public boolean isCameraRotated() {
        if (rotationDegrees == -1) {
            throw new IllegalStateException("Rotation not calculated yet. Call configure() first.");
        }
        return rotationDegrees % 180 != 0;
    }
@return true if the camera rotation is perpendicular to the current display rotation.
zxing-android-embedded/src/com/journeyapps/barcodescanner/camera/CameraManager.java