAlignment Alignment.Center ) { Image( painter rememberAsyncImagePainter(model imageUrls[pageIndex]), contentDescription 商品图片${pageIndex 1}, modifier Modifier .fillMaxSize() .padding(20.dp), contentScale ContentScale.Crop ) Text( text ${pageIndex 1}/${imageUrls.size}, fontSize 20.sp, color Color.White, modifier Modifier .background(Color.Black.copy(alpha 0.5f)) .padding(8.dp) .align(Alignment.BottomCenter) ) } } } }注意:1 页面预加载与优化 默认仅加载可见页面通过beyondViewportPageCount设置屏幕外预加载页面数2 状态管理与滚动监听 使用LaunchedEffect(pagerState.currentPage)监听页面变化避免在pageContent中直接监听导致重复重组。3 滚动控制 滚动需在协程中调用