探索 CameraX 音视频相机技术（7）：扩展 API

import androidx.camera.extensions.ExtensionMode;
import androidx.camera.extensions.ExtensionsManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    final LifecycleOwner lifecycleOwner = this;

    final ListenableFuture<ProcessCameraProvider> cameraProviderFuture =
            ProcessCameraProvider.getInstance(getApplicationContext());

    cameraProviderFuture.addListener(() -> {
        try {
            // 获取进程相机提供程序实例
            // 相机提供程序提供对设备相关相机集的访问。
            // 从提供程序获取的相机将绑定到活动生命周期。
            final ProcessCameraProvider cameraProvider = cameraProviderFuture.get();

            final ListenableFuture<ExtensionsManager> extensionsManagerFuture =
                    ExtensionsManager.getInstanceAsync(getApplicationContext(), cameraProvider);
            extensionsManagerFuture.addListener(() -> {
                // 获取扩展管理器实例
                // 扩展管理器使相机能够使用设备上可用的扩展功能。
                try {
                    final ExtensionsManager extensionsManager = extensionsManagerFuture.get();

                    // 选择相机
                    final CameraSelector cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA;

                    // 查询扩展是否可用。
                    // 并非所有设备都支持扩展，或者可能只支持部分扩展。
                    if (extensionsManager.isExtensionAvailable(
                            cameraSelector,
                            ExtensionMode.NIGHT
                    )) {
                        // 在启用不同扩展模式之前，先解除绑定所有用例。
                        cameraProvider.unbindAll();

                        // 获取启用了扩展的相机选择器
                        final CameraSelector nightCameraSelector = extensionsManager
                                .getExtensionEnabledCameraSelector(cameraSelector, ExtensionMode.NIGHT);

                        // 使用启用了扩展的相机选择器绑定图像捕获和预览用例。
                        final ImageCapture imageCapture = new ImageCapture.Builder().build();
                        final Preview preview = new Preview.Builder().build();
                        // 将预览连接到接收相机输出帧的表面。
                        // 这将允许在 TextureView 或 SurfaceView 中显示相机帧。
                        // SurfaceProvider 可以从 PreviewView 获得。
                        preview.setSurfaceProvider(surfaceProvider);

                        cameraProvider.bindToLifecycle(
                                lifecycleOwner,
                                nightCameraSelector,
                                imageCapture,
                                preview
                        );
                    }
                } catch (ExecutionException | InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }, ContextCompat.getMainExecutor(this));

        } catch (ExecutionException | InterruptedException e) {
            throw new RuntimeException(e);
        }

    }, ContextCompat.getMainExecutor(this));
}

dependencies {
  val camerax_version = "1.2.0-rc01"
  implementation("androidx.camera:camera-core:${camerax_version}")
  implementation("androidx.camera:camera-camera2:${camerax_version}")
  implementation("androidx.camera:camera-lifecycle:${camerax_version}")
  // CameraX 扩展库
  implementation("androidx.camera:camera-extensions:${camerax_version}")
    ...
}