GtkUIManager
constructing menus and toolbars from an XML description
A #GtkUIManager constructs a user interface (menus and toolbars) from
one or more UI definitions, which reference actions from one or more
action groups.
UI Definitions
The UI definitions are specified in an XML format which can be
roughly described by the following DTD.
<!ELEMENT ui (menubar|toolbar|popup|accelerator)* >
<!ELEMENT menubar (menuitem|separator|placeholder|menu)* >
<!ELEMENT menu (menuitem|separator|placeholder|menu)* >
<!ELEMENT popup (menuitem|separator|placeholder|menu)* >
<!ELEMENT toolbar (toolitem|separator|placeholder)* >
<!ELEMENT placeholder (menuitem|toolitem|separator|placeholder|menu)* >
<!ELEMENT menuitem EMPTY >
<!ELEMENT toolitem EMPTY >
<!ELEMENT separator EMPTY >
<!ELEMENT accelerator EMPTY >
<!ATTLIST menubar name #IMPLIED >
<!ATTLIST toolbar name #IMPLIED >
<!ATTLIST popup name #IMPLIED >
<!ATTLIST placeholder name #IMPLIED >
<!ATTLIST menu name #IMPLIED
action #REQUIRED
position (top|bot) #IMPLIED >
<!ATTLIST menuitem name #IMPLIED
action #REQUIRED
position (top|bot) #IMPLIED >
<!ATTLIST toolitem name #IMPLIED
action #REQUIRED
position (top|bot) #IMPLIED >
<!ATTLIST accelerator name #IMPLIED
action #REQUIRED >
There are some additional restrictions beyond those specified in the
DTD, e.g. every toolitem must have a toolbar in its anchestry and
every menuitem must have a menubar or popup in its anchestry. Since
a #GMarkup parser is used to parse the UI description, it must not only
be valid XML, but valid #GMarkup. If a name is not specified, it defaults
to the action. If an action is not specified either, the element name is
used.
A UI definition
<ui>
<menubar>
<menu name="FileMenu" action="FileMenuAction">
<menuitem name="New" action="New2Action" />
<placeholder name="FileMenuAdditions" />
</menu>
<menu name="JustifyMenu" action="JustifyMenuAction">
<menuitem name="Left" action="justify-left"/>
<menuitem name="Centre" action="justify-center"/>
<menuitem name="Right" action="justify-right"/>
<menuitem name="Fill" action="justify-fill"/>
</menu>
</menubar>
<toolbar action="toolbar1">
<placeholder name="JustifyToolItems">
<separator/>
<toolitem name="Left" action="justify-left"/>
<toolitem name="Centre" action="justify-center"/>
<toolitem name="Right" action="justify-right"/>
<toolitem name="Fill" action="justify-fill"/>
<separator/>
</placeholder>
</toolbar>
</ui>
The constructed widget hierarchy is very similar to the element tree
of the XML, with the exception that placeholders are merged into their
parents. The correspondence of XML elements to widgets should be
almost obvious:
menubar
a #GtkMenuBar
toolbar
a #GtkToolbar
popup
a toplevel #GtkMenu
menu
a #GtkMenu attached to a menuitem
menuitem
a #GtkMenuItem subclass, the exact type depends on the
action
toolitem
a #GtkToolItem subclass, the exact type depends on the
action
separator
a #GtkSeparatorMenuItem or
#GtkSeparatorToolItem
accelerator
a keyboard accelerator
The "position" attribute determines where a constructed widget is positioned
wrt. to its siblings in the partially constructed tree. If it is
"top", the widget is prepended, otherwise it is appended.
UI Merging
The most remarkable feature of #GtkUIManager is that it can overlay a set
of menuitems and toolitems over another one, and demerge them later.
Merging is done based on the name of the XML elements. Each element is
identified by a path which consists of the names of its anchestors, separated
by slashes. For example, the menuitem named "Left" in the example above
has the path /ui/menubar/JustifyMenu/Left and the
toolitem with the same name has path
/ui/toolbar1/JustifyToolItems/Left.
Accelerators
Every action has an accelerator path. Accelerators are installed together with
menuitem proxies, but they can also be explicitly added with <accelerator>
elements in the UI definition. This makes it possible to have accelerators for
actions even if they have no visible proxies.
Smart Separators
The separators created by #GtkUIManager are "smart", i.e. they do not show up
in the UI unless they end up between two visible menu or tool items. Separators
which are located at the very beginning or end of the menu or toolbar
containing them, or multiple separators next to each other, are hidden. This
is a useful feature, since the merging of UI elements from multiple sources
can make it hard or impossible to determine in advance whether a separator
will end up in such an unfortunate position.
Empty Menus
Submenus pose similar problems to separators inconnection with merging. It is
impossible to know in advance whether they will end up empty after merging.
#GtkUIManager offers two ways to treat empty submenus:
make them disappear by hiding the menu item they're attached to
add an insensitive "Empty" item
The behaviour is chosen based on the "is_important" property of the action
to which the submenu is associated.
The GtkUIManager struct contains only private
members and should not be accessed directly.
@Returns:
@self:
@add_tearoffs:
@self:
@Returns:
@self:
@action_group:
@pos:
@self:
@action_group:
@self:
@Returns:
@self:
@Returns:
@self:
@path:
@Returns:
@self:
@path:
@Returns:
@self:
@buffer:
@length:
@error:
@Returns:
@self:
@filename:
@error:
@Returns:
@self:
@Returns:
These enumeration values are used by gtk_ui_manager_add_ui() to determine
what UI element to create.
@GTK_UI_MANAGER_AUTO: Pick the type of the UI element according to context.
@GTK_UI_MANAGER_MENUBAR: Create a menubar.
@GTK_UI_MANAGER_MENU: Create a menu.
@GTK_UI_MANAGER_TOOLBAR: Create a toolbar.
@GTK_UI_MANAGER_PLACEHOLDER: Insert a placeholder.
@GTK_UI_MANAGER_POPUP: Create a popup menu.
@GTK_UI_MANAGER_MENUITEM: Create a menuitem.
@GTK_UI_MANAGER_TOOLITEM: Create a toolitem.
@GTK_UI_MANAGER_SEPARATOR: Create a separator.
@GTK_UI_MANAGER_ACCELERATOR: Install an accelerator.
@self:
@merge_id:
@path:
@name:
@action:
@type:
@top:
@self:
@merge_id:
@self:
@Returns:
@self:
@uimanager: the object which received the signal.
@uimanager: the object which received the signal.
@widget: