public CameraInstance getCameraInstance() {
        return cameraInstance;
    }
Get the current CameraInstance. This may be null, and may change when
pausing / resuming the preview.

While the preview is active, getCameraInstance() will never be null.

@return the current CameraInstance
@see #isPreviewActive()
zxing-android-embedded/src/com/journeyapps/barcodescanner/CameraPreview.java