Camera2 扩展 API

注意：此页面指的是 Camera2 包。除非您的应用程序需要 Camera2 中的特定低级功能，否则建议使用 CameraX。CameraX 和 Camera2 都支持 Android 5.0（API 级别 21）及更高版本。

Camera2 提供扩展 API 来访问设备制造商已在各种 Android 设备上实施的 扩展。有关支持的扩展模式列表，请参阅 相机扩展。

有关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架构。

Camera2 应用程序可以通过 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 库进行通信的方法。这使您的应用程序能够使用夜间、HDR、自动、散景或人脸修饰等扩展。

测试相机设备以确保其与 Camera2 扩展 API 兼容

以下代码片段检查设备是否支持 Camera2 Extensions API。并非所有设备都支持扩展，或者设备可能只支持部分扩展。该代码片段返回支持相机扩展的兼容相机 ID 列表。

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()

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

Camera2 Extensions API 在与兼容设备一起使用时，允许您访问某些相机扩展。以下代码片段展示了如何为现有 Camera2 应用程序创建 CameraExtensionSession 以使用夜间拍摄模式的示例。

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)
}

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

有关更多信息，请参阅 CameraExtensionCharacteristics 并查看公共的 Camera2 Extensions API 示例 以了解更多信息。