Android- Zxing Scanner Add Preview in the centre

问题

I'm using Zxing library in Android, Camera Activity is showing correct width and height of scan area but it is not showing in the middle of the screen. Camera Scan area should be added in the middle. Please guide how to fix it. I have attached screenshot of the issue. I have added Camera Manager class below.

[![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

来源：https://stackoverflow.com/questions/58329776/android-zxing-scanner-add-preview-in-the-centre