Glib.Menu_Model

Description

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.

Cb_Gmenu_Model_Gint_Gint_Gint_Void

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);

Parameters

Self

Position

Removed

Added

Cb_GObject_Gint_Gint_Gint_Void

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);

Parameters

Self

Position

Removed

Added

Get_Item_Attribute_Value

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

Parameters

Self

Item_Index

the index of the item

Attribute

the attribute to query

Expected_Type

the expected type of the attribute, or null

Return Value

the value of the attribute. Has transfer-ownership='full'.

Get_Item_Link

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

Parameters

Self

Item_Index

the index of the item

Link

the link to query

Return Value

the linked Glib.Menu_Model.Gmenu_Model, or null. Has transfer-ownership='full'.

Get_N_Items

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

Parameters

Self

Return Value

the number of items

Get_Name

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

Parameters

Self

Return Value

the name of the attribute

Get_Name

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

Parameters

Self

Return Value

the type of the link

Get_Type_Menu_Attribute_Iter

function Get_Type_Menu_Attribute_Iter return Glib.GType

Return Value

Get_Type_Menu_Link_Iter

function Get_Type_Menu_Link_Iter return Glib.GType

Return Value

Get_Type_Menu_Model

function Get_Type_Menu_Model return Glib.GType

Return Value

Get_Value

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

Parameters

Self

Return Value

the value of the current attribute. Has transfer-ownership='full'.

Get_Value

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

Parameters

Self

Return Value

the Glib.Menu_Model.Gmenu_Model that is linked to. Has transfer-ownership='full'.

Gmenu_Attribute_Iter

type Gmenu_Attribute_Iter is access all Gmenu_Attribute_Iter_Record'Class;

Gmenu_Attribute_Iter_Record

type Gmenu_Attribute_Iter_Record is new GObject_Record with null record;

Gmenu_Link_Iter

type Gmenu_Link_Iter is access all Gmenu_Link_Iter_Record'Class;

Gmenu_Link_Iter_Record

type Gmenu_Link_Iter_Record is new GObject_Record with null record;

Gmenu_Model

type Gmenu_Model is access all Gmenu_Model_Record'Class;

Gmenu_Model_Record

type Gmenu_Model_Record is new GObject_Record with null record;

Is_Mutable

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

Parameters

Self

Return Value

True if the model is mutable (ie: "items-changed" may be emitted).

Items_Changed

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

Parameters

Self

Position

the position of the change

Removed

the number of items removed

Added

the number of items added

Iterate_Item_Attributes

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

Parameters

Self

Item_Index

the index of the item

Return Value

a new Glib.Menu_Model.Gmenu_Attribute_Iter. Has transfer-ownership='full'.

Iterate_Item_Links

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

Parameters

Self

Item_Index

the index of the item

Return Value

a new Glib.Menu_Model.Gmenu_Link_Iter. Has transfer-ownership='full'.

Next

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

Parameters

Self

Return Value

True on success, or False when there are no more attributes

Next

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

Parameters

Self

Return Value

True on success, or False when there are no more links

On_Items_Changed

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

Parameters

Self

Call

After

On_Items_Changed

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

Parameters

Self

Call

Slot

After

Signal_Items_Changed

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