function makeFileManaged() {
            if (!isset($_FILES['croppedfile']))
                return NULL;
            $path = $_FILES['croppedfile']['tmp_name'];
            if (!file_exists($path))
                return NULL;
            $result_filename = $_FILES['croppedfile']['name'];
            $uri = file_unmanaged_move($path, 'private://' . $result_filename, FILE_EXISTS_RENAME);
            if ($uri == FALSE)
                return NULL;
            $file = File::Create([
                        'uri' => $uri,
            ]);
            $file->save();
            return $file->id();
        }