src/misc/events.c

   1 /*****************************************************************************
   2  * events.c: events interface
   3  * This library provides an interface to the send and receive events.
   4  * It is more lightweight than variable based callback.
   5  *****************************************************************************
   6  * Copyright (C) 1998-2005 VLC authors and VideoLAN
   7  *
   8  * Authors: Pierre d'Herbemont <pdherbemont # videolan.org >
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU Lesser General Public License as published by
  12  * the Free Software Foundation; either version 2.1 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  18  * GNU Lesser General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU Lesser General Public License
  21  * along with this program; if not, write to the Free Software Foundation,
  22  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28
  29 #ifdef HAVE_CONFIG_H
  30 # include "config.h"
  31 #endif
  32
  33 #include <vlc_common.h>
  34
  35 #include <assert.h>
  36
  37 #include <vlc_events.h>
  38 #include <vlc_arrays.h>
  39
  40 /*****************************************************************************
  41  * Documentation : Read vlc_events.h
  42  *****************************************************************************/
  43
  44 /*****************************************************************************
  45  *  Private types.
  46  *****************************************************************************/
  47
  48 typedef struct vlc_event_listener_t
  49 {
  50     void *               p_user_data;
  51     vlc_event_callback_t pf_callback;
  52 } vlc_event_listener_t;
  53
  54 /*****************************************************************************
  55  *
  56  *****************************************************************************/
  57
  58 #undef vlc_event_manager_init
  59 /**
  60  * Initialize event manager object
  61  * p_obj is the object that contains the event manager. But not
  62  * necessarily a vlc_object_t (an input_item_t is not a vlc_object_t
  63  * for instance).
  64  */
  65 void vlc_event_manager_init( vlc_event_manager_t * p_em, void * p_obj )
  66 {
  67     p_em->p_obj = p_obj;
  68     /* This is an unsafe work-around for a long-standing playlist bug.
  69      * Do not rely on this. */
  70     vlc_mutex_init_recursive( &p_em->lock );
  71
  72     for( size_t i = 0; i < ARRAY_SIZE(p_em->events); i++ )
  73        ARRAY_INIT( p_em->events[i].listeners );
  74 }
  75
  76 /**
  77  * Destroy the event manager
  78  */
  79 void vlc_event_manager_fini( vlc_event_manager_t * p_em )
  80 {
  81     struct vlc_event_listener_t * listener;
  82
  83     for( size_t i = 0; i < ARRAY_SIZE(p_em->events); i++ )
  84     {
  85         struct vlc_event_listeners_group_t *slot = p_em->events + i;
  86
  87         ARRAY_FOREACH( listener, slot->listeners )
  88             free( listener );
  89
  90         ARRAY_RESET( slot->listeners );
  91     }
  92 }
  93
  94 /**
  95  * Send an event to the listener attached to this p_em.
  96  */
  97 void vlc_event_send( vlc_event_manager_t * p_em,
  98                      vlc_event_t * p_event )
  99 {
 100     vlc_event_listeners_group_t *slot = &p_em->events[p_event->type];
 101     vlc_event_listener_t * listener;
 102
 103     /* Fill event with the sending object now */
 104     p_event->p_obj = p_em->p_obj;
 105
 106     vlc_mutex_lock( &p_em->lock ) ;
 107
 108     ARRAY_FOREACH( listener, slot->listeners )
 109         listener->pf_callback( p_event, listener->p_user_data );
 110
 111     vlc_mutex_unlock( &p_em->lock );
 112 }
 113
 114 #undef vlc_event_attach
 115 /**
 116  * Add a callback for an event.
 117  */
 118 int vlc_event_attach( vlc_event_manager_t * p_em,
 119                       vlc_event_type_t event_type,
 120                       vlc_event_callback_t pf_callback,
 121                       void *p_user_data )
 122 {
 123     vlc_event_listener_t * listener;
 124     vlc_event_listeners_group_t *slot = &p_em->events[event_type];
 125
 126     listener = malloc(sizeof(vlc_event_listener_t));
 127     if( !listener )
 128         return VLC_ENOMEM;
 129
 130     listener->p_user_data = p_user_data;
 131     listener->pf_callback = pf_callback;
 132
 133     vlc_mutex_lock( &p_em->lock );
 134     ARRAY_APPEND( slot->listeners, listener );
 135     vlc_mutex_unlock( &p_em->lock );
 136     return VLC_SUCCESS;
 137 }
 138
 139 /**
 140  * Remove a callback for an event.
 141  */
 142
 143 void vlc_event_detach( vlc_event_manager_t *p_em,
 144                        vlc_event_type_t event_type,
 145                        vlc_event_callback_t pf_callback,
 146                        void *p_user_data )
 147 {
 148     vlc_event_listeners_group_t *slot = &p_em->events[event_type];
 149
 150     vlc_mutex_lock( &p_em->lock );
 151
 152     for (int i = 0; i < slot->listeners.i_size; ++i)
 153     {
 154         struct vlc_event_listener_t *listener = slot->listeners.p_elems[i];
 155         if( listener->pf_callback == pf_callback &&
 156             listener->p_user_data == p_user_data )
 157         {
 158             /* that's our listener */
 159             ARRAY_REMOVE( slot->listeners, i );
 160             vlc_mutex_unlock( &p_em->lock );
 161             free( listener );
 162             return;
 163         }
 164     }
 165
 166     vlc_assert_unreachable();
 167 }