Re: GMenuModel has landed

[Stefan Sauer <ensonic hora-obscura de>]

On 12/09/2011 01:00 AM, Ryan Lortie wrote:
> hi,
>
> Today I landed the GMenuModel work on glib master.  A release will be
> following shortly.

Just one quick question - why is this in GLib? Is that to allow
command-line apps to have a menu?

Stefan
> There is related work in the 'wip/gmenu' branch of Gtk+ that will
> hopefully be landing soon.  There is a trivial example in
> gtk+/examples/bloatpad.c that demonstrates some of the ideas here.
>
> The main thing to understand about this work is that we are changing how
> menus work in Gtk+.  The days of constructing a GtkMenuBar widget and
> packing it into a VBox at the top of your window are gone.
>
> GMenuModel is an interface to describe the content of a menu and GMenu
> is its obvious implementation (think GtkTreeView vs. GtkTreeStore).
> Your application will construct a series of interlinked GMenu instances
> to describe the content of your menus.  Fortunately, there is an XML
> parser to do this automatically.  It is integrated with GtkBuilder.
>
> Providing the menu in abstract form instead of GtkWidget form addresses
> a few long-standing issues in Gtk.  The most notable one is that we will
> finally have proper support for the menubar on the mac.
>
> Menubars are no longer a per-window concept.  They are now set for the
> entire application.  This is done for two reasons:
>
>   1) every app already has the same menubar (content) in each window
>
>   2) this is how the mac universe operates
>
> The API to set the menubar for the application is, unsurprisingly:
>
> void      g_application_set_menubar     (GApplication *application,
>                                          GMenuModel   *menubar);
>
> A new type of menu has also been introduced: the application menu.  This
> is the menu that gnome-shell currently only has a "Quit" item in.  Your
> application can now control the contents of this menu by whipping up a
> GMenu and setting it:
>
> void      g_application_set_app_menu     (GApplication *application,
>                                           GMenuModel   *app_menu);
>
>
> We may add other types of menus in the future.  A jumplist/dock menu
> comes to mind.
>
> GMenuModel is a strictly read-only API.  It describes the structure of a
> menu, but has no support for invoking actions when items in the menu are
> clicked.  This is handled through the already-existing (but now
> improved) GActionGroup API.
>
> When creating a menu item, you specify an action name.  This looks like
> "app.preferences" or "win.fullscreen".  The part before the dot is the
> location of the action (in this case the hard-coded strings "app" and
> "win" refer to app-wide and window-specific actions, respectively).
>
> For example:
>
>   <item label='_Quit' action='app.quit'/>
>
> Clicking this menu item would result in the 'quit' action being invoked
> on your GApplication.
>
> There is a new GActionMap interface that GApplication now implements.
> It can be used to easily add actions to your GApplication.
>
> Gtk also has a new class called GtkApplicationWindow that implements
> GActionMap.  That's where the "win." actions go.  Even though the menu
> is globally-specified at the level of the application, the actions are
> correctly routed to the appropriate window automatically.
>
> There are two new XSettings properties that have been added to
> gnome-settings-daemon that specify if the shell will show the
> application menu or the menubar.  These values have hard-wired defaults
> on non-X platforms.
>
>                     shows-app-menu       shows-menubar
>   gnome-shell:      yes                  no
>   GNOME 2:          no                   no
>   unity:            yes                  yes
>   mac os:           yes                  yes
>
> If a particular desktop environment doesn't show a menu then it will be
> displayed at the top of each GtkApplicationWindow associated with that
> application.  For example, on gnome-shell, the menubar set with
> g_application_set_menubar() will be at the top of each window, but on
> the mac, it will be at the top of the screen.
>
>
> We're currently open to making changes to the APIs, so please check them
> out and give feedback, but remember that they may change.  If you have
> questions about how to use something, please reply here and I'll answer
> it for the benefit of all.  I hope to use the contents of this thread as
> the basis for writing some introductory material on the topic.
>
> Cheers
>
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