使用 M3 在 Compose 中获取用户位置

Question

我正在尝试在 Compose 中获取用户位置。

我找到了这个链接并尝试了米奇解决方案。但它有一个无限循环，并且不显示小吃栏。从其他链接我读到它需要连接到脚手架，但似乎 M3 不再有效。

我将无限循环更改为：

LaunchedEffect(true) {
    while (true) {
        isGPSEnabled = isGPSEnabled(context)
        delay(2.seconds)
    }
}

致：

LaunchedEffect(true) {
    while (!isGPSEnabled) {   //while (true) {
        isGPSEnabled = isGPSEnabled(context)
        delay(2.seconds)
    }
}

但我不知道如何让小吃栏显示：

DisposableEffect(
    isGPSEnabled,
    permissions.shouldShowRationale,
    permissions.allPermissionsGranted,
) {
    if (!permissions.allPermissionsGranted || permissions.shouldShowRationale) {
        scope.launch {
            val result = snackbarHostState.showSnackbar(
                "Missing required permissions",
                "Grant",
                withDismissAction = true,
                duration = SnackbarDuration.Indefinite,
            )

            when (result) {
                SnackbarResult.Dismissed -> {

                }

                SnackbarResult.ActionPerformed -> {
                    permissions.launchMultiplePermissionRequest()
                }
            }
        }
        return@DisposableEffect SimulatedDisposableEffectResult
    }

我知道代码 [val result = SnackbarHostState.showSnackbar(...) ] 被执行，因为我在调试中有一个断点到达它。它停留在那里，永远不会到达 [when(result)]，因为它有 [duration = SnackbarDuration.Indefinite]

在我的屏幕上，我有以下调用该函数的内容：

Image(painter = painterResource(R.drawable.baseline_my_location_24),
                contentDescription = "Get Coordinates",
                modifier = Modifier
                    .clickable {
                        doGet = true
                    }
                    .size(40.dp)
            )

            if (doGet) {
                ExampleForegroundLocationTrackerScreen()
            }

这是出于测试目的，但我真的想接收值（纬度，经度）以将它们显示在屏幕上，然后保存在数据库中。

Answer 1

许多天或几周后，我最终使用了 BottomSheetScaffold。

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun LocationScreen(
startLocationUpdates: ()->Unit,
context: Context,
currentLocation: LatLng
) {

////// This permissions are use down bellow at a Button Click event that
////// actually calls for the GPS location. The Button  is part of the BottomSheet content.
val permissions = arrayOf(
    Manifest.permission.ACCESS_COARSE_LOCATION,
    Manifest.permission.ACCESS_FINE_LOCATION,
)

////// startActivityForResult function is deprecated and in Jetpack Compose the solution is 
////// to use "rememberLauncherForActivityResult" with "ActivityResultContracts" 
val launchMultiplePermissions = rememberLauncherForActivityResult(
    ActivityResultContracts.RequestMultiplePermissions()
) { permissionMaps ->
    val areGranted = permissionMaps.values.reduce { acc, next -> acc && next }
    if (areGranted) {
        locationRequired = true
        startLocationUpdates()
        Toast.makeText(context, "Permission Granted", Toast.LENGTH_SHORT).show()
    } else {
        Toast.makeText(context, "Permission Denied", Toast.LENGTH_SHORT).show()
    }
}

var readable by remember { mutableStateOf("") }
//val scope = rememberCoroutineScope()
val scaffoldState = rememberBottomSheetScaffoldState()

BottomSheetScaffold(
    //modifier = Modifier.heightIn(min=0.dp, max=400.dp),
    scaffoldState = scaffoldState,
    sheetPeekHeight = 590.dp,
    sheetSwipeEnabled = false,
    sheetContent = {

        Column(
            Modifier
                .fillMaxWidth()
                .padding(6.dp),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            if (currentLocation.latitude != 0.toDouble() && currentLocation.longitude != 0.toDouble() && readable != "") {
                WebViewScreen(location = currentLocation) //, address = readable)
                showdialog.value = false
            } else {Text(text = "Please click [Get your location]")}
            
        }
    }) { innerPadding ->
    Box(Modifier.padding(innerPadding)) {

        Column(
            modifier = Modifier.fillMaxWidth(),
            verticalArrangement = Arrangement.SpaceEvenly,
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            Text(text = "Your location: ${currentLocation.latitude}/${currentLocation.longitude}")
            if (currentLocation.latitude != 0.toDouble() && currentLocation.longitude != 0.toDouble()) {
                Text(
                    text = "Readable location: $currentLocation"
                )
                location = ""
                readable = getReadableLocation(currentLocation.latitude, currentLocation.longitude, context)
                glocation = currentLocation
            }
    //////Here is where the permissions are used to call for the system permissions pop up.
            Button(onClick = {
                if (permissions.all {
                        ContextCompat.checkSelfPermission(
                            context,
                            it
                        ) == PackageManager.PERMISSION_GRANTED
                    }) {
                    //Get Locations
                    startLocationUpdates()
                } else {
                    launchMultiplePermissions.launch(permissions)
                }
                =
            }) {
                Text(text = "Get your location")
            }
        }
    }
}

}

也许您可以阅读这篇post以获得更好的解释。那里的示例是针对图片而不是 GPS 位置。