BottomSheetScaffold 导航回来时不会保留sheetPeekHeight (Jetpack Compose)

Question

根据 AndroidX Compose Material 3 示例，这个

BottomSheetScaffold

的

peekHeight

= 128dp。此时它只有两个

state

：

Expanded

和

PartiallyExpanded

。当我导航到另一个屏幕然后返回时，

BottomSheetScaffold

似乎失去了

peekHeight

，现在它可以是

Hidden

。我有我的解决方案，但这并不完全是我想要的。在这种情况下我该如何保持

peekHeight

？

这是我的代码

@ExperimentalMaterial3Api
@Composable
fun ScreenA(
    navController: NavController
) {
    val scaffoldState = rememberBottomSheetScaffoldState(
        bottomSheetState = rememberStandardBottomSheetState(
            initialValue = SheetValue.Expanded,
            confirmValueChange = {
                it != SheetValue.Hidden  // Prevent collapsing but not what I want
            }
        )
    )

    BottomSheetScaffold(
        scaffoldState = scaffoldState,
        sheetPeekHeight = 128.dp,
        sheetContent = {
            Box(
                Modifier
                    .fillMaxWidth()
                    .height(128.dp),
                contentAlignment = Alignment.Center
            ) {
                Text("Swipe up to expand sheet")
            }
            Column(
                Modifier
                    .fillMaxWidth()
                    .padding(64.dp),
                horizontalAlignment = Alignment.CenterHorizontally
            ) {
                Text("Sheet content")
                Spacer(Modifier.height(20.dp))
                Button(
                    onClick = {
                        navController.navigate("ScreenB") // navigate to another screen
                    }
                ) {
                    Text("Click to collapse sheet")
                }
            }
        }) { innerPadding ->
        Box(Modifier.padding(innerPadding)) {
            Text("Scaffold Content")
        }
    }
    LaunchedEffect(scaffoldState.bottomSheetState.currentValue) {
        println(scaffoldState.bottomSheetState.currentValue) // check scaffold state
    }
}

Answer 1

这应该有帮助：

 val scaffoldSheetState = rememberBottomSheetScaffoldState(
        SheetState(
            skipHiddenState = true,
            skipPartiallyExpanded = false,
            initialValue = SheetValue.PartiallyExpanded
        )
    )

来自文档：skipHiddenState - 是否应跳过隐藏状态。如果为 true，则工作表将始终展开到“已展开”状态，并以编程方式或通过用户交互移动到“部分展开”（如果可用）。

Answer 2

我遇到了类似的问题，事实证明，重新创建 Activity 时，

skipHiddenState

无法恢复。 我引入了一个自定义函数而不是

rememberStandardBottomSheetState()

来保存和恢复参数。

@Composable
@ExperimentalMaterial3Api
fun rememberCustomBottomSheetState(
    skipPartiallyExpanded: Boolean = false,
    confirmValueChange: (SheetValue) -> Boolean = { true },
    initialValue: SheetValue = SheetValue.PartiallyExpanded,
    skipHiddenState: Boolean = true,
): SheetState {
    return rememberSaveable(
        skipPartiallyExpanded, skipHiddenState, confirmValueChange,
        saver = Saver(
            save = { it.currentValue },
            restore = { savedValue ->
                SheetState(skipPartiallyExpanded, savedValue, confirmValueChange, skipHiddenState)
            }
        )
    ) {
        SheetState(skipPartiallyExpanded, initialValue, confirmValueChange, skipHiddenState)
    }
}

返回的状态可以传递给脚手架状态

val bottomSheetState = rememberCustomBottomSheetState()
val scaffoldState = rememberBottomSheetScaffoldState(
            bottomSheetState = bottomSheetState
)

我已将问题提交给问题跟踪器。可能会在 Material3 的未来版本中修复