src/mixer_plugin.h

   1 /*
   2  * Copyright (C) 2003-2010 The Music Player Daemon Project
   3  * http://www.musicpd.org
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 /** \file
  21  *
  22  * This header declares the mixer_plugin class.  It should not be
  23  * included directly; use mixer_api.h instead in mixer
  24  * implementations.
  25  */
  26
  27 #ifndef MPD_MIXER_PLUGIN_H
  28 #define MPD_MIXER_PLUGIN_H
  29
  30 #include <glib.h>
  31
  32 #include <stdbool.h>
  33
  34 struct config_param;
  35 struct mixer;
  36
  37 struct mixer_plugin {
  38         /**
  39          * Alocates and configures a mixer device.
  40          *
  41          * @param ao the pointer returned by audio_output_plugin.init
  42          * @param param the configuration section, or NULL if there is
  43          * no configuration
  44          * @param error_r location to store the error occuring, or
  45          * NULL to ignore errors
  46          * @return a mixer object, or NULL on error
  47          */
  48         struct mixer *(*init)(void *ao, const struct config_param *param,
  49                               GError **error_r);
  50
  51         /**
  52          * Finish and free mixer data
  53          */
  54         void (*finish)(struct mixer *data);
  55
  56         /**
  57          * Open mixer device
  58          *
  59          * @param error_r location to store the error occuring, or
  60          * NULL to ignore errors
  61          * @return true on success, false on error
  62          */
  63         bool (*open)(struct mixer *data, GError **error_r);
  64
  65         /**
  66          * Close mixer device
  67          */
  68         void (*close)(struct mixer *data);
  69
  70         /**
  71          * Reads the current volume.
  72          *
  73          * @param error_r location to store the error occuring, or
  74          * NULL to ignore errors
  75          * @return the current volume (0..100 including) or -1 if
  76          * unavailable or on error (error_r set, mixer will be closed)
  77          */
  78         int (*get_volume)(struct mixer *mixer, GError **error_r);
  79
  80         /**
  81          * Sets the volume.
  82          *
  83          * @param error_r location to store the error occuring, or
  84          * NULL to ignore errors
  85          * @param volume the new volume (0..100 including)
  86          * @return true on success, false on error
  87          */
  88         bool (*set_volume)(struct mixer *mixer, unsigned volume,
  89                            GError **error_r);
  90
  91         /**
  92          * If true, then the mixer is automatically opened, even if
  93          * its audio output is not open.  If false, then the mixer is
  94          * disabled as long as its audio output is closed.
  95          */
  96         bool global;
  97 };
  98
  99 #endif