如何将一个 Composable 作为参数传递给另一个 Composable 并在 Jetpack Compose 中显示/运行它

Question

我有一个在 youtube 上学会制作的抽屉

https://www.youtube.com/watch?v=JLICaBEiJS0&list=PLQkwcJG4YTCSpJ2NLhDTHhi6XBNfk9WiC&index=31 菲利普·拉克纳

我想将抽屉添加到我的应用程序中，该应用程序有多个屏幕，其中一些不需要抽屉，因此我使用屏幕实现了导航，并且一些屏幕还需要将抽屉包裹在其顶部。

这是抽屉的代码

val scaffoldState = rememberScaffoldState()
                val scope = rememberCoroutineScope()
                Scaffold(
                    drawerGesturesEnabled = scaffoldState.drawerState.isOpen,
                    scaffoldState = scaffoldState, topBar = {
                    AppBar(onNavigationIconClick = {
                        scope.launch {
                            scaffoldState.drawerState.open()
                        }

                    })
                }, drawerContent = {
                    DrawerHeader()
                    DrawerBody(items = listOf(
                        MenuItem(
                            id = "home",
                            title = "Home",
                            contentDescription = "Go to home screen",
                            icon = Icons.Default.Home
                        ),
                        MenuItem(
                            id = "settings",
                            title = "Settings",
                            contentDescription = "Go to Settings screen",
                            icon = Icons.Default.Settings
                        ),
                        MenuItem(
                            id = "help",
                            title = "Help",
                            contentDescription = "Go to help screen",
                            icon = Icons.Default.Info
                        ),
                    ), onItemClick = {
                        println("Clicked on ${it.title}")

                        when (it.id) {
                            "home" -> {
                                println("Clicked on ${it.title}")
                            }
                            "settings" -> {
                                println("Clicked on ${it.title}")
                            }
                            "help" -> {
                                println("Clicked on ${it.title}")
                            }
                        }
                    })

                }) {

                    Text(text = "Hello World")

                }

Text = Hellow world 是我想传递屏幕参数的地方，但我不知道该怎么做。我想添加一个参数，该参数采用可组合函数并在内部运行它

我按照这个导航视频了解如何在 kotlin 中导航

https://www.youtube.com/watch?v=4gUeyNkGE3g&list=PLQkwcJG4YTCSpJ2NLhDTHhi6XBNfk9WiC&index=18

其中有 3 个大文件，所以如果您要求，我会将它们发布在这里，但我会尝试更具体地说明需要什么

composable(route = Screen.RegisterScreen.route) {
            RegisterScreen(navController = navCotroller)
        }

如果我将代码放在抽屉中，效果很好，但我想将代码拆分得更干净，因为我在更多地方使用抽屉

代码的工作方式如下例所示

composable(route = Screen.PreferenceScreen.route) {
            val scaffoldState = rememberScaffoldState()
            val scope = rememberCoroutineScope()
            Scaffold(

                drawerGesturesEnabled = scaffoldState.drawerState.isOpen,
                scaffoldState = scaffoldState,
                topBar = {
                    AppBar(onNavigationIconClick = {
                        scope.launch {
                            scaffoldState.drawerState.open()
                        }

                    })
                },
                drawerContent = {
                    DrawerHeader()
                    DrawerBody(items = listOf(
                        MenuItem(
                            id = "swipe",
                            title = "Swipe",
                            contentDescription = "Go to Swipe screen",
                            icon = Icons.Default.Home
                        ),
                        MenuItem(
                            id = "settings",
                            title = "Settings",
                            contentDescription = "Go to Settings screen",
                            icon = Icons.Default.Settings
                        ),
                        MenuItem(
                            id = "profile",
                            title = "Profile",
                            contentDescription = "Go to profile screen",
                            icon = Icons.Default.Info
                        ),
                    ), onItemClick = {
                        when (it.id) {
                            "swipe" -> {
                                navCotroller.navigate(Screen.SwipeScreen.route)
                            }
                            "settings" -> {
                                navCotroller.navigate(Screen.PreferenceScreen.route)
                            }
                            "profile" -> {
                                navCotroller.navigate(Screen.CelebProfileScreen.route)
                            }
                        }
                    })

                }) {

         ----->        PreferenceScreen(navController = navCotroller)

            }

        }

但这不是干净的代码！我怎样才能使用函数指针来完成这项工作？

Answer 1

I can\'t compile your code and I\'m not sure if this will solve your issue, but based on this

\n

\n

\xe2\x80\xa6 I want to add a parameter that takes a composable function and runs\nit inside

\n

\n

You can use this as a reference. Consider this composable that takes any composable and runs it inside

\n

@Composable\nfun AnyComposable(\n    anyComposable: @Composable () -> Unit\n) {\n    anyComposable()\n}\n

\n

And another composable that uses the composable above and passes any other composable to it like this

\n

@Composable\nfun MyScreen() {\n\n    // big red Box composable\n    val composable1 = @Composable {\n        Box (\n            modifier = Modifier\n                .size(200.dp)\n                .background(Color.Red)\n        )\n    }\n\n    // small blue Box composable\n    val composable2 = @Composable {\n        Box(\n            modifier = Modifier\n                .size(80.dp)\n                .background(Color.Blue)\n        )\n    }\n\n    // small green rectangular Box composable\n    val composable3 = @Composable {\n        Box(\n            modifier = Modifier\n                .size(width = 100.dp, height = 30.dp)\n                .background(Color.Green)\n        )\n    }\n\n    var dynamicComposable by remember { mutableStateOf<@Composable () -> Unit> (@Composable { composable1() }) }\n\n    Column(\n        modifier = Modifier.fillMaxSize(),\n        horizontalAlignment = Alignment.CenterHorizontally\n    ) {\n\n        Row(\n            modifier = Modifier.fillMaxWidth(),\n            verticalAlignment = Alignment.CenterVertically,\n            horizontalArrangement = Arrangement.SpaceBetween\n        ) {\n            Button(onClick = {\n                dynamicComposable = composable1\n            }) {\n                Text("Comp 1")\n            }\n\n            Button(onClick = {\n                dynamicComposable = composable2\n            }) {\n                Text("Comp 2")\n            }\n\n            Button(onClick = {\n                dynamicComposable = composable3\n            }) {\n                Text("Comp 3")\n            }\n        }\n\n        AnyComposable {\n            dynamicComposable()\n        }\n    }\n}\n

\n

and the output:

\n

\n

Answer 2

或者，如果接收可组合项有，比如说 a Column，并且您想预先设置参数可组合项Alignment，则可以考虑这个。

相同的可组合接收器接受任何可组合项，但预期布局是Column.

@Composable
fun AnyComposable(
    anyComposable: @Composable () -> Unit
) {
    Column(
        modifier = Modifier.fillMaxSize()
    ) {
        anyComposable()
    }
}

@Composable
fun MyScreen() {

    // big red box at Start of Column
    val composable1 : @Composable ColumnScope.() -> Unit = @Composable {
        Box (
            modifier = Modifier
                .align(Alignment.Start)
                .size(200.dp)
                .background(Color.Red)
        )
    }

    // small blue box at Center of Column
    val composable2 : @Composable ColumnScope.() -> Unit = @Composable {
        Box(
            modifier = Modifier
                .align(Alignment.CenterHorizontally)
                .size(80.dp)
                .background(Color.Blue)
        )
    }

    // small green rectangle at end of column
    val composable3 : @Composable ColumnScope.() -> Unit = @Composable {
        Box(
            modifier = Modifier
                .align(Alignment.End)
                .size(width = 100.dp, height = 30.dp)
                .background(Color.Green)
        )
    }

    var dynamicComposable by remember { mutableStateOf<@Composable ColumnScope.() -> Unit> (@Composable { composable1() }) }

    Column(
        modifier = Modifier.fillMaxSize(),
        horizontalAlignment = Alignment.CenterHorizontally
    ) {

        Row(
            modifier = Modifier.fillMaxWidth(),
            verticalAlignment = Alignment.CenterVertically,
            horizontalArrangement = Arrangement.SpaceBetween
        ) {
            Button(onClick = {
                dynamicComposable = composable1
            }) {
                Text("Comp 1")
            }

            Button(onClick = {
                dynamicComposable = composable2
            }) {
                Text("Comp 2")
            }

            Button(onClick = {
                dynamicComposable = composable3
            }) {
                Text("Comp 3")
            }
        }

        AnyComposable {
            dynamicComposable()
        }
    }
}

输出：

Answer 3

嘿伙计们，如果您想知道我如何解决我自己的应用程序中的问题，请参阅此代码

最终结果

https://github.com/dolev146/Politi-Cal/tree/main/app/src/main/java/com/example/politi_cal

这是导航文件，我只是使用答案中描述的概念将屏幕作为参数传递

类似于抽屉包裹内容屏幕的东西

 composable(route = Screen.AdminOnlyScreen.route) {
            DrawerTopBar(navController = navCotroller, screen = { navController ->
                // this is the screen that will be drawn after the drawer
                // swipe screen
                AdminOnlyScreen(navController = navController, auth = auth)

            })
        }

        composable(route = Screen.UserAnalyticsScreen.route) {
            DrawerTopBar(navController = navCotroller, screen = { navController ->
                // this is the screen that will be drawn after the drawer
                // swipe screen


                UserAnalyticsScreen(
                    navController = navController,
                    auth = auth

                )

            })
        }

抽屉看起来像 https://github.com/dolev146/Politi-Cal/tree/main/app/src/main/java/com/example/politi_cal/screens/NavDrawer

// the drawer TopBar should get the navController as a parameter ,
// and the composable screen function that it needs to draw after the drawer
@Composable
fun DrawerTopBar(
    navController: NavController,
    auth: FirebaseAuth = FirebaseAuth.getInstance(),
    screen: @Composable (navController: NavController) -> Unit
) {
    var isAdminState by remember {
        mutableStateOf(false)
    }


    val scaffoldState = rememberScaffoldState()
    val scope = rememberCoroutineScope()
    val context = LocalContext.current
    isAdmin(context) {
        isAdminState = true
    }
    var menuContent = mutableListOf(
        MenuItem(
            id = "search",
            title = "Search",
            contentDescription = "Go to Search screen",
            icon = Icons.Default.Search
        ),

//        MenuItem(
//            id = "swipe",
//            title = "Swipe",
//            contentDescription = "Go to Swipe screen",
//            icon = Icons.Default.Home
//        ),
//        MenuItem(
//            id = "preferences",
//            title = "Preferences",
//            contentDescription = "Go to Preferences screen",
//            icon = Icons.Default.Settings
//        ),
//        MenuItem(
//            id = "logout",
//            title = "Logout",
//            contentDescription = "Go to Logout screen",
//            icon = Icons.Default.ExitToApp
//        ),
//        MenuItem(
//            id = "user analytics",
//            title = "User Analytics",
//            contentDescription = "Go to User Analytics screen",
//            icon = Icons.Default.MoreVert
//        )


    )

    if (isAdminState) {

        menuContent.add(
            MenuItem(
                id = "user analytics",
                title = "Analytics",
                contentDescription = "Go to User Analytics screen",
                icon = Icons.Default.MoreVert
            )
        )



        menuContent.add(
            MenuItem(
                id = "add celeb",
                title = "Add Celeb",
                contentDescription = "Go to User profile screen",
                icon = Icons.Default.Add
            )
        )
        menuContent.add(
            MenuItem(
                id = "admin analytics",
                title = "Admin Analytics",
                contentDescription = "Go to Admin Analytics screen",
                icon = Icons.Default.MoreVert
            )
        )
        menuContent.add(
            MenuItem(
                id = "admin user management",
                title = "User Search",
                contentDescription = "Go to Admin User Management screen",
                icon = Icons.Default.MoreVert
            )
        )











        menuContent.add(
            MenuItem(
                id = "logout",
                title = "Logout",
                contentDescription = "Go to Logout screen",
                icon = Icons.Default.ExitToApp
            )
        )


    } else {
        // this is user menu
        menuContent.add(
            MenuItem(
                id = "swipe",
                title = "Swipe",
                contentDescription = "Go to Swipe screen",
                icon = Icons.Default.Home
            )
        )

        menuContent.add(
            MenuItem(
                id = "user analytics",
                title = "Analytics",
                contentDescription = "Go to User Analytics screen",
                icon = Icons.Default.MoreVert
            )
        )

        menuContent.add(
            MenuItem(
                id = "preferences",
                title = "Preferences",
                contentDescription = "Go to Preferences screen",
                icon = Icons.Default.Settings
            )
        )

        menuContent.add(
            MenuItem(
                id = "my profile",
                title = "My Profile",
                contentDescription = "Go to User profile screen",
                icon = Icons.Default.Person
            )
        )














        menuContent.add(
            MenuItem(
                id = "logout",
                title = "Logout",
                contentDescription = "Go to Logout screen",
                icon = Icons.Default.ExitToApp
            )
        )


    }



    Scaffold(

        drawerGesturesEnabled = scaffoldState.drawerState.isOpen,
        scaffoldState = scaffoldState,
        topBar = {
            AppBar(onNavigationIconClick = {
                scope.launch {
                    scaffoldState.drawerState.open()
                }

            })
        },
        drawerContent = {
            DrawerHeader()
            DrawerBody(items = menuContent, onItemClick = {
                when (it.id) {
                    "swipe" -> {
                        navController.navigate(Screen.SwipeScreen.route)
                    }
                    "preferences" -> {
                        navController.navigate(Screen.PreferenceScreen2.route)
                    }
                    "user profile" -> {
                        navController.navigate(Screen.UserProfileScreen.route)
                    }
                    "add celeb" -> {
                        navController.navigate(Screen.AddCelebScreen.route)
                    }
                    "user analytics" -> {
                        navController.navigate(Screen.UserAnalyticsScreen.route)
                    }
                    "logout" -> {
//                        auth.signOut()
                        navController.navigate(Screen.SplashScreen.route)
                    }
                    "search" -> {
                        navController.navigate(Screen.SearchScreen.route)
                    }
                    "my profile" ->{

                        navController.navigate(Screen.UserProfileScreen.route)
                    }


                    "admin only" -> {
                        // check that the user is admin
                        // if not, show a message
                        // if yes, navigate to the admin only screen
                        if (isAdminState) {
                            navController.navigate(Screen.AdminOnlyScreen.route)
                        } else {
                            // show a message
                            Toast.makeText(context, "You are not an admin", Toast.LENGTH_SHORT)
                                .show()
                        }
                    }
                    "admin analytics" -> {
                        navController.navigate(Screen.AdminAnalyticsMenuScreen.route)
                    }
                    "admin user management" -> {
                        navController.navigate(Screen.AdminUserManagementScreen.route)
                    }


                }
            })

        }) {

        screen(navController = navController)

    }
}

观看链接中的完整代码，如果您喜欢我的解决方案，请投票:)祝您编码愉快