Signal Handlers for Message Dialogs in GTK+ using Glade (and C)

2
votes

I am having trouble figuring out how to write signal handlers in my C code for the message dialogs that I am creating in GLADE. If I were not using GLADE, the signal handler would include the necessary information to construct the message dialog itself. For example, an "are you sure you want to quit?" message dialog would have the form:

void show_question(GtkWidget *widget, gpointer window) {

  GtkWidget *dialog;
  dialog = gtk_message_dialog_new(GTK_WINDOW(window),
          GTK_DIALOG_DESTROY_WITH_PARENT,
          GTK_MESSAGE_QUESTION,
          GTK_BUTTONS_YES_NO,
          "Are you sure to quit?");
  gtk_window_set_title(GTK_WINDOW(dialog), "Question");
  gtk_dialog_run(GTK_DIALOG(dialog));
  gtk_widget_destroy(dialog);
}

Likewise, an "about window" would have the form:

void show_about(GtkWidget *widget, gpointer data) {

  GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file("battery.png", NULL);

  GtkWidget *dialog = gtk_about_dialog_new();
  gtk_about_dialog_set_name(GTK_ABOUT_DIALOG(dialog), "Battery");
  gtk_about_dialog_set_version(GTK_ABOUT_DIALOG(dialog), "0.9"); 
  gtk_about_dialog_set_copyright(GTK_ABOUT_DIALOG(dialog), "(c) Jan Bodnar");
  gtk_about_dialog_set_comments(GTK_ABOUT_DIALOG(dialog), "Battery is a simple tool for battery checking.");
  gtk_about_dialog_set_website(GTK_ABOUT_DIALOG(dialog), "http://www.batteryhq.net");
  gtk_about_dialog_set_logo(GTK_ABOUT_DIALOG(dialog), pixbuf);
  g_object_unref(pixbuf), pixbuf = NULL;
  gtk_dialog_run(GTK_DIALOG (dialog));
  gtk_widget_destroy(dialog);
}

Now that I am fully creating these windows within GLADE, I am not sure what form the signal handler should take (in C) in order to connect, say, clicking Help -> About to the about window created in GLADE, or connecting clicking File -> Quit with the "are you sure you want to quit" message dialog created in GLADE. I am new to both GTK+ and Glade and I can't seem to find anything that has been of use in resolving this. Any help would be greatly appreciated.

EDIT: Below is an example glade XML file that consists of two top level windows. The first is the main window with a single box containing a menu bar. The second is an about dialog. What I am looking for is help in writing the signal handler that will open the about window after clicking File -> About in the menu bar.

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.18.3 -->
<interface>
  <requires lib="gtk+" version="3.12"/>
  <object class="GtkWindow" id="window1">
    <property name="can_focus">False</property>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkMenuBar" id="menubar1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkMenuItem" id="menuitem1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_File</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu1">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem1">
                        <property name="label">gtk-new</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                       <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                     <object class="GtkImageMenuItem" id="imagemenuitem2">
                        <property name="label">gtk-open</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem3">
                        <property name="label">gtk-save</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem4">
                        <property name="label">gtk-save-as</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkSeparatorMenuItem" id="separatormenuitem1">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem5">
                        <property name="label">gtk-quit</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem2">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_Edit</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu2">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem6">
                        <property name="label">gtk-cut</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem7">
                        <property name="label">gtk-copy</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                     <object class="GtkImageMenuItem" id="imagemenuitem8">
                        <property name="label">gtk-paste</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem9">
                        <property name="label">gtk-delete</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
           <child>
              <object class="GtkMenuItem" id="menuitem3">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_View</property>
                <property name="use_underline">True</property>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem4">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_Help</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu3">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem10">
                        <property name="label">gtk-about</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                       <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
  <object class="GtkAboutDialog" id="window_about">
    <property name="can_focus">False</property>
    <property name="type_hint">dialog</property>
    <property name="program_name">Glade</property>
    <property name="logo_icon_name">image-missing</property>
    <child internal-child="vbox">
      <object class="GtkBox" id="aboutdialog-vbox1">
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <property name="spacing">2</property>
        <child internal-child="action_area">
          <object class="GtkButtonBox" id="aboutdialog-action_area1">
            <property name="can_focus">False</property>
            <property name="layout_style">end</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">False</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <placeholder/>
        </child>
      </object>
    </child>
  </object>
</interface>
2
cgtkglade
You're not planning on trying to display things like message dialogs from within a signal handler, are you? The only functions that can safely be called from within a signal handler are async-signal-safe functions. – Andrew Henle
I'm not trying to do that. It seems as though that is what is happening with the functions defined above. I'm just looking for clarification on how the signal handlers should be constructed given the Glade XML file having predefined the message dialog windows. – Leigh K

2 Answers

4
votes

If understood correctly, instead of creating the dialogs programmatically, you want to create the dialogs via glade.

By using glade you must use GtkBuilder.

Let's say you create a simple Yes, No dialog with glade (yesno_dialog.ui):

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.20.2 -->
<interface>
  <requires lib="gtk+" version="3.20"/>
  <object class="GtkDialog" id="dialog1">
    <property name="can_focus">False</property>
    <property name="modal">True</property>
    <property name="default_width">275</property>
    <property name="default_height">130</property>
    <property name="type_hint">dialog</property>
    <child internal-child="vbox">
      <object class="GtkBox">
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <property name="spacing">2</property>
        <child internal-child="action_area">
          <object class="GtkButtonBox">
            <property name="can_focus">False</property>
            <property name="hexpand">True</property>
            <property name="layout_style">spread</property>
            <child>
              <object class="GtkButton" id="button1">
                <property name="label">gtk-yes</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <property name="use_stock">True</property>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkButton" id="button2">
                <property name="label">gtk-no</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <property name="use_stock">True</property>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkLabel">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="halign">center</property>
            <property name="valign">center</property>
            <property name="hexpand">True</property>
            <property name="vexpand">True</property>
            <property name="label" translatable="yes">Are you sure to quit?</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
    <action-widgets>
      <action-widget response="1">button1</action-widget>
      <action-widget response="2">button2</action-widget>
    </action-widgets>
    <child>
      <placeholder/>
    </child>
  </object>
</interface>

Which should look like this:

enter image description here

Notice the response_id as 1 for later reference.

Let's test a simple window with a button which will trigger a dialog via its clicked signal handler / callback:

#include <gtk/gtk.h>

void on_button_clicked (GtkButton *button, gpointer user_data) {
   int response;
   GtkWidget  *dialog;
   GtkBuilder *builder;

   g_return_if_fail (user_data != NULL);

   builder = gtk_builder_new_from_file("yesno_dialog.ui");

   dialog = GTK_WIDGET(gtk_builder_get_object (builder, "dialog1"));
   gtk_window_set_transient_for (GTK_WINDOW(dialog), GTK_WINDOW(user_data));

   gtk_widget_show_all(dialog);

   response = gtk_dialog_run(GTK_DIALOG(dialog));

   gtk_widget_destroy(dialog);

   g_object_unref(G_OBJECT(builder));

   g_print ("Response is %s\n", response == 1 ? "Yes" : "No");
}


int main(int argc, char *argv[]) {
   GtkWidget *button;
   GtkWidget *window;

   gtk_init(&argc,&argv);

   button = gtk_button_new_with_label("Press for dialog");
   window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

   gtk_container_add(GTK_CONTAINER(window), button);

   g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(on_button_clicked), window);
   g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);

   gtk_widget_show_all(window);

   gtk_main();

   return 0;
}

When you construct a dialog programmatically with standard response ids then you can use the predefined enumerators to check the response. Using glade, even though we've defined Stock buttons, we must define (user-defined) response ids so that the gtk_dialog_run functions understands that the user has chosen a response.

Compiling with:

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

Should result in something similar to this:

enter image description here

2
votes

After discussions with @Jose Fonte, the solution to my question is the following:

// Signal Handler for Clicking File -> Quit
void file_quit_clicked (__attribute__((unused)) GtkMenuItem *item, gpointer user_data) 
{
    GtkBuilder *builder = (GtkBuilder *) user_data;

    GtkDialog *dialog = GTK_DIALOG(gtk_builder_get_object(builder, "quit_dialog"));

    gtk_widget_show_all(GTK_WIDGET(dialog));

    // This switch statement and gtk_widget_hide is needed so that the dialog window can be closed 
    // and reopened again without causing errors (i.e. if the user clicks "no" when asked "are you
    // sure you want to quit." Without these, the window errors out the second time opened.
    gint result = gtk_dialog_run (dialog);
    switch (result)
    {
        case GTK_RESPONSE_ACCEPT:
           // do_application_specific_something (); - Nothing Required
           break;
        default:
           // do_nothing_since_dialog_was_cancelled (); - Nothing Required
           break;
    }
    gtk_widget_hide(GTK_WIDGET(dialog));

}

with the following snippet inserted into the main function:

    // So the "Are you sure you want to quit?" Dialog Box is hidden after clicking "x"
    GtkDialog *quit_dialog = GTK_DIALOG(gtk_builder_get_object(builder, "quit_dialog"));
    gtk_widget_hide_on_delete (GTK_WIDGET(quit_dialog));