使用camera2 API获取单张图像并用ImageView显示

我想使用 Camera2 API 从相机获取单个帧并使用 ImageView 显示它。 我发现了一些密切的问题，例如

https://stackoverflow.com/questions/25462277/camera-preview-image-data-processing-with-android-l-and-camera2-api https://stackoverflow.com/questions/25462277/camera-preview-image-data-processing-with-android-l-and-camera2-api

我还查看了 Camera2Basic 示例，但它太复杂并且不完全是我所需要的。

我编写的代码是基于我在网上看到的一些示例，应该可以实现，但它不起作用，我不明白为什么。

应用程序不会崩溃，但只是不在 ImageView 上显示任何内容。 我在任何函数调用中都使用了日志消息，以便尝试保持 logcat 清晰。

另外，该应用程序是 logcat 说“该应用程序可能在后台做了太多工作......”我不明白这怎么可能，因为我做了一个captureRequest而不是一个repeatingCaptureRequest.

这是代码和 logcat： 代码：

public class CameraImageReaderActivity extends AppCompatActivity {

private final static String TAG = "CAMERA_IMAGE_READY: ";
private ImageReader imageReader;
private String cameraId;
private CameraDevice camera;
private HandlerThread handlerThread;
private Handler handler;
private Surface imageReaderSurface;
private ImageView imageView;

private CameraDevice.StateCallback cameraStateCallback = new CameraDevice.StateCallback() {
    @Override
    public void onOpened(CameraDevice cameraDevice) {
        Log.d(TAG, "onOpend: CAMERA OPENED");
        camera = cameraDevice;
        getFrames();
    }

    @Override
    public void onDisconnected(CameraDevice cameraDevice) {
        Log.d(TAG, "onDisconnected: CAMERA DISCONNECTED");
        cameraDevice.close();
        camera = null;
    }

    @Override
    public void onError(CameraDevice cameraDevice, int i) {
        Log.d(TAG, "onError: CAMERA ERROR");
        cameraDevice.close();
        camera = null;
    }
};

private CameraCaptureSession.StateCallback captureSessionStateCallback = new CameraCaptureSession.StateCallback() {
    @Override
    public void onConfigured(CameraCaptureSession cameraCaptureSession) {
        Log.d(TAG, "onConfigured: build request and capture");
        try {
            CaptureRequest.Builder requestBuilder = cameraCaptureSession.getDevice().createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
            requestBuilder.addTarget(imageReaderSurface);

            cameraCaptureSession.capture(requestBuilder.build(), null, handler);
        } catch (CameraAccessException e) {
            Log.d(TAG, "onConfigured: CANT CREATE CAPTURE REQUEST");
            e.printStackTrace();
        }
    }

    @Override
    public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {
        Log.d(TAG, "onConfiguredFailed: CANT CONFIGURE CAMERA");
    }
};

private ImageReader.OnImageAvailableListener imageReaderListener = new ImageReader.OnImageAvailableListener() {
    @Override
    public void onImageAvailable(ImageReader imageReader) {
        Log.d(TAG, "onImageAvailable: IMAGE AVAILABLE");
        Image image = imageReader.acquireLatestImage();
        int imgFormat = image.getFormat();
        ByteBuffer pixelArray1 = image.getPlanes()[0].getBuffer();
        int pixelStride = image.getPlanes()[0].getPixelStride();
        int rowStride = image.getPlanes()[0].getRowStride();
        int rowPadding = rowStride - pixelStride * 640;

        Bitmap bitmap = Bitmap.createBitmap(640 + rowPadding/pixelStride, 480, Bitmap.Config.RGB_565);
        bitmap.copyPixelsFromBuffer(pixelArray1);
        imageView.setImageBitmap(bitmap);

        image.close();
    }
};

/**
 * Sets the cameraId with the front camera id and sets imageReader properties.
 */
public void setupCamera(int width, int height) {
    imageReader = ImageReader.newInstance(width, height, ImageFormat.RGB_565, 30);
    CameraManager cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);
    try {
        for (String allCamerasId : cameraManager.getCameraIdList()) {
            CameraCharacteristics cameraCharacteristics = cameraManager.getCameraCharacteristics(allCamerasId);
            if (cameraCharacteristics.get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_FRONT) {
                continue;
            }
            cameraId = allCamerasId;
            Log.d(TAG, "setupCamera: CameraId is: " + cameraId);
            return;
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }

}

/**
 * Connects to the front facing camera.
 * After the connection to the camera, the onOpened callback method will be invoked.
 */
public void connectCamera() {
    CameraManager cameraManager = (CameraManager) getSystemService(CAMERA_SERVICE);
    try {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            Log.d(TAG, "CANT OPEN CAMERA");
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        cameraManager.openCamera(cameraId, cameraStateCallback, handler);
        Log.d(TAG, "connectCamera: CAMERA OPENED!");
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

/**
 * Build the captureSessionRequest and start in repeat.
 */
public void getFrames() {
    Log.d(TAG, "getFrames: CREATE CAPTURE SESSION");
    imageReaderSurface = imageReader.getSurface();
    List<Surface> surfaceList = new ArrayList<>();
    surfaceList.add(imageReaderSurface);
    try {
        camera.createCaptureSession(surfaceList, captureSessionStateCallback, handler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

public void startBackgroundThread() {
    handlerThread = new HandlerThread("CameraImageReaderActivity");
    handlerThread.start();
    handler = new Handler(handlerThread.getLooper());
}

public void stopBackgroundThread() {
    handlerThread.quitSafely();
    try {
        handlerThread.join();
        handlerThread = null;
        handler = null;
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

public void closeCamera() {
    if (camera != null) {
        camera.close();
        camera = null;
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_camera_image_reader);
    imageView = (ImageView) findViewById(R.id.imageView);
    setupCamera(640, 480);
    connectCamera();
}

@Override
protected void onPause() {
    closeCamera();
    startBackgroundThread();
    super.onPause();
}

@Override
protected void onResume() {
    super.onResume();
    startBackgroundThread();
    //connectCamera();
}

以及（相关的）logcat：

03-22 14:27:32.900 18806-18806/com.example.noamm_000.talkwithcompviawifi D/CAMERA_IMAGE_READY:: setupCamera: CameraId is: 0
03-22 14:27:32.904 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value mw_continuous-picture
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value emboss
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value sketch
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value neon
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value asd
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value backlight
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value flowers
03-22 14:27:32.905 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value AR
03-22 14:27:32.912 18806-18806/com.example.noamm_000.talkwithcompviawifi I/CameraManager: Using legacy camera HAL.
03-22 14:27:33.685 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value mw_continuous-picture
03-22 14:27:33.685 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value emboss
03-22 14:27:33.685 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value sketch
03-22 14:27:33.685 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value neon
03-22 14:27:33.686 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value asd
03-22 14:27:33.686 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value backlight
03-22 14:27:33.686 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value flowers
03-22 14:27:33.686 18806-18806/com.example.noamm_000.talkwithcompviawifi W/ArrayUtils: Ignoring invalid value AR
03-22 14:27:33.702 18806-18806/com.example.noamm_000.talkwithcompviawifi D/CAMERA_IMAGE_READY:: connectCamera: CAMERA OPENED!
03-22 14:27:33.719 18806-18806/com.example.noamm_000.talkwithcompviawifi I/Choreographer: Skipped 56 frames!  The application may be doing too much work on its main thread.
03-22 14:27:33.787 18806-18806/com.example.noamm_000.talkwithcompviawifi D/CAMERA_IMAGE_READY:: onOpend: CAMERA OPENED
03-22 14:27:33.787 18806-18806/com.example.noamm_000.talkwithcompviawifi D/CAMERA_IMAGE_READY:: getFrames: CREATE CAPTURE SESSION
03-22 14:27:33.789 18806-18806/com.example.noamm_000.talkwithcompviawifi I/CameraDeviceState: Legacy camera service transitioning to state CONFIGURING
03-22 14:27:33.789 18806-19149/com.example.noamm_000.talkwithcompviawifi I/RequestThread-0: Configure outputs: 1 surfaces configured.
03-22 14:27:33.790 18806-19149/com.example.noamm_000.talkwithcompviawifi D/Camera: app passed NULL surface
03-22 14:27:33.838 18806-18806/com.example.noamm_000.talkwithcompviawifi I/CameraDeviceState: Legacy camera service transitioning to state IDLE
03-22 14:27:33.843 18806-19150/com.example.noamm_000.talkwithcompviawifi D/CAMERA_IMAGE_READY:: onConfigured: build request and capture
03-22 14:27:33.874 18806-19149/com.example.noamm_000.talkwithcompviawifi W/LegacyRequestMapper: convertRequestMetadata - control.awbRegions setting is not supported, ignoring value
03-22 14:27:33.875 18806-19149/com.example.noamm_000.talkwithcompviawifi W/LegacyRequestMapper: Only received metering rectangles with weight 0.
03-22 14:27:33.875 18806-19149/com.example.noamm_000.talkwithcompviawifi W/LegacyRequestMapper: Only received metering rectangles with weight 0.
03-22 14:27:34.070 18806-18806/com.example.noamm_000.talkwithcompviawifi I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@13c07070 time:331143683
03-22 14:27:34.317 18806-19155/com.example.noamm_000.talkwithcompviawifi I/CameraDeviceState: Legacy camera service transitioning to state CAPTURING
03-22 14:27:34.353 18806-19149/com.example.noamm_000.talkwithcompviawifi I/CameraDeviceState: Legacy camera service transitioning to state IDLE
03-22 14:27:34.403 18806-18806/com.example.noamm_000.talkwithcompviawifi D/BubblePopupHelper: isShowingBubblePopup : false
03-22 14:27:34.403 18806-18806/com.example.noamm_000.talkwithcompviawifi D/BubblePopupHelper: isShowingBubblePopup : false
03-22 14:27:34.404 18806-18806/com.example.noamm_000.talkwithcompviawifi D/BubblePopupHelper: isShowingBubblePopup : false
03-22 14:27:34.404 18806-18806/com.example.noamm_000.talkwithcompviawifi D/BubblePopupHelper: isShowingBubblePopup : false
03-22 14:28:07.684 18806-18823/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.684 18806-18822/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.684 18806-19184/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.685 18806-18823/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.685 18806-18822/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.685 18806-19184/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.686 18806-18823/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned
03-22 14:28:07.686 18806-18822/com.example.noamm_000.talkwithcompviawifi E/BufferQueueProducer: [unnamed-18806-1] cancelBuffer: BufferQueue has been abandoned

谢谢， 诺姆

尝试这种方法更好地在后台线程中处理它。

 public void onImageAvailable(ImageReader reader) {
        new ImageSaver(reader.acquireLatestImage());
    } 

   private class ImageSaver implements Runnable {

        private final Image mImage;

        public ImageSaver(Image image) {
            mImage = image;
        }

        @Override
        public void run() {
            File mImageFileName = null;
            if (mImage != null) {

                ByteBuffer byteBuffer = mImage.getPlanes()[0].getBuffer();
                byte[] bytes = new byte[byteBuffer.remaining()];
                byteBuffer.get(bytes);

                FileOutputStream fileOutputStream = null;
                try {
                    mImageFileName = createImageFileName();
                    fileOutputStream = new FileOutputStream(mImageFileName);
                    fileOutputStream.write(bytes);
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    mImage.close();
                    if (mImageFileName != null) {
                        Intent mediaStoreUpdateIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
                        mediaStoreUpdateIntent.setData(Uri.fromFile(mImageFileName));
                        sendBroadcast(mediaStoreUpdateIntent);
                        loadImageFromStorage(mImageFileName);
                    }
                    if (fileOutputStream != null) {
                        try {
                            fileOutputStream.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }

        private void loadImageFromStorage(File mImageFileName) {
            imageView.setImageBitmap(BitmapFactory.decodeFile(mImageFileName.getAbsolutePath()));
        }
    }

    private File createImageFileName() throws IOException {
        String timestamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String prepend = "IMAGE_" + timestamp + "_";
        File imageFile = File.createTempFile(prepend, ".jpg", createImageFolder());
        return imageFile;
    }

    private File createImageFolder() {
        File imageFile = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
        File mImageFolder = new File(imageFile, "myFolder");
        if (!mImageFolder.exists()) {
            mImageFolder.mkdirs();
        }
        return mImageFolder;
    }