禅道的任务工时 如何实现在输完日期和工时后 剩余工时自动算出

Question

 public function recordEstimate($taskID)    {        $this->commonAction($taskID);        if(!empty($_POST))        {            $this->task->recordEstimate($taskID);            if(isonlybody()) die(js::closeModal('parent.parent', 'this'));            die(js::locate($this->createLink('task', 'view', "taskID=$taskID"), 'parent'));        }        $this->session->set('estimateList', $this->app->getURI(true));        $this->view->task      = $this->task->getById($taskID);        $this->view->estimates = $this->task->getTaskEstimate($taskID);        $this->view->title     = $this->lang->task->record;         $this->display();    }如何改代码