Implement audio controls

lib/src/Makefile.am

@@ -9,7 +9,9 @@ libsugarprivate_la_CPPFLAGS =			\
 
 noinst_LTLIBRARIES = libsugarprivate.la
 
-libsugarprivate_la_LIBADD = $(GECKO_LIBS)
+libsugarprivate_la_LIBADD = $(LIB_LIBS) 		\
+			    -lgstinterfaces-0.10	\
+			    -lgstaudio-0.10
 
 libsugarprivate_la_SOURCES =		\
 	$(BUILT_SOURCES)		\

lib/src/sugar-audio-manager.c

@@ -16,23 +16,153 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  */
 
+#include <gst/gst.h>
+#include <gst/audio/mixerutils.h>
+#include <gst/interfaces/mixer.h>
+#include <gst/interfaces/propertyprobe.h>
+
 #include "sugar-audio-manager.h"
 
+struct _SugarAudioManagerPrivate
+{
+	GstMixer *mixer;
+	GstMixerTrack *track;
+	guint timer_id;
+};
+
 G_DEFINE_TYPE(SugarAudioManager, sugar_audio_manager, G_TYPE_OBJECT)
 
-static void
-sugar_audio_manager_class_init(SugarAudioManagerClass *grabber_class)
+#define SUGAR_AUDIO_MANAGER_GET_PRIVATE(object) (G_TYPE_INSTANCE_GET_PRIVATE ((object), SUGAR_TYPE_AUDIO_MANAGER, SugarAudioManagerPrivate))
+
+/* This is a modified version of code from gnome-control-center */
+
+static gboolean
+mixer_close_real(SugarAudioManager *manager)
 {
-	GObjectClass *g_object_class = G_OBJECT_CLASS (grabber_class);
+	if (manager->priv->mixer != NULL)
+	{
+		gst_element_set_state(GST_ELEMENT(manager->priv->mixer), GST_STATE_NULL);
+		gst_object_unref(GST_OBJECT(manager->priv->mixer));	    
+		g_object_unref(G_OBJECT(manager->priv->track));
+		manager->priv->mixer = NULL;
+		manager->priv->track = NULL;
+	}
+	
+	manager->priv->timer_id = 0;
+
+	return FALSE;
+}
+
+static gboolean
+set_mixer_helper(GstMixer *mixer, gpointer user_data)
+{
+	const GList *tracks;
+
+	tracks = gst_mixer_list_tracks(mixer);
+
+	while (tracks != NULL) {
+		GstMixerTrack *track = GST_MIXER_TRACK(tracks->data);
+
+		if (GST_MIXER_TRACK_HAS_FLAG(track, GST_MIXER_TRACK_MASTER)) {
+			SugarAudioManager *manager;
+
+			manager = SUGAR_AUDIO_MANAGER(user_data);
+
+			manager->priv->mixer = mixer;
+			manager->priv->track = track;
+
+			/* no need to ref the mixer element */
+			g_object_ref(manager->priv->track);
+			return TRUE;
+		}
+
+		tracks = tracks->next;
+	}
+
+	return FALSE;
+}
+
+static gboolean
+mixer_open(SugarAudioManager *manager)
+{
+	GList *mixer_list;
+
+	if (manager->priv->timer_id != 0) {
+		g_source_remove (manager->priv->timer_id);
+		manager->priv->timer_id = 0;
+		return TRUE;
+	}
+		
+	mixer_list = gst_audio_default_registry_mixer_filter
+					(set_mixer_helper, TRUE, manager);
+
+	if (mixer_list == NULL)
+		return FALSE;
+
+	/* do not unref the mixer as we keep the ref for manager->priv->mixer */
+	g_list_free (mixer_list);
+
+	return TRUE;
 }
 
 static void
-sugar_audio_manager_init(SugarAudioManager *grabber)
+mixer_close(SugarAudioManager *manager)
 {
+	manager->priv->timer_id = g_timeout_add (4000, (GSourceFunc)mixer_close_real, manager);
 }
 
 void
 sugar_audio_manager_set_volume (SugarAudioManager *manager,
 				int                level)
 {
+	gint i, *volumes, volume;
+	GstMixerTrack *track;
+
+	if (mixer_open(manager) == FALSE)
+		return;
+
+	track = manager->priv->track;
+	volume = CLAMP(level, 0, 100);
+
+	/* Rescale the volume from [0, 100] to [track min, track max]. */
+	volume = (volume / 100.0) * (track->max_volume - track->min_volume) +
+		 track->min_volume;
+
+	volumes = g_new(gint, track->num_channels);
+	for (i = 0; i < track->num_channels; ++i)
+		volumes[i] = (gint)volume;
+	gst_mixer_set_volume(manager->priv->mixer, track, volumes);
+	g_free (volumes);
+ 	
+ 	mixer_close(manager);
 }
+
+static void
+sugar_audio_manager_finalize (GObject *object)
+{
+	SugarAudioManager *manager = SUGAR_AUDIO_MANAGER(object);
+
+	mixer_close_real(manager);
+
+	G_OBJECT_CLASS(sugar_audio_manager_parent_class)->finalize(object);
+}
+
+static void
+sugar_audio_manager_class_init(SugarAudioManagerClass *klass)
+{
+	GObjectClass *object_class = G_OBJECT_CLASS(klass);
+
+	gst_init (NULL, NULL);
+
+	object_class->finalize = sugar_audio_manager_finalize;
+
+	g_type_class_add_private(klass, sizeof(SugarAudioManagerPrivate));
+}
+
+static void
+sugar_audio_manager_init(SugarAudioManager *manager)
+{
+	manager->priv = SUGAR_AUDIO_MANAGER_GET_PRIVATE(manager);
+}
+
+

lib/src/sugar-audio-manager.h

@@ -36,6 +36,9 @@ typedef struct _SugarAudioManagerPrivate SugarAudioManagerPrivate;
 
 struct _SugarAudioManager {
 	GObject base_instance;
+
+	/*< private >*/
+	SugarAudioManagerPrivate *priv;
 };
 
 struct _SugarAudioManagerClass {