16. Compose 权限申请Permission

01. Compose 可组合组件之Row And Column

02. Compose 可组合组件之 属性 modifier

03. Compose 可组合组件之Card 图片

04. Compose 字体

05. Compose State

06. Compose SnackBar

07. Compose List

08. Compose ConstrainLayout

09. Compose Button

10. Compose CheckBox

11. Compose 对于复杂界面的尝试

12. Compose 之原生xml布局加入Compose代码

13. Compose 之Compose代码插入xml布局

14. Compose 之简易朋友圈列表

15. Compose 使用CameraX

16. Compose 权限申请Permission

@ExperimentalPermissionsApi
class PermissionActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            FeatureThatRequiresCameraPermission { startAppSettings() }
//            FeatureThatRequiresCameraPermission1 { startAppSettings() }
        }
    }

    private fun startAppSettings() {
        val intent = Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS)
        intent.data = Uri.parse("package:$packageName")
        startActivity(intent)
    }

    
    @Composable
    private fun FeatureThatRequiresCameraPermission(navigateToSettingsScreen: () -> Unit) {
        // Track if the user doesn't want to see the rationale any more.
        var doNotShowRationale by rememberSaveable { mutableStateOf(false) }

        val cameraPermissionState = rememberPermissionState(android.Manifest.permission.CAMERA)
        PermissionRequired(
            permissionState = cameraPermissionState,
            permissionNotGrantedContent = {
                if (doNotShowRationale) {
                    Text("Feature not available")
                } else {
                    Column {
                        Text("The camera is important for this app. Please grant the permission.")
                        Spacer(modifier = Modifier.height(8.dp))
                        Row {
                            Button(onClick = { cameraPermissionState.launchPermissionRequest() }) {
                                Text("Ok!")
                            }
                            Spacer(Modifier.width(8.dp))
                            Button(onClick = { doNotShowRationale = true }) {
                                Text("Nope")
                            }
                        }
                    }
                }
            },
            permissionNotAvailableContent = {
                Column {
                    Text(
                        "Camera permission denied. See this FAQ with information about why we " +
                                "need this permission. Please, grant us access on the Settings screen."
                    )
                    Spacer(modifier = Modifier.height(8.dp))
                    Button(onClick = navigateToSettingsScreen) {
                        Text("Open Settings")
                    }
                }
            }
        ) {
            Text("Camera permission Granted")
        }
    }

    @Composable
    private fun FeatureThatRequiresCameraPermission1(
        navigateToSettingsScreen: () -> Unit
    ) {
        // Track if the user doesn't want to see the rationale any more.
        var doNotShowRationale by rememberSaveable { mutableStateOf(false) }

        // Camera permission state
        val cameraPermissionState = rememberPermissionState(
            android.Manifest.permission.CAMERA
        )

        when {
            // If the camera permission is granted, then show screen with the feature enabled
            cameraPermissionState.hasPermission -> {
                Text("Camera permission Granted")
            }
            // If the user denied the permission but a rationale should be shown, or the user sees
            // the permission for the first time, explain why the feature is needed by the app and allow
            // the user to be presented with the permission again or to not see the rationale any more.
            cameraPermissionState.shouldShowRationale ||
                    !cameraPermissionState.permissionRequested -> {
                if (doNotShowRationale) {
                    Text("Feature not available")
                } else {
                    Column {
                        Text("The camera is important for this app. Please grant the permission.")
                        Spacer(modifier = Modifier.height(8.dp))
                        Row {
                            Button(onClick = { cameraPermissionState.launchPermissionRequest() }) {
                                Text("Request permission")
                            }
                            Spacer(Modifier.width(8.dp))
                            Button(onClick = { doNotShowRationale = true }) {
                                Text("Don't show rationale again")
                            }
                        }
                    }
                }
            }
            // If the criteria above hasn't been met, the user denied the permission. Let's present
            // the user with a FAQ in case they want to know more and send them to the Settings screen
            // to enable it the future there if they want to.
            else -> {
                Column {
                    Text(
                        "Camera permission denied. See this FAQ with information about why we " +
                                "need this permission. Please, grant us access on the Settings screen."
                    )
                    Spacer(modifier = Modifier.height(8.dp))
                    Button(onClick = navigateToSettingsScreen) {
                        Text("Open Settings")
                    }
                }
            }
        }
    }
}