建構輔助窗格版面配置

輔助窗格標準版面配置會聚焦於使用者註意應用程式的主要內容，同時顯示相關的輔助內容。舉例來說，主要內容窗格可能會顯示最近電影的資訊，支援窗格則顯示主題類似的其他電影清單，或顯示相同主題的演員或知名演員。如要進一步瞭解輔助窗格標準版面配置，請參閱 Material 3 輔助窗格指南。

實作輔助窗格

SupportingPaneScaffold 包含最多三個窗格：主要窗格、輔助窗格和選用的額外窗格。Scaffold 會處理所有將視窗空間分配到三個窗格的計算。在大螢幕上，Sscaffold 會顯示主要窗格，其側邊具有輔助窗格。在小螢幕上，Sscaffold 會顯示主要或支援窗格的全螢幕。

圖 1. 輔助窗格版面配置。

新增依附元件

注意： 自動調整導覽套件程式庫為 Alpha 版，隨時可能變更。

SupportingPaneScaffold 是 Material 3 自動調整版面配置程式庫的一部分。

為應用程式或模組的 build.gradle 檔案新增下列三個相關依附元件：

Kotlin

implementation("androidx.compose.material3.adaptive:adaptive")
implementation("androidx.compose.material3.adaptive:adaptive-layout")
implementation("androidx.compose.material3.adaptive:adaptive-navigation")

Groovy

implementation 'androidx.compose.material3.adaptive:adaptive'
implementation 'androidx.compose.material3.adaptive:adaptive-layout'
implementation 'androidx.compose.material3.adaptive:adaptive-navigation'

• 自動調整 - 低階建構模塊，例如 HingeInfo 和 Posture
• 自動調整版面配置：自動調整式版面配置，例如 SupportingPaneScaffold
• 自動調整導覽 - 用於在窗格內或之間導覽的可組合項

建立導覽器和 Scaffold

在小型視窗中，系統一次只會顯示一個窗格，因此請使用 ThreePaneScaffoldNavigator 在窗格之間來回移動。使用 rememberSupportingPaneScaffoldNavigator 建立導覽器例項。如要處理返回手勢，請使用 BackHandler 檢查 canNavigateBack() 並呼叫 navigateBack()：

val navigator = rememberSupportingPaneScaffoldNavigator()

BackHandler(navigator.canNavigateBack()) {
    navigator.navigateBack()
}
SampleSupportingPaneScaffold.kt

Scaffold 需要 PaneScaffoldDirective 用於控制分割畫面和間距多少，以及 ThreePaneScaffoldValue 以提供目前的隱藏狀態 (例如針對預設行為，請分別使用導覽器的 scaffoldDirective 和 scaffoldValue：

SupportingPaneScaffold(
    directive = navigator.scaffoldDirective,
    value = navigator.scaffoldValue,
    mainPane = { /*...*/ },
    supportingPane = { /*...*/ },
)
SampleSupportingPaneScaffold.kt

主要窗格和輔助窗格是包含內容的可組合項。請使用 AnimatedPane，在導覽期間套用預設窗格動畫。使用 Scaffold 值檢查輔助窗格是否已隱藏。如果是，會顯示呼叫 navigateTo(ThreePaneScaffoldRole.Secondary) 以顯示支援窗格的按鈕。

以下是 Scaffold 的完整實作：

val navigator = rememberSupportingPaneScaffoldNavigator()

BackHandler(navigator.canNavigateBack()) {
    navigator.navigateBack()
}

SupportingPaneScaffold(
    directive = navigator.scaffoldDirective,
    value = navigator.scaffoldValue,
    mainPane = {
        AnimatedPane(modifier = Modifier.safeContentPadding()) {
            // Main pane content
            if (navigator.scaffoldValue[SupportingPaneScaffoldRole.Supporting] == PaneAdaptedValue.Hidden) {
                Button(
                    modifier = Modifier.wrapContentSize(),
                    onClick = {
                        navigator.navigateTo(SupportingPaneScaffoldRole.Supporting)
                    }
                ) {
                    Text("Show supporting pane")
                }
            } else {
                Text("Supporting pane is shown")
            }
        }
    },
    supportingPane = {
        AnimatedPane(modifier = Modifier.safeContentPadding()) {
            // Supporting pane content
            Text("Supporting pane")
        }
    },
)
SampleSupportingPaneScaffold.kt

擷取窗格可組合項

將 SupportingPaneScaffold 的個別窗格擷取至專屬的可組合項，使其可重複使用且可供測試。如要取得預設動畫，請使用 ThreePaneScaffoldScope 存取 AnimatedPane：

@Composable
fun ThreePaneScaffoldScope.MainPane(
    shouldShowSupportingPaneButton: Boolean,
    onNavigateToSupportingPane: () -> Unit,
    modifier: Modifier = Modifier,
) {
    AnimatedPane(modifier = modifier.safeContentPadding()) {
        // Main pane content
        if (shouldShowSupportingPaneButton) {
            Button(onClick = onNavigateToSupportingPane) {
                Text("Show supporting pane")
            }
        } else {
            Text("Supporting pane is shown")
        }
    }
}

@Composable
fun ThreePaneScaffoldScope.SupportingPane(
    modifier: Modifier = Modifier,
) {
    AnimatedPane(modifier = modifier.safeContentPadding()) {
        // Supporting pane content
        Text("This is the supporting pane")
    }
}
SampleSupportingPaneScaffold.kt

將窗格擷取至可組合項，可簡化 SupportingPaneScaffold 的使用方式 (比較以下程式碼與上一節中 Scaffold 的完整實作)：

val navigator = rememberSupportingPaneScaffoldNavigator()

BackHandler(navigator.canNavigateBack()) {
    navigator.navigateBack()
}

SupportingPaneScaffold(
    directive = navigator.scaffoldDirective,
    value = navigator.scaffoldValue,
    mainPane = {
        MainPane(
            shouldShowSupportingPaneButton = navigator.scaffoldValue.secondary == PaneAdaptedValue.Hidden,
            onNavigateToSupportingPane = { navigator.navigateTo(ThreePaneScaffoldRole.Secondary) }
        )
    },
    supportingPane = { SupportingPane() },
)
SampleSupportingPaneScaffold.kt