Glib.Menu_Model.Gmenu_Model represents the contents of a menu -- an ordered list of menu items. The items are associated with actions, which can be activated through them. Items can be grouped in sections, and may have submenus associated with them. Both items and sections usually have some representation data, such as labels or icons. The type of the associated action (ie whether it is stateful, and what kind of state it has) can influence the representation of the item.
The conceptual model of menus in Glib.Menu_Model.Gmenu_Model is hierarchical: sections and submenus are again represented by GMenu_Models. Menus themselves do not define their own roles. Rather, the role of a particular Glib.Menu_Model.Gmenu_Model is defined by the item that references it (or, in the case of the 'root' menu, is defined by the context in which it is used).
As an example, consider the visible portions of this menu:
## An example menu # {menu-example}
There are 8 "menus" visible in the screenshot: one menubar, two submenus and 5 sections:
the toplevel menubar (containing 4 items) - the View submenu (containing
3 sections) - the first section of the View submenu (containing 2 items) - the second section of the View submenu (containing 1 item) - the final section of the View submenu (containing 1 item) - the Highlight Mode submenu (containing 2 sections) - the Sources section (containing 2 items)
the Markup section (containing 2 items)
The [example][menu-model] illustrates the conceptual connection between these 8 menus. Each large block in the figure represents a menu and the smaller blocks within the large block represent items in that menu. Some items contain references to other menus.
## A menu example # {menu-model}
Notice that the separators visible in the [example][menu-example] appear nowhere in the [menu model][menu-model]. This is because separators are not explicitly represented in the menu model. Instead, a separator is inserted between any two non-empty sections of a menu. Section items can have labels just like any other item. In that case, a display system may show a section header instead of a separator.
The motivation for this abstract model of application controls is that modern user interfaces tend to make these controls available outside the application. Examples include global menus, jumplists, dash boards, etc. To support such uses, it is necessary to 'export' information about actions and their representation in menus, which is exactly what the [GActionGroup exporter][gio-GActionGroup-exporter] and the [GMenuModel exporter][gio-GMenuModel-exporter] do for Glib.Action_Group.Gaction_Group and Glib.Menu_Model.Gmenu_Model. The client-side counterparts to make use of the exported information are Gdbus.Action_Group.Gdbus_Action_Group and Gdbus.Menu_Model.Gdbus_Menu_Model.
The API of Glib.Menu_Model.Gmenu_Model is very generic, with iterators for the attributes and links of an item, see Glib.Menu_Model.Iterate_Item_Attributes and Glib.Menu_Model.Iterate_Item_Links. The 'standard' attributes and link types have predefined names: G_MENU_ATTRIBUTE_LABEL, G_MENU_ATTRIBUTE_ACTION, G_MENU_ATTRIBUTE_TARGET, G_MENU_LINK_SECTION and G_MENU_LINK_SUBMENU.
Items in a Glib.Menu_Model.Gmenu_Model represent active controls if they refer to an action that can get activated when the user interacts with the menu item. The reference to the action is encoded by the string id in the G_MENU_ATTRIBUTE_ACTION attribute. An action id uniquely identifies an action in an action group. Which action group(s) provide actions depends on the context in which the menu model is used. E.g. when the model is exported as the application menu of a Gtk.Application.Gtk_Application, actions can be application-wide or window-specific (and thus come from two different action groups). By convention, the application-wide actions have names that start with "app.", while the names of window-specific actions start with "win.".
While a wide variety of stateful actions is possible, the following is the minimum that is expected to be supported by all users of exported menu information: - an action with no parameter type and no state - an action with no parameter type and boolean state - an action with string parameter type and string state
## Stateless
A stateless action typically corresponds to an ordinary menu item.
Selecting such a menu item will activate the action (with no parameter).
## Boolean State
An action with a boolean state will most typically be used with a "toggle" or "switch" menu item. The state can be set directly, but activating the action (with no parameter) results in the state being toggled.
Selecting a toggle menu item will activate the action. The menu item should be rendered as "checked" when the state is true.
## String Parameter and State
Actions with string parameters and state will most typically be used to represent an enumerated choice over the items available for a group of radio menu items. Activating the action with a string parameter is equivalent to setting that parameter as the state.
Radio menu items, in addition to being associated with the action, will have a target value. Selecting that menu item will result in activation of the action with the target value as the parameter. The menu item should be rendered as "selected" when the state of the action is equal to the target value of the menu item.
type Cb_Gmenu_Model_Gint_Gint_Gint_Void is not null access procedure
(Self : access Gmenu_Model_Record'Class;
Position : Glib.Gint;
Removed : Glib.Gint;
Added : Glib.Gint);
type Cb_GObject_Gint_Gint_Gint_Void is not null access procedure
(Self : access Glib.Object.GObject_Record'Class;
Position : Glib.Gint;
Removed : Glib.Gint;
Added : Glib.Gint);
function Get_Item_Attribute_Value
(Self : not null access Gmenu_Model_Record;
Item_Index : Glib.Gint;
Attribute : UTF8_String;
Expected_Type : Glib.Variant.Gvariant_Type)
return Glib.Variant.Gvariant
Queries the item at position Item_Index in Model for the attribute specified by Attribute. If Expected_Type is non-null then it specifies the expected type of the attribute. If it is null then any type will be accepted. If the attribute exists and matches Expected_Type (or if the expected type is unspecified) then the value is returned. If the attribute does not exist, or does not match the expected type then null is returned. Since: gtk+ 2.32
the index of the item
the attribute to query
the expected type of the attribute, or null
the value of the attribute
function Get_Item_Link
(Self : not null access Gmenu_Model_Record;
Item_Index : Glib.Gint;
Link : UTF8_String) return Gmenu_Model
Queries the item at position Item_Index in Model for the link specified by Link. If the link exists, the linked Glib.Menu_Model.Gmenu_Model is returned. If the link does not exist, null is returned. Since: gtk+ 2.32
the index of the item
the link to query
the linked Glib.Menu_Model.Gmenu_Model, or null
function Get_N_Items
(Self : not null access Gmenu_Model_Record) return Glib.Gint
Query the number of items in Model. Since: gtk+ 2.32
the number of items
function Get_Name
(Self : not null access Gmenu_Attribute_Iter_Record)
return UTF8_String
Gets the name of the attribute at the current iterator position, as a string. The iterator is not advanced. Since: gtk+ 2.32
the name of the attribute
function Get_Name
(Self : not null access Gmenu_Link_Iter_Record) return UTF8_String
Gets the name of the link at the current iterator position. The iterator is not advanced. Since: gtk+ 2.32
the type of the link
function Get_Type_Menu_Attribute_Iter return Glib.GType
function Get_Type_Menu_Link_Iter return Glib.GType
function Get_Type_Menu_Model return Glib.GType
function Get_Value
(Self : not null access Gmenu_Attribute_Iter_Record)
return Glib.Variant.Gvariant
Gets the value of the attribute at the current iterator position. The iterator is not advanced. Since: gtk+ 2.32
the value of the current attribute
function Get_Value
(Self : not null access Gmenu_Link_Iter_Record) return Gmenu_Model
Gets the linked Glib.Menu_Model.Gmenu_Model at the current iterator position. The iterator is not advanced. Since: gtk+ 2.32
the Glib.Menu_Model.Gmenu_Model that is linked to
type Gmenu_Attribute_Iter is access all Gmenu_Attribute_Iter_Record'Class;
type Gmenu_Attribute_Iter_Record is new GObject_Record with null record;
type Gmenu_Link_Iter is access all Gmenu_Link_Iter_Record'Class;
type Gmenu_Link_Iter_Record is new GObject_Record with null record;
type Gmenu_Model is access all Gmenu_Model_Record'Class;
type Gmenu_Model_Record is new GObject_Record with null record;
function Is_Mutable
(Self : not null access Gmenu_Model_Record) return Boolean
Queries if Model is mutable. An immutable Glib.Menu_Model.Gmenu_Model will never emit the Glib.Menu_Model.Gmenu_Model::items-changed signal. Consumers of the model may make optimisations accordingly. Since: gtk+ 2.32
True if the model is mutable (ie: "items-changed" may be emitted).
procedure Items_Changed
(Self : not null access Gmenu_Model_Record;
Position : Glib.Gint;
Removed : Glib.Gint;
Added : Glib.Gint)
Requests emission of the Glib.Menu_Model.Gmenu_Model::items-changed signal on Model. This function should never be called except by Glib.Menu_Model.Gmenu_Model subclasses. Any other calls to this function will very likely lead to a violation of the interface of the model. The implementation should update its internal representation of the menu before emitting the signal. The implementation should further expect to receive queries about the new state of the menu (and particularly added menu items) while signal handlers are running. The implementation must dispatch this call directly from a mainloop entry and not in response to calls -- particularly those from the Glib.Menu_Model.Gmenu_Model API. Said another way: the menu must not change while user code is running without returning to the mainloop. Since: gtk+ 2.32
the position of the change
the number of items removed
the number of items added
function Iterate_Item_Attributes
(Self : not null access Gmenu_Model_Record;
Item_Index : Glib.Gint) return Gmenu_Attribute_Iter
Creates a Glib.Menu_Model.Gmenu_Attribute_Iter to iterate over the attributes of the item at position Item_Index in Model. You must free the iterator with g_object_unref when you are done. Since: gtk+ 2.32
the index of the item
a new Glib.Menu_Model.Gmenu_Attribute_Iter
function Iterate_Item_Links
(Self : not null access Gmenu_Model_Record;
Item_Index : Glib.Gint) return Gmenu_Link_Iter
Creates a Glib.Menu_Model.Gmenu_Link_Iter to iterate over the links of the item at position Item_Index in Model. You must free the iterator with g_object_unref when you are done. Since: gtk+ 2.32
the index of the item
a new Glib.Menu_Model.Gmenu_Link_Iter
function Next
(Self : not null access Gmenu_Attribute_Iter_Record) return Boolean
Attempts to advance the iterator to the next (possibly first) attribute. True is returned on success, or False if there are no more attributes. You must call this function when you first acquire the iterator to advance it to the first attribute (and determine if the first attribute exists at all). Since: gtk+ 2.32
True on success, or False when there are no more attributes
function Next
(Self : not null access Gmenu_Link_Iter_Record) return Boolean
Attempts to advance the iterator to the next (possibly first) link. True is returned on success, or False if there are no more links. You must call this function when you first acquire the iterator to advance it to the first link (and determine if the first link exists at all). Since: gtk+ 2.32
True on success, or False when there are no more links
procedure On_Items_Changed
(Self : not null access Gmenu_Model_Record;
Call : Cb_Gmenu_Model_Gint_Gint_Gint_Void;
After : Boolean := False)
Emitted when a change has occurred to the menu.
The only changes that can occur to a menu is that items are removed or added. Items may not change (except by being removed and added back in the same location). This signal is capable of describing both of those changes (at the same time).
The signal means that starting at the index Position, Removed items were removed and Added items were added in their place. If Removed is zero then only items were added. If Added is zero then only items were removed.
As an example, if the menu contains items a, b, c, d (in that order) and the signal (2, 1, 3) occurs then the new composition of the menu will be a, b, _, _, _, d (with each _ representing some new item).
Signal handlers may query the model (particularly the added items) and expect to see the results of the modification that is being reported. The signal is emitted after the modification.
Callback parameters: -- @param Position the position of the change -- @param Removed the number of items removed -- @param Added the number of items added
procedure On_Items_Changed
(Self : not null access Gmenu_Model_Record;
Call : Cb_GObject_Gint_Gint_Gint_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
Emitted when a change has occurred to the menu.
The only changes that can occur to a menu is that items are removed or added. Items may not change (except by being removed and added back in the same location). This signal is capable of describing both of those changes (at the same time).
The signal means that starting at the index Position, Removed items were removed and Added items were added in their place. If Removed is zero then only items were added. If Added is zero then only items were removed.
As an example, if the menu contains items a, b, c, d (in that order) and the signal (2, 1, 3) occurs then the new composition of the menu will be a, b, _, _, _, d (with each _ representing some new item).
Signal handlers may query the model (particularly the added items) and expect to see the results of the modification that is being reported. The signal is emitted after the modification.
Callback parameters: -- @param Position the position of the change -- @param Removed the number of items removed -- @param Added the number of items added
Signal_Items_Changed : constant Glib.Signal_Name := "items-changed";
Emitted when a change has occurred to the menu.
The only changes that can occur to a menu is that items are removed or added. Items may not change (except by being removed and added back in the same location). This signal is capable of describing both of those changes (at the same time).
The signal means that starting at the index Position, Removed items were removed and Added items were added in their place. If Removed is zero then only items were added. If Added is zero then only items were removed.
As an example, if the menu contains items a, b, c, d (in that order) and the signal (2, 1, 3) occurs then the new composition of the menu will be a, b, _, _, _, d (with each _ representing some new item).
Signal handlers may query the model (particularly the added items) and expect to see the results of the modification that is being reported. The signal is emitted after the modification.
Callback parameters: -- @param Position the position of the change -- @param Removed the number of items removed -- @param Added the number of items added