php - How to calculate rows in foreach loop recursive? ← (PHP, MySQL, HTML)

This code below returns category tree.

How can I get the count of the products in each category that has sub categories? I mean to sum values in each subcategory.

Until now I succeed to get the count only for the last level of child category:

function menuList($data, $parent = 0 ){
    static $i = 1;
    $tab = str_repeat(' ',$i);
    if($data[$parent]){
        $html = $tab.'<ul id="menu'.$i.'">';
        $i++;
        $count=0;

        foreach($data[$parent] as $v){
            $id = $v->id;
            $categoryname=$v->bg_category;
            if(in_array($id, $_SESSION['active_product_categories'])){
                 $q='select distinct product_id from products_to_categories where category_id="'.$id.'"';
                 $res=mysql_query($q) or die());
                 $num_rows=mysql_num_rows($res);
                 $count='( '.$num_rows.' )';
            }
            $child = menuList($data, $v->id);
            $html .= $tab.'<li>';
            $html .= '<a href="'.$v->WebSite.'/shop/index.php?offers='.$id.'">'.$categoryname.' '.$count.' </a>';

            if($child){
                $i–;
                $html .= $child;
                $html .= $tab;
            }
            $html .= '</li>';
        }
        $html .= $tab.'</ul>';
        return $html;
    } else {
        return false;
    }
}

$query = mysql_query('select * from products_categories where visible="1" group by bg_category order by bg_category ASC');

while($r=mysql_fetch_object($query)){
    $data[$r->parent][] = $r;
}

$menu = menuList($data);
echo $menu;

Please have a look at the screenshot.

Here is the screenshot: http://tinypic.com/view.php?pic=zwgvoz&s=8#.U957sizlrDc

  $q = 'SELECT parent_id, parent_name, count(child_id) FROM your_table GROUP BY parent_id';

Class Menu
{
  private $aSubMenus
  public function __construct()
  public function getNumberOfItems()
  public function addMenuItem()
  public function getHTML()
  public function load($menuID)
}

Class MenuItem
{
  public function __construct()
  public function getHTML()
}