Camera2BasicFragment - problems modifying to switch front/back cameras

Question

I'm trying to modify the Camera2BasicFragment sample project to support switching between the front and back cameras. I added a switch button overlay on the preview screen, and the following code to handle the click. Also a class variable cameraDirection to remember which camera is currently in use:

@Override
public void onClick(View view) {
    switch (view.getId()) {
        case R.id.button_take_photo:
            takePicture();
            break;

        case R.id.button_reverse_camera:
            CameraManager manager = (CameraManager) getActivity().getSystemService(Context.CAMERA_SERVICE);
            try {
                String[] cameraIds = manager.getCameraIdList();
                CameraCharacteristics cameraCharacteristics = manager.getCameraCharacteristics(mCameraId);
                for (String id : cameraIds) {
                    if (! id.equals(mCameraId)) {
                        closeCamera();
                        cameraDirection = cameraDirection == CameraCharacteristics.LENS_FACING_FRONT?CameraCharacteristics.LENS_FACING_BACK:
                                CameraCharacteristics.LENS_FACING_FRONT;
                        mCameraId = id;
                        openCamera(mPreviewSize.getWidth(), mPreviewSize.getHeight());
                    }
                }

            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
            break;

    }
}

The annoying thing is that the first switch of the camera works fine. But subsequent switches don't work. What happens is that the preview fades a little, like something is happening, but it remains on the currently selected camera. After a few more clicks on the switch button, the application crashes, and even more annoying is that there's no stack trace. So I've got no idea what the problem is. I suspect a camera lock isn't being released properly, but that's just a guess.

So I'm hoping that someone has successfully modified this sample to handle camera switching, or can recommend an alternative Camera2 fragment implementation.

Answer 1

The problem is in the method setUpCameraOutputs(int width, int height) , where it sets mCameraId=cameraId;, because as it says in its comments

// We don't use a front facing camera in this sample.

I tried with

if(mCameraId==null){
    mCameraId=cameraId;
}

but it's not enough because it does not set the preview size corrrectly for me.

You could modify the method to setUpCameraOutputs(int width, int height, String cameraId) and do the setup correctly.