public function getWidth($revision = null)
	{
		// Without revision, use current info
		if (!isset($revision)) {
			return (int)$this->info['width'];
		}

		// Obtain the properties of the revision
		if (($info = $this->getRevision($revision)) === null) {
			return -1;
		}

		return (int)$info['width'];
	}