class: MenuModel

[88:7] extends: object

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 GMenuModels. 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 [iface@Gio.ActionGroup] and [class@Gio.MenuModel]. The client-side counterparts to make use of the exported information are [class@Gio.DBusActionGroup] and [class@Gio.DBusMenuModel]. The API of GMenuModel is very generic, with iterators for the attributes and links of an item, see [method@Gio.MenuModel.iterate_item_attributes] and [method@Gio.MenuModel.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.

Members

• handleObj
• lib
• retainedCallbacks
• signalHandlerNames
• signalSetterHandlers

Methods

• MenuModel (Handle = null)

  Creates a new MenuModel by wrapping a native handle or another wrapper.

  • @p Handle is the native handle or another wrapper whose handle to adopt.

• toNativeHandle (Source)

  Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from fn.call(...), another generated wrapper exposing handle(), or null. Returns null when the argument carries no pointer.

  • @p Source is the raw handle, raw buffer, wrapper, or null.
  • @r A raw pointer carrier or null when no pointer is present.

• getLib ()

  Returns the opened native library for this generated wrapper.

  • @r The opened native library.

• handle ()

  Returns the wrapped NativeHandle.

  • @r The wrapped NativeHandle.

• isNull ()

  Returns true when the wrapped handle is null.

  • @r A bool.

• describe ()

  Returns a small string for debugging generated wrappers.

  • @r A string.

• asObject ()

  Wraps this handle as Object.

  • @r A Object object.

• connectSignal (string Name, CallbackObj)

  Connects one generated callback wrapper to a named signal.

  • @p Name is the signal name.
  • @p CallbackObj is the generated callback wrapper to connect.
  • @r The connected handler id.

• disconnectSignalHandler (int HandlerId)

  Disconnects one retained signal handler id.

  • @p HandlerId is the signal handler id to disconnect.
  • @r None.

• setOnItemschanged (callback Fn, UserData = null)

  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.

  • @p Fn is the Aussom callback.
  • @p Fn is called with (MenuModel Self, int Position, int Removed, int Added).
  • @p UserData is retained and passed through to the generated callback wrapper when provided.
  • @r The connected handler id.

• get_item_attribute_value (int item_index, string attribute, object expected_type)

  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.

  • @p item_index is the index of the item.
  • @p attribute is the attribute to query.
  • @p expected_type is the expected type of the attribute, or %NULL.

• get_item_link (int item_index, string link)

  Queries the item at position @item_index in @model for the link specified by @link. If the link exists, the linked #GMenuModel is returned. If the link does not exist, %NULL is returned.

  • @p item_index is the index of the item.
  • @p link is the link to query.

• get_n_items ()

  Query the number of items in @model.

• is_mutable ()

  Queries if @model is mutable. An immutable #GMenuModel will never emit the #GMenuModel::items-changed signal. Consumers of the model may make optimisations accordingly.

• items_changed (int position, int removed, int added)

  Requests emission of the #GMenuModel::items-changed signal on @model. This function should never be called except by #GMenuModel 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 #GMenuModel API. Said another way: the menu must not change while user code is running without returning to the mainloop.

  • @p position is the position of the change.
  • @p removed is the number of items removed.
  • @p added is the number of items added.
  • @r None.

• iterate_item_attributes (int item_index)

  Creates a #GMenuAttributeIter 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.

  • @p item_index is the index of the item.

• iterate_item_links (int item_index)

  Creates a #GMenuLinkIter 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.

  • @p item_index is the index of the item.

class: MenuModelMeta

[410:14] static extends: object

Generated metadata helpers for MenuModel class surfaces.

Methods

• signals ()

  Returns signal metadata for MenuModel.

  • @r A list.

class: MenuModelItemschangedCallback

[340:7] extends: object

Generated low-level callback wrapper for GIR callback items-changed.

Members

• callbackObj
• userFn
• userData
• hasUserData

Methods

• MenuModelItemschangedCallback (callback Fn, UserData = null)

  Creates one native callback wrapper. The wrapper owns a trampoline that converts native pointers into generated wrapper objects before invoking Fn.

  • @p Fn is the Aussom callback implementation.
  • @p UserData is retained and passed through to Fn on each invocation when provided.

• trampoline (nativeSelf, position, removed, added, nativeUserData)

  Internal trampoline. Converts native pointer arguments into generated wrapper instances, then invokes the user's callback.

• callback ()

  Returns the wrapped NativeCallback.

• handle ()

  Returns the callback as a NativeHandle.

• close ()

  Closes the underlying NativeCallback.

• isClosed ()

  Returns true when the callback has been closed.