# MessageDialog (C)

Monica Kochofar
monicakochofar@gmail.com 2012
A message window

# MessageDialog

A modal message dialog which can cause the world to explode.

To test out the application once it has started running, you can click on the "Message Dialog" tab that appears in the top menubar of the screen.

#include <gtk/gtk.h>

/* Callback function in which reacts to the "response" signal from the user in * the message dialog window. * This function is used to interact with the user in the terminal. */ static void on_response (GtkDialog *dialog, gint response_id, gpointer user_data) { /* If the button clicked gives response OK (response_id being -5) */ if (response_id == GTK_RESPONSE_OK) g_print ("*boom*\n");

/* If the button clicked gives response CANCEL (response_id being -6) */ else if (response_id == GTK_RESPONSE_CANCEL) g_print ("good choice\n");

/* If the message dialog is destroyed (for example by pressing escape) */ else if (response_id == GTK_RESPONSE_DELETE_EVENT) g_print ("dialog closed or cancelled\n");

/* Destroy the dialog after one of the above actions have taken place */ gtk_widget_destroy (GTK_WIDGET (dialog));

}

/* Callback function for the response signal "activate" related to the SimpleAction * message_action. * This function is used to cause the message dialog window to popup. */ static void message_cb (GSimpleAction *simple, GVariant *parameter, gpointer user_data) { /* the parent variable in this case represents the window */ GtkWidget *message_dialog; GtkWindow *parent = user_data;

/* Create a new message dialog, and set the parameters as follows: * Dialog Flags - make the constructed dialog modal * (modal windows prevent interaction with other windows in the application) * Message Type - nonfatal warning message * Buttons Type - use the ok and cancel buttons * message_format - text that you want the user to see in the window */ message_dialog = gtk_message_dialog_new (parent, GTK_DIALOG_MODAL, GTK_MESSAGE_WARNING, GTK_BUTTONS_OK_CANCEL, "This action will cause the universe to stop existing.");

gtk_widget_show_all (message_dialog);

g_signal_connect (GTK_DIALOG (message_dialog), "response", G_CALLBACK (on_response), NULL);

}

static void activate (GtkApplication *app, gpointer user_data) { GtkWidget *window; GtkWidget *label;

GSimpleAction *message_action;

/* Create a window with a title and a default size */ window = gtk_application_window_new (app); gtk_window_set_title (GTK_WINDOW (window), "GMenu Example"); gtk_window_set_default_size (GTK_WINDOW (window), 400, 200);

/* Create a label and add it to the window */ label = gtk_label_new ("This application goes boom!"); gtk_container_add (GTK_CONTAINER (window), label);

/* Create a new simple action, giving it a NULL parameter type. It will * always be NULL for actions invoked from a menu. (e.g clicking on an "ok" * or "cancel" button) */ message_action = g_simple_action_new ("message", NULL);

/* Connect the "activate" signal to the appropriate callback function */ g_signal_connect (message_action, "activate", G_CALLBACK (message_cb), GTK_WINDOW (window));

/* Adds the message_action to the overall action map. An Action map is an * interface that contains a number of named GAction instances * (such as message_action) */ g_action_map_add_action (G_ACTION_MAP (window), G_ACTION (message_action));

gtk_widget_show_all (window); }

/* Callback function for the response signal "activate" from the "quit" action * in the function directly below. */ static void quit_cb (GSimpleAction *simple, GVariant *parameter, gpointer user_data) { GApplication *application = user_data;

g_application_quit (application); }

/* Startup function for the menu we are creating in this sample */ static void startup (GApplication *app, gpointer user_data) { GMenu *menu; GSimpleAction *quit_action;

/* Initialize the GMenu, and add a menu item with label "Message" and action * "win.message". Also add another menu item with label "Quit" and action * "app.quit" */ menu = g_menu_new (); g_menu_append (menu, "Message", "win.message"); g_menu_append (menu, "Quit", "app.quit");

/* Create a new simple action for the application. (In this case it is the * "quit" action. */ quit_action = g_simple_action_new ("quit", NULL);

/* Ensure that the menu we have just created is set for the overall application */ gtk_application_set_app_menu (GTK_APPLICATION (app), G_MENU_MODEL (menu));

g_signal_connect (quit_action, "activate", G_CALLBACK (quit_cb), app);

g_action_map_add_action (G_ACTION_MAP (app), G_ACTION (quit_action));

}

/* Startup function for the application */ int main (int argc, char **argv) { GtkApplication *app; int status;

app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE); g_signal_connect (app, "activate", G_CALLBACK (activate), NULL); g_signal_connect (app, "startup", G_CALLBACK (startup), NULL); status = g_application_run (G_APPLICATION (app), argc, argv); g_object_unref (app);

return status; }

In this sample we used the following:

GtkApplication

GApplication

GtkWindow

GtkMessageDialog

GSimpleAction

GActionMap

GMenu