如需将共享元素与 navigation-compose 依赖项搭配使用,您可以使用之前所示的相同概念:使用将 AnimatedVisibilityScope
作为参数的 Modifier.sharedElement()
。您可以使用此方法来决定何时显示什么内容。
以下示例展示了如何将 navigation-compose
与共享元素搭配使用:
@Preview @Composable fun SharedElement_PredictiveBack() { SharedTransitionLayout { val navController = rememberNavController() NavHost( navController = navController, startDestination = "home" ) { composable("home") { HomeScreen( navController, this@SharedTransitionLayout, this@composable ) } composable( "details/{item}", arguments = listOf(navArgument("item") { type = NavType.IntType }) ) { backStackEntry -> val id = backStackEntry.arguments?.getInt("item") val snack = listSnacks[id!!] DetailsScreen( navController, id, snack, this@SharedTransitionLayout, this@composable ) } } } } @Composable private fun DetailsScreen( navController: NavHostController, id: Int, snack: Snack, sharedTransitionScope: SharedTransitionScope, animatedContentScope: AnimatedContentScope ) { with(sharedTransitionScope) { Column( Modifier .fillMaxSize() .clickable { navController.navigate("home") } ) { Image( painterResource(id = snack.image), contentDescription = snack.description, contentScale = ContentScale.Crop, modifier = Modifier .sharedElement( sharedTransitionScope.rememberSharedContentState(key = "image-$id"), animatedVisibilityScope = animatedContentScope ) .aspectRatio(1f) .fillMaxWidth() ) Text( snack.name, fontSize = 18.sp, modifier = Modifier .sharedElement( sharedTransitionScope.rememberSharedContentState(key = "text-$id"), animatedVisibilityScope = animatedContentScope ) .fillMaxWidth() ) } } } @Composable private fun HomeScreen( navController: NavHostController, sharedTransitionScope: SharedTransitionScope, animatedContentScope: AnimatedContentScope ) { LazyColumn( modifier = Modifier .fillMaxSize() .padding(8.dp), verticalArrangement = Arrangement.spacedBy(8.dp) ) { itemsIndexed(listSnacks) { index, item -> Row( Modifier.clickable { navController.navigate("details/$index") } ) { Spacer(modifier = Modifier.width(8.dp)) with(sharedTransitionScope) { Image( painterResource(id = item.image), contentDescription = item.description, contentScale = ContentScale.Crop, modifier = Modifier .sharedElement( sharedTransitionScope.rememberSharedContentState(key = "image-$index"), animatedVisibilityScope = animatedContentScope ) .size(100.dp) ) Spacer(modifier = Modifier.width(8.dp)) Text( item.name, fontSize = 18.sp, modifier = Modifier .align(Alignment.CenterVertically) .sharedElement( sharedTransitionScope.rememberSharedContentState(key = "text-$index"), animatedVisibilityScope = animatedContentScope, ) ) } } } } } data class Snack( val name: String, val description: String, @DrawableRes val image: Int )
使用共享元素的预测性返回
如果您想将预测性返回与共享元素搭配使用,请确保使用上一部分中的代码段,使用最新的 navigation-compose
依赖项。
dependencies {
def nav_version = "2.8.0-beta02"
implementation "androidx.navigation:navigation-compose:$nav_version"
}
将 android:enableOnBackInvokedCallback="true"
添加到 AndroidManifest.xml
文件以启用预测性返回:
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
android:maxSdkVersion="28" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:enableOnBackInvokedCallback="true"
android:theme="@style/Theme.Snippets">