有没有一种好的方法来复制一个Gtk小部件？ [英] Is there a good way to copy a Gtk widget?

问题描述

有没有一种方法，使用C中的Gtk库克隆一个Gtk按钮（例如），并将它打包到应用程序中的其他位置。我知道你不能将相同的部件打包两次。而且这段代码显然不起作用，但显示了当我尝试按钮的浅拷贝时会发生什么：

  GtkButton * a = g_object_new（GTK_TYPE_BUTTON，label，o_0，NULL）; 
 GtkButton * b = g_memdup（a，sizeof * a）; 
 gtk_box_pack_start_defaults（GTK_BOX（vbox），GTK_WIDGET（b））; 
  

周围的代码创建一个vbox并将其打包在一个窗口中并运行gtk_main（）。这会导致这些难以理解的错误信息：

 （main：6044）：Gtk-CRITICAL **：gtk_widget_hide：assertion `GTK_IS_WIDGET（widget）'失败
 
（main：6044）：Gtk-CRITICAL **：gtk_widget_realize：assertion`GTK_WIDGET_ANCHORED（widget）|| GTK_IS_INVISIBLE（widget）'失败
 ** 
 Gtk：ERROR：/build/buildd/gtk+2.0-2.18.3/gtk/gtkwidget.c：8431：gtk_widget_real_map：断言失败：（GTK_WIDGET_REALIZED（widget ））
  

沿着同样的路线，如果我要写我自己的GObject（不一定是一个Gtk小部件），是否有写好拷贝构造函数的好方法。我认为它应该是一个可选钩子的接口，主要基于属性，以某种方式处理类的层次结构。

我想这样做： p>

  GtkButton * b = copyable_copy（COPYABLE（a））; 
  

如果GtkButton可以使用理论上可复制的界面。

  GObject * $ b  $ b g_object_clone（GObject * src）
 {
 GObject * dst; 
 GParameter * params; 
 GParamSpec **规格; 
 guint n，n_specs，n_params; 
 
 specs = g_object_class_list_properties（G_OBJECT_GET_CLASS（src），& n_specs）; 
 params = g_new0（GParameter，n_specs）; 
 n_params = 0; （n = 0; n  if（strcmp（specs [n]  - > name，parent）&& $ b的
 
 $ b（specs [n]  - > flags& G_PARAM_READWRITE）== G_PARAM_READWRITE）{
 params [n_params] .name = g_intern_string（specs [n]  - > name）; 
 g_value_init（& params [n_params] .value，specs [n]  - > value_type）; 
 g_object_get_property（src，specs [n]  - > name，& params [n_params] .value）; 
 ++ n_params; 
} 
 
 dst = g_object_newv（G_TYPE_FROM_INSTANCE（src），n_params，params）; 
 g_free（specs）; 
 g_free（params）; 
 
 return dst; 
} 
  

虽然克隆小部件并不是那么简单，但上述方法可用于大多数情况下（肯定是在 GtkButton 中）。

我不关心那些未暴露的状态属性（所有适当的小部件都应该完全由可用于 GtkBuilder 的属性定义），但是很多角落案例会使得强大的克隆非常困难（界面和容器是第一个那些出现在我脑海中的）。

Is there a way, using the Gtk library in C, to clone a Gtk button (for instance), and pack it somewhere else in the app. I know you can't pack the same widget twice. And that this code obviously wouldn't work, but shows what happens when I attempt a shallow copy of the button:

GtkButton *a = g_object_new(GTK_TYPE_BUTTON, "label", "o_0", NULL);
GtkButton *b = g_memdup(a, sizeof *a);
gtk_box_pack_start_defaults(GTK_BOX(vbox), GTK_WIDGET(b));

There is surrounding code which creates a vbox and packs it in a window and runs gtk_main(). This will result in these hard to understand error messages:

(main:6044): Gtk-CRITICAL **: gtk_widget_hide: assertion `GTK_IS_WIDGET (widget)' failed

(main:6044): Gtk-CRITICAL **: gtk_widget_realize: assertion `GTK_WIDGET_ANCHORED (widget) || GTK_IS_INVISIBLE (widget)' failed
**
Gtk:ERROR:/build/buildd/gtk+2.0-2.18.3/gtk/gtkwidget.c:8431:gtk_widget_real_map: assertion failed: (GTK_WIDGET_REALIZED (widget))

Along the same lines, if I were to write my own GObject (not necessarily a Gtk widget), is there a good way to write a copy constructor. Im thinking it should be an interface with optional hooks and based mostly on the properties, handling the class's hierarchy in some way.

I'd want to do this:

GtkButton *b = copyable_copy(COPYABLE(a));

If GtkButton could use a theoretical copyable interface.

解决方案

A clone throught properties is a viable solution:

GObject *
g_object_clone(GObject *src)
{
    GObject *dst;
    GParameter *params;
    GParamSpec **specs;
    guint n, n_specs, n_params;

    specs = g_object_class_list_properties(G_OBJECT_GET_CLASS(src), &n_specs);
    params = g_new0(GParameter, n_specs);
    n_params = 0;

    for (n = 0; n < n_specs; ++n)
        if (strcmp(specs[n]->name, "parent") &&
            (specs[n]->flags & G_PARAM_READWRITE) == G_PARAM_READWRITE) {
            params[n_params].name = g_intern_string(specs[n]->name);
            g_value_init(&params[n_params].value, specs[n]->value_type);
            g_object_get_property(src, specs[n]->name, &params[n_params].value);
            ++ n_params;
        }

    dst = g_object_newv(G_TYPE_FROM_INSTANCE(src), n_params, params);
    g_free(specs);
    g_free(params);

    return dst;
}

Cloning a widget is not that trivial though, but the above approach is usable in most cases (on a GtkButton for sure).

I'd not care that much of states not exposed with properties (all proper widgets should be fully defined by properties to be usable with GtkBuilder) but a lot of corner cases will make a robust cloning quite difficult (interfaces and containers being the first ones that come to my mind).

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