example-4.c

Developing with Gnome一书examples例子代码

/* This program shows a preferences window, which contains
 * RadioButtons, a color selection widget, and a font selection
 * widget.  It does manual signal connection the gtk way (as opposed
 * to either the automatic libglade way or the manual libglade way,
 * the latter of which is sort of ugly IMO), pops up a (modal) window
 * to confirm whether the user really wants to exit, demonstrates how
 * to use pango markup, and shows how to manually free the memory
 * used by widgets when they're not wanted any more.
 */

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

/* A bunch of data to be set and used in the callbacks */
typedef struct _QuitData QuitData;
struct _QuitData
{
  GtkFontSelection* font_selection;
  GtkDialog       * annoying_confirmation_window;
  GtkLabel        * warning_label;
  GdkColor          color;
  gchar             location[10];
};

void
new_location_selected (GtkWidget *widget, gpointer data)
{
  QuitData * quit_choices = (QuitData*) data;

  /* Copy the widget name to quit_choices->location */
  snprintf(quit_choices->location, 10, gtk_widget_get_name (widget));
}

void
new_color_selected (GtkWidget *widget, gpointer data)
{
  QuitData * quit_choices = (QuitData*) data;
  gtk_color_selection_get_current_color (GTK_COLOR_SELECTION (widget),
                                         &quit_choices->color);
}

/* This simple helper function which converts an RGB triplet (which is
 * part of a GdkColor) into a "#RRGGBB" string.
 */
void
convert_color_to_string (GdkColor * color, gchar * color_string)
{
  color_string[0] = '#';

  /* GdkColor stores its red, green, and blue as 0..65536 instead of 0..256 */
  sprintf(&color_string[1], "%.2X", color->red  /256);
  sprintf(&color_string[3], "%.2X", color->green/256);
  sprintf(&color_string[5], "%.2X", color->blue /256);
}

/* This makes the confirmation window pop up to ask the user if they really
 * want to quit.  The message to the user changes slightly depending on the
 * preferences they had set.
 */
void
time_to_quit (GtkWidget *widget, gpointer data)
{
  QuitData * quit_choices = (QuitData*) data;

  /* Create a color string of the form #RRGGBB, where R, G, & B are hex digits */
  gchar color_string[8];
  convert_color_to_string(&quit_choices->color, color_string);

  /* Get the warning message, and find where we want to modify it */
  const gchar * message = gtk_label_get_label (quit_choices->warning_label);
  gchar * end_span = g_strrstr (message, "span");
  gchar * beg_span = g_strrstr_len (message, end_span-message, "span");

  /* Now, modify the string--namely the second span markup stuff */
  GString * new_message = g_string_new(NULL);
  g_string_append_len(new_message, message, beg_span-message-1);
  g_string_append_printf(new_message,
                         "<span font_desc=\"%s\" foreground=\"%s\">%s</span>",
                         gtk_font_selection_get_font_name (quit_choices->
                                                           font_selection),
                         color_string,
                         quit_choices->location);
  g_string_append_printf(new_message, "%s", end_span+5);

  /* Update the label and free our temporary string */
  gtk_label_set_label (quit_choices->warning_label, new_message->str);
  g_string_free (new_message, TRUE);

  /* Make sure the confirmation window is shown */
  gtk_widget_show (GTK_WIDGET (quit_choices->annoying_confirmation_window));
}

/* This exists simply because delete_event and clicked signals require different
 * numbers of arguments and return types.  This just calls time_to_quit.
 */
gboolean
time_to_quit_dumb_events (GtkWidget *widget, GdkEvent *event, gpointer data)
{
  time_to_quit (widget, data);
  return TRUE;
}

/* clean_up merely frees the data being passed around to all the callbacks */
void
clean_up (GtkWidget *widget, gpointer data)
{
  QuitData * quit_choices = (QuitData*) data;
  g_free(quit_choices);
}

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

  /* Get the preferences and confirmation windows */
  GtkWidget *preferences  = glade_xml_get_widget (the_widgets, "MainWindow");
  GtkWidget *are_you_sure = glade_xml_get_widget (the_widgets, "ConfirmClose");
  GtkWidget *font_sel     = glade_xml_get_widget (the_widgets, "FontSelection");

  /* FIRST, allocate some data needed by callbacks and initialize some of it. */

  QuitData * the_data = (QuitData*)malloc (sizeof (QuitData));
  the_data->font_selection = GTK_FONT_SELECTION (font_sel);
  the_data->annoying_confirmation_window = GTK_DIALOG (are_you_sure);
  sprintf(the_data->location, "undefined");

  /* SECOND, we handle setting up defaults and connect callbacks for
   * the confirmation window.
   */

  /* Have the delete event (window close) do nothing */
  g_signal_connect (G_OBJECT (are_you_sure), "delete_event",
                    G_CALLBACK (gtk_true), NULL);

  /* Have the cancel button hide the confirmation window */
  widget = glade_xml_get_widget (the_widgets, "CancelButton");
  g_signal_connect_swapped (G_OBJECT (widget), "clicked",
                            G_CALLBACK (gtk_widget_hide),
                            G_OBJECT (are_you_sure));

  /* Have the "Exit anyway" button close everything */
  widget = glade_xml_get_widget (the_widgets, "ExitButton");
  g_signal_connect (G_OBJECT (widget), "clicked",
                    G_CALLBACK (gtk_main_quit), NULL);

  /* Get the warning label so we can modify it later. */
  GtkWidget *info_label = glade_xml_get_widget (the_widgets, "InfoLabel");
  the_data->warning_label = GTK_LABEL (info_label);

  /* Make the window start hidden */
  gtk_widget_hide (are_you_sure);

  /* THIRD, we handle setting up defaults and connect callbacks for
   * the preferences window.
   */

  /* Keep track of when the location changes */
  widget = glade_xml_get_widget (the_widgets, "Here");
  g_signal_connect (G_OBJECT (widget), "toggled",
                    G_CALLBACK (new_location_selected),
                    (gpointer)the_data);
  widget = glade_xml_get_widget (the_widgets, "There");
  g_signal_connect (G_OBJECT (widget), "toggled",
                    G_CALLBACK (new_location_selected),
                    (gpointer)the_data);
  /* Make 'There' be the default; note this also emits the toggled signal */
  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (widget), TRUE);

  /* Keep track of when the color changes */
  widget = glade_xml_get_widget (the_widgets, "ColorSelection");
  g_signal_connect (G_OBJECT (widget), "color_changed",
                    G_CALLBACK (new_color_selected),
                    (gpointer)the_data);
  /* Set the default to whatever the ColorSelection widget defaults to */
  gtk_color_selection_get_current_color (GTK_COLOR_SELECTION (widget),
                                         &the_data->color);
  /* Turn off the opacity slider */
  gtk_color_selection_set_has_opacity_control (GTK_COLOR_SELECTION (widget),
                                               FALSE);

  /* Have the quit button show the confirmation window */
  widget = glade_xml_get_widget (the_widgets, "QuitButton");
  g_signal_connect (G_OBJECT (widget), "clicked",
                    G_CALLBACK (time_to_quit),
                    (gpointer)the_data);

  /* Have the delete event (window close) also show the confirmation window */
  g_signal_connect (G_OBJECT (preferences), "delete_event",
                    G_CALLBACK (time_to_quit_dumb_events),
                    (gpointer)the_data);

  /* Have the destroy signal call the cleanup callback, to free the_data */
  g_signal_connect (G_OBJECT (preferences), "destroy",
                    G_CALLBACK (clean_up),
                    (gpointer)the_data);
}

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

  gtk_init (&argc, &argv);

  /* load the interface */
  all_da_widgets = glade_xml_new ("example-4.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 ();

  /* Free the memory used by the widgets we're no longer using */
  gtk_widget_destroy( glade_xml_get_widget (all_da_widgets, "MainWindow"));
  gtk_widget_destroy( glade_xml_get_widget (all_da_widgets, "ConfirmClose"));

  return 0;
}