Chapter 14. Menu Widget

Table of Contents
14.1. Manual Menu Creation
14.2. Manual Menu Example
14.3. Using ItemFactory
14.4. Item Factory Example
There are two ways to create menus: there's the easy way, and there's the hard way. Both have their uses, but you can usually use the Itemfactory (the easy way). The "hard" way is to create all the menus using the calls directly. The easy way is to use the GtkItemFactory calls. This is much simpler, but there are advantages and disadvantages to each approach.

The Itemfactory is much easier to use, and to add new menus to, although writing a few wrapper functions to create menus using the manual method could go a long way towards usability. With the Itemfactory, it is not possible to add images or the character '/' to the menus.

14.1. Manual Menu Creation

In the true tradition of teaching, we'll show you the hard way first. :)

There are three widgets that go into making a menubar and submenus:

This is slightly complicated by the fact that menu item widgets are used for two different things. They are both the widgets that are packed into the menu, and the widget that is packed into the menubar, which, when selected, activates the menu.

Let's look at the functions that are used to create menus and menubars. This first function is used to create a new menubar.
 
    menu_bar = GtkMenuBar()

This rather self explanatory function creates a new menubar. You use the GtkContainer add() method to pack this into a window, or the GtkBox pack methods to pack it into a box - the same as buttons.
 
    menu = GtkMenu()

This function returns a reference to a new menu; it is never actually shown (with the show() method), it is just a container for the menu items. I hope this will become more clear when you look at the example below.

The next two calls are used to create menu items that are packed into the menu (and menubar).
 
    menu_item = GtkMenuItem()
    menu_item = GtkMenuItem(label)

These calls are used to create the menu items that are to be displayed. Remember to differentiate between a "menu" as created with GtkMenu() and a "menu item" as created by the GtkMenuItem() functions. The menu item will be an actual button with an associated action, whereas a menu will be a container holding menu items.

The GtkMenuItem() calls are just as you'd expect after reading about the buttons. One creates a new menu item with a label already packed into it, and the other just creates a blank menu item.

Once you've created a menu item you have to put it into a menu. This is done using the append() method. In order to capture when the item is selected by the user, we need to connect to the activate signal in the usual way. So, if we wanted to create a standard File menu, with the options Open, Save, and Quit, the code would look something like:
 
    file_menu = GtkMenu()    # Don't need to show menus

    # Create the menu items
    open_item = GtkMenuItem("Open")
    save_item = GtkMenuItem("Save")
    quit_item = GtkMenuItem("Quit")

    # Add them to the menu
    file_menu.append(open_item)
    file_menu.append(save_item)
    file_menu.append(quit_item)

    # Attach the callback functions to the activate signal
    open_item.connect_object("activate", menuitem_response, "file.open")
    save_item.connect_object("activate", menuitem_response, "file.save")

    # We can attach the Quit menu item to our exit function
    quit_item.connect_object ("activate", destroy, "file.quit")

    # We do need to show menu items
    open_item.show()
    save_item.show()
    quit_item.show()

At this point we have our menu. Now we need to create a menubar and a menu item for the File entry, to which we add our menu. The code looks like this:
 
    menu_bar = GtkMenuBar()
    window.add(menu_bar)
    menu_bar.show()

    file_item = GtkMenuItem("File")
    file_item.show()

Now we need to associate the menu with file_item. This is done with the method:
 
    menu_item.set_submenu(submenu)

So, our example would continue with:
 
    menu_item.set_submenu(file_menu)

All that is left to do is to add the menu to the menubar, which is accomplished using the method:
 
    menu_bar.append(menu_item)

which in our case looks like this:
 
    menu_bar.append(file_item)

If we wanted the menu right justified on the menubar, such as help menus often are, we can use the following method (again on file_item in the current example) before attaching it to the menubar.
 
    menu_item.right_justify()

Here is a summary of the steps needed to create a menu bar with menus attached:

Creating a popup menu is nearly the same. The difference is that the menu is not posted "automatically" by a menubar, but explicitly by calling the popup() method from a button-press event, for example. Take these steps: