protected function _getCommand()
        {
            $command = $this->_bin;

            $command .= ($this->getCopies() > 1) ? " --copies " . $this->getCopies() : "";
            $command .= " --orientation " . $this->getOrientation();
            $command .= " --page-size " . $this->getPageSize();

            foreach($this->getMargins() as $position => $margin) {
                $command .= (false === is_null($margin)) ? sprintf(' --margin-%s %s', $position, $margin) : '';
            }

            $command .= ($this->getWindowStatus()) ? " --window-status ".$this->getWindowStatus()."" : "";
            $command .= ($this->getTOC()) ? " --toc" : "";
            $command .= ($this->getGrayscale()) ? " --grayscale" : "";
            $command .= (mb_strlen($this->getPassword()) > 0)
            ? " --password " . $this->getPassword() . ""
            : "";
            $command .= (mb_strlen($this->getUsername()) > 0)
            ? " --username " . $this->getUsername() . ""
            : "";
            $command .= (mb_strlen($this->getFooterHtml()) > 0)
            ? " --margin-bottom 20 --footer-html \"" . $this->getFooterHtml() . "\""
            : "";
            $command .= ($this->getTitle())
            ? ' --title "' . $this->getTitle() . '"'
            : '';

            $command .= ' "%input%"';
            $command .= " -";
            if ($this->getRunInVirtualX()) {
                $command = 'xvfb-run ' . $command;
            }
            return $command;
        }