Multiple products checkout simultaneously

-- url of the page with the problem -- : www.harmonyfarm.com.tw/orders/cyber-orders/category/42-.html
-- HikaShop version -- : 2.4.0
-- Joomla version -- : 3.4.1
-- PHP version -- : 5.5
-- Browser(s) name and version -- : firefox 38

In many product-selling websites, customers can choose multiple products of the same page simultaneously and then click the checkout button for just one time. This is really convenient for customers who already being familiar with the products and accelerate the shopping process. The most famous site is Pizza Hut.
Many customers of mine asked me : "why can't we shop on your site just like Pizza Hut?". I said to them : " Don't worry, the Hikashop guys are brilliant and they will make this possible."
Please see the attachments. Our original process is the first snapshot. And i simulate the change we expected in the second snapshot.
Can we do that ?
If you can make this true, your kindness will be highly appreciated by many people.
Thanks in advance.

Hi,

You have to change the value of the option "Display the quantity field on the product page" in Configuration > Main > Products to "Global on listings".

After changing to global on listings, the quantity field on the single product page disappeared. I don't know whether this is a bug. But i still need a quantity field in single product page.

Please help me for that.
Thanks

Hi,

Please try to add the code:

if(JRequest::getVar('task','listing') == 'show' && $params->get('show_quantity_field') == '2'){
	$params->set('show_quantity_field',1);
}

			$show_quantity_field=$config->get('show_quantity_field',0);
			if($params->get('show_quantity_field',0)=='-1')$params->set('show_quantity_field',$show_quantity_field);

Dear Sir:
No luck, it showed
"Parse error: syntax error, unexpected '''' (T_CONSTANT_ENCAPSED_STRING) in /home/dalusoha/public_html/harmonyfarm/administrator/components/com_hikashop/helpers/cart.php on line 62"
after adding that code

any idea ?

This is the problematic cart.php file

This is the snapshot around LINE 62