Date::extractOffset

static function extractOffset(array $field, array $request)
{
	$tzName = 'tz_'.$field['Field'];
	$tz = isset($request[$tzName]) ? $request[$tzName] : null;
	if (is_array($tz))
	{
		$tz = isset($field['Index']) ? $tz[$field['Index']] : $tz[0];
	}

	if ($tz === 'current')
	{
		return CTimeZone::GetOffset();
	}
	elseif ($tz)
	{
		$localTime = new DateTime();
		$localOffset = $localTime->getOffset();

		$userTime = new DateTime(null, new DateTimeZone($tz));
		$userOffset = $userTime->getOffset();

		return $userOffset - $localOffset;
	}

	return 0;
}