Craft\FormBuilder2Controller::actionGetFormFields PHP Method

    public function actionGetFormFields()
    {
        $formId = craft()->request->getPost('formId');
        $form = craft()->formBuilder2_form->getFormById($formId);
        if ($formId) {
            $field = [];
            $fields = $form->fieldLayout->getFieldLayout()->getFields();
            foreach ($fields as $key => $value) {
                $field[$key] = $value->getField();
            }
            $this->returnJson($field);
        }
    }