private void initCamera() {
        if (cameraInstance != null) {
            Log.w(TAG, "initCamera called twice");
            return;
        }

        cameraInstance = createCameraInstance();

        cameraInstance.setReadyHandler(stateHandler);
        cameraInstance.open();

        // Keep track of the orientation we opened at, so that we don't reopen the camera if we
        // don't need to.
        openedOrientation = getDisplayRotation();
    }
Considered active if between resume() and pause().

@return true if active
zxing-android-embedded/src/com/journeyapps/barcodescanner/CameraPreview.java