Merge pull request opencv#19046 from alalek:issue_16861

Author: alalek

modules/java/generator/android-21/java/org/opencv/android/JavaCamera2View.java

@@ -43,17 +43,17 @@ public class JavaCamera2View extends CameraBridgeViewBase {
 
     private static final String LOGTAG = "JavaCamera2View";
 
-    private ImageReader mImageReader;
-    private int mPreviewFormat = ImageFormat.YUV_420_888;
+    protected ImageReader mImageReader;
+    protected int mPreviewFormat = ImageFormat.YUV_420_888;
 
-    private CameraDevice mCameraDevice;
-    private CameraCaptureSession mCaptureSession;
-    private CaptureRequest.Builder mPreviewRequestBuilder;
-    private String mCameraID;
-    private android.util.Size mPreviewSize = new android.util.Size(-1, -1);
+    protected CameraDevice mCameraDevice;
+    protected CameraCaptureSession mCaptureSession;
+    protected CaptureRequest.Builder mPreviewRequestBuilder;
+    protected String mCameraID;
+    protected android.util.Size mPreviewSize = new android.util.Size(-1, -1);
 
     private HandlerThread mBackgroundThread;
-    private Handler mBackgroundHandler;
+    protected Handler mBackgroundHandler;
 
     public JavaCamera2View(Context context, int cameraId) {
         super(context, cameraId);