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