Gio.MenuModel
Description: Reference for Gio.MenuModel

### Class

# GioMenuModel

since: 2.32

#### Description [src]

    abstract class Gio.MenuModel : GObject.Object
    {
      GMenuModelPrivate* priv
    }

`GMenuModel` 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 `GMenuModel` is hierarchical: sections and submenus are again represented by `GMenuModel`s. Menus themselves do not define their own roles. Rather, the role of a particular `GMenuModel` 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

While this kind of deeply nested menu is no longer considered good UI practice, it serves as a good example of the concepts in `GMenuModel`. 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 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

Notice that the separators visible in the example appear nowhere in the 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 action group exporter and the menu model exporter do for `GActionGroup` and `GMenuModel`. The client-side counterparts to make use of the exported information are `GDBusActionGroup` and `GDBusMenuModel`.

The API of `GMenuModel` is very generic, with iterators for the attributes and links of an item, see `g_menu_model_iterate_item_attributes()` and `g_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 `GMenuModel` 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 `GtkApplication`, 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.

Available since: 2.32

#### Hierarchy

#### Ancestors

- GObject

#### Descendants

- GDBusMenuModel
- GMenu

#### Instance methods

###### g_menu_model_get_item_attribute

Queries item at position `item_index` in `model` for the attribute specified by `attribute`.

since: 2.32

###### g_menu_model_get_item_attribute_value

Queries the item at position `item_index` in `model` for the attribute specified by `attribute`.

since: 2.32

###### g_menu_model_get_item_link

Queries the item at position `item_index` in `model` for the link specified by `link`.

since: 2.32

###### g_menu_model_get_n_items

Query the number of items in `model`.

since: 2.32

###### g_menu_model_is_mutable

Queries if `model` is mutable.

since: 2.32

###### g_menu_model_items_changed

Requests emission of the `GMenuModel::items-changed` signal on `model`.

since: 2.32

###### g_menu_model_iterate_item_attributes

Creates a `GMenuAttributeIter` to iterate over the attributes of the item at position `item_index` in `model`.

since: 2.32

###### g_menu_model_iterate_item_links

Creates a `GMenuLinkIter` to iterate over the links of the item at position `item_index` in `model`.

since: 2.32

##### Methods inherited from GObject (43)

Please see GObject for a full list of methods.

#### Signals

###### Gio.MenuModel::items-changed

Emitted when a change has occurred to the menu.

##### Signals inherited from GObject (1)

###### GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

#### Class structure

    struct GioMenuModelClass {
      GObjectClass parent_class;
      gboolean (* is_mutable) (
        GMenuModel* model
      );
      gint (* get_n_items) (
        GMenuModel* model
      );
      void (* get_item_attributes) (
        GMenuModel* model,
        gint item_index,
        GHashTable** attributes
      );
      GMenuAttributeIter* (* iterate_item_attributes) (
        GMenuModel* model,
        gint item_index
      );
      GVariant* (* get_item_attribute_value) (
        GMenuModel* model,
        gint item_index,
        const gchar* attribute,
        const GVariantType* expected_type
      );
      void (* get_item_links) (
        GMenuModel* model,
        gint item_index,
        GHashTable** links
      );
      GMenuLinkIter* (* iterate_item_links) (
        GMenuModel* model,
        gint item_index
      );
      GMenuModel* (* get_item_link) (
        GMenuModel* model,
        gint item_index,
        const gchar* link
      );

    }

No description available.

###### Class members

`parent_class: GObjectClass`

  No description available.

`is_mutable: gboolean (* is_mutable) ( GMenuModel* model )`

  No description available.

`get_n_items: gint (* get_n_items) ( GMenuModel* model )`

  No description available.

`get_item_attributes: void (* get_item_attributes) ( GMenuModel* model, gint item_index, GHashTable** attributes )`

  No description available.

`iterate_item_attributes: GMenuAttributeIter* (* iterate_item_attributes) ( GMenuModel* model, gint item_index )`

  No description available.

`get_item_attribute_value: GVariant* (* get_item_attribute_value) ( GMenuModel* model, gint item_index, const gchar* attribute, const GVariantType* expected_type )`

  No description available.

`get_item_links: void (* get_item_links) ( GMenuModel* model, gint item_index, GHashTable** links )`

  No description available.

`iterate_item_links: GMenuLinkIter* (* iterate_item_links) ( GMenuModel* model, gint item_index )`

  No description available.

`get_item_link: GMenuModel* (* get_item_link) ( GMenuModel* model, gint item_index, const gchar* link )`

  No description available.

#### Virtual methods

###### Gio.MenuModelClass.get_item_attribute_value

Queries the item at position `item_index` in `model` for the attribute specified by `attribute`.

since: 2.32

###### Gio.MenuModelClass.get_item_attributes

Gets all the attributes associated with the item in the menu model.

###### Gio.MenuModelClass.get_item_link

Queries the item at position `item_index` in `model` for the link specified by `link`.

since: 2.32

###### Gio.MenuModelClass.get_item_links

Gets all the links associated with the item in the menu model.

###### Gio.MenuModelClass.get_n_items

Query the number of items in `model`.

since: 2.32

###### Gio.MenuModelClass.is_mutable

Queries if `model` is mutable.

since: 2.32

###### Gio.MenuModelClass.iterate_item_attributes

Creates a `GMenuAttributeIter` to iterate over the attributes of the item at position `item_index` in `model`.

since: 2.32

###### Gio.MenuModelClass.iterate_item_links

Creates a `GMenuLinkIter` to iterate over the links of the item at position `item_index` in `model`.

since: 2.32