GtkApplication

## GtkApplication GtkApplication — Application class |

## Synopsis

    #include <gtk/gtk.h>

    struct              GtkApplication;
    GtkApplication *    gtk_application_new                 (const gchar *application_id,
                                                             GApplicationFlags flags);
    void                gtk_application_add_window          (GtkApplication *application,
                                                             GtkWindow *window);
    void                gtk_application_remove_window       (GtkApplication *application,
                                                             GtkWindow *window);
    GList *             gtk_application_get_windows         (GtkApplication *application);

    GMenuModel *        gtk_application_get_app_menu        (GtkApplication *application);
    void                gtk_application_set_app_menu        (GtkApplication *application,
                                                             GMenuModel *model);
    GMenuModel *        gtk_application_get_menubar         (GtkApplication *application);
    void                gtk_application_set_menubar         (GtkApplication *application,
                                                             GMenuModel *model);

## Object Hierarchy

      GObject
       +----GApplication
             +----GtkApplication

## Implemented Interfaces

GtkApplication implements GActionGroup and GActionMap.

## Signals

      "window-added"                                   : Run First
      "window-removed"                                 : Run First

## Description

GtkApplication is a class that handles many important aspects of a GTK+ application in a convenient fashion, without enforcing a one-size-fits-all application model.

Currently, GtkApplication handles GTK+ initialization, application uniqueness, provides some basic scriptability and desktop shell integration by exporting actions and menus and manages a list of toplevel windows whose life-cycle is automatically tied to the life-cycle of your application.

While GtkApplication works fine with plain GtkWindows, it is recommended to use it together with GtkApplicationWindow.

When GDK threads are enabled, GtkApplication will acquire the GDK lock when invoking actions that arrive from other processes. The GDK lock is not touched for local action invocations. In order to have actions invoked in a predictable context it is therefore recommended that the GDK lock be held while invoking actions locally with `g_action_group_activate_action()`. The same applies to actions associated with GtkApplicationWindow and to the 'activate' and 'open' GApplication methods.

To set an application menu on a GtkApplication, use `g_application_set_app_menu()`. The GMenuModel that this function expects is usually constructed using GtkBuilder, as seen in the following example. To set a menubar that will be automatically picked up by GApplicationWindows, use `g_application_set_menubar()`. GTK+ makes these menus appear as expected, depending on the platform the application is running on.

Figure Menu integration in OS X.

Figure Menu integration in GNOME.

Figure Menu integration in Xfce.

Example 109. A simple application

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    #include <stdlib.h>
    #include <gtk/gtk.h>

    static void
    activate_toggle (GSimpleAction *action,
                     GVariant      *parameter,
                     gpointer       user_data)
    {
      GVariant *state;

      state = g_action_get_state (G_ACTION (action));
      g_action_change_state (G_ACTION (action), g_variant_new_boolean (!g_variant_get_boolean (state)));
      g_variant_unref (state);
    }

    static void
    change_fullscreen_state (GSimpleAction *action,
                             GVariant      *state,
                             gpointer       user_data)
    {
      if (g_variant_get_boolean (state))
        gtk_window_fullscreen (user_data);
      else
        gtk_window_unfullscreen (user_data);

      g_simple_action_set_state (action, state);
    }

    static GtkClipboard *
    get_clipboard (GtkWidget *widget)
    {
      return gtk_widget_get_clipboard (widget, gdk_atom_intern_static_string ("CLIPBOARD"));
    }

    static void
    window_copy (GSimpleAction *action,
                 GVariant      *parameter,
                 gpointer       user_data)
    {
      GtkWindow *window = GTK_WINDOW (user_data);
      GtkTextView *text = g_object_get_data ((GObject*)window, "bloatpad-text");

      gtk_text_buffer_copy_clipboard (gtk_text_view_get_buffer (text),
                                      get_clipboard ((GtkWidget*) text));
    }

    static void
    window_paste (GSimpleAction *action,
                  GVariant      *parameter,
                  gpointer       user_data)
    {
      GtkWindow *window = GTK_WINDOW (user_data);
      GtkTextView *text = g_object_get_data ((GObject*)window, "bloatpad-text");

      gtk_text_buffer_paste_clipboard (gtk_text_view_get_buffer (text),
                                       get_clipboard ((GtkWidget*) text),
                                       NULL,
                                       TRUE);

    }

    static GActionEntry win_entries[] = {
      { "copy", window_copy, NULL, NULL, NULL },
      { "paste", window_paste, NULL, NULL, NULL },
      { "fullscreen", activate_toggle, NULL, "false", change_fullscreen_state }
    };

    static void
    new_window (GApplication *app,
                GFile        *file)
    {
      GtkWidget *window, *grid, *scrolled, *view;

      window = gtk_application_window_new (GTK_APPLICATION (app));
      gtk_window_set_default_size ((GtkWindow*)window, 640, 480);
      g_action_map_add_action_entries (G_ACTION_MAP (window), win_entries, G_N_ELEMENTS (win_entries), window);
      gtk_window_set_title (GTK_WINDOW (window), "Bloatpad");

      grid = gtk_grid_new ();
      gtk_container_add (GTK_CONTAINER (window), grid);

      scrolled = gtk_scrolled_window_new (NULL, NULL);
      gtk_widget_set_hexpand (scrolled, TRUE);
      gtk_widget_set_vexpand (scrolled, TRUE);
      view = gtk_text_view_new ();

      g_object_set_data ((GObject*)window, "bloatpad-text", view);

      gtk_container_add (GTK_CONTAINER (scrolled), view);

      gtk_grid_attach (GTK_GRID (grid), scrolled, 0, 0, 1, 1);

      if (file != NULL)
        {
          gchar *contents;
          gsize length;

          if (g_file_load_contents (file, NULL, &contents, &length, NULL, NULL))
            {
              GtkTextBuffer *buffer;

              buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));
              gtk_text_buffer_set_text (buffer, contents, length);
              g_free (contents);
            }
        }

      gtk_widget_show_all (GTK_WIDGET (window));
    }

    static void
    bloat_pad_activate (GApplication *application)
    {
      new_window (application, NULL);
    }

    static void
    bloat_pad_open (GApplication  *application,
                    GFile        **files,
                    gint           n_files,
                    const gchar   *hint)
    {
      gint i;

      for (i = 0; i < n_files; i++)
        new_window (application, files[i]);
    }

    typedef GtkApplication BloatPad;
    typedef GtkApplicationClass BloatPadClass;

    G_DEFINE_TYPE (BloatPad, bloat_pad, GTK_TYPE_APPLICATION)

    static void
    bloat_pad_finalize (GObject *object)
    {
      G_OBJECT_CLASS (bloat_pad_parent_class)->finalize (object);
    }

    static void
    new_activated (GSimpleAction *action,
                   GVariant      *parameter,
                   gpointer       user_data)
    {
      g_application_activate (user_data);
    }

    static void
    show_about (GSimpleAction *action,
                GVariant      *parameter,
                gpointer       user_data)
    {
      gtk_show_about_dialog (NULL,
                             "program-name", "Bloatpad",
                             "title", "About Bloatpad",
                             "comments", "Not much to say, really.",
                             NULL);
    }

    static void
    quit_app (GSimpleAction *action,
              GVariant      *parameter,
              gpointer       user_data)
    {
      GList *list, *next;
      GtkWindow *win;

      g_print ("Going down...\n");

      list = gtk_application_get_windows (GTK_APPLICATION (g_application_get_default ()));
      while (list)
        {
          win = list->data;
          next = list->next;

          gtk_widget_destroy (GTK_WIDGET (win));

          list = next;
        }
    }

    static GActionEntry app_entries[] = {
      { "new", new_activated, NULL, NULL, NULL },
      { "about", show_about, NULL, NULL, NULL },
      { "quit", quit_app, NULL, NULL, NULL },
    };

    static void
    bloat_pad_startup (GApplication *application)
    {
      GtkBuilder *builder;

      G_APPLICATION_CLASS (bloat_pad_parent_class)
        ->startup (application);

      g_action_map_add_action_entries (G_ACTION_MAP (application), app_entries, G_N_ELEMENTS (app_entries), application);

      builder = gtk_builder_new ();
      gtk_builder_add_from_string (builder,
                                   "<interface>"
                                   "  <menu id='app-menu'>"
                                   "    <section>"
                                   "      <item label='_New Window' action='app.new' accel='<Primary>n'/>"
                                   "    </section>"
                                   "    <section>"
                                   "      <item label='_About Bloatpad' action='app.about'/>"
                                   "    </section>"
                                   "    <section>"
                                   "      <item label='_Quit' action='app.quit' accel='<Primary>q'/>"
                                   "    </section>"
                                   "  </menu>"
                                   "  <menu id='menubar'>"
                                   "    <submenu label='_Edit'>"
                                   "      <section>"
                                   "        <item label='_Copy' action='win.copy' accel='<Primary>c'/>"
                                   "        <item label='_Paste' action='win.paste' accel='<Primary>v'/>"
                                   "      </section>"
                                   "    </submenu>"
                                   "    <submenu label='_View'>"
                                   "      <section>"
                                   "        <item label='_Fullscreen' action='win.fullscreen'/>"
                                   "      </section>"
                                   "    </submenu>"
                                   "  </menu>"
                                   "</interface>", -1, NULL);
      gtk_application_set_app_menu (GTK_APPLICATION (application), G_MENU_MODEL (gtk_builder_get_object (builder, "app-menu")));
      gtk_application_set_menubar (GTK_APPLICATION (application), G_MENU_MODEL (gtk_builder_get_object (builder, "menubar")));
      g_object_unref (builder);
    }

    static void
    bloat_pad_init (BloatPad *app)
    {
    }

    static void
    bloat_pad_class_init (BloatPadClass *class)
    {
      GApplicationClass *application_class = G_APPLICATION_CLASS (class);
      GObjectClass *object_class = G_OBJECT_CLASS (class);

      application_class->startup = bloat_pad_startup;
      application_class->activate = bloat_pad_activate;
      application_class->open = bloat_pad_open;

      object_class->finalize = bloat_pad_finalize;

    }

    BloatPad *
    bloat_pad_new (void)
    {
      g_type_init ();

      return g_object_new (bloat_pad_get_type (),
                           "application-id", "org.gtk.Test.bloatpad",
                           "flags", G_APPLICATION_HANDLES_OPEN,
                           NULL);
    }

    int
    main (int argc, char **argv)
    {
      BloatPad *bloat_pad;
      int status;

      bloat_pad = bloat_pad_new ();
      gtk_application_add_accelerator (GTK_APPLICATION (bloat_pad),
                                       "F11", "win.fullscreen", NULL);
      status = g_application_run (G_APPLICATION (bloat_pad), argc, argv);
      g_object_unref (bloat_pad);

      return status;
    }

## Details

### struct GtkApplication

    struct GtkApplication;

### gtk_application_new ()

    GtkApplication *    gtk_application_new                 (const gchar *application_id,
                                                             GApplicationFlags flags);

Creates a new GtkApplication instance.

This function calls `g_type_init()` for you. `gtk_init()` is called as soon as the application gets registered as the primary instance.

Note that commandline arguments are not passed to `gtk_init()`. All GTK+ functionality that is available via commandline arguments can also be achieved by setting suitable environment variables such as <envvar>G_DEBUG</envvar>, so this should not be a big problem. If you absolutely must support GTK+ commandline arguments, you can explicitly call `gtk_init()` before creating the application instance.

The application id must be valid. See `g_application_id_is_valid()`.

`application_id` : | the application id
`flags` : | the application flags
Returns : | a new GtkApplication instance

### gtk_application_add_window ()

    void                gtk_application_add_window          (GtkApplication *application,
                                                             GtkWindow *window);

Adds a window from `application`.

This call is equivalent to setting the "application" property of `window` to `application`.

Normally, the connection between the application and the window will remain until the window is destroyed, but you can explicitly remove it with `gtk_application_remove_window()`.

GTK+ will keep the application running as long as it has any windows.

`application` : | a GtkApplication
`window` : | a GtkWindow

Since 3.0

### gtk_application_remove_window ()

    void                gtk_application_remove_window       (GtkApplication *application,
                                                             GtkWindow *window);

Remove a window from `application`.

If `window` belongs to `application` then this call is equivalent to setting the "application" property of `window` to `NULL`.

The application may stop running as a result of a call to this function.

`application` : | a GtkApplication
`window` : | a GtkWindow

Since 3.0

### gtk_application_get_windows ()

    GList *             gtk_application_get_windows         (GtkApplication *application);

Gets a list of the GtkWindows associated with `application`.

The list is sorted by most recently focused window, such that the first element is the currently focused window. (Useful for choosing a parent for a transient window.)

The list that is returned should not be modified in any way. It will only remain valid until the next focus change or window creation or deletion.

`application` : | a GtkApplication
Returns : | a GList of GtkWindow. [element-type GtkWindow][transfer none]

Since 3.0

### gtk_application_get_app_menu ()

    GMenuModel *        gtk_application_get_app_menu        (GtkApplication *application);

Returns the menu model that has been set with `g_application_set_app_menu()`.

`application` : | a GtkApplication
Returns : | the application menu of `application`

Since 3.4

### gtk_application_set_app_menu ()

    void                gtk_application_set_app_menu        (GtkApplication *application,
                                                             GMenuModel *model);

Sets or unsets the application menu for `application`.

The application menu is a single menu containing items that typically impact the application as a whole, rather than acting on a specific window or document. For example, you would expect to see "Preferences" or "Quit" in an application menu, but not "Save" or "Print".

If supported, the application menu will be rendered by the desktop environment.

`application` : | a GtkApplication
`app_menu` : | a GMenuModel, or `NULL`. [allow-none]

Since 3.4

### gtk_application_get_menubar ()

    GMenuModel *        gtk_application_get_menubar         (GtkApplication *application);

Returns the menu model that has been set with `g_application_set_menubar()`.

`application` : | a GtkApplication
Returns : | the menubar for windows of `application`

Since 3.4

### gtk_application_set_menubar ()

    void                gtk_application_set_menubar         (GtkApplication *application,
                                                             GMenuModel *model);

Sets or unsets the menubar for windows of `application`.

This is a menubar in the traditional sense.

Depending on the desktop environment, this may appear at the top of each window, or at the top of the screen. In some environments, if both the application menu and the menubar are set, the application menu will be presented as if it were the first item of the menubar. Other environments treat the two as completely separate -- for example, the application menu may be rendered by the desktop shell while the menubar (if set) remains in each individual window.

`application` : | a GtkApplication
`menubar` : | a GMenuModel, or `NULL`. [allow-none]

Since 3.4

## Signal Details

### The `"window-added"` signal

    void                user_function                      (GtkApplication *application,
                                                            GtkWindow      *window,
                                                            gpointer        user_data)        : Run First

Emitted when a GtkWindow is added to `application` through `gtk_application_add_window()`.

`application` : | the GtkApplication which emitted the signal
`window` : | the newly-added GtkWindow
`user_data` : | user data set when the signal handler was connected.

Since 3.2

### The `"window-removed"` signal

    void                user_function                      (GtkApplication *application,
                                                            GtkWindow      *window,
                                                            gpointer        user_data)        : Run First

Emitted when a GtkWindow is removed from `application`, either as a side-effect of being destroyed or explicitly through `gtk_application_remove_window()`.

`application` : | the GtkApplication which emitted the signal
`window` : | the GtkWindow that is being removed
`user_data` : | user data set when the signal handler was connected.

Since 3.2