GAction

GAction — An action interface

Properties

Types and Values

Object Hierarchy

    GInterface
    ╰── GAction

Prerequisites

GAction requires GObject.

Known Implementations

GAction is implemented by GPropertyAction and GSimpleAction.

Includes

#include <gio/gio.h>

Description

GAction represents a single named action.

The main interface to an action is that it can be activated with g_action_activate(). This results in the 'activate' signal being emitted. An activation has a GVariant parameter (which may be NULL). The correct type for the parameter is determined by a static parameter type (which is given at construction time).

An action may optionally have a state, in which case the state may be set with g_action_change_state(). This call takes a GVariant. The correct type for the state is determined by a static state type (which is given at construction time).

The state may have a hint associated with it, specifying its valid range.

GAction is merely the interface to the concept of an action, as described above. Various implementations of actions exist, including GSimpleAction.

In all cases, the implementing class is responsible for storing the name of the action, the parameter type, the enabled state, the optional state type and the state and emitting the appropriate signals when these change. The implementor is responsible for filtering calls to g_action_activate() and g_action_change_state() for type safety and for the state being enabled.

Probably the only useful thing to do with a GAction is to put it inside of a GSimpleActionGroup.

Functions

g_action_name_is_valid ()

gboolean
g_action_name_is_valid (const gchar *action_name);

Checks if action_name is valid.

action_name is valid if it consists only of alphanumeric characters, plus '-' and '.'. The empty string is not a valid action name.

It is an error to call this function with a non-utf8 action_name . action_name must not be NULL.

Parameters

action_name

an potential action name

 

Returns

TRUE if action_name is valid

Since: 2.38


g_action_get_name ()

const gchar *
g_action_get_name (GAction *action);

Queries the name of action .

Parameters

action

a GAction

 

Returns

the name of the action

Since: 2.28


g_action_get_parameter_type ()

const GVariantType *
g_action_get_parameter_type (GAction *action);

Queries the type of the parameter that must be given when activating action .

When activating the action using g_action_activate(), 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.

Parameters

action

a GAction

 

Returns

the parameter type.

[nullable]

Since: 2.28


g_action_get_state_type ()

const GVariantType *
g_action_get_state_type (GAction *action);

Queries the type of the state of action .

If the action is stateful (e.g. created with g_simple_action_new_stateful()) then this function returns the GVariantType of the state. This is the type of the initial value given as the state. All calls to g_action_change_state() must give a GVariant of this type and g_action_get_state() will return a GVariant of the same type.

If the action is not stateful (e.g. created with g_simple_action_new()) then this function will return NULL. In that case, g_action_get_state() will return NULL and you must not call g_action_change_state().

Parameters

action

a GAction

 

Returns

the state type, if the action is stateful.

[nullable]

Since: 2.28


g_action_get_state_hint ()

GVariant *
g_action_get_state_hint (GAction *action);

Requests a hint about the valid range of values for the state of action .

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.

Parameters

action

a GAction

 

Returns

the state range hint.

[nullable][transfer full]

Since: 2.28


g_action_get_enabled ()

gboolean
g_action_get_enabled (GAction *action);

Checks if action is currently enabled.

An action must be enabled in order to be activated or in order to have its state changed from outside callers.

Parameters

action

a GAction

 

Returns

whether the action is enabled

Since: 2.28


g_action_get_state ()

GVariant *
g_action_get_state (GAction *action);

Queries the current state of action .

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_get_state_type().

The return value (if non-NULL) should be freed with g_variant_unref() when it is no longer required.

Parameters

action

a GAction

 

Returns

the current state of the action.

[transfer full]

Since: 2.28


g_action_change_state ()

void
g_action_change_state (GAction *action,
                       GVariant *value);

Request for the state of action to be changed to value .

The action must be stateful and value must be of the correct type. See g_action_get_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_get_state_hint().

If the value GVariant is floating, it is consumed.

Parameters

action

a GAction

 

value

the new state

 

Since: 2.30


g_action_activate ()

void
g_action_activate (GAction *action,
                   GVariant *parameter);

Activates the action.

parameter must be the correct type of parameter for the action (ie: the parameter type given at construction time). If the parameter type was NULL then parameter must also be NULL.

If the parameter GVariant is floating, it is consumed.

Parameters

action

a GAction

 

parameter

the parameter to the activation.

[nullable]

Since: 2.28


g_action_parse_detailed_name ()

gboolean
g_action_parse_detailed_name (const gchar *detailed_name,
                              gchar **action_name,
                              GVariant **target_value,
                              GError **error);

Parses a detailed action name into its separate name and target components.

Detailed action names can have three formats.

The first format is used to represent an action name with no target value and consists of just an action name containing no whitespace nor the characters ':', '(' or ')'. For example: "app.action".

The second format is used to represent an action with a target value that is a non-empty string consisting only of alphanumerics, plus '-' and '.'. In that case, the action name and target value are separated by a double colon ("::"). For example: "app.action::target".

The third format is used to represent an action with any type of target value, including strings. The target value follows the action name, surrounded in parens. For example: "app.action(42)". The target value is parsed using g_variant_parse(). If a tuple-typed value is desired, it must be specified in the same way, resulting in two sets of parens, for example: "app.action((1,2,3))". A string target can be specified this way as well: "app.action('target')". For strings, this third format must be used if * target value is empty or contains characters other than alphanumerics, '-' and '.'.

Parameters

detailed_name

a detailed action name

 

action_name

the action name.

[out]

target_value

the target value, or NULL for no target.

[out]

error

a pointer to a NULL GError, or NULL

 

Returns

TRUE if successful, else FALSE with error set

Since: 2.38


g_action_print_detailed_name ()

gchar *
g_action_print_detailed_name (const gchar *action_name,
                              GVariant *target_value);

Formats a detailed action name from action_name and target_value .

It is an error to call this function with an invalid action name.

This function is the opposite of g_action_parse_detailed_name(). It will produce a string that can be parsed back to the action_name and target_value by that function.

See that function for the types of strings that will be printed by this function.

Parameters

action_name

a valid action name

 

target_value

a GVariant target value, or NULL.

[nullable]

Returns

a detailed format string

Since: 2.38

Types and Values

GAction

typedef struct _GAction GAction;

GAction is an opaque data structure and can only be accessed using the following functions.


struct GActionInterface

struct GActionInterface {
  GTypeInterface g_iface;

  /* virtual functions */
  const gchar *        (* get_name)             (GAction  *action);
  const GVariantType * (* get_parameter_type)   (GAction  *action);
  const GVariantType * (* get_state_type)       (GAction  *action);
  GVariant *           (* get_state_hint)       (GAction  *action);

  gboolean             (* get_enabled)          (GAction  *action);
  GVariant *           (* get_state)            (GAction  *action);

  void                 (* change_state)         (GAction  *action,
                                                 GVariant *value);
  void                 (* activate)             (GAction  *action,
                                                 GVariant *parameter);
};

The virtual function table for GAction.

Members

get_name ()

the virtual function pointer for g_action_get_name()

 

get_parameter_type ()

the virtual function pointer for g_action_get_parameter_type()

 

get_state_type ()

the virtual function pointer for g_action_get_state_type()

 

get_state_hint ()

the virtual function pointer for g_action_get_state_hint()

 

get_enabled ()

the virtual function pointer for g_action_get_enabled()

 

get_state ()

the virtual function pointer for g_action_get_state()

 

change_state ()

the virtual function pointer for g_action_change_state()

 

activate ()

the virtual function pointer for g_action_activate(). Note that GAction does not have an 'activate' signal but that implementations of it may have one.

 

Since: 2.28

Property Details

The “enabled” property

  “enabled”                  gboolean

If action is currently enabled.

If the action is disabled then calls to g_action_activate() and g_action_change_state() have no effect.

Flags: Read

Default value: TRUE

Since: 2.28


The “name” property

  “name”                     gchar *

The name of the action. This is mostly meaningful for identifying the action once it has been added to a GActionGroup. It is immutable.

Flags: Read

Default value: NULL

Since: 2.28


The “parameter-type” property

  “parameter-type”           GVariantType *

The type of the parameter that must be given when activating the action. This is immutable, and may be NULL if no parameter is needed when activating the action.

Flags: Read

Since: 2.28


The “state” property

  “state”                    GVariant *

The state of the action, or NULL if the action is stateless.

Flags: Read

Allowed values: GVariant<*>

Default value: NULL

Since: 2.28


The “state-type” property

  “state-type”               GVariantType *

The GVariantType of the state that the action has, or NULL if the action is stateless. This is immutable.

Flags: Read

Since: 2.28