example-1.c

Developing with Gnome一书examples例子代码

/* This program monitors the /apps/metacity/general/reduced_resources
 * gconf key, and allows the user to change it as well.
 */

#include <gtk/gtk.h>
#include <glade/glade.h>
#include <gconf/gconf-client.h>

static gboolean old_setting;

void
gconf_key_changed_callback (GConfClient* client,
                            guint cnxn_id,
                            GConfEntry* entry,
                            gpointer user_data)
{
  GtkWidget* button;
  button = GTK_WIDGET (user_data);

  /* Make sure the preference has a valid value */
  if (gconf_entry_get_value (entry) != NULL && 
      gconf_entry_get_value (entry)->type == GCONF_VALUE_BOOL)
    {
      /* Get the new value */
      gboolean new_setting =
        gconf_value_get_bool (gconf_entry_get_value (entry));

      /* Try to handle asynchronous-ness of GConf and prevent calling
       * checkbutton_toggled_callback again if this function was
       * called as a result of the gconf_client_set_bool function call.
       */
      if (new_setting != old_setting)
        {
          old_setting = new_setting;
          gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (button), new_setting);
        }
    }
}

void
checkbutton_toggled_callback (GtkWidget* check_button, gpointer user_data)
{
  GConfClient* client = GCONF_CLIENT (user_data);

  /* Determine whether the checkbutton is already set or not */
  gboolean is_set = 
    gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (check_button));
 
  /* Try to handle asynchronous-ness of GConf and prevent calling
   * gconf_key_changed_callback again if this function was called as a
   * result of the gtk_toggle_button_set_active function call.
   */
  if (is_set != old_setting)
    {
      old_setting = is_set;
      gconf_client_set_bool (client,
                             "/apps/metacity/general/reduced_resources",
                             is_set,
                             NULL);
    }
}

void
hook_up_callbacks_and_set_defaults (GladeXML * the_widgets)
{
  GtkWidget *widget;

  /* Get the GconfClient, tell it we want to monitor /apps/metacity/general */
  GConfClient* client = gconf_client_get_default();
  gconf_client_add_dir(client,
                       "/apps/metacity/general",
                       GCONF_CLIENT_PRELOAD_NONE,
                       NULL);

  /* Get the check_button */
  widget = glade_xml_get_widget (the_widgets, "Reduced Resources");

  /* Connect the check_button to a callback that can toggle it when the option
   * is changed by some outside program.
   */
  gconf_client_notify_add(client,
                          "/apps/metacity/general/reduced_resources",
                          gconf_key_changed_callback,
                          widget,
                          NULL,
                          NULL);

  /* Connect the check_button's clicked callback up so that it can change the
   * gconf setting.
   */
  g_signal_connect(G_OBJECT (widget), "clicked",
                   G_CALLBACK (checkbutton_toggled_callback), client);

  /* Determine whether button should start activated or not */
  old_setting =
    gconf_client_get_bool (client,
                           "/apps/metacity/general/reduced_resources",
                           NULL);
  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (widget), old_setting);


  /* Get the main_window and connect the close button to gtk_main_quit */
  widget = glade_xml_get_widget (the_widgets, "MainWindow");
  g_signal_connect (G_OBJECT (widget), "delete_event",
                    G_CALLBACK (gtk_main_quit), NULL);

  /* Get the quit button and it to gtk_main_quit */
  widget = glade_xml_get_widget (the_widgets, "CloseButton");
  g_signal_connect (G_OBJECT (widget), "clicked",
                    G_CALLBACK (gtk_main_quit), NULL);
}

int
main (int argc, char **argv)
{
  GladeXML *all_da_widgets;

  gtk_init (&argc, &argv);
  gconf_init(argc, argv, NULL);

  /* load the interface */
  all_da_widgets = glade_xml_new ("example-1.glade", NULL, NULL);

  /* Connect all the signals to the appropriate callbacks */
  hook_up_callbacks_and_set_defaults (all_da_widgets);

  /* start the event loop */
  gtk_main ();

  return 0;
}