GTK+ dialogs

In this part of the GTK+ programming tutorial, we will introduce dialogs.

Dialog windows or dialogs are an indispensable part of most modern GUI applications. A dialog is defined as a conversation between two or more persons. In a computer application a dialog is a window which is used to "talk" to the application. A dialog is used to input data, modify data, change the application settings etc. Dialogs are important means of communication between a user and a computer program.

Message dialogs

Message dialogs are convenient dialogs that provide messages to the user of the application. The message consists of textual and image data.

#include <gtk/gtk.h>


void show_info(GtkWidget *widget, gpointer window)
{
  GtkWidget *dialog;
  dialog = gtk_message_dialog_new(GTK_WINDOW(window),
            GTK_DIALOG_DESTROY_WITH_PARENT,
            GTK_MESSAGE_INFO,
            GTK_BUTTONS_OK,
            "Download Completed", "title");
  gtk_window_set_title(GTK_WINDOW(dialog), "Information");
  gtk_dialog_run(GTK_DIALOG(dialog));
  gtk_widget_destroy(dialog);
}

void show_error(GtkWidget *widget, gpointer window)
{
  GtkWidget *dialog;
  dialog = gtk_message_dialog_new(GTK_WINDOW(window),
            GTK_DIALOG_DESTROY_WITH_PARENT,
            GTK_MESSAGE_ERROR,
            GTK_BUTTONS_OK,
            "Error loading file");
  gtk_window_set_title(GTK_WINDOW(dialog), "Error");
  gtk_dialog_run(GTK_DIALOG(dialog));
  gtk_widget_destroy(dialog);
}

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);
}

void show_warning(GtkWidget *widget, gpointer window)
{
  GtkWidget *dialog;
  dialog = gtk_message_dialog_new(GTK_WINDOW(window),
            GTK_DIALOG_DESTROY_WITH_PARENT,
            GTK_MESSAGE_WARNING,
            GTK_BUTTONS_OK,
            "Unallowed operation");
  gtk_window_set_title(GTK_WINDOW(dialog), "Warning");
  gtk_dialog_run(GTK_DIALOG(dialog));
  gtk_widget_destroy(dialog);
}

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

  GtkWidget *window;
  GtkWidget *table;

  GtkWidget *info;
  GtkWidget *warn;
  GtkWidget *que;
  GtkWidget *err;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 220, 150);
  gtk_window_set_title(GTK_WINDOW(window), "Message dialogs");

  table = gtk_table_new(2, 2, TRUE);
  gtk_table_set_row_spacings(GTK_TABLE(table), 2);
  gtk_table_set_col_spacings(GTK_TABLE(table), 2);

  info = gtk_button_new_with_label("Info");
  warn = gtk_button_new_with_label("Warning");
  que = gtk_button_new_with_label("Question");
  err = gtk_button_new_with_label("Error");

  gtk_table_attach(GTK_TABLE(table), info, 0, 1, 0, 1, GTK_FILL, GTK_FILL, 3, 3);
  gtk_table_attach(GTK_TABLE(table), warn, 1, 2, 0, 1, GTK_FILL, GTK_FILL, 3, 3);
  gtk_table_attach(GTK_TABLE(table), que, 0, 1, 1, 2, GTK_FILL, GTK_FILL, 3, 3);
  gtk_table_attach(GTK_TABLE(table), err, 1, 2, 1, 2, GTK_FILL, GTK_FILL, 3, 3);
  
  gtk_container_add(GTK_CONTAINER(window), table);
  gtk_container_set_border_width(GTK_CONTAINER(window), 15);

  g_signal_connect(G_OBJECT(info), "clicked", 
        G_CALLBACK(show_info), (gpointer) window); 

  g_signal_connect(G_OBJECT(warn), "clicked", 
        G_CALLBACK(show_warning), (gpointer) window); 

  g_signal_connect(G_OBJECT(que), "clicked", 
        G_CALLBACK(show_question), (gpointer) window); 

  g_signal_connect(G_OBJECT(err), "clicked", 
        G_CALLBACK(show_error), (gpointer) window); 

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), G_OBJECT(window));

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

In our example, we will show four kinds of message dialogs: Information, Warning, Question and Error message dialogs.

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);
}

In the show_question() function, we pop up the message dialog. The message dialog is created using the gtk_message_dialog_new() call. The parameters of the function specify, what kind of message dialog we create. The GTK_MESSAGE_QUESTION constant creates a question type dialog. GTK_BUTTONS_YES_NO constant will No and Yes buttons in the dialog. The last parameter is the text that we display in the dialog.

gtk_window_set_title(GTK_WINDOW(dialog), "Warning");
gtk_dialog_run(GTK_DIALOG(dialog));
gtk_widget_destroy(dialog);

Here we set a title for the message dialogs. And finally run the dialogs. The dialogs must be destroyed manually.

Information message dialog Warning message dialog Question message dialog Error message dialog
Figure: Message dialogs

GtkAboutDialog

The GtkAboutDialog displays information about the application. GtkAboutDialog can display a logo, the name of the application, version, copyright, website or licence information. It is also possible to give credits to the authors, documenters, translators and artists

#include <gtk/gtk.h>


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);
}


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

  GtkWidget *window;
  GtkWidget *about;
  GdkPixbuf *battery;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 220, 150);
  gtk_window_set_title(GTK_WINDOW(window), "Battery");

  gtk_container_set_border_width(GTK_CONTAINER(window), 15);
  gtk_widget_add_events(window, GDK_BUTTON_PRESS_MASK);

  battery = gtk_image_get_pixbuf(GTK_IMAGE(
      gtk_image_new_from_file("battery.png")));

  g_signal_connect(G_OBJECT(window), "button-press-event", 
        G_CALLBACK(show_about), (gpointer) window); 

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), G_OBJECT(window));

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

The code example uses a GtkAboutDialog with some of its features. To pop up the about dialog, we click on the client area of the window.

GtkWidget *dialog = gtk_about_dialog_new();

We create a new GtkAboutDialog.

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");

These function calls set a name, version and the copyright.

GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file("battery.png", NULL);
...
gtk_about_dialog_set_logo(GTK_ABOUT_DIALOG(dialog), pixbuf);
g_object_unref(pixbuf), pixbuf = NULL;

This code creates a logo.

GtkAboutDialog
Figure: GtkAboutDialog

GtkFontSelectionDialog

The GtkFontSelectionDialog is a dialog for selecting fonts. It is typically used in applications that do some text editing or formatting.

#include <gtk/gtk.h>


void select_font(GtkWidget *widget, gpointer label)
{

  GtkResponseType result;

  GtkWidget *dialog = gtk_font_selection_dialog_new("Select Font");
  result = gtk_dialog_run(GTK_DIALOG(dialog));

  if (result == GTK_RESPONSE_OK || result == GTK_RESPONSE_APPLY)
  {

    PangoFontDescription *font_desc;
    gchar *fontname = gtk_font_selection_dialog_get_font_name(
                            GTK_FONT_SELECTION_DIALOG(dialog));

    font_desc = pango_font_description_from_string(fontname);

    gtk_widget_modify_font(GTK_WIDGET(label), font_desc);

    g_free(fontname);
   }

  gtk_widget_destroy(dialog);
}


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

  GtkWidget *window;
  GtkWidget *label;
  GtkWidget *vbox;

  GtkWidget *toolbar;
  GtkToolItem *font;

  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 280, 200);
  gtk_window_set_title(GTK_WINDOW(window), "Font Selection Dialog");

  vbox = gtk_vbox_new(FALSE, 0);
  gtk_container_add(GTK_CONTAINER(window), vbox);

  toolbar = gtk_toolbar_new();
  gtk_toolbar_set_style(GTK_TOOLBAR(toolbar), GTK_TOOLBAR_ICONS);

  gtk_container_set_border_width(GTK_CONTAINER(toolbar), 2);

  font = gtk_tool_button_new_from_stock(GTK_STOCK_SELECT_FONT);
  gtk_toolbar_insert(GTK_TOOLBAR(toolbar), font, -1);

  gtk_box_pack_start(GTK_BOX(vbox), toolbar, FALSE, FALSE, 5);

  label = gtk_label_new("ZetCode");
  gtk_label_set_justify(GTK_LABEL(label), GTK_JUSTIFY_CENTER);
  gtk_box_pack_start(GTK_BOX(vbox), label, TRUE, FALSE, 5);


  g_signal_connect(G_OBJECT(font), "clicked", 
        G_CALLBACK(select_font), label);

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), NULL);

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

In the code example, we put a simple label into the center of the window. We show a font selecting dialog by clicking on the toolbar button.

GtkWidget *dialog = gtk_font_selection_dialog_new("Select Font");
result = gtk_dialog_run(GTK_DIALOG(dialog));

We create and show the GtkFontSelectionDialog.

if (result == GTK_RESPONSE_OK || result == GTK_RESPONSE_APPLY)
{
  PangoFontDescription *font_desc;
  gchar *fontname = gtk_font_selection_dialog_get_font_name(
                           GTK_FONT_SELECTION_DIALOG(dialog));

  font_desc = pango_font_description_from_string(fontname);

  gtk_widget_modify_font(GTK_WIDGET(label), font_desc);
  g_free(fontname);
}

If the user clicked on the OK or APPLY button, we proceed. We get the selected font name. Than we change the label's font to the selected font name.

GtkFontSelectionDialog
Figure: GtkFontSelectionDialog

GtkColorSelectionDialog

GtkColorSelectionDialog is a dialog for selecting a colour.

#include <gtk/gtk.h>


void select_font(GtkWidget *widget, gpointer label)
{
  GtkResponseType result;
  GtkColorSelection *colorsel;

  GtkWidget *dialog = gtk_color_selection_dialog_new("Font Color");
  result = gtk_dialog_run(GTK_DIALOG(dialog));

  if (result == GTK_RESPONSE_OK)
  {

    GdkColor color;

    colorsel = GTK_COLOR_SELECTION(
                   GTK_COLOR_SELECTION_DIALOG(dialog)->colorsel);
    gtk_color_selection_get_current_color(colorsel,
                   &color);

    gtk_widget_modify_fg(GTK_WIDGET(label),
                   GTK_STATE_NORMAL,
                   &color);
  } 

  gtk_widget_destroy(dialog);
}


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

  GtkWidget *window;
  GtkWidget *widget;
  GtkWidget *label;
  GtkWidget *vbox;

  GtkWidget *toolbar;
  GtkToolItem *font;


  gtk_init(&argc, &argv);

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 280, 200);
  gtk_window_set_title(GTK_WINDOW(window), "Color Selection Dialog");

  vbox = gtk_vbox_new(FALSE, 0);
  gtk_container_add(GTK_CONTAINER(window), vbox);


  toolbar = gtk_toolbar_new();
  gtk_toolbar_set_style(GTK_TOOLBAR(toolbar), GTK_TOOLBAR_ICONS);

  gtk_container_set_border_width(GTK_CONTAINER(toolbar), 2);

  font = gtk_tool_button_new_from_stock(GTK_STOCK_SELECT_COLOR);
  gtk_toolbar_insert(GTK_TOOLBAR(toolbar), font, -1);

  gtk_box_pack_start(GTK_BOX(vbox), toolbar, FALSE, FALSE, 5);

  label = gtk_label_new("ZetCode");
  gtk_label_set_justify(GTK_LABEL(label), GTK_JUSTIFY_CENTER);
  gtk_box_pack_start(GTK_BOX(vbox), label, TRUE, FALSE, 5);


  g_signal_connect(G_OBJECT(font), "clicked", 
        G_CALLBACK(select_font), label);

  g_signal_connect_swapped(G_OBJECT(window), "destroy",
        G_CALLBACK(gtk_main_quit), NULL);

  gtk_widget_show_all(window);

  gtk_main();

  return 0;
}

The example is very similar to the previous one. This time we change the colour of the label.

GtkWidget *dialog = gtk_color_selection_dialog_new("Font Color");
result = gtk_dialog_run(GTK_DIALOG(dialog));

We create and show the GtkColorSelectionDialog.

if (result == GTK_RESPONSE_OK)
{
  GdkColor color;

  colorsel = GTK_COLOR_SELECTION(
                 GTK_COLOR_SELECTION_DIALOG(dialog)->colorsel);
  gtk_color_selection_get_current_color(colorsel,
                 &color);

  gtk_widget_modify_fg(GTK_WIDGET(label),
                 GTK_STATE_NORMAL,
                 &color);
} 

If the user pressed OK, we get the colour and modify the label's colour.

GtkColorSelectionDialog
Figure: GtkColorSelectionDialog

This chapter was about dialogs in GTK+.