Material 清單/詳細資料食譜

本食譜說明如何使用 Material 3 自動調整式程式庫中的 ListDetailSceneStrategy，建立自動調整式清單詳細資料版面配置。這個版面配置會根據可用的螢幕寬度自動調整，顯示一個、兩個或三個窗格。

運作方式

這個範例有三個目的地：ConversationList、ConversationDetail 和 Profile。

ListDetailSceneStrategy

這項食譜的關鍵在於 rememberListDetailSceneStrategy，可提供自適應版面配置的邏輯。

  • 窗格角色：每個目的地都會使用中繼資料指派角色：

    • ListDetailSceneStrategy.listPane()：主要 (清單) 內容。這個窗格一律會顯示在畫面上。如果沒有選取詳細資料內容，可以提供預留位置，在詳細資料窗格區域中顯示。
    • ListDetailSceneStrategy.detailPane()：次要 (詳細) 內容。
    • ListDetailSceneStrategy.extraPane()：適用於第三層內容。

  • 自動調整式版面配置：ListDetailSceneStrategy 會自動處理版面配置。在較小的螢幕上，一次只會顯示一個窗格。在較寬的螢幕上，清單和詳細資料窗格會並排顯示。在極寬螢幕上，則可顯示所有三個窗格：清單、詳細資料和額外窗格。

  • 導覽：在窗格之間導覽時，系統會照常在返回堆疊中新增及移除目的地。ListDetailSceneStrategy 會觀察返回堆疊，並據此調整版面配置。

package com.example.nav3recipes.material.listdetail

/*
 * Copyright 2025 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
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import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.foundation.layout.Column
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
import androidx.compose.material3.adaptive.currentWindowAdaptiveInfoV2
import androidx.compose.material3.adaptive.layout.calculatePaneScaffoldDirective
import androidx.compose.material3.adaptive.navigation3.ListDetailSceneStrategy
import androidx.compose.material3.adaptive.navigation3.rememberListDetailSceneStrategy
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.unit.dp
import androidx.lifecycle.compose.dropUnlessResumed
import androidx.navigation3.runtime.NavKey
import androidx.navigation3.runtime.entryProvider
import androidx.navigation3.runtime.rememberNavBackStack
import androidx.navigation3.ui.NavDisplay
import com.example.nav3recipes.content.ContentBlue
import com.example.nav3recipes.content.ContentGreen
import com.example.nav3recipes.content.ContentRed
import com.example.nav3recipes.content.ContentYellow
import com.example.nav3recipes.ui.setEdgeToEdgeConfig
import kotlinx.serialization.Serializable

@Serializable
private object ConversationList : NavKey

@Serializable
private data class ConversationDetail(val id: String) : NavKey

@Serializable
private data object Profile : NavKey

class MaterialListDetailActivity : ComponentActivity() {

    @OptIn(ExperimentalMaterial3AdaptiveApi::class)
    override fun onCreate(savedInstanceState: Bundle?) {
        setEdgeToEdgeConfig()
        super.onCreate(savedInstanceState)

        setContent {

            val backStack = rememberNavBackStack(ConversationList)

            // Override the defaults so that there isn't a horizontal space between the panes.
            // See b/418201867
            val windowAdaptiveInfo = currentWindowAdaptiveInfoV2()
            val directive = remember(windowAdaptiveInfo) {
                calculatePaneScaffoldDirective(windowAdaptiveInfo)
                    .copy(horizontalPartitionSpacerSize = 0.dp)
            }
            val listDetailStrategy = rememberListDetailSceneStrategy<NavKey>(directive = directive)

            NavDisplay(
                backStack = backStack,
                onBack = { backStack.removeLastOrNull() },
                sceneStrategies = listOf(listDetailStrategy),
                entryProvider = entryProvider {
                    entry<ConversationList>(
                        metadata = ListDetailSceneStrategy.listPane(
                            detailPlaceholder = {
                                ContentYellow("Choose a conversation from the list")
                            }
                        )
                    ) {
                        ContentRed("Welcome to Nav3") {
                            Button(onClick = dropUnlessResumed {
                                backStack.add(ConversationDetail("ABC"))
                            }) {
                                Text("View conversation")
                            }
                        }
                    }
                    entry<ConversationDetail>(
                        metadata = ListDetailSceneStrategy.detailPane()
                    ) { conversation ->
                        ContentBlue("Conversation ${conversation.id} ") {
                            Column(horizontalAlignment = Alignment.CenterHorizontally) {
                                Button(onClick = dropUnlessResumed {
                                    backStack.add(Profile)
                                }) {
                                    Text("View profile")
                                }
                            }
                        }
                    }
                    entry<Profile>(
                        metadata = ListDetailSceneStrategy.extraPane()
                    ) {
                        ContentGreen("Profile")
                    }
                }
            )
        }
    }
}