gio/gaction.c

   1 /*
   2  * Copyright © 2010 Codethink Limited
   3  *
   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.
   8  *
   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.
  13  *
  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.
  18  *
  19  * Authors: Ryan Lortie <desrt@desrt.ca>
  20  */
  21
  22 #include "config.h"
  23 #include "gaction.h"
  24 #include "glibintl.h"
  25
  26 G_DEFINE_INTERFACE (GAction, g_action, G_TYPE_OBJECT)
  27
  28 /**
  29  * SECTION:gaction
  30  * @title: GAction
  31  * @short_description: An action interface
  32  *
  33  * #GAction represents a single named action.
  34  *
  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).
  40  *
  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).
  45  *
  46  * The state may have a hint associated with it, specifying its valid
  47  * range.
  48  *
  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.
  52  *
  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.
  59  *
  60  * Probably the only useful thing to do with a #GAction is to put it
  61  * inside of a #GSimpleActionGroup.
  62  **/
  63
  64 /**
  65  * GActionInterface:
  66  * @get_name: the virtual function pointer for g_action_get_name()
  67  * @get_parameter_type: the virtual function pointer for g_action_get_parameter_type()
  68  * @get_state_type: the virtual function pointer for g_action_get_state_type()
  69  * @get_state_hint: the virtual function pointer for g_action_get_state_hint()
  70  * @get_enabled: the virtual function pointer for g_action_get_enabled()
  71  * @get_state: the virtual function pointer for g_action_get_state()
  72  * @change_state: the virtual function pointer for g_action_change_state()
  73  * @activate: the virtual function pointer for g_action_activate().  Note that #GAction does not have an
  74  *            'activate' signal but that implementations of it may have one.
  75  *
  76  * The virtual function table for #GAction.
  77  *
  78  * Since: 2.28
  79  */
  80
  81 void
  82 g_action_default_init (GActionInterface *iface)
  83 {
  84   /**
  85    * GAction:name:
  86    *
  87    * The name of the action.  This is mostly meaningful for identifying
  88    * the action once it has been added to a #GActionGroup.
  89    *
  90    * Since: 2.28
  91    **/
  92   g_object_interface_install_property (iface,
  93                                        g_param_spec_string ("name",
  94                                                             P_("Action Name"),
  95                                                             P_("The name used to invoke the action"),
  96                                                             NULL,
  97                                                             G_PARAM_READABLE |
  98                                                             G_PARAM_STATIC_STRINGS));
  99
 100   /**
 101    * GAction:parameter-type:
 102    *
 103    * The type of the parameter that must be given when activating the
 104    * action.
 105    *
 106    * Since: 2.28
 107    **/
 108   g_object_interface_install_property (iface,
 109                                        g_param_spec_boxed ("parameter-type",
 110                                                            P_("Parameter Type"),
 111                                                            P_("The type of GVariant passed to activate()"),
 112                                                            G_TYPE_VARIANT_TYPE,
 113                                                            G_PARAM_READABLE |
 114                                                            G_PARAM_STATIC_STRINGS));
 115
 116   /**
 117    * GAction:enabled:
 118    *
 119    * If @action is currently enabled.
 120    *
 121    * If the action is disabled then calls to g_action_activate() and
 122    * g_action_change_state() have no effect.
 123    *
 124    * Since: 2.28
 125    **/
 126   g_object_interface_install_property (iface,
 127                                        g_param_spec_boolean ("enabled",
 128                                                              P_("Enabled"),
 129                                                              P_("If the action can be activated"),
 130                                                              TRUE,
 131                                                              G_PARAM_READABLE |
 132                                                              G_PARAM_STATIC_STRINGS));
 133
 134   /**
 135    * GAction:state-type:
 136    *
 137    * The #GVariantType of the state that the action has, or %NULL if the
 138    * action is stateless.
 139    *
 140    * Since: 2.28
 141    **/
 142   g_object_interface_install_property (iface,
 143                                        g_param_spec_boxed ("state-type",
 144                                                            P_("State Type"),
 145                                                            P_("The type of the state kept by the action"),
 146                                                            G_TYPE_VARIANT_TYPE,
 147                                                            G_PARAM_READABLE |
 148                                                            G_PARAM_STATIC_STRINGS));
 149
 150   /**
 151    * GAction:state:
 152    *
 153    * The state of the action, or %NULL if the action is stateless.
 154    *
 155    * Since: 2.28
 156    **/
 157   g_object_interface_install_property (iface,
 158                                        g_param_spec_variant ("state",
 159                                                              P_("State"),
 160                                                              P_("The state the action is in"),
 161                                                              G_VARIANT_TYPE_ANY,
 162                                                              NULL,
 163                                                              G_PARAM_READABLE |
 164                                                              G_PARAM_STATIC_STRINGS));
 165 }
 166
 167 /**
 168  * g_action_change_state:
 169  * @action: a #GAction
 170  * @value: the new state
 171  *
 172  * Request for the state of @action to be changed to @value.
 173  *
 174  * The action must be stateful and @value must be of the correct type.
 175  * See g_action_get_state_type().
 176  *
 177  * This call merely requests a change.  The action may refuse to change
 178  * its state or may change its state to something other than @value.
 179  * See g_action_get_state_hint().
 180  *
 181  * If the @value GVariant is floating, it is consumed.
 182  *
 183  * Since: 2.30
 184  **/
 185 void
 186 g_action_change_state (GAction  *action,
 187                        GVariant *value)
 188 {
 189   const GVariantType *state_type;
 190
 191   g_return_if_fail (G_IS_ACTION (action));
 192   g_return_if_fail (value != NULL);
 193   state_type = g_action_get_state_type (action);
 194   g_return_if_fail (state_type != NULL);
 195   g_return_if_fail (g_variant_is_of_type (value, state_type));
 196
 197   g_variant_ref_sink (value);
 198
 199   G_ACTION_GET_IFACE (action)
 200     ->change_state (action, value);
 201
 202   g_variant_unref (value);
 203 }
 204
 205 /**
 206  * g_action_get_state:
 207  * @action: a #GAction
 208  *
 209  * Queries the current state of @action.
 210  *
 211  * If the action is not stateful then %NULL will be returned.  If the
 212  * action is stateful then the type of the return value is the type
 213  * given by g_action_get_state_type().
 214  *
 215  * The return value (if non-%NULL) should be freed with
 216  * g_variant_unref() when it is no longer required.
 217  *
 218  * Returns: (transfer full): the current state of the action
 219  *
 220  * Since: 2.28
 221  **/
 222 GVariant *
 223 g_action_get_state (GAction *action)
 224 {
 225   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 226
 227   return G_ACTION_GET_IFACE (action)
 228     ->get_state (action);
 229 }
 230
 231 /**
 232  * g_action_get_name:
 233  * @action: a #GAction
 234  *
 235  * Queries the name of @action.
 236  *
 237  * Returns: the name of the action
 238  *
 239  * Since: 2.28
 240  **/
 241 const gchar *
 242 g_action_get_name (GAction *action)
 243 {
 244   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 245
 246   return G_ACTION_GET_IFACE (action)
 247     ->get_name (action);
 248 }
 249
 250 /**
 251  * g_action_get_parameter_type:
 252  * @action: a #GAction
 253  *
 254  * Queries the type of the parameter that must be given when activating
 255  * @action.
 256  *
 257  * When activating the action using g_action_activate(), the #GVariant
 258  * given to that function must be of the type returned by this function.
 259  *
 260  * In the case that this function returns %NULL, you must not give any
 261  * #GVariant, but %NULL instead.
 262  *
 263  * Returns: (allow-none): the parameter type
 264  *
 265  * Since: 2.28
 266  **/
 267 const GVariantType *
 268 g_action_get_parameter_type (GAction *action)
 269 {
 270   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 271
 272   return G_ACTION_GET_IFACE (action)
 273     ->get_parameter_type (action);
 274 }
 275
 276 /**
 277  * g_action_get_state_type:
 278  * @action: a #GAction
 279  *
 280  * Queries the type of the state of @action.
 281  *
 282  * If the action is stateful (e.g. created with
 283  * g_simple_action_new_stateful()) then this function returns the
 284  * #GVariantType of the state.  This is the type of the initial value
 285  * given as the state. All calls to g_action_change_state() must give a
 286  * #GVariant of this type and g_action_get_state() will return a
 287  * #GVariant of the same type.
 288  *
 289  * If the action is not stateful (e.g. created with g_simple_action_new())
 290  * then this function will return %NULL. In that case, g_action_get_state()
 291  * will return %NULL and you must not call g_action_change_state().
 292  *
 293  * Returns: (allow-none): the state type, if the action is stateful
 294  *
 295  * Since: 2.28
 296  **/
 297 const GVariantType *
 298 g_action_get_state_type (GAction *action)
 299 {
 300   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 301
 302   return G_ACTION_GET_IFACE (action)
 303     ->get_state_type (action);
 304 }
 305
 306 /**
 307  * g_action_get_state_hint:
 308  * @action: a #GAction
 309  *
 310  * Requests a hint about the valid range of values for the state of
 311  * @action.
 312  *
 313  * If %NULL is returned it either means that the action is not stateful
 314  * or that there is no hint about the valid range of values for the
 315  * state of the action.
 316  *
 317  * If a #GVariant array is returned then each item in the array is a
 318  * possible value for the state.  If a #GVariant pair (ie: two-tuple) is
 319  * returned then the tuple specifies the inclusive lower and upper bound
 320  * of valid values for the state.
 321  *
 322  * In any case, the information is merely a hint.  It may be possible to
 323  * have a state value outside of the hinted range and setting a value
 324  * within the range may fail.
 325  *
 326  * The return value (if non-%NULL) should be freed with
 327  * g_variant_unref() when it is no longer required.
 328  *
 329  * Returns: (transfer full): the state range hint
 330  *
 331  * Since: 2.28
 332  **/
 333 GVariant *
 334 g_action_get_state_hint (GAction *action)
 335 {
 336   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 337
 338   return G_ACTION_GET_IFACE (action)
 339     ->get_state_hint (action);
 340 }
 341
 342 /**
 343  * g_action_get_enabled:
 344  * @action: a #GAction
 345  *
 346  * Checks if @action is currently enabled.
 347  *
 348  * An action must be enabled in order to be activated or in order to
 349  * have its state changed from outside callers.
 350  *
 351  * Returns: whether the action is enabled
 352  *
 353  * Since: 2.28
 354  **/
 355 gboolean
 356 g_action_get_enabled (GAction *action)
 357 {
 358   g_return_val_if_fail (G_IS_ACTION (action), FALSE);
 359
 360   return G_ACTION_GET_IFACE (action)
 361     ->get_enabled (action);
 362 }
 363
 364 /**
 365  * g_action_activate:
 366  * @action: a #GAction
 367  * @parameter: (allow-none): the parameter to the activation
 368  *
 369  * Activates the action.
 370  *
 371  * @parameter must be the correct type of parameter for the action (ie:
 372  * the parameter type given at construction time).  If the parameter
 373  * type was %NULL then @parameter must also be %NULL.
 374  *
 375  * Since: 2.28
 376  **/
 377 void
 378 g_action_activate (GAction  *action,
 379                    GVariant *parameter)
 380 {
 381   g_return_if_fail (G_IS_ACTION (action));
 382
 383   if (parameter != NULL)
 384     g_variant_ref_sink (parameter);
 385
 386   G_ACTION_GET_IFACE (action)
 387     ->activate (action, parameter);
 388
 389   if (parameter != NULL)
 390     g_variant_unref (parameter);
 391 }