寻找 GtkWidget 的孩子

Question

我需要能够以编程方式探索 GTK GUI 的结构。我有 GtkWidget，我想找到该小部件的任何子级。现在我知道 GtkContainer 有一个查找孩子的功能，而且 GtkContainer 是从 GtkWidget 派生的。

无论如何我可以检查一个小部件是否是一个 GtkContainer 然后执行转换？如果没有，有没有其他方法可以发现我所拥有的 GtkWidget 的孩子？

Answer 1

是的，每个 GObject 类型都有宏来检查对象是否属于该类型：

if(GTK_IS_CONTAINER(widget)) {
    GList *children = gtk_container_get_children(GTK_CONTAINER(widget));
    ...
}

如果小部件是GtkBin，它只有一个孩子。在这种情况下，以下操作比处理GList 更简单：

if(GTK_IS_BIN(widget)) {
    GtkWidget *child = gtk_bin_get_child(GTK_BIN(widget));
    ...
}

Answer 2

在下面的代码中，我实现了find_child 函数，它按名称递归搜索小部件。想法建立在@ptomato 的答案和following PHP 示例的基础上：

    #include <gtk/gtk.h>

    GtkWidget*
    find_child(GtkWidget* parent, const gchar* name)
    {
            if (g_strcasecmp(gtk_widget_get_name((GtkWidget*)parent), (gchar*)name) == 0) { 
                    return parent;
            }

            if (GTK_IS_BIN(parent)) {
                    GtkWidget *child = gtk_bin_get_child(GTK_BIN(parent));
                    return find_child(child, name);
            }

            if (GTK_IS_CONTAINER(parent)) {
                    GList *children = gtk_container_get_children(GTK_CONTAINER(parent));
                    while ((children = g_list_next(children)) != NULL) {
                            GtkWidget* widget = find_child(children->data, name);
                            if (widget != NULL) {
                                    return widget;
                            }
                    }
            }

            return NULL;
    }

    int
    main(int argc, char *argv[])
    {
            gtk_init(&argc, &argv);

            GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
            GtkWidget *frame = gtk_frame_new(NULL);
            GtkWidget *vbox1 = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
            GtkWidget *textView = gtk_text_view_new();
            GtkWidget *hbox1 = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 5);
            GtkWidget *button1 = gtk_button_new_with_label("button1");
            gtk_widget_set_name(button1, "btn1");
            GtkWidget *button2 = gtk_button_new_with_label("button2");
            gtk_widget_set_name(button2, "btn2");

            gtk_window_set_title(GTK_WINDOW(window), "Hello");
            gtk_container_set_border_width(GTK_CONTAINER(window), 10);
            gtk_window_set_default_size(GTK_WINDOW(window), 450, 400);

            gtk_container_add(GTK_CONTAINER(window), frame);
            gtk_container_add(GTK_CONTAINER(frame), vbox1);

            gtk_box_pack_start(GTK_BOX(vbox1), textView, 1, 1, 0);
            gtk_box_pack_start(GTK_BOX(vbox1), hbox1, 0, 1, 0);
            gtk_box_pack_start(GTK_BOX(hbox1), button1, 0, 1, 0);
            gtk_box_pack_start(GTK_BOX(hbox1), button2, 0, 1, 0);

            gtk_widget_show_all(window);

            g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

            GtkWidget* child = find_child(window, "btn2");
            if (child == button2) {
                    g_print("found it!\n");
            } else {
                    g_print("not found it!\n");
            }

            gtk_main();
            return 0;
    }

Answer 3

我创建了这些函数，它们基于与接受的答案相同的原则。

在find_child_by_index 中，depth 等于您需要传递的索引数量。第一个索引是针对parent 的孩子，第二个索引是针对孙辈，依此类推。

void print_children_helper(GtkWidget* parent, int indent_size, int depth)
{
    for (int i = 0; i < depth * indent_size; i++)
        printf(" ");
    printf("%s\n", gtk_widget_get_name(parent));

    GList* children = NULL;
    if (GTK_IS_CONTAINER(parent))
        children = gtk_container_get_children(GTK_CONTAINER(parent));

    while (children != NULL)
    {
        print_children(children->data, indent_size, depth + 1);
        children = children->next;
    }
}

void print_children(GtkWidget* parent, int indent_size)
{
    print_children_helper(parent, indent_size, 0);
}

GtkWidget* find_child_by_name(GtkWidget* parent, const gchar* name)
{
    if (g_strcmp0(gtk_widget_get_name(parent), name) == 0)
        return parent;

    GList* children = NULL;
    if (GTK_IS_CONTAINER(parent))
        children = gtk_container_get_children(GTK_CONTAINER(parent));

    while (children != NULL)
    {
        GtkWidget* widget = find_child_by_name(children->data, name);

        if (widget != NULL)
            return widget;

        children = children->next;
    }

    return NULL;
}

GtkWidget* find_child_by_index(GtkWidget* parent, int depth, ...)
{
    va_list argp;
    va_start(argp, depth);

    for (int i = 0; i < depth; i++)
    {
        int index = va_arg(argp, int);

        GList* children = NULL;
        if (GTK_IS_CONTAINER(parent))
            children = gtk_container_get_children(GTK_CONTAINER(parent));

        for (int j = 0; j < index; j++)
            if (children != NULL)
                children = children->next;

        if (children != NULL)
            parent = children->data;
        else
            return NULL;
    }

    va_end(argp);
    return parent;
}

Answer 4

如果使用 GTK4 作为 GtkContainer 不再存在，则需要一种不同的方法。见migration guide

一个遍历小部件层次结构的简单函数：

void print_widget_names(GtkWidget* parent, int level) {
  for (int i=0; i < level; i++) { 
    g_print("    ");
  }
  level++;
  g_print("%s\n", gtk_widget_get_name(GTK_WIDGET(parent)));
  GtkWidget *widget = gtk_widget_get_first_child(GTK_WIDGET(parent));
  GtkWidget *next;
  if (widget != NULL) {
    print_widget_names(widget, level);
    while ((next = gtk_widget_get_next_sibling(widget)) != NULL) {
      widget = next;
      print_widget_names(widget, level);
    }
  }
}