注意:本页介绍的是 Camera2 软件包。除非您的应用需要 Camera2 的特定低层级功能,否则我们建议您使用 CameraX。CameraX 和 Camera2 都支持 Android 5.0(API 级别 21)及更高版本。
Camera2 提供了一个 Extensions API,用于访问设备制造商在各种 Android 设备上实现的扩展。如需查看支持的扩展模式的列表,请参阅相机扩展。
如需查看支持扩展的设备列表,请参阅支持的设备。
扩展架构
下图显示了相机扩展程序架构。
![](https://developer.android.google.cn/static/images/training/camera/camera2/camera2-camera-extensions-architecture.png?authuser=2&hl=he)
Camera2 应用可以通过 Camera2 API 使用扩展。Camera2 API 提供了查询可用扩展、配置扩展相机会话以及与相机扩展 OEM 库通信的方法。这样,您的应用就可以使用夜间、HDR、自动、焦外成像或脸部照片修复等扩展程序。
测试相机设备的 Camera2 Extensions API 兼容性
以下代码段会检查设备是否支持 Camera2 Extensions API。并非所有设备都支持扩展,或者设备可能支持一部分扩展。该代码段会返回支持相机扩展的兼容相机 ID 的列表。
Kotlin
private fun getExtensionCameraIds(cameraManager: CameraManager): List<String> = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) { cameraManager.cameraIdList.filter { cameraId -> val characteristics = cameraManager.getCameraCharacteristics(cameraId) val extensionCharacteristics = cameraManager.getCameraExtensionCharacteristics(cameraId) val capabilities = characteristics.get(CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES) extensionCharacteristics.supportedExtensions.isNotEmpty() && capabilities?.contains( CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_BACKWARD_COMPATIBLE ) ?: false } } else emptyList()
Java
private List<String> getExtensionCameraIds(CameraManager cameraManager) throws CameraAccessException { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) { return Arrays.stream(cameraManager.getCameraIdList()).filter(cameraId -> { try { CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId); CameraExtensionCharacteristics extensionCharacteristics = cameraManager.getCameraExtensionCharacteristics(cameraId); IntStream capabilities = Arrays.stream( characteristics.get( CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES ) ); return !extensionCharacteristics.getSupportedExtensions().isEmpty() && capabilities.anyMatch(capability -> capability == CameraCharacteristics .REQUEST_AVAILABLE_CAPABILITIES_BACKWARD_COMPATIBLE ); } catch (CameraAccessException e) { throw new RuntimeException(e); } }).collect(Collectors.toList()); } else { return Collections.emptyList(); } }
使用 Camera2 Extensions API 创建 CameraExtensionSession
在与兼容的设备搭配使用时,Camera2 Extensions API 可让您访问某些相机扩展。以下代码段举例说明了如何创建 CameraExtensionSession
,以便为现有 Camera2 应用使用夜间拍摄模式。
Kotlin
private val captureCallbacks = object : CameraExtensionSession.ExtensionCaptureCallback() { // Implement Capture Callbacks } private val extensionSessionStateCallback = object : CameraExtensionSession.StateCallback() { override fun onConfigured(session: CameraExtensionSession) { cameraExtensionSession = session try { val captureRequest = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW).apply { addTarget(previewSurface) }.build() session.setRepeatingRequest( captureRequest, Dispatchers.IO.asExecutor(), captureCallbacks ) } catch (e: CameraAccessException) { Snackbar.make( previewView, "Failed to preview capture request", Snackbar.LENGTH_SHORT ).show() requireActivity().finish() } } override fun onClosed(session: CameraExtensionSession) { super.onClosed(session) cameraDevice.close() } override fun onConfigureFailed(session: CameraExtensionSession) { Snackbar.make( previewView, "Failed to start camera extension preview", Snackbar.LENGTH_SHORT ).show() requireActivity().finish() } } private fun startExtensionSession() { val outputConfig = arrayListOf( OutputConfiguration(stillImageReader.surface), OutputConfiguration(previewSurface) ) val extensionConfiguration = ExtensionSessionConfiguration( CameraExtensionCharacteristics.EXTENSION_NIGHT, outputConfig, Dispatchers.IO.asExecutor(), extensionSessionStateCallback ) cameraDevice.createExtensionSession(extensionConfiguration) }
Java
private CameraExtensionSession.ExtensionCaptureCallback captureCallbacks = new CameraExtensionSession.ExtensionCaptureCallback() { // Implement Capture Callbacks }; private CameraExtensionSession.StateCallback extensionSessionStateCallback = new CameraExtensionSession.StateCallback() { @Override public void onConfigured(@NonNull CameraExtensionSession session) { cameraExtensionSession = session; try { CaptureRequest.Builder captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); captureRequestBuilder.addTarget(previewSurface); CaptureRequest captureRequest = captureRequestBuilder.build(); session.setRepeatingRequest(captureRequest, backgroundExecutor, captureCallbacks); } catch (CameraAccessException e) { Snackbar.make( previewView, "Failed to preview capture request", Snackbar.LENGTH_SHORT ).show(); requireActivity().finish(); } } @Override public void onClosed(@NonNull CameraExtensionSession session) { super.onClosed(session); cameraDevice.close(); } @Override public void onConfigureFailed(@NonNull CameraExtensionSession session) { Snackbar.make( previewView, "Failed to start camera extension preview", Snackbar.LENGTH_SHORT ).show(); requireActivity().finish(); } }; private void startExtensionSession() { ArrayList<OutputConfiguration> outputConfig = new ArrayList<>(); outputConfig.add(new OutputConfiguration(stillImageReader.getSurface())); outputConfig.add(new OutputConfiguration(previewSurface)); ExtensionSessionConfiguration extensionConfiguration = new ExtensionSessionConfiguration( CameraExtensionCharacteristics.EXTENSION_NIGHT, outputConfig, backgroundExecutor, extensionSessionStateCallback ); }
其他资源
如需了解详情,请参阅 CameraExtensionCharacteristics
并查看公开的 Camera2 Extensions API 示例。