rt_GUI 事件循环函数处理的疑问

发布于 2015-05-04 18:05:08 浏览：1827 订阅该版

rt_inline void _rtgui_application_event_loop(struct rtgui_app *app)
{
    rt_err_t result;
    rt_uint16_t current_ref;
    struct rtgui_event *event;

_rtgui_application_check(app);

/* point to event buffer */
    event = (struct rtgui_event *)app->event_buffer;

current_ref = ++app->ref_count;   //  A 这个语句是什么作用

while (current_ref <= app->ref_count)//  B 这个语句是什么作用
    {
        RT_ASSERT(current_ref == app->ref_count);

if (app->on_idle != RT_NULL)
        {
            result = rtgui_recv_nosuspend(event, sizeof(union rtgui_event_generic));
            if (result == RT_EOK)
                RTGUI_OBJECT(app)->event_handler(RTGUI_OBJECT(app), event);
            else if (result == -RT_ETIMEOUT)
                app->on_idle(RTGUI_OBJECT(app), RT_NULL);
        }
        else
        {
            result = rtgui_recv(event, sizeof(union rtgui_event_generic));
            if (result == RT_EOK)
                RTGUI_OBJECT(app)->event_handler(RTGUI_OBJECT(app), event);
        }
    }
}

看了rt-GUI事件处理的函数，有如下的疑问：
1:语句注释A 与注释B 的作用是用来干什么？
2:因为外边有注消APP内存的语句，所以在什么时候（处理什么事件或动作）程序就跳出循环 while (current_ref <= app->ref_count)？