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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

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+.