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Functions
Known Implementations
GActionGroup is implemented by GApplication, GDBusActionGroup and GSimpleActionGroup.
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.
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.
Parameters
action_group |
||
action_name |
the name of an action in the group |
|
enabled |
if the action is presently enabled. |
[out] |
parameter_type |
the parameter type, or |
[out][allow-none] |
state_type |
the state type, or |
[out][allow-none] |
state_hint |
the state hint, or |
[out][allow-none] |
state |
the current state, or |
[out][allow-none] |
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
.
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.
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.
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.
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.
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.
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.
Parameters
action_group |
||
action_name |
the name of the action to request the change on |
|
value |
the new state |
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().
Parameters
action_group |
||
action_name |
the name of the action to activate |
|
parameter |
parameters to the activation. |
[allow-none] |
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.
Parameters
action_group |
||
action_name |
the name of an action in the group |
|
enabled |
whether or not the action is now enabled |
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.
Parameters
action_group |
||
action_name |
the name of an action in the group |
|
state |
the new state of the named action |
Since 2.28
Types and Values
GActionGroup
typedef struct _GActionGroup GActionGroup;
GActionGroup is an opaque data structure and can only be accessed using the following functions.
struct GActionGroupInterface
struct GActionGroupInterface {
GTypeInterface g_iface;
/* virtual functions */
gboolean (* has_action) (GActionGroup *action_group,
const gchar *action_name);
gchar ** (* list_actions) (GActionGroup *action_group);
gboolean (* get_action_enabled) (GActionGroup *action_group,
const gchar *action_name);
const GVariantType * (* get_action_parameter_type) (GActionGroup *action_group,
const gchar *action_name);
const GVariantType * (* get_action_state_type) (GActionGroup *action_group,
const gchar *action_name);
GVariant * (* get_action_state_hint) (GActionGroup *action_group,
const gchar *action_name);
GVariant * (* get_action_state) (GActionGroup *action_group,
const gchar *action_name);
void (* change_action_state) (GActionGroup *action_group,
const gchar *action_name,
GVariant *value);
void (* activate_action) (GActionGroup *action_group,
const gchar *action_name,
GVariant *parameter);
/* signals */
void (* action_added) (GActionGroup *action_group,
const gchar *action_name);
void (* action_removed) (GActionGroup *action_group,
const gchar *action_name);
void (* action_enabled_changed) (GActionGroup *action_group,
const gchar *action_name,
gboolean enabled);
void (* action_state_changed) (GActionGroup *action_group,
const gchar *action_name,
GVariant *state);
/* more virtual functions */
gboolean (* query_action) (GActionGroup *action_group,
const gchar *action_name,
gboolean *enabled,
const GVariantType **parameter_type,
const GVariantType **state_type,
GVariant **state_hint,
GVariant **state);
};
The virtual function table for GActionGroup.
Members
GTypeInterface |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the virtual function pointer for |
||
the class closure for the “action-added” signal |
||
the class closure for the “action-removed” signal |
||
the class closure for the “action-enabled-changed” signal |
||
the class closure for the “action-enabled-changed” signal |
||
the virtual function pointer for |
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.
Parameters
action_group |
the GActionGroup that changed |
|
action_name |
the name of the action in |
|
user_data |
user data set when the signal handler was connected. |
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.
Parameters
action_group |
the GActionGroup that changed |
|
action_name |
the name of the action in |
|
enabled |
whether the action is enabled or not |
|
user_data |
user data set when the signal handler was connected. |
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.
Parameters
action_group |
the GActionGroup that changed |
|
action_name |
the name of the action in |
|
user_data |
user data set when the signal handler was connected. |
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.
Parameters
action_group |
the GActionGroup that changed |
|
action_name |
the name of the action in |
|
value |
the new value of the state |
|
user_data |
user data set when the signal handler was connected. |
Flags: Has Details
Since 2.28