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glib/gio/gaction.c
Matthias Clasen 33b775308b Document behaviour wrt. to floating variants
2010-08-21 19:18:17 -04:00

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/*
* Copyright © 2010 Codethink Limited
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2 of the licence or (at
* your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors: Ryan Lortie <desrt@desrt.ca>
*/
#include "config.h"
#include "gaction.h"
#include "glibintl.h"
G_DEFINE_TYPE (GAction, g_action, G_TYPE_OBJECT)
/**
* SECTION:gaction
* @title: GAction
* @short_description: an action
*
* #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_set_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 intended to be used both as a simple action class and as
* a base class for more complicated action types. The base class
* itself supports activation and state. Not supported are state hints
* and filtering requests to set the state based on the requested value.
* You should subclass if you require either of these abilities.
*
* In all cases, the base 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 base class is also responsbile for filtering calls to
* g_action_activate() and g_action_set_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.
**/
struct _GActionPrivate
{
gchar *name;
GVariantType *parameter_type;
guint enabled : 1;
guint state_set : 1;
GVariant *state;
};
enum
{
PROP_NONE,
PROP_NAME,
PROP_PARAMETER_TYPE,
PROP_ENABLED,
PROP_STATE_TYPE,
PROP_STATE
};
enum
{
SIGNAL_ACTIVATE,
NR_SIGNALS
};
static guint g_action_signals[NR_SIGNALS];
static void
g_action_real_set_state (GAction *action,
GVariant *value)
{
if (action->priv->state == value)
return;
if (!action->priv->state || !g_variant_equal (action->priv->state, value))
{
if (action->priv->state)
g_variant_unref (action->priv->state);
action->priv->state = g_variant_ref (value);
g_object_notify (G_OBJECT (action), "state");
}
}
static GVariant *
g_action_real_get_state_hint (GAction *action)
{
return NULL;
}
static void
g_action_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GAction *action = G_ACTION (object);
switch (prop_id)
{
case PROP_NAME:
g_assert (action->priv->name == NULL);
action->priv->name = g_value_dup_string (value);
break;
case PROP_PARAMETER_TYPE:
g_assert (action->priv->parameter_type == NULL);
action->priv->parameter_type = g_value_dup_boxed (value);
break;
case PROP_ENABLED:
g_action_set_enabled (action, g_value_get_boolean (value));
break;
case PROP_STATE:
/* PROP_STATE is marked as G_PARAM_CONSTRUCT so we always get a
* call during object construction, even if it is NULL. We treat
* that first call differently, for a number of reasons.
*
* First, we don't want the value to be rejected by the
* possibly-overridden .set_state() function. Second, we don't
* want to be tripped by the assertions in g_action_set_state()
* that would enforce the catch22 that we only provide a value of
* the same type as the existing value (when there is not yet an
* existing value).
*/
if (action->priv->state_set)
g_action_set_state (action, g_value_get_variant (value));
else /* this is the special case */
{
/* only do it the first time. */
action->priv->state_set = TRUE;
/* blindly set it. */
action->priv->state = g_value_dup_variant (value);
}
break;
default:
g_assert_not_reached ();
}
}
static void
g_action_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GAction *action = G_ACTION (object);
switch (prop_id)
{
case PROP_NAME:
g_value_set_string (value, g_action_get_name (action));
break;
case PROP_PARAMETER_TYPE:
g_value_set_boxed (value, g_action_get_parameter_type (action));
break;
case PROP_ENABLED:
g_value_set_boolean (value, g_action_get_enabled (action));
break;
case PROP_STATE_TYPE:
g_value_set_boxed (value, g_action_get_state_type (action));
break;
case PROP_STATE:
g_value_set_variant (value, g_action_get_state (action));
break;
default:
g_assert_not_reached ();
}
}
static void
g_action_finalize (GObject *object)
{
GAction *action = G_ACTION (object);
g_free (action->priv->name);
if (action->priv->parameter_type)
g_variant_type_free (action->priv->parameter_type);
if (action->priv->state)
g_variant_unref (action->priv->state);
G_OBJECT_CLASS (g_action_parent_class)
->finalize (object);
}
void
g_action_init (GAction *action)
{
action->priv = G_TYPE_INSTANCE_GET_PRIVATE (action,
G_TYPE_ACTION,
GActionPrivate);
}
void
g_action_class_init (GActionClass *class)
{
GObjectClass *object_class = G_OBJECT_CLASS (class);
class->get_state_hint = g_action_real_get_state_hint;
class->set_state = g_action_real_set_state;
object_class->get_property = g_action_get_property;
object_class->set_property = g_action_set_property;
object_class->finalize = g_action_finalize;
/**
* GAction::activate:
* @action: the #GAction
* @parameter: (allow-none): the parameter to the activation
*
* Indicates that the action was just activated.
*
* @parameter will always be of the expected type. In the event that
* an incorrect type was given, no signal will be emitted.
*
* Since: 2.26
*/
g_action_signals[SIGNAL_ACTIVATE] =
g_signal_new (I_("activate"),
G_TYPE_ACTION,
G_SIGNAL_RUN_LAST,
G_STRUCT_OFFSET (GActionClass, activate),
NULL, NULL,
g_cclosure_marshal_VOID__VARIANT,
G_TYPE_NONE, 1,
G_TYPE_VARIANT);
/**
* GAction:name:
*
* The name of the action. This is mostly meaningful for identifying
* the action once it has been added to a #GActionGroup.
*
* Since: 2.26
**/
g_object_class_install_property (object_class, PROP_NAME,
g_param_spec_string ("name",
P_("Action Name"),
P_("The name used to invoke the action"),
NULL,
G_PARAM_READWRITE |
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GAction:parameter-type:
*
* The type of the parameter that must be given when activating the
* action.
*
* Since: 2.26
**/
g_object_class_install_property (object_class, PROP_PARAMETER_TYPE,
g_param_spec_boxed ("parameter-type",
P_("Parameter Type"),
P_("The type of GVariant passed to activate()"),
G_TYPE_VARIANT_TYPE,
G_PARAM_READWRITE |
G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GAction:enabled:
*
* If @action is currently enabled.
*
* If the action is disabled then calls to g_action_activate() and
* g_action_set_state() have no effect.
*
* Since: 2.26
**/
g_object_class_install_property (object_class, PROP_ENABLED,
g_param_spec_boolean ("enabled",
P_("Enabled"),
P_("If the action can be activated"),
TRUE,
G_PARAM_CONSTRUCT |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
/**
* GAction:state-type:
*
* The #GVariantType of the state that the action has, or %NULL if the
* action is stateless.
*
* Since: 2.26
**/
g_object_class_install_property (object_class, PROP_STATE_TYPE,
g_param_spec_boxed ("state-type",
P_("State Type"),
P_("The type of the state kept by the action"),
G_TYPE_VARIANT_TYPE,
G_PARAM_READABLE |
G_PARAM_STATIC_STRINGS));
/**
* GAction:state:
*
* The state of the action, or %NULL if the action is stateless.
*
* Since: 2.26
**/
g_object_class_install_property (object_class, PROP_STATE,
g_param_spec_variant ("state",
P_("State"),
P_("The state the action is in"),
G_VARIANT_TYPE_ANY,
NULL,
G_PARAM_CONSTRUCT |
G_PARAM_READWRITE |
G_PARAM_STATIC_STRINGS));
g_type_class_add_private (class, sizeof (GActionPrivate));
}
/**
* g_action_set_state:
* @action: a #GAction
* @value: the new state
*
* 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.
*
* Since: 2.26
**/
void
g_action_set_state (GAction *action,
GVariant *value)
{
const GVariantType *state_type;
g_return_if_fail (G_IS_ACTION (action));
g_return_if_fail (value != NULL);
state_type = g_action_get_state_type (action);
g_return_if_fail (state_type != NULL);
g_return_if_fail (g_variant_is_of_type (value, state_type));
g_variant_ref_sink (value);
if (action->priv->enabled)
G_ACTION_GET_CLASS (action)
->set_state (action, value);
g_variant_unref (value);
}
/**
* g_action_get_state:
* @action: a #GAction
*
* 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().
*
* Returns: (allow-none) (transfer none): the current state of the action
*
* Since: 2.26
**/
GVariant *
g_action_get_state (GAction *action)
{
g_return_val_if_fail (G_IS_ACTION (action), NULL);
return action->priv->state;
}
/**
* g_action_get_name:
* @action: a #GAction
*
* Queries the name of @action.
*
* Returns: the name of the action
*
* Since: 2.26
**/
const gchar *
g_action_get_name (GAction *action)
{
g_return_val_if_fail (G_IS_ACTION (action), NULL);
return action->priv->name;
}
/**
* g_action_get_parameter_type:
* @action: a #GAction
*
* 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.
*
* Returns: (allow-none): the parameter type
*
* Since: 2.26
**/
const GVariantType *
g_action_get_parameter_type (GAction *action)
{
g_return_val_if_fail (G_IS_ACTION (action), NULL);
return action->priv->parameter_type;
}
/**
* g_action_get_state_type:
* @action: a #GAction
*
* Queries the type of the state of @action.
*
* If the action is stateful (ie: was created with
* g_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_set_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 (ie: created with g_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_set_state().
*
* Returns: (allow-none): the state type, if the action is stateful
*
* Since: 2.26
**/
const GVariantType *
g_action_get_state_type (GAction *action)
{
g_return_val_if_fail (G_IS_ACTION (action), NULL);
if (action->priv->state != NULL)
return g_variant_get_type (action->priv->state);
else
return NULL;
}
/**
* g_action_get_state_hint:
* @action: a #GAction
*
* 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.
*
* Returns: (allow-none): the state range hint
*
* Since: 2.26
**/
GVariant *
g_action_get_state_hint (GAction *action)
{
g_return_val_if_fail (G_IS_ACTION (action), NULL);
return G_ACTION_GET_CLASS (action)->get_state_hint (action);
}
/**
* g_action_get_enabled:
* @action: a #GAction
*
* 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: whether the action is enabled
*
* Since: 2.26
**/
gboolean
g_action_get_enabled (GAction *action)
{
g_return_val_if_fail (G_IS_ACTION (action), FALSE);
return action->priv->enabled;
}
/**
* g_action_set_enabled:
* @action: a #GAction
* @enabled: whether the action is enabled
*
* Sets the action as enabled or not.
*
* An action must be enabled in order to be activated or in order to
* have its state changed from outside callers.
*
* Since: 2.26
**/
void
g_action_set_enabled (GAction *action,
gboolean enabled)
{
g_return_if_fail (G_IS_ACTION (action));
enabled = !!enabled;
if (action->priv->enabled != enabled)
{
action->priv->enabled = enabled;
g_object_notify (G_OBJECT (action), "enabled");
}
}
/**
* g_action_activate:
* @action: a #GAction
* @parameter: (allow-none): the parameter to the activation
*
* 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.
*
* Since: 2.26
**/
void
g_action_activate (GAction *action,
GVariant *parameter)
{
g_return_if_fail (G_IS_ACTION (action));
g_return_if_fail (action->priv->parameter_type == NULL ?
parameter == NULL :
(parameter != NULL &&
g_variant_is_of_type (parameter,
action->priv->parameter_type)));
if (parameter != NULL)
g_variant_ref_sink (parameter);
if (action->priv->enabled)
g_signal_emit (action, g_action_signals[SIGNAL_ACTIVATE], 0, parameter);
if (parameter != NULL)
g_variant_unref (parameter);
}
/**
* g_action_new:
* @name: the name of the action
* @parameter_type: (allow-none): the type of parameter to the activate function
*
* Creates a new action.
*
* The created action is stateless. See g_action_new_stateful().
*
* Returns: a new #GAction
*
* Since: 2.26
**/
GAction *
g_action_new (const gchar *name,
const GVariantType *parameter_type)
{
return g_object_new (G_TYPE_ACTION,
"name", name,
"parameter-type", parameter_type,
NULL);
}
/**
* g_action_new_stateful:
* @name: the name of the action
* @parameter_type: (allow-none): the type of the parameter to the activate function
* @state: the initial state of the action
*
* Creates a new stateful action.
*
* @state is the initial state of the action. All future state values
* must have the same #GVariantType as the initial state.
*
* If the @state GVariant is floating, it is consumed.
*
* Returns: a new #GAction
*
* Since: 2.26
**/
GAction *
g_action_new_stateful (const gchar *name,
const GVariantType *parameter_type,
GVariant *state)
{
return g_object_new (G_TYPE_ACTION,
"name", name,
"parameter-type", parameter_type,
"state", state,
NULL);
}
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