private function _arc($x1, $y1, $x2, $y2, $x3, $y3)
{
$h = $this->h;
$this->_out(sprintf('%.2F %.2F %.2F %.2F %.2F %.2F c ', $x1 * $this->k, ($h - $y1) * $this->k, $x2 * $this->k, ($h - $y2) * $this->k, $x3 * $this->k, ($h - $y3) * $this->k));
}