android - 如何在撰写中初始化相机

Question

我想通过撰写 androidView 获得相机视图，但以下代码似乎对我不起作用。

@Composable
fun CameraPreviewScreen() {
    val lifecycleOwner = LifecycleOwnerAmbient.current
    val context = ContextAmbient.current
    val cameraProviderFuture = remember { ProcessCameraProvider.getInstance(context) }
    val previewView = remember { PreviewView(context) }
    AndroidView(viewBlock = { previewView }) {
        cameraProviderFuture.addListener(Runnable {
            val cameraProvider = cameraProviderFuture.get()
            val preview = Preview.Builder().build()
            preview.setSurfaceProvider(it.surfaceProvider)
            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA
            try {
                cameraProvider.unbindAll()
                cameraProvider.bindToLifecycle(
                    lifecycleOwner, cameraSelector, preview)
            } catch(exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }
        }, ContextCompat.getMainExecutor(context))
    }
}

下面的截图。

报告错误。

Permission Denial：不能使用相机
不能打开相机“0”没有相机权限（代码1）

标签： androidandroid-cameraxandroid-jetpack-compose

Answer 1

由于您的问题似乎与相机权限有关，您可以使用Accompanist库中的Permissions API向用户询问权限。

文档显示了一个带有相机的示例

@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")
    }
}