Module: Gio::Action

Defined in:
lib/gio2/action.rb

Overview

GAction represents a single named action.

The main interface to an action is that it can be activated with
[methodGio.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 [methodGio.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
[classGio.SimpleAction].

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
[methodGio.Action.activate] and [methodGio.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 [classGio.SimpleActionGroup].

Instance Method Summary collapse

Instance Method Details

#activate(parameter = nil) ⇒ nil

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 nil then parameter must also be nil.

If the parameter GVariant is floating, it is consumed.

Parameters:

  • parameter (GLib::Variant) (defaults to: nil) —

    the parameter to the activation

Returns:

  • (nil) 


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# File 'lib/gio2/action.rb', line 20

def activate(parameter=nil)
  case parameter
  when nil, GLib::Variant
    # do nothing
  else
    parameter = GLib::Variant.new(parameter)
  end
  activate_raw(parameter)
end

#activate_raw ⇒ nil

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 nil then parameter must also be nil.

If the parameter GVariant is floating, it is consumed.

Parameters:

  • parameter (GLib::Variant) —

    the parameter to the activation

Returns:

  • (nil) 



# File 'lib/gio2/action.rb', line 19

#change_state(value) ⇒ nil

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:

  • value (GLib::Variant) —

    the new state

Returns:

  • (nil) 


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# File 'lib/gio2/action.rb', line 31

def change_state(value)
  case value
  when GLib::Variant
    # do nothing
  else
    value = GLib::Variant.new(value, state_type)
  end
  change_state_raw(value)
end

#change_state_raw ⇒ nil

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:

  • value (GLib::Variant) —

    the new state

Returns:

  • (nil) 



# File 'lib/gio2/action.rb', line 30

#enabled ⇒ Boolean

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.

Returns:

  • (Boolean) —

    whether the action is enabled

#name ⇒ String

Queries the name of action.

Returns:

  • (String) —

    the name of the action

#parameter_type ⇒ GLib::VariantType

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 nil, you must not give any
#GVariant, but nil instead.

Returns:

  • (GLib::VariantType) —

    the parameter type

#state ⇒ GLib::Variant

Queries the current state of action.

If the action is not stateful then nil 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-nil) should be freed with
g_variant_unref() when it is no longer required.

Returns:

  • (GLib::Variant) —

    the current state of the action

#state_hint ⇒ GLib::Variant

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

If nil 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-nil) should be freed with
g_variant_unref() when it is no longer required.

Returns:

  • (GLib::Variant) —

    the state range hint

#state_type ⇒ GLib::VariantType

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
GVariant::Type 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 nil. In that case, g_action_get_state()
will return nil and you must not call g_action_change_state().

Returns:

  • (GLib::VariantType) —

    the state type, if the action is stateful