example-2-with-libglade-connection.c

Developing with Gnome一书examples例子代码

/* This program displays a "pulsing" (or whatever it's called)
 * ProgressBar, adds a timeout function to keep it updated, shows how
 * to obtain an individual widget that libglade created, and also
 * manually sets up the callback for the delete_event on the main
 * window so that some data (a glib timer) can be attached to the
 * callback.
 *
 * Note that most programs update progress bars during some kind of
 * function that doesn't return to the main event loop (unlike this
 * simple example).  In that case, you must manually tell gtk to
 * update widgets yourself by calling g_main_context_iteration.  (See
 * example-3.c for an example of doing this in a different context).
 */

#include <gtk/gtk.h>
#include <glib.h>
#include <glade/glade.h>

/* This is the callback for the delete_event, i.e. window closing */
void
inform_user_of_time_wasted (GtkWidget *widget, GdkEvent * event, gpointer data)
{
  /* Get the elapsed time since the timer was started */
  GTimer * timer = (GTimer*) data;
  gulong dumb_API_needs_this_variable;
  gdouble time_elapsed = g_timer_elapsed (timer, &dumb_API_needs_this_variable);

  /* Tell the user how much time they used */
  printf ("You wasted %.2f seconds with this program.\n", time_elapsed);

  /* Free the memory from the timer */
  g_timer_destroy (timer);

  /* Make the main event loop quit */
  gtk_main_quit ();
}

gboolean
update_progress_bar (gpointer data)
{
  gtk_progress_bar_pulse (GTK_PROGRESS_BAR (data));

  /* Return true so the function will be called again; returning false removes
   * this timeout function.
   */
  return TRUE;
}

int
main (int argc, char *argv[])
{
  GladeXML *what_a_waste;

  gtk_init (&argc, &argv);

  /* load the interface, but don't call glade_xml_signal_autoconnect
   * since we want to connect data to the callbacks--meaning that we
   * have to manually connect callbacks.
   */
  what_a_waste = glade_xml_new ("example-2.glade", NULL, NULL);

  /* Get the progress bar widget and change it to "activity mode", i.e. a block
   * that bounces back and forth instead of a normal progress bar that fills
   * to completion.
   */
  GtkWidget *progress_bar = glade_xml_get_widget (what_a_waste, "Progress Bar");
  gtk_progress_bar_pulse (GTK_PROGRESS_BAR (progress_bar));

  /* Add a timeout to update the progress bar every 100 milliseconds or so */
  gint func_ref = g_timeout_add (100, update_progress_bar, progress_bar);

  /* Start the wasted_time_tracker timer, and connect it to the callback */
  GTimer *wasted_time_tracker = g_timer_new ();
  glade_xml_signal_connect_data (what_a_waste,
                                 "inform_user_of_time_wasted",
                                 G_CALLBACK (inform_user_of_time_wasted),
                                 wasted_time_tracker);

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

  /* Remove the timeout function--not that it matters since we're about to end */
  g_source_remove (func_ref);

  return 0;
}