Android- Zxing扫描仪在中心添加预览

Question

我在Android中使用Zxing库，“相机活动”显示正确的扫描区域宽度和高度，但未在屏幕中间显示。相机扫描区域应添加在中间。请指导如何修复它。我已附上问题的屏幕截图。我在下面添加了相机管理器类。

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/51QiN.jpg


**CameraManager Class**



public final class CameraManager {

  private static final String TAG = CameraManager.class.getSimpleName();

  private static final int MIN_FRAME_WIDTH = 240;
  private static final int MIN_FRAME_HEIGHT = 240;
  private static final int MAX_FRAME_WIDTH = 600;
  private static final int MAX_FRAME_HEIGHT = 400;

  private final Context context;
  private final com.scan.camera.CameraConfigurationManager configManager;
  private Camera camera;
  private Rect framingRect;
  private Rect framingRectInPreview;
  private boolean initialized;
  private boolean previewing;
  private boolean reverseImage;
  private int requestedFramingRectWidth;
  private int requestedFramingRectHeight;


  private final PreviewCallback previewCallback;

  private final AutoFocusCallback autoFocusCallback;

  public CameraManager(Context context) {
    this.context = context;
    this.configManager = new com.scan.camera.CameraConfigurationManager(context);
    previewCallback = new PreviewCallback(configManager);
    autoFocusCallback = new AutoFocusCallback();
  }


  public void openDriver(SurfaceHolder holder) throws IOException {
    Camera theCamera = camera;
    if (theCamera == null) {
      theCamera = Camera.open();
      theCamera.setDisplayOrientation(90);
      if (theCamera == null) {
        throw new IOException();
      }
      camera = theCamera;
    }
    theCamera.setPreviewDisplay(holder);

    if (!initialized) {
      initialized = true;
      configManager.initFromCameraParameters(theCamera);
      if (requestedFramingRectWidth > 0 && requestedFramingRectHeight > 0) {
        setManualFramingRect(requestedFramingRectWidth, requestedFramingRectHeight);
        requestedFramingRectWidth = 0;
        requestedFramingRectHeight = 0;
      }
    }
    configManager.setDesiredCameraParameters(theCamera);

    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
    reverseImage = false;
  }

  public void closeDriver() {
    if (camera != null) {
      camera.release();
      camera = null;
      // Make sure to clear these each time we close the camera, so that any scanning rect
      // requested by intent is forgotten.
      framingRect = null;
      framingRectInPreview = null;
    }
  }
  public void startPreview() {
    Camera theCamera = camera;
    if (theCamera != null && !previewing) {
      theCamera.startPreview();
      previewing = true;
    }
  }

  public void stopPreview() {
    if (camera != null && previewing) {
      camera.stopPreview();
      previewCallback.setHandler(null, 0);
      autoFocusCallback.setHandler(null, 0);
      previewing = false;
    }
  }


  public void requestPreviewFrame(Handler handler, int message) {
    Camera theCamera = camera;
    if (theCamera != null && previewing) {
      previewCallback.setHandler(handler, message);
      theCamera.setOneShotPreviewCallback(previewCallback);
    }
  }


  public void requestAutoFocus(Handler handler, int message) {
    if (camera != null && previewing) {
      autoFocusCallback.setHandler(handler, message);
      camera.autoFocus(autoFocusCallback);
    }
  }



  public Rect getFramingRect() {
    if (framingRect == null) {
      if (camera == null) {
        return null;
      }
      Point screenResolution = configManager.getScreenResolution();
      int width = screenResolution.x * 3 / 4;

      int height = screenResolution.y * 3 / 4;
      Log.v("Framing rect is : ", "width is "+width+"   and height is "+height);
      int leftOffset = (screenResolution.x - width) / 2;
      int topOffset = (screenResolution.y - height) / 2;
      framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
      Log.d(TAG, "Calculated framing rect: " + framingRect);
    }
    return framingRect;
  }


  public Rect getFramingRectInPreview() {
    if (framingRectInPreview == null) {
      Rect framingRect = getFramingRect();
      if (framingRect == null) {
        return null;
      }
      Rect rect = new Rect(framingRect);
      Point cameraResolution = configManager.getCameraResolution();
      if (cameraResolution == null) {
        return framingRect;
      }
      Point screenResolution = configManager.getScreenResolution();
      rect.left = rect.left * cameraResolution.x / screenResolution.x;
      rect.right = rect.right * cameraResolution.x / screenResolution.x;
      rect.top = 50+ rect.top * cameraResolution.y / screenResolution.y;
      rect.bottom = rect.bottom * cameraResolution.y / screenResolution.y;
      framingRectInPreview = rect;
    }
    return framingRectInPreview;
  }


  public void setManualFramingRect(int width, int height) {
    if (initialized) {
      Point screenResolution = configManager.getScreenResolution();
      if (width > screenResolution.x) {
        width = screenResolution.x;
      }
      if (height > screenResolution.y) {
        height = screenResolution.y;
      }
      int leftOffset = (screenResolution.x - width) / 2;
      int topOffset = (screenResolution.y - height) / 2;
      framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
      Log.d(TAG, "Calculated manual framing rect: " + framingRect);
      framingRectInPreview = null;
    } else {
      requestedFramingRectWidth = width;
      requestedFramingRectHeight = height;
    }
  }


  public PlanarYUVLuminanceSource buildLuminanceSource(byte[] data, int width, int height) {
    Rect rect = getFramingRectInPreview();
    if (rect == null) {
      return null;
    }
    // Go ahead and assume it's YUV rather than die.
    return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
                                        rect.width(), rect.height(), reverseImage);
  }

}


Please guide how to fix it. Thanks