I get "Image is already closed" when I try to get each Camera2 frame by using ImageReader

Question

I have tried to get each frame from camera using Camer2 API for image processing purposes but I get a FATAL EXCEPTION which says

FATAL EXCEPTION: main Process: com.example.avoor.camera2api, PID: 2831 java.lang.IllegalStateException: Image is already closed

I successfully can open the camera and send it to TuxtureView for previewing but the app crashes when it comes to OnImageAvailableListener.

Here is the codes that are used:

protected void createCameraPreview() {
    try {
        SurfaceTexture texture = textureView.getSurfaceTexture();
        assert texture != null;
        texture.setDefaultBufferSize(imageDimension.getWidth(), imageDimension.getHeight());
        Surface surface = new Surface(texture);
        ImageReader reader = ImageReader.newInstance(640, 480, ImageFormat.YUV_420_888, 3);
        //reader.setOnImageAvailableListener(mOnImageAvailableListener, mBackgroundHandler);
        captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        captureRequestBuilder.addTarget(surface);
        captureRequestBuilder.addTarget(reader.getSurface());
        List<Surface> outputSurfaces = new ArrayList<>();
        outputSurfaces.add(reader.getSurface());
        outputSurfaces.add(surface);
        ///////////////////////////////////////////////////////////////////
        ImageReader.OnImageAvailableListener readerListener = new ImageReader.OnImageAvailableListener() {
            @Override
            public void onImageAvailable(ImageReader reader) {
                Image image = null;
                try {
                    image = reader.acquireLatestImage();
                    final byte[] bytes;
bytes = convertYUV420888ToNV21(image);
                                Log.d(TAG,"Height:"+String.valueOf(image.getHeight())+
                                        " Width: "+String.valueOf(image.getWidth()));
                                Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
                                imageView.setImageBitmap(bitmap);

                            }
                        }
                    });
                }
                catch (IllegalStateException e) {
                    Log.e(TAG, "Too many images queued for saving, dropping image for request: ");
return;
                }
                finally {
                    if (image != null) {
                        image.close();
                    }
                }
            }
        };
        reader.setOnImageAvailableListener(readerListener, mBackgroundHandler);

        ///////////////////////////////////////////////////////////////////
        cameraDevice.createCaptureSession(outputSurfaces, 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) {
                Toast.makeText(MainActivity.this, "Configuration change", Toast.LENGTH_SHORT).show();
            }
        }, mBackgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

and here:

protected void updatePreview() {
    if(null == cameraDevice) {
        Log.e(TAG, "updatePreview error, return");
    }
    captureRequestBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
    try {
        cameraCaptureSessions.setRepeatingRequest(captureRequestBuilder.build(), null, mBackgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

and I have started the BackgroundThread when the camera is opened

Answer 1

Your reader is likely getting garbage collected; you're not saving it anywhere, and it goes out of scope at the end of createCameraPreview.

You do get a Surface from it, but Surface is like a weak reference; it won't keep ImageReader from being collected.