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_READWRITE |
  98                                                             G_PARAM_CONSTRUCT_ONLY |
  99                                                             G_PARAM_STATIC_STRINGS));
 100
 101   /**
 102    * GAction:parameter-type:
 103    *
 104    * The type of the parameter that must be given when activating the
 105    * action.
 106    *
 107    * Since: 2.28
 108    **/
 109   g_object_interface_install_property (iface,
 110                                        g_param_spec_boxed ("parameter-type",
 111                                                            P_("Parameter Type"),
 112                                                            P_("The type of GVariant passed to activate()"),
 113                                                            G_TYPE_VARIANT_TYPE,
 114                                                            G_PARAM_READWRITE |
 115                                                            G_PARAM_CONSTRUCT_ONLY |
 116                                                            G_PARAM_STATIC_STRINGS));
 117
 118   /**
 119    * GAction:enabled:
 120    *
 121    * If @action is currently enabled.
 122    *
 123    * If the action is disabled then calls to g_action_activate() and
 124    * g_action_change_state() have no effect.
 125    *
 126    * Since: 2.28
 127    **/
 128   g_object_interface_install_property (iface,
 129                                        g_param_spec_boolean ("enabled",
 130                                                              P_("Enabled"),
 131                                                              P_("If the action can be activated"),
 132                                                              TRUE,
 133                                                              G_PARAM_READWRITE |
 134                                                              G_PARAM_CONSTRUCT_ONLY |
 135                                                              G_PARAM_STATIC_STRINGS));
 136
 137   /**
 138    * GAction:state-type:
 139    *
 140    * The #GVariantType of the state that the action has, or %NULL if the
 141    * action is stateless.
 142    *
 143    * Since: 2.28
 144    **/
 145   g_object_interface_install_property (iface,
 146                                        g_param_spec_boxed ("state-type",
 147                                                            P_("State Type"),
 148                                                            P_("The type of the state kept by the action"),
 149                                                            G_TYPE_VARIANT_TYPE,
 150                                                            G_PARAM_READABLE |
 151                                                            G_PARAM_STATIC_STRINGS));
 152
 153   /**
 154    * GAction:state:
 155    *
 156    * The state of the action, or %NULL if the action is stateless.
 157    *
 158    * Since: 2.28
 159    **/
 160   g_object_interface_install_property (iface,
 161                                        g_param_spec_variant ("state",
 162                                                              P_("State"),
 163                                                              P_("The state the action is in"),
 164                                                              G_VARIANT_TYPE_ANY,
 165                                                              NULL,
 166                                                              G_PARAM_READWRITE |
 167                                                              G_PARAM_CONSTRUCT_ONLY |
 168                                                              G_PARAM_STATIC_STRINGS));
 169 }
 170
 171 /**
 172  * g_action_change_state:
 173  * @action: a #GAction
 174  * @value: the new state
 175  *
 176  * Request for the state of @action to be changed to @value.
 177  *
 178  * The action must be stateful and @value must be of the correct type.
 179  * See g_action_get_state_type().
 180  *
 181  * This call merely requests a change.  The action may refuse to change
 182  * its state or may change its state to something other than @value.
 183  * See g_action_get_state_hint().
 184  *
 185  * If the @value GVariant is floating, it is consumed.
 186  *
 187  * Since: 2.30
 188  **/
 189 void
 190 g_action_change_state (GAction  *action,
 191                        GVariant *value)
 192 {
 193   const GVariantType *state_type;
 194
 195   g_return_if_fail (G_IS_ACTION (action));
 196   g_return_if_fail (value != NULL);
 197   state_type = g_action_get_state_type (action);
 198   g_return_if_fail (state_type != NULL);
 199   g_return_if_fail (g_variant_is_of_type (value, state_type));
 200
 201   g_variant_ref_sink (value);
 202
 203   G_ACTION_GET_IFACE (action)
 204     ->change_state (action, value);
 205
 206   g_variant_unref (value);
 207 }
 208
 209 /**
 210  * g_action_get_state:
 211  * @action: a #GAction
 212  *
 213  * Queries the current state of @action.
 214  *
 215  * If the action is not stateful then %NULL will be returned.  If the
 216  * action is stateful then the type of the return value is the type
 217  * given by g_action_get_state_type().
 218  *
 219  * The return value (if non-%NULL) should be freed with
 220  * g_variant_unref() when it is no longer required.
 221  *
 222  * Returns: (transfer full): the current state of the action
 223  *
 224  * Since: 2.28
 225  **/
 226 GVariant *
 227 g_action_get_state (GAction *action)
 228 {
 229   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 230
 231   return G_ACTION_GET_IFACE (action)
 232     ->get_state (action);
 233 }
 234
 235 /**
 236  * g_action_get_name:
 237  * @action: a #GAction
 238  *
 239  * Queries the name of @action.
 240  *
 241  * Returns: the name of the action
 242  *
 243  * Since: 2.28
 244  **/
 245 const gchar *
 246 g_action_get_name (GAction *action)
 247 {
 248   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 249
 250   return G_ACTION_GET_IFACE (action)
 251     ->get_name (action);
 252 }
 253
 254 /**
 255  * g_action_get_parameter_type:
 256  * @action: a #GAction
 257  *
 258  * Queries the type of the parameter that must be given when activating
 259  * @action.
 260  *
 261  * When activating the action using g_action_activate(), the #GVariant
 262  * given to that function must be of the type returned by this function.
 263  *
 264  * In the case that this function returns %NULL, you must not give any
 265  * #GVariant, but %NULL instead.
 266  *
 267  * Returns: (allow-none): the parameter type
 268  *
 269  * Since: 2.28
 270  **/
 271 const GVariantType *
 272 g_action_get_parameter_type (GAction *action)
 273 {
 274   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 275
 276   return G_ACTION_GET_IFACE (action)
 277     ->get_parameter_type (action);
 278 }
 279
 280 /**
 281  * g_action_get_state_type:
 282  * @action: a #GAction
 283  *
 284  * Queries the type of the state of @action.
 285  *
 286  * If the action is stateful (e.g. created with
 287  * g_simple_action_new_stateful()) then this function returns the
 288  * #GVariantType of the state.  This is the type of the initial value
 289  * given as the state. All calls to g_action_change_state() must give a
 290  * #GVariant of this type and g_action_get_state() will return a
 291  * #GVariant of the same type.
 292  *
 293  * If the action is not stateful (e.g. created with g_simple_action_new())
 294  * then this function will return %NULL. In that case, g_action_get_state()
 295  * will return %NULL and you must not call g_action_change_state().
 296  *
 297  * Returns: (allow-none): the state type, if the action is stateful
 298  *
 299  * Since: 2.28
 300  **/
 301 const GVariantType *
 302 g_action_get_state_type (GAction *action)
 303 {
 304   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 305
 306   return G_ACTION_GET_IFACE (action)
 307     ->get_state_type (action);
 308 }
 309
 310 /**
 311  * g_action_get_state_hint:
 312  * @action: a #GAction
 313  *
 314  * Requests a hint about the valid range of values for the state of
 315  * @action.
 316  *
 317  * If %NULL is returned it either means that the action is not stateful
 318  * or that there is no hint about the valid range of values for the
 319  * state of the action.
 320  *
 321  * If a #GVariant array is returned then each item in the array is a
 322  * possible value for the state.  If a #GVariant pair (ie: two-tuple) is
 323  * returned then the tuple specifies the inclusive lower and upper bound
 324  * of valid values for the state.
 325  *
 326  * In any case, the information is merely a hint.  It may be possible to
 327  * have a state value outside of the hinted range and setting a value
 328  * within the range may fail.
 329  *
 330  * The return value (if non-%NULL) should be freed with
 331  * g_variant_unref() when it is no longer required.
 332  *
 333  * Returns: (transfer full): the state range hint
 334  *
 335  * Since: 2.28
 336  **/
 337 GVariant *
 338 g_action_get_state_hint (GAction *action)
 339 {
 340   g_return_val_if_fail (G_IS_ACTION (action), NULL);
 341
 342   return G_ACTION_GET_IFACE (action)
 343     ->get_state_hint (action);
 344 }
 345
 346 /**
 347  * g_action_get_enabled:
 348  * @action: a #GAction
 349  *
 350  * Checks if @action is currently enabled.
 351  *
 352  * An action must be enabled in order to be activated or in order to
 353  * have its state changed from outside callers.
 354  *
 355  * Returns: whether the action is enabled
 356  *
 357  * Since: 2.28
 358  **/
 359 gboolean
 360 g_action_get_enabled (GAction *action)
 361 {
 362   g_return_val_if_fail (G_IS_ACTION (action), FALSE);
 363
 364   return G_ACTION_GET_IFACE (action)
 365     ->get_enabled (action);
 366 }
 367
 368 /**
 369  * g_action_activate:
 370  * @action: a #GAction
 371  * @parameter: (allow-none): the parameter to the activation
 372  *
 373  * Activates the action.
 374  *
 375  * @parameter must be the correct type of parameter for the action (ie:
 376  * the parameter type given at construction time).  If the parameter
 377  * type was %NULL then @parameter must also be %NULL.
 378  *
 379  * Since: 2.28
 380  **/
 381 void
 382 g_action_activate (GAction  *action,
 383                    GVariant *parameter)
 384 {
 385   g_return_if_fail (G_IS_ACTION (action));
 386
 387   if (parameter != NULL)
 388     g_variant_ref_sink (parameter);
 389
 390   G_ACTION_GET_IFACE (action)
 391     ->activate (action, parameter);
 392
 393   if (parameter != NULL)
 394     g_variant_unref (parameter);
 395 }