使用 Glade 和 GTK+（在 C 中）将切换按钮相互绑定

Question

我有两个名为 RUN 和 KILL 的切换按钮。当我打开（即按下）RUN 按钮时，我只想通过按下 KILL 切换按钮来关闭它（而不是通过关闭 RUN 按钮）。我希望在 RUN 按钮上的任何后续鼠标点击都不执行任何操作，除非按下 KILL 按钮。同样，当 KILL 按钮打开时，我只希望它通过按下 RUN 按钮来关闭（同样，不是通过关闭 KILL 按钮）。我不确定如何构造将这两个切换按钮的操作绑定在一起的事件处理程序。我将 GTK+ 与 Glade 和 C 编程一起使用。

Answer 1

由于GtkToggleButton是一个通用按钮，它会随着所有用户交互而切换，我们必须防止它在某些条件下切换。在这种情况下，被切换后的按钮不能在自身上再次切换，而是通过另一个切换按钮。要实现这一目标，您必须：

1. 防止按钮事件在特定条件下切换按钮
2. 用反转逻辑绑定两个按钮（互斥）

为了实现 1) 我们可以将回调连接到GtkWidget "button-press-event"信号并根据需要的条件返回，TRUE 阻止信号传播，否则 FALSE。

然后，为了处理 2)，我们可以使用 g_object_bind_property 作为GtkToggleButton "active"带有G_BINDING_INVERTED_BOOLEAN标志的属性来获得所需的行为。请注意，我们必须将其中一个设置为 active 作为开始条件。

所以，一个简单的例子可能是：

#include <gtk/gtk.h>

gboolean on_toggle_button_press_event(GtkWidget *widget, GdkEventButton *event, gpointer user_data) {
   if (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(widget)) == TRUE) {
      return TRUE;
   }

   return FALSE;
}

void on_run_toggle_active(GObject *obj, GParamSpec *pspec, gpointer user_data) {
   g_return_if_fail (user_data != NULL);

   GtkLabel *label = GTK_LABEL(user_data);
   GtkToggleButton *button = GTK_TOGGLE_BUTTON(obj);

   if (gtk_toggle_button_get_active(button) == TRUE) {
      gtk_label_set_text (label, "Running...");
   } else {
      gtk_label_set_text (label, "Idle");
   }
}

gint main(gint argc, gchar **argv) {
   GtkLabel *status;
   GtkWindow *window;
   GtkBuilder *builder;
   GtkToggleButton *run_toggle;
   GtkToggleButton *kill_toggle;

   gtk_init(&argc, &argv);

   builder = gtk_builder_new_from_file("gui.ui");

   window      = GTK_WINDOW(gtk_builder_get_object(builder, "window1"));
   status      = GTK_LABEL(gtk_builder_get_object(builder, "status"));
   run_toggle  = GTK_TOGGLE_BUTTON(gtk_builder_get_object(builder, "toggle"));
   kill_toggle = GTK_TOGGLE_BUTTON(gtk_builder_get_object(builder, "kill"));

   g_object_bind_property (G_OBJECT(run_toggle), "active", G_OBJECT(kill_toggle), "active", G_BINDING_INVERT_BOOLEAN);
   g_object_bind_property (G_OBJECT(kill_toggle), "active", G_OBJECT(run_toggle), "active", G_BINDING_INVERT_BOOLEAN);

   g_signal_connect(G_OBJECT(run_toggle), "button-press-event", G_CALLBACK(on_toggle_button_press_event), NULL);
   g_signal_connect(G_OBJECT(kill_toggle), "button-press-event", G_CALLBACK(on_toggle_button_press_event), NULL);
   g_signal_connect(G_OBJECT(run_toggle), "notify::active", G_CALLBACK(on_run_toggle_active), status);
   g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);

   gtk_widget_show_all(GTK_WIDGET(window));

   gtk_main();

   return 0;
}

为简化起见，我用Glade ( gui.ui )概述了用户界面：

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.20.2 -->
<interface>
  <requires lib="gtk+" version="3.18"/>
  <object class="GtkWindow" id="window1">
    <property name="can_focus">False</property>
    <child>
      <object class="GtkGrid">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="halign">center</property>
        <property name="valign">center</property>
        <property name="row_spacing">20</property>
        <child>
          <object class="GtkLabel" id="status">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="label" translatable="yes">Idle</property>
          </object>
          <packing>
            <property name="left_attach">0</property>
            <property name="top_attach">1</property>
            <property name="width">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkBox">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkToggleButton" id="toggle">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="focus_on_click">False</property>
                <property name="receives_default">True</property>
                <child>
                  <object class="GtkBox">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <property name="spacing">3</property>
                    <child>
                      <object class="GtkImage">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="icon_name">media-playback-start-symbolic</property>
                      </object>
                      <packing>
                        <property name="expand">False</property>
                        <property name="fill">True</property>
                        <property name="position">0</property>
                      </packing>
                    </child>
                    <child>
                      <object class="GtkLabel" id="label1">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="label" translatable="yes">Run</property>
                      </object>
                      <packing>
                        <property name="expand">False</property>
                        <property name="fill">True</property>
                        <property name="position">1</property>
                      </packing>
                    </child>
                  </object>
                </child>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkToggleButton" id="kill">
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <property name="active">True</property>
                <child>
                  <object class="GtkBox">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <property name="spacing">3</property>
                    <child>
                      <object class="GtkImage">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="icon_name">user-trash-symbolic</property>
                      </object>
                      <packing>
                        <property name="expand">False</property>
                        <property name="fill">True</property>
                        <property name="position">0</property>
                      </packing>
                    </child>
                    <child>
                      <object class="GtkLabel" id="label2">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="label" translatable="yes">Kill</property>
                      </object>
                      <packing>
                        <property name="expand">False</property>
                        <property name="fill">True</property>
                        <property name="position">1</property>
                      </packing>
                    </child>
                  </object>
                </child>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
            <style>
              <class name="linked"/>
            </style>
          </object>
          <packing>
            <property name="left_attach">0</property>
            <property name="top_attach">0</property>
            <property name="width">2</property>
          </packing>
        </child>
      </object>
    </child>
    <child type="titlebar">
      <placeholder/>
    </child>
  </object>
  <object class="GtkSizeGroup">
    <widgets>
      <widget name="label1"/>
      <widget name="label2"/>
    </widgets>
  </object>
</interface>

编译：

gcc -o main main.c `pkg-config --cflags --libs gtk+-3.0`

输出应该是这样的：

切换按钮是相互排斥的，在活动时按下它们不会产生任何视觉效果。

PS：假设没有键盘处理，否则我们必须处理这些信号并采取相应的行动。