Description
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

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 GActionGroup exporter
and the GMenuModel 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.
Functions
g_menu_model_is_mutable ()
gboolean
g_menu_model_is_mutable (GMenuModel *model);
Queries if model
is mutable.
An immutable GMenuModel will never emit the “items-changed”
signal. Consumers of the model may make optimisations accordingly.
Returns
TRUE if the model is mutable (ie: "items-changed" may be
emitted).
Since: 2.32
g_menu_model_get_n_items ()
gint
g_menu_model_get_n_items (GMenuModel *model);
Query the number of items in model
.
Returns
the number of items
Since: 2.32
g_menu_model_get_item_attribute_value ()
GVariant *
g_menu_model_get_item_attribute_value (GMenuModel *model,
gint item_index,
const gchar *attribute,
const GVariantType *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.
Returns
the value of the attribute.
[transfer full]
Since: 2.32
g_menu_model_get_item_attribute ()
gboolean
g_menu_model_get_item_attribute (GMenuModel *model,
gint item_index,
const gchar *attribute,
const gchar *format_string,
...);
Queries item at position item_index
in model
for the attribute
specified by attribute
.
If the attribute exists and matches the GVariantType corresponding
to format_string
then format_string
is used to deconstruct the
value into the positional parameters and TRUE is returned.
If the attribute does not exist, or it does exist but has the wrong
type, then the positional parameters are ignored and FALSE is
returned.
This function is a mix of g_menu_model_get_item_attribute_value() and
g_variant_get(), followed by a g_variant_unref(). As such,
format_string
must make a complete copy of the data (since the
GVariant may go away after the call to g_variant_unref()). In
particular, no '&' characters are allowed in format_string
.
Returns
TRUE if the named attribute was found with the expected
type
Since: 2.32
g_menu_model_get_item_link ()
GMenuModel *
g_menu_model_get_item_link (GMenuModel *model,
gint item_index,
const gchar *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.
Returns
the linked GMenuModel, or NULL.
[transfer full]
Since: 2.32
g_menu_model_iterate_item_attributes ()
GMenuAttributeIter *
g_menu_model_iterate_item_attributes (GMenuModel *model,
gint 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.
Since: 2.32
g_menu_model_iterate_item_links ()
GMenuLinkIter *
g_menu_model_iterate_item_links (GMenuModel *model,
gint 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.
Since: 2.32
g_menu_model_items_changed ()
void
g_menu_model_items_changed (GMenuModel *model,
gint position,
gint removed,
gint added);
Requests emission of the “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.
Since: 2.32
g_menu_attribute_iter_get_next ()
gboolean
g_menu_attribute_iter_get_next (GMenuAttributeIter *iter,
const gchar **out_name,
GVariant **value);
This function combines g_menu_attribute_iter_next() with
g_menu_attribute_iter_get_name() and g_menu_attribute_iter_get_value().
First the iterator is advanced to the next (possibly first) attribute.
If that fails, then FALSE is returned and there are no other
effects.
If successful, name
and value
are set to the name and value of the
attribute that has just been advanced to. At this point,
g_menu_attribute_iter_get_name() and g_menu_attribute_iter_get_value() will
return the same values again.
The value returned in name
remains valid for as long as the iterator
remains at the current position. The value returned in value
must
be unreffed using g_variant_unref() when it is no longer in use.
Returns
TRUE on success, or FALSE if there is no additional
attribute
Since: 2.32
g_menu_attribute_iter_get_name ()
const gchar *
g_menu_attribute_iter_get_name (GMenuAttributeIter *iter);
Gets the name of the attribute at the current iterator position, as
a string.
The iterator is not advanced.
Returns
the name of the attribute
Since: 2.32
g_menu_attribute_iter_get_value ()
GVariant *
g_menu_attribute_iter_get_value (GMenuAttributeIter *iter);
Gets the value of the attribute at the current iterator position.
The iterator is not advanced.
Returns
the value of the current attribute.
[transfer full]
Since: 2.32
g_menu_attribute_iter_next ()
gboolean
g_menu_attribute_iter_next (GMenuAttributeIter *iter);
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).
Returns
TRUE on success, or FALSE when there are no more attributes
Since: 2.32
g_menu_link_iter_get_name ()
const gchar *
g_menu_link_iter_get_name (GMenuLinkIter *iter);
Gets the name of the link at the current iterator position.
The iterator is not advanced.
Returns
the type of the link
Since: 2.32
g_menu_link_iter_get_next ()
gboolean
g_menu_link_iter_get_next (GMenuLinkIter *iter,
const gchar **out_link,
GMenuModel **value);
This function combines g_menu_link_iter_next() with
g_menu_link_iter_get_name() and g_menu_link_iter_get_value().
First the iterator is advanced to the next (possibly first) link.
If that fails, then FALSE is returned and there are no other effects.
If successful, out_link
and value
are set to the name and GMenuModel
of the link that has just been advanced to. At this point,
g_menu_link_iter_get_name() and g_menu_link_iter_get_value() will return the
same values again.
The value returned in out_link
remains valid for as long as the iterator
remains at the current position. The value returned in value
must
be unreffed using g_object_unref() when it is no longer in use.
Returns
TRUE on success, or FALSE if there is no additional link
Since: 2.32
g_menu_link_iter_get_value ()
GMenuModel *
g_menu_link_iter_get_value (GMenuLinkIter *iter);
Gets the linked GMenuModel at the current iterator position.
The iterator is not advanced.
Returns
the GMenuModel that is linked to.
[transfer full]
Since: 2.32
g_menu_link_iter_next ()
gboolean
g_menu_link_iter_next (GMenuLinkIter *iter);
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).
Returns
TRUE on success, or FALSE when there are no more links
Since: 2.32
Types and Values
GMenuModel
typedef struct _GMenuModel GMenuModel;
GMenuModel is an opaque structure type. You must access it using the
functions below.
Since: 2.32
G_MENU_ATTRIBUTE_ACTION
#define G_MENU_ATTRIBUTE_ACTION "action"
The menu item attribute which holds the action name of the item. Action
names are namespaced with an identifier for the action group in which the
action resides. For example, "win." for window-specific actions and "app."
for application-wide actions.
See also g_menu_model_get_item_attribute() and g_menu_item_set_attribute().
Since: 2.32
G_MENU_ATTRIBUTE_ACTION_NAMESPACE
#define G_MENU_ATTRIBUTE_ACTION_NAMESPACE "action-namespace"
The menu item attribute that holds the namespace for all action names in
menus that are linked from this item.
Since: 2.36
G_MENU_ATTRIBUTE_TARGET
#define G_MENU_ATTRIBUTE_TARGET "target"
The menu item attribute which holds the target with which the item's action
will be activated.
See also g_menu_item_set_action_and_target()
Since: 2.32
G_MENU_ATTRIBUTE_LABEL
#define G_MENU_ATTRIBUTE_LABEL "label"
The menu item attribute which holds the label of the item.
Since: 2.32
G_MENU_ATTRIBUTE_ICON
#define G_MENU_ATTRIBUTE_ICON "icon"
The menu item attribute which holds the icon of the item.
The icon is stored in the format returned by g_icon_serialize().
This attribute is intended only to represent 'noun' icons such as
favicons for a webpage, or application icons. It should not be used
for 'verbs' (ie: stock icons).
Since: 2.38
G_MENU_LINK_SECTION
#define G_MENU_LINK_SECTION "section"
The name of the link that associates a menu item with a section. The linked
menu will usually be shown in place of the menu item, using the item's label
as a header.
See also g_menu_item_set_link().
Since: 2.32
G_MENU_LINK_SUBMENU
#define G_MENU_LINK_SUBMENU "submenu"
The name of the link that associates a menu item with a submenu.
See also g_menu_item_set_link().
Since: 2.32
struct GMenuAttributeIter
struct GMenuAttributeIter;
GMenuAttributeIter is an opaque structure type. You must access it
using the functions below.
Since: 2.32
struct GMenuLinkIter
struct GMenuLinkIter;
GMenuLinkIter is an opaque structure type. You must access it using
the functions below.
Since: 2.32
Signal Details
The “items-changed” signal
void
user_function (GMenuModel *model,
gint position,
gint removed,
gint added,
gpointer user_data)
Emitted when a change has occured 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.
Flags: Run Last