无法隐藏和显示小部件以响应事件

Question

问题

我有一个问题，通过 gtk_widget_hide_on_delete 关闭带有删除事件的小部件无法通过交换的 gtk_widget_show_all 再次显示菜单小部件，并将相应的小部件作为参数传递给它。

背景

我正在创建一个程序，其中包含一个带有多个按钮小部件的选择菜单。按一个按钮将隐藏菜单，并显示一个包含标签和 TextEntry 的 window 小部件，此 window 小部件的删除事件将隐藏该小部件，并再次显示菜单。

示例程序

我已经为这个问题创建了一个最小的例子。该代码只是通过 GtkBuilder 加载 ui，然后进入主 gtk 循环。

我依赖 gtk_widget_show_all、gtk_widget_hide 和 gtk_widget_hide_on_delete，但是当我使用 delete-event 关闭 练习小部件 时，window 消失，但菜单小部件未显示。

#include <gtk/gtk.h>
#include <stdio.h>

int main(int argc, char **argv)
{
    GtkBuilder * builder;
    GtkWidget * menu;
    GError *error = NULL;

    gtk_init(&argc, &argv);
    builder = gtk_builder_new();
    if (!gtk_builder_add_from_file(builder, "example.glade", &error)) {
        g_warning("%s", error->message);
        g_free(error);
        fprintf(stderr, "Failed to load build file");
    }

    menu = (GtkWidget *) gtk_builder_get_object(builder, "menu");
  
    gtk_builder_connect_signals(builder, NULL);
    gtk_widget_show(menu);

    gtk_main();
  
    return 0;
}

已使用 Glade 创建 XML 文件 example.glade。

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.16.1 -->
<interface>
  <requires lib="gtk+" version="3.10"/>
  <object class="GtkWindow" id="exercise">
    <property name="can_focus">False</property>
    <property name="window_position">center</property>
    <signal name="delete-event" handler="gtk_widget_hide_on_delete" swapped="no"/>
    <signal name="delete-event" handler="gtk_widget_show_all" object="menu" after="yes" swapped="yes"/>
    <child>
      <object class="GtkGrid" id="grid2">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <child>
          <object class="GtkEntry" id="entry1">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="hexpand">True</property>
          </object>
          <packing>
            <property name="left_attach">0</property>
            <property name="top_attach">1</property>
            <property name="width">1</property>
            <property name="height">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel" id="label1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="hexpand">True</property>
            <property name="vexpand">True</property>
            <property name="label" translatable="yes">A window where stuff will happen.</property>
          </object>
          <packing>
            <property name="left_attach">0</property>
            <property name="top_attach">0</property>
            <property name="width">1</property>
            <property name="height">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
  <object class="GtkWindow" id="menu">
    <property name="can_focus">False</property>
    <property name="window_position">center</property>
    <signal name="destroy" handler="gtk_main_quit" swapped="no"/>
    <child>
      <object class="GtkGrid" id="grid1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <child>
          <object class="GtkButton" id="button1">
            <property name="label" translatable="yes">button1</property>
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <property name="hexpand">True</property>
            <property name="vexpand">True</property>
            <signal name="clicked" handler="gtk_widget_hide" object="menu" swapped="yes"/>
            <signal name="clicked" handler="gtk_widget_show_all" object="exercise" swapped="yes"/>
          </object>
          <packing>
            <property name="left_attach">0</property>
            <property name="top_attach">0</property>
            <property name="width">1</property>
            <property name="height">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkButton" id="button2">
            <property name="label" translatable="yes">button2</property>
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <property name="hexpand">True</property>
            <property name="vexpand">True</property>
            <signal name="clicked" handler="gtk_widget_hide" object="menu" swapped="yes"/>
            <signal name="clicked" handler="gtk_widget_show_all" object="exercise" swapped="yes"/>
          </object>
          <packing>
            <property name="left_attach">0</property>
            <property name="top_attach">1</property>
            <property name="width">1</property>
            <property name="height">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Answer 1

问题出在您的 Glade 文件的这两行中：

<signal name="delete-event" handler="gtk_widget_hide_on_delete" swapped="no"/>
<signal name="delete-event" handler="gtk_widget_show_all" object="menu" after="yes" swapped="yes"/>

查看 gtk_widget_hide_on_delete() 的 manual page，我们看到：

Utility function; intended to be connected to the “delete-event” signal on a GtkWindow. The function calls gtk_widget_hide() on its argument, then returns TRUE.

如果我们查看 delete-event 信号，我们会看到：

Returns

TRUE to stop other handlers from being invoked for the event. FALSE to propagate the event further.

这意味着在调用 gtk_widget_hide_on_delete() 之后，返回 TRUE，这将阻止 GTK 运行时调用 gtk_widget_show_all()。

要实现你想要的，你可以使用自定义的处理程序，如下所示：

删除那两行并替换为以下内容：

<signal name="delete-event" handler="my_custom_func" object="menu" swapped="no"/>

将自定义处理程序添加到 C 文件：

G_MODULE_EXPORT gboolean
my_custom_func(GtkWidget *w, GdkEvent *e, gpointer u) {
    gtk_widget_hide(w);
    gtk_widget_show_all(GTK_WIDGET(u));
    return TRUE;
}

无法隐藏和显示小部件以响应事件

Trouble hiding and showing widgets in response to event

c

xml

user-interface

gtk3

问题

背景

示例程序

Returns