2 * Copyright © 2010 Codethink Limited
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License as published
6 * by the Free Software Foundation; either version 2 of the licence or (at
7 * your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General
15 * Public License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
17 * Boston, MA 02111-1307, USA.
19 * Authors: Ryan Lortie <desrt@desrt.ca>
26 G_DEFINE_INTERFACE (GAction, g_action, G_TYPE_OBJECT)
31 * @short_description: An action
33 * #GAction represents a single named action.
35 * The main interface to an action is that it can be activated with
36 * g_action_activate(). This results in the 'activate' signal being
37 * emitted. An activation has a #GVariant parameter (which may be
38 * %NULL). The correct type for the parameter is determined by a static
39 * parameter type (which is given at construction time).
41 * An action may optionally have a state, in which case the state may be
42 * set with g_action_change_state(). This call takes a #GVariant. The
43 * correct type for the state is determined by a static state type
44 * (which is given at construction time).
46 * The state may have a hint associated with it, specifying its valid
49 * #GAction is merely the interface to the concept of an action, as
50 * described above. Various implementations of actions exist, including
51 * #GSimpleAction and #GtkAction.
53 * In all cases, the implementing class is responsible for storing the
54 * name of the action, the parameter type, the enabled state, the
55 * optional state type and the state and emitting the appropriate
56 * signals when these change. The implementor responsible for filtering
57 * calls to g_action_activate() and g_action_change_state() for type
58 * safety and for the state being enabled.
60 * Probably the only useful thing to do with a #GAction is to put it
61 * inside of a #GSimpleActionGroup.
65 g_action_default_init (GActionInterface *iface)
70 * The name of the action. This is mostly meaningful for identifying
71 * the action once it has been added to a #GActionGroup.
75 g_object_interface_install_property (iface,
76 g_param_spec_string ("name",
78 P_("The name used to invoke the action"),
81 G_PARAM_CONSTRUCT_ONLY |
82 G_PARAM_STATIC_STRINGS));
85 * GAction:parameter-type:
87 * The type of the parameter that must be given when activating the
92 g_object_interface_install_property (iface,
93 g_param_spec_boxed ("parameter-type",
95 P_("The type of GVariant passed to activate()"),
98 G_PARAM_CONSTRUCT_ONLY |
99 G_PARAM_STATIC_STRINGS));
104 * If @action is currently enabled.
106 * If the action is disabled then calls to g_action_activate() and
107 * g_action_change_state() have no effect.
111 g_object_interface_install_property (iface,
112 g_param_spec_boolean ("enabled",
114 P_("If the action can be activated"),
118 G_PARAM_STATIC_STRINGS));
121 * GAction:state-type:
123 * The #GVariantType of the state that the action has, or %NULL if the
124 * action is stateless.
128 g_object_interface_install_property (iface,
129 g_param_spec_boxed ("state-type",
131 P_("The type of the state kept by the action"),
134 G_PARAM_STATIC_STRINGS));
139 * The state of the action, or %NULL if the action is stateless.
143 g_object_interface_install_property (iface,
144 g_param_spec_variant ("state",
146 P_("The state the action is in"),
150 G_PARAM_STATIC_STRINGS));
154 * g_action_change_state:
155 * @action: a #GAction
156 * @value: the new state
158 * Request for the state of @action to be changed to @value.
160 * The action must be stateful and @value must be of the correct type.
161 * See g_action_get_state_type().
163 * This call merely requests a change. The action may refuse to change
164 * its state or may change its state to something other than @value.
165 * See g_action_get_state_hint().
167 * If the @value GVariant is floating, it is consumed.
172 g_action_change_state (GAction *action,
175 const GVariantType *state_type;
177 g_return_if_fail (G_IS_ACTION (action));
178 g_return_if_fail (value != NULL);
179 state_type = g_action_get_state_type (action);
180 g_return_if_fail (state_type != NULL);
181 g_return_if_fail (g_variant_is_of_type (value, state_type));
183 g_variant_ref_sink (value);
185 G_ACTION_GET_IFACE (action)
186 ->change_state (action, value);
188 g_variant_unref (value);
192 * g_action_get_state:
193 * @action: a #GAction
195 * Queries the current state of @action.
197 * If the action is not stateful then %NULL will be returned. If the
198 * action is stateful then the type of the return value is the type
199 * given by g_action_get_state_type().
201 * The return value (if non-%NULL) should be freed with
202 * g_variant_unref() when it is no longer required.
204 * Returns: (transfer full): the current state of the action
209 g_action_get_state (GAction *action)
211 g_return_val_if_fail (G_IS_ACTION (action), NULL);
213 return G_ACTION_GET_IFACE (action)
214 ->get_state (action);
219 * @action: a #GAction
221 * Queries the name of @action.
223 * Returns: the name of the action
228 g_action_get_name (GAction *action)
230 g_return_val_if_fail (G_IS_ACTION (action), NULL);
232 return G_ACTION_GET_IFACE (action)
237 * g_action_get_parameter_type:
238 * @action: a #GAction
240 * Queries the type of the parameter that must be given when activating
243 * When activating the action using g_action_activate(), the #GVariant
244 * given to that function must be of the type returned by this function.
246 * In the case that this function returns %NULL, you must not give any
247 * #GVariant, but %NULL instead.
249 * Returns: (allow-none): the parameter type
254 g_action_get_parameter_type (GAction *action)
256 g_return_val_if_fail (G_IS_ACTION (action), NULL);
258 return G_ACTION_GET_IFACE (action)
259 ->get_parameter_type (action);
263 * g_action_get_state_type:
264 * @action: a #GAction
266 * Queries the type of the state of @action.
268 * If the action is stateful (e.g. created with
269 * g_simple_action_new_stateful()) then this function returns the
270 * #GVariantType of the state. This is the type of the initial value
271 * given as the state. All calls to g_action_change_state() must give a
272 * #GVariant of this type and g_action_get_state() will return a
273 * #GVariant of the same type.
275 * If the action is not stateful (e.g. created with g_simple_action_new())
276 * then this function will return %NULL. In that case, g_action_get_state()
277 * will return %NULL and you must not call g_action_change_state().
279 * Returns: (allow-none): the state type, if the action is stateful
284 g_action_get_state_type (GAction *action)
286 g_return_val_if_fail (G_IS_ACTION (action), NULL);
288 return G_ACTION_GET_IFACE (action)
289 ->get_state_type (action);
293 * g_action_get_state_hint:
294 * @action: a #GAction
296 * Requests a hint about the valid range of values for the state of
299 * If %NULL is returned it either means that the action is not stateful
300 * or that there is no hint about the valid range of values for the
301 * state of the action.
303 * If a #GVariant array is returned then each item in the array is a
304 * possible value for the state. If a #GVariant pair (ie: two-tuple) is
305 * returned then the tuple specifies the inclusive lower and upper bound
306 * of valid values for the state.
308 * In any case, the information is merely a hint. It may be possible to
309 * have a state value outside of the hinted range and setting a value
310 * within the range may fail.
312 * The return value (if non-%NULL) should be freed with
313 * g_variant_unref() when it is no longer required.
315 * Returns: (transfer full): the state range hint
320 g_action_get_state_hint (GAction *action)
322 g_return_val_if_fail (G_IS_ACTION (action), NULL);
324 return G_ACTION_GET_IFACE (action)
325 ->get_state_hint (action);
329 * g_action_get_enabled:
330 * @action: a #GAction
332 * Checks if @action is currently enabled.
334 * An action must be enabled in order to be activated or in order to
335 * have its state changed from outside callers.
337 * Returns: whether the action is enabled
342 g_action_get_enabled (GAction *action)
344 g_return_val_if_fail (G_IS_ACTION (action), FALSE);
346 return G_ACTION_GET_IFACE (action)
347 ->get_enabled (action);
352 * @action: a #GAction
353 * @parameter: (allow-none): the parameter to the activation
355 * Activates the action.
357 * @parameter must be the correct type of parameter for the action (ie:
358 * the parameter type given at construction time). If the parameter
359 * type was %NULL then @parameter must also be %NULL.
364 g_action_activate (GAction *action,
367 g_return_if_fail (G_IS_ACTION (action));
369 if (parameter != NULL)
370 g_variant_ref_sink (parameter);
372 G_ACTION_GET_IFACE (action)
373 ->activate (action, parameter);
375 if (parameter != NULL)
376 g_variant_unref (parameter);