在 Android 上获取预览会话的相机对焦状态

如何解决在 Android 上获取预览会话的相机对焦状态

我在 Android 上编写了一个使用相机的应用。它在 SurfaceTexture 上创建预览，并使用 PreviewBulder / CaptureRequestBuilder / RepeatingRequest。我需要知道焦点是否已解决，但我只找到了在 Capturesession 期间获取焦点状态的方法。有谁知道如何在预览期间实现这一目标？我不使用任何捕获，而是使用预览中的帧。

感谢您的帮助:)

对应的代码部分（对不起，它不可爱:)）：

private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
    @override
    public void onOpened(CameraDevice camera) {
        //This is called when the camera is open
        // Log.e(TAG,"onOpened");
        cameraDevice = camera;
        createCameraPreview();
    }

    @override
    public void onDisconnected(CameraDevice camera) {
        cameraDevice.close();
    }

    @override
    public void onError(CameraDevice camera,int error) {
        cameraDevice.close();
        cameraDevice = null;
    }
};

final CameraCaptureSession.CaptureCallback captureCallbackListener = new CameraCaptureSession.CaptureCallback() {
    @override
    public void onCaptureCompleted(CameraCaptureSession session,CaptureRequest request,TotalCaptureResult result) {
        super.onCaptureCompleted(session,request,result);
        // makeText(MainActivity.this,"Saved:" + file,LENGTH_SHORT).show();
        createCameraPreview();
    }
};

protected void startBackgroundThread() {
    mBackgroundThread = new HandlerThread("Camera Background");
    mBackgroundThread.start();
    mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}

protected void stopBackgroundThread() {
    mBackgroundThread.quitSafely();
    try {
        mBackgroundThread.join();
        mBackgroundThread = null;
        mBackgroundHandler = null;
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}


protected void createCameraPreview() {
    try {
        SurfaceTexture texture = textureView.getSurfaceTexture();
        assert texture != null;
        texture.setDefaultBufferSize(imageDimension.getWidth(),imageDimension.getHeight());
        Surface surface = new Surface(texture);

        CameraManager manager;
        manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        try {
            String camerId = manager.getCameraIdList()[0];

            CameraCharacteristics characteristics = manager.getCameraCharacteristics(camerId);

            boolean aelockavailable = characteristics.get(CameraCharacteristics.CONTROL_AE_LOCK_AVAILABLE);
        } catch (Exception e) {}


        captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,captureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
        //captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,captureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
        captureRequestBuilder.addTarget(surface);
        cameraDevice.createCaptureSession(Arrays.asList(surface),new CameraCaptureSession.StateCallback() {
                @override
                public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
                    //The camera is already closed
                    if (null == cameraDevice) {
                        return;
                    }
                    // When the session is ready,we start displaying the preview.
                    cameraCaptureSessions = cameraCaptureSession;
                    updatePreview();
                }

                @override
                public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
                    //makeText(MainActivity.this,"Configuration change",LENGTH_SHORT).show();
                }
            },null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

void openCamera() {
    CameraManager manager = (CameraManager)
    getSystemService(Context.CAMERA_SERVICE);
    //Log.e(TAG,"is camera open");
    try {
        cameraId = manager.getCameraIdList()[0];
        CameraCharacteristics characteristics =
            manager.getCameraCharacteristics(cameraId);
        StreamConfigurationMap map =
            characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
        assert map != null;
        imageDimension = map.getOutputSizes(SurfaceTexture.class)[0];
        // Add permission for camera and let user grant the permission
        if (ActivityCompat.checkSelfPermission(this,Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED &&
            ActivityCompat.checkSelfPermission(this,Manifest.permission.WRITE_EXTERNAL_STORAGE) !=
            PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(MainActivity.this,new String[] {
                    Manifest.permission.CAMERA,Manifest.permission.WRITE_EXTERNAL_STORAGE
                },REQUEST_CAMERA_PERMISSION);
            return;
        }
        manager.openCamera(cameraId,stateCallback,null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
    //Log.e(TAG,"openCamera X");
}

void updatePreview() {
    if (null == cameraDevice) {
        //Log.e(TAG,"updatePreview error,return");
    }
    captureRequestBuilder.set(CaptureRequest.CONTROL_MODE,CameraMetadata.CONTROL_MODE_AUTO);
    captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,captureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
    //captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
    if (flashchanged) {
        flashchanged = false;
        if (lamp && autoflash) {
            captureRequestBuilder.set(CaptureRequest.FLASH_MODE,CaptureRequest.FLASH_MODE_TORCH);
        } else {
            captureRequestBuilder.set(CaptureRequest.FLASH_MODE,CaptureRequest.FLASH_MODE_OFF);
        }
    }
    try {
        cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(),null,mBackgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private void closeCamera() {
    if (null != cameraDevice) {
        cameraDevice.close();
        cameraDevice = null;
    }
    if (null != imageReader) {
        imageReader.close();
        imageReader = null;
    }
}```