Description
GActionGroup represents a group of actions. Actions can be used to
expose functionality in a structured way, either from one part of a
program to another, or to the outside world. Action groups are often
used together with a GMenuModel that provides additional
representation data for displaying the actions to the user, e.g. in
a menu.
The main way to interact with the actions in a GActionGroup is to
activate them with g_action_group_activate_action(). Activating an
action may require a GVariant parameter. The required type of the
parameter can be inquired with g_action_group_get_action_parameter_type().
Actions may be disabled, see g_action_group_get_action_enabled().
Activating a disabled action has no effect.
Actions may optionally have a state in the form of a GVariant. The
current state of an action can be inquired with
g_action_group_get_action_state(). Activating a stateful action may
change its state, but it is also possible to set the state by calling
g_action_group_change_action_state().
As typical example, consider a text editing application which has an
option to change the current font to 'bold'. A good way to represent
this would be a stateful action, with a boolean state. Activating the
action would toggle the state.
Each action in the group has a unique name (which is a string). All
method calls, except g_action_group_list_actions() take the name of
an action as an argument.
The GActionGroup API is meant to be the 'public' API to the action
group. The calls here are exactly the interaction that 'external
forces' (eg: UI, incoming D-Bus messages, etc.) are supposed to have
with actions. 'Internal' APIs (ie: ones meant only to be accessed by
the action group implementation) are found on subclasses. This is
why you will find - for example - g_action_group_get_action_enabled()
but not an equivalent set() call.
Signals are emitted on the action group in response to state changes
on individual actions.
Implementations of GActionGroup should provide implementations for
the virtual functions g_action_group_list_actions() and
g_action_group_query_action(). The other virtual functions should
not be implemented - their "wrappers" are actually implemented with
calls to g_action_group_query_action().
Functions
g_action_group_list_actions ()
gchar **
g_action_group_list_actions (GActionGroup *action_group);
Lists the actions contained within action_group
.
The caller is responsible for freeing the list with g_strfreev() when
it is no longer required.
Returns
a NULL-terminated array of the names of the
actions in the group.
[transfer full]
Since: 2.28
g_action_group_query_action ()
gboolean
g_action_group_query_action (GActionGroup *action_group,
const gchar *action_name,
gboolean *enabled,
const GVariantType **parameter_type,
const GVariantType **state_type,
GVariant **state_hint,
GVariant **state);
Queries all aspects of the named action within an action_group
.
This function acquires the information available from
g_action_group_has_action(), g_action_group_get_action_enabled(),
g_action_group_get_action_parameter_type(),
g_action_group_get_action_state_type(),
g_action_group_get_action_state_hint() and
g_action_group_get_action_state() with a single function call.
This provides two main benefits.
The first is the improvement in efficiency that comes with not having
to perform repeated lookups of the action in order to discover
different things about it. The second is that implementing
GActionGroup can now be done by only overriding this one virtual
function.
The interface provides a default implementation of this function that
calls the individual functions, as required, to fetch the
information. The interface also provides default implementations of
those functions that call this function. All implementations,
therefore, must override either this function or all of the others.
If the action exists, TRUE is returned and any of the requested
fields (as indicated by having a non-NULL reference passed in) are
filled. If the action doesn't exist, FALSE is returned and the
fields may or may not have been modified.
Returns
TRUE if the action exists, else FALSE
Since: 2.32
g_action_group_has_action ()
gboolean
g_action_group_has_action (GActionGroup *action_group,
const gchar *action_name);
Checks if the named action exists within action_group
.
Returns
whether the named action exists
Since: 2.28
g_action_group_get_action_enabled ()
gboolean
g_action_group_get_action_enabled (GActionGroup *action_group,
const gchar *action_name);
Checks if the named action within action_group
is currently enabled.
An action must be enabled in order to be activated or in order to
have its state changed from outside callers.
Returns
whether or not the action is currently enabled
Since: 2.28
g_action_group_get_action_parameter_type ()
const GVariantType *
g_action_group_get_action_parameter_type
(GActionGroup *action_group,
const gchar *action_name);
Queries the type of the parameter that must be given when activating
the named action within action_group
.
When activating the action using g_action_group_activate_action(),
the GVariant given to that function must be of the type returned
by this function.
In the case that this function returns NULL, you must not give any
GVariant, but NULL instead.
The parameter type of a particular action will never change but it is
possible for an action to be removed and for a new action to be added
with the same name but a different parameter type.
Returns
the parameter type.
[nullable]
Since: 2.28
g_action_group_get_action_state_type ()
const GVariantType *
g_action_group_get_action_state_type (GActionGroup *action_group,
const gchar *action_name);
Queries the type of the state of the named action within
action_group
.
If the action is stateful then this function returns the
GVariantType of the state. All calls to
g_action_group_change_action_state() must give a GVariant of this
type and g_action_group_get_action_state() will return a GVariant
of the same type.
If the action is not stateful then this function will return NULL.
In that case, g_action_group_get_action_state() will return NULL
and you must not call g_action_group_change_action_state().
The state type of a particular action will never change but it is
possible for an action to be removed and for a new action to be added
with the same name but a different state type.
Returns
the state type, if the action is stateful.
[nullable]
Since: 2.28
g_action_group_get_action_state_hint ()
GVariant *
g_action_group_get_action_state_hint (GActionGroup *action_group,
const gchar *action_name);
Requests a hint about the valid range of values for the state of the
named action within action_group
.
If NULL is returned it either means that the action is not stateful
or that there is no hint about the valid range of values for the
state of the action.
If a GVariant array is returned then each item in the array is a
possible value for the state. If a GVariant pair (ie: two-tuple) is
returned then the tuple specifies the inclusive lower and upper bound
of valid values for the state.
In any case, the information is merely a hint. It may be possible to
have a state value outside of the hinted range and setting a value
within the range may fail.
The return value (if non-NULL) should be freed with
g_variant_unref() when it is no longer required.
Returns
the state range hint.
[nullable][transfer full]
Since: 2.28
g_action_group_get_action_state ()
GVariant *
g_action_group_get_action_state (GActionGroup *action_group,
const gchar *action_name);
Queries the current state of the named action within action_group
.
If the action is not stateful then NULL will be returned. If the
action is stateful then the type of the return value is the type
given by g_action_group_get_action_state_type().
The return value (if non-NULL) should be freed with
g_variant_unref() when it is no longer required.
Returns
the current state of the action.
[nullable][transfer full]
Since: 2.28
g_action_group_change_action_state ()
void
g_action_group_change_action_state (GActionGroup *action_group,
const gchar *action_name,
GVariant *value);
Request for the state of the named action within action_group
to be
changed to value
.
The action must be stateful and value
must be of the correct type.
See g_action_group_get_action_state_type().
This call merely requests a change. The action may refuse to change
its state or may change its state to something other than value
.
See g_action_group_get_action_state_hint().
If the value
GVariant is floating, it is consumed.
Since: 2.28
g_action_group_activate_action ()
void
g_action_group_activate_action (GActionGroup *action_group,
const gchar *action_name,
GVariant *parameter);
Activate the named action within action_group
.
If the action is expecting a parameter, then the correct type of
parameter must be given as parameter
. If the action is expecting no
parameters then parameter
must be NULL. See
g_action_group_get_action_parameter_type().
Since: 2.28
g_action_group_action_added ()
void
g_action_group_action_added (GActionGroup *action_group,
const gchar *action_name);
Emits the “action-added” signal on action_group
.
This function should only be called by GActionGroup implementations.
Since: 2.28
g_action_group_action_removed ()
void
g_action_group_action_removed (GActionGroup *action_group,
const gchar *action_name);
Emits the “action-removed” signal on action_group
.
This function should only be called by GActionGroup implementations.
Since: 2.28
g_action_group_action_enabled_changed ()
void
g_action_group_action_enabled_changed (GActionGroup *action_group,
const gchar *action_name,
gboolean enabled);
Emits the “action-enabled-changed” signal on action_group
.
This function should only be called by GActionGroup implementations.
Since: 2.28
g_action_group_action_state_changed ()
void
g_action_group_action_state_changed (GActionGroup *action_group,
const gchar *action_name,
GVariant *state);
Emits the “action-state-changed” signal on action_group
.
This function should only be called by GActionGroup implementations.
Since: 2.28
Signal Details
The “action-added” signal
void
user_function (GActionGroup *action_group,
gchar *action_name,
gpointer user_data)
Signals that a new action was just added to the group.
This signal is emitted after the action has been added
and is now visible.
Flags: Has Details
Since: 2.28
The “action-enabled-changed” signal
void
user_function (GActionGroup *action_group,
gchar *action_name,
gboolean enabled,
gpointer user_data)
Signals that the enabled status of the named action has changed.
Flags: Has Details
Since: 2.28
The “action-removed” signal
void
user_function (GActionGroup *action_group,
gchar *action_name,
gpointer user_data)
Signals that an action is just about to be removed from the group.
This signal is emitted before the action is removed, so the action
is still visible and can be queried from the signal handler.
Flags: Has Details
Since: 2.28
The “action-state-changed” signal
void
user_function (GActionGroup *action_group,
gchar *action_name,
GVariant *value,
gpointer user_data)
Signals that the state of the named action has changed.
Flags: Has Details
Since: 2.28