public function index()
{
    $this->load->helper('phantomjs');
    $this->load->helper('url');
    $viewbox['generationStatus'] = 'PDF Generation successful';
    $url = 'http://google.com';
    $filename = strtotime(date('Y-m-d H:i:s')).'.pdf';
    $resp = rasterize_wrapper($url,$filename);
    $viewbox['filename'] = $resp;
    if($resp == 0)
    {
        $viewbox['filename'] = '';
        $viewbox['generationStatus'] = 'PDF Generation failed';
    }
    $this->load->view('welcome_message',$viewbox);
}

if ( ! function_exists('rasterize_wrapper'))
    {
        function rasterize_wrapper($url='', $output=''){
          if($url=='' || $output=='')
            {
              show_error('URL or Output file name not defined correctly');
              log_message('error','rasterize_wrapper: not initialized');
              exit;
            }
            $url = escapeshellcmd($url);
            exec('phantomjs '.realpath('js/rasterize.js').' '.$url.' '.realpath('pdf').'/'.$output,$output_status, $return_status);
            if($return_status == '0'){ return $output;}
            return 0;
        }
    }

var page = new WebPage();
if (phantom.args.length < 2 || phantom.args.length > 3) {
    console.log('Usage: rasterize.js URL filename');
    phantom.exit();
} else {
    address = phantom.args[0];

    output = phantom.args[1];
    page.viewportSize = { width: 600, height: 600 };
    page.open(address, function (status) {
        if (status !== 'success') {
            console.log('Unable to load the address!');
        } else {
            window.setTimeout(function () {
                page.render(output);
                phantom.exit();
            }, 200);
        }
    });
}