如何从G_DEFINE_TYPE声明的自定义类型中获取GtkWindow或顶级部件？

我需要从使用G_DEFINE_TYPE声明的自定义类型中获取GtkWindow或顶级部件，以下是我的代码实现：

MyAppWindow.c #

#include "MyAppWindow.h"

struct _MyAppWindow
{
    GtkApplicationWindow parent;
};

G_DEFINE_TYPE (MyAppWindow, my_app_window, GTK_TYPE_APPLICATION_WINDOW);

void my_app_window_init (MyAppWindow *app)
{
}

void my_app_window_class_init (MyAppWindowClass *class)
{
}

MyAppWindow * my_app_window_new (MyApp *app)
{
    return g_object_new (MY_APP_WINDOW_TYPE, "application", app, NULL);
}

MyAppWindow.h #

#ifndef _MY_APP_WINDOW_H_INCLUDED
#define _MY_APP_WINDOW_H_INCLUDED

#include "MyApp.h"

#define MY_APP_WINDOW_TYPE (my_app_window_get_type ())
G_DECLARE_FINAL_TYPE (MyAppWindow, my_app_window, MY, APP_WINDOW, GtkApplicationWindow)

MyAppWindow * my_app_window_new (MyApp *);

#endif

MyApp.c #

struct _MyApp
{
    GtkApplication parent;
};

G_DEFINE_TYPE (MyApp, my_app, GTK_TYPE_APPLICATION);

void my_app_init (MyApp *app)
{
}

void my_app_activate (GApplication *app)
{
    MyAppWindow *win;

// 创建窗口:
    win = my_app_window_new (MY_APP (app));
}

void my_app_class_init (MyAppClass *class)
{
    G_APPLICATION_CLASS (class)->activate = my_app_activate;
}

MyApp *my_app_new (AppData *pad)
{
    MyApp *obj = g_object_new (MY_APP_TYPE, "application-id", PROJECT_APPID, "flags", G_APPLICATION_DEFAULT_FLAGS, NULL);
    return obj;
}

activate函数补充实现 #

void my_app_activate (GApplication *app)
{
     MyAppWindow *win = my_app_window_new (MY_APP (app));
     // .. 更多代码
     g_action_map_add_action_entries (G_ACTION_MAP (app), entries, G_N_ELEMENTS (entries), app);
}

回调函数cb_showmsg #

void cb_showmsg (GSimpleAction *action, GVariant *parameter, gpointer user_data)
{
     // user_data: 需要同时访问GApplication和MyAppWindow
    // 用户Holger提供的一种方案：
    GtkWindow* toplevel = gtk_application_get_active_window (user_data);
   // 
}

我需要获取MyAppWindow来显示或隐藏顶级窗口，请问有什么可行的解决思路？

• 类型转换直接获取：因为MyAppWindow是GtkApplicationWindow的子类，而GtkApplicationWindow本身就是GtkWindow的子类，可直接用类型宏转换。注意先做类型检查避免错误：

  void cb_showmsg (GSimpleAction *action, GVariant *parameter, gpointer user_data)
  {
      GtkWindow* toplevel = gtk_application_get_active_window (GTK_APPLICATION(user_data));
      if (GTK_IS_APPLICATION_WINDOW(toplevel) && MY_IS_APP_WINDOW(toplevel)) {
          MyAppWindow *win = MY_APP_WINDOW(toplevel);
          // 执行显示/隐藏操作，如gtk_widget_show(GTK_WIDGET(win))或gtk_widget_hide(GTK_WIDGET(win))
      }
  }
  

• 保存窗口引用到App实例：在MyApp结构体中添加成员存储窗口指针，后续通过App实例直接获取：

  1. 修改MyApp结构体（需在头文件声明）：

     struct _MyApp
     {
         GtkApplication parent;
         MyAppWindow *window; // 新增窗口成员
     };
     

  2. 在my_app_activate中赋值：

     void my_app_activate (GApplication *app)
     {
         MyApp *my_app = MY_APP(app);
         my_app->window = my_app_window_new (my_app);
         gtk_widget_show(GTK_WIDGET(my_app->window)); // 显示窗口
         g_action_map_add_action_entries (G_ACTION_MAP (app), entries, G_N_ELEMENTS (entries), app);
     }
     

  3. 在回调中直接调用：

     void cb_showmsg (GSimpleAction *action, GVariant *parameter, gpointer user_data)
     {
         MyApp *my_app = MY_APP(user_data);
         if (my_app->window != NULL) {
             gtk_widget_hide(GTK_WIDGET(my_app->window)); // 示例：隐藏窗口
         }
     }
     

• 封装结构体作为user_data传递：如果需要同时访问App和窗口，可封装一个结构体作为回调的user_data：

  1. 定义结构体：

     typedef struct {
         MyApp *app;
         MyAppWindow *window;
     } CallbackData;
     

  2. 在my_app_activate中创建并传递：

     void my_app_activate (GApplication *app)
     {
         MyAppWindow *win = my_app_window_new (MY_APP(app));
         CallbackData *data = g_new(CallbackData, 1);
         data->app = MY_APP(app);
         data->window = win;
         g_action_map_add_action_entries (G_ACTION_MAP (app), entries, G_N_ELEMENTS (entries), data);
         // 记得在App退出时释放data，例如在my_app_shutdown函数中处理
     }
     

  3. 在回调中使用：

     void cb_showmsg (GSimpleAction *action, GVariant *parameter, gpointer user_data)
     {
         CallbackData *data = user_data;
         if (data->window != NULL) {
             gtk_widget_show(GTK_WIDGET(data->window)); // 示例：显示窗口
         }
     }
     

内容的提问来源于stack exchange，提问作者Joel