如何在Camera2 API Android 5.0中获得单个预览帧？

我正在尝试使用Camera2 API获取二维码扫描功能的预览帧。在旧的摄像头API中，它非常简单：

    android.hardware.Camera mCamera;
    ...
    mCamera.setPreviewCallback(new Camera.PreviewCallback() {
        @Override
        public void onPreviewFrame(byte[] data, Camera camera) {
            // will be invoked for every preview frame in addition to displaying them on the screen             
        }
    });

---

但是，我无法通过使用新的Camera2 API找到实现这一点的方法。我想接收多个可以处理的帧——最好是像旧API一样接收字节数组。有什么办法吗？

请使用下面的代码

 CameraManager manager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
        try {
            CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraDevice.getId());
            Size[] jpegSizes = null;
            if (characteristics != null) {
                jpegSizes = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(ImageFormat.JPEG);
            }
            int width = 480;//480x320
            int height = 320;
            if (jpegSizes != null && 0 < jpegSizes.length) {
                width = jpegSizes[0].getWidth();
                height = jpegSizes[0].getHeight();
            }
            ImageReader reader = ImageReader.newInstance(width, height, ImageFormat.JPEG, 1);
            List<Surface> outputSurfaces = new ArrayList<Surface>(2);
            outputSurfaces.add(reader.getSurface());
            outputSurfaces.add(new Surface(textureView.getSurfaceTexture()));
            final CaptureRequest.Builder captureBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
            captureBuilder.addTarget(reader.getSurface());
            captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
            // Orientation
            int rotation = ((Activity) context).getWindowManager().getDefaultDisplay().getRotation();
            captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
            final File file = getFileDir();
            ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
                @Override
                public void onImageAvailable(ImageReader reader) {
                    Image image = null;
                    try {
                        image = reader.acquireLatestImage();
                        ByteBuffer buffer = image.getPlanes()[0].getBuffer();
                        byte[] bytes = new byte[buffer.capacity()];
                        buffer.get(bytes);
                        save(bytes);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {
                        if (image != null) {
                            image.close();
                        }
                    }
                }

                private void save(byte[] bytes) throws IOException {
                    OutputStream output = null;
                    try {
                        output = new FileOutputStream(file);
                        output.write(bytes);
                    } finally {
                        if (null != output) {
                            output.close();
                        }
                    }
                }
            };
            reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }

CameraManager=（CameraManager）context.getSystemService（context.CAMERA_服务）；
试一试{
CameraCharacteristics characteristics=manager.getCameraCharacteristics（cameraDevice.getId（））；
Size[]jpegsize=null；
如果（特征！=null）{
jpegSizes=characteristics.get（CameraCharacteristics.SCALER\u STREAM\u CONFIGURATION\u MAP）.getOutputSizes（ImageFormat.JPEG）；
}
int width=480；//480x320
内部高度=320；
if（jpegSizes！=null&&0

有点晚了，但总比没有好：

通常使用

TextureView

来显示相机的预览。您可以使用

TextureView.SurfacetTextureListener

在每次曲面更改时获取回调

TextureView

提供了一种方法

getBitmap（Bitmap）

，您可以使用该方法获得与

TextureView

相同大小的预览帧

你可以用它作为起点。只需更新SurfaceTextRelister，如下所示：

private val surfaceTextureListener = object : TextureView.SurfaceTextureListener {

    override fun onSurfaceTextureAvailable(texture: SurfaceTexture, width: Int, height: Int) {
        openCamera(width, height)
    }

    override fun onSurfaceTextureSizeChanged(texture: SurfaceTexture, width: Int, height: Int) {
        configureTransform(width, height)
    }

    override fun onSurfaceTextureDestroyed(texture: SurfaceTexture) = true

    override fun onSurfaceTextureUpdated(texture: SurfaceTexture) {
        // Start changes
        // Get the bitmap
        val frame = Bitmap.createBitmap(textureView.width, textureView.height, Bitmap.Config.ARGB_8888)
        textureView.getBitmap(frame)

        // Do whatever you like with the frame
        frameProcessor?.processFrame(frame)
        // End changes
    }

}

---

看看这个问题。我发布了这个例子，它使用最新的android2摄像头API来读取二维码。享受cameraDevice从何而来？您正在演示如何捕获图像，问题是如何在捕获图像之前获取预览帧。例如，将imagereader作为捕获的目标RequestBuilder会降低帧速率难以置信，您知道如何获取吗