GTK中的信号机制

一、            为了方便用户使用，定义了如下的宏

/* --- 便于使用的宏定义*/

#define g_signal_connect(instance, detailed_signal, c_handler, data) \

    g_signal_connect_data ((instance), (detailed_signal), (c_handler), (data), NULL, (GConnectFlags) 0)

#define g_signal_connect_after(instance, detailed_signal, c_handler, data) \

    g_signal_connect_data ((instance), (detailed_signal), (c_handler), (data), NULL, G_CONNECT_AFTER)

#define g_signal_connect_swapped(instance, detailed_signal, c_handler, data) \

    g_signal_connect_data ((instance), (detailed_signal), (c_handler), (data), NULL, G_CONNECT_SWAPPED)

#define          g_signal_handlers_disconnect_by_func(instance, func, data)                                                                 \

    g_signal_handlers_disconnect_matched ((instance),                                                                                     \

                                                            (GSignalMatchType) (G_SIGNAL_MATCH_FUNC | G_SIGNAL_MATCH_DATA), \

                                                            0, 0, NULL, (func), (data))

#define          g_signal_handlers_block_by_func(instance, func, data)                                                                           \

    g_signal_handlers_block_matched      ((instance),                                                                                    \

                                                         (GSignalMatchType) (G_SIGNAL_MATCH_FUNC | G_SIGNAL_MATCH_DATA),        \

                                                         0, 0, NULL, (func), (data))

#define          g_signal_handlers_unblock_by_func(instance, func, data)                                                                       \

    g_signal_handlers_unblock_matched    ((instance),                                                                                    \

                                                         (GSignalMatchType) (G_SIGNAL_MATCH_FUNC | G_SIGNAL_MATCH_DATA),        \

                                                         0, 0, NULL, (func), (data))

二、 /* 信号连接实现函数*/

gulong

g_signal_connect_data (gpointer       instance,//发送信号的对象

                     const gchar   *detailed_signal,//信号名称

                     GCallback      c_handler,//回调函数

                     gpointer       data,//传递给回调函数的参数

                     GClosureNotify destroy_data,//销毁数据的函数

                     GConnectFlags  connect_flags)//信号连接的选项

{

       （1）/****************为了安全起见，做如下检查******************/

     //检查发送信号的对象是否存在

     g_return_val_if_fail (G_TYPE_CHECK_INSTANCE (instance), 0);

     //检查发送的信号是否存在

     g_return_val_if_fail (detailed_signal != NULL, 0);

     //检查回调函数是否存在

     g_return_val_if_fail (c_handler != NULL, 0);

       （2）//根据信号名称获取信号id

     signal_id = signal_parse_name (detailed_signal, itype, &detail, TRUE);

       （3）//根据信号id 获取信号节点

      SignalNode *node = LOOKUP_SIGNAL_NODE (signal_id);

       （4）//根据信号节点判断信号的有效性

      if (detail && !(node->flags & G_SIGNAL_DETAILED))

       g_warning ("%s: signal `%s' does not support details", G_STRLOC, detailed_signal);

      else if (!g_type_is_a (itype, node->itype))

       g_warning ("%s: signal `%s' is invalid for instance `%p'", G_STRLOC, detailed_signal, instance);

      else

       {

         （5）//生成信号处理器

         Handler *handler = handler_new (after);

 

         //信号处理器 序号

         handler_seq_no = handler->sequential_number;

         handler->detail = detail;

         //信号处理函数

         handler->closure = g_closure_ref ((swapped ? g_cclosure_new_swap : g_cclosure_new) (c_handler, data, destroy_data));

         g_closure_sink (handler->closure);

         （6）//根据信号id，发出信号的对象，信号处理器插入到信号处理器列表中

         handler_insert (signal_id, instance, handler);

}

三、            信号的触发（信号处理器的执行）

       gtk_main()进入事件循环，生成GMainLoop对象，

       由GMainLoop管理GMainContext对象，而GMainContext则管理则所有的事件源！

       当相应的事件发生时候，查找信号处理器列表，然后执行。