Rewrite PulseAudio backend into a threaded class

Converts the Mixer PulseAudio backend from a C library to a PaClient
class which runs in its own QThread.  This faciliates isolation of
PaControlModel updates to the QML thread where they belong. It also
provides the foundation for runtime updates of the model and reuse
of the PaClient class in other apps.

AGL-Bug: SPEC-548
Change-Id: I13c4c220fde2fd4bc4aea2e04f39152a963b5fa0
Signed-off-by: Matt Porter <mporter@konsulko.com>

9 files changed, 359 insertions, 304 deletions

diff --git a/app/Mixer.qml b/app/Mixer.qml
index 7a099ce..75673fe 100644
--- a/app/Mixer.qml
+++ b/app/Mixer.qml
@@ -53,7 +53,7 @@ ApplicationWindow {
 		anchors.top: title.bottom
 		anchors.margins: 80
 		anchors.fill: parent
-		model: PaControlModel {}
+		model: PaControlModel { objectName: "pacm" }
 		delegate: ColumnLayout {
 			width: parent.width
 			spacing: 40
diff --git a/app/app.pro b/app/app.pro
index e8fe05b..34c37f4 100644
--- a/app/app.pro
+++ b/app/app.pro
@@ -3,11 +3,11 @@ QT = quickcontrols2
 
 HEADERS += \
     pacontrolmodel.h \
-    pac.h
+    paclient.h
 
 SOURCES = main.cpp \
     pacontrolmodel.cpp \
-    pac.c
+    paclient.cpp
 
 CONFIG += link_pkgconfig
 PKGCONFIG += libpulse
diff --git a/app/main.cpp b/app/main.cpp
index d89287c..76e755b 100644
--- a/app/main.cpp
+++ b/app/main.cpp
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2016 The Qt Company Ltd.
- * Copyright (C) 2016 Konsulko Group
+ * Copyright (C) 2016,2017 Konsulko Group
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,9 +15,13 @@
  * limitations under the License.
  */
 
+#include "paclient.h"
+#include "pacontrolmodel.h"
+
 #include <QtCore/QDebug>
 #include <QtCore/QDir>
 #include <QtCore/QStandardPaths>
+#include <QtCore/QThread>
 #include <QtGui/QGuiApplication>
 #include <QtQml/QQmlApplicationEngine>
 #include <QtQml/QQmlContext>
@@ -26,7 +30,6 @@
 #include <QtQuick/qquickitem.h>
 #include <QtQuick/qquickview.h>
 
-#include "pacontrolmodel.h"
 
 #ifdef HAVE_LIBHOMESCREEN
 #include <libhomescreen.hpp>
@@ -47,10 +50,28 @@ int main(int argc, char *argv[])
 
 	QQuickStyle::setStyle("AGL");
 
+	// Fire up PA client QThread
+	QThread* pat = new QThread;
+	PaClient* client = new PaClient();
+	client->moveToThread(pat);
+	pat->start();
+
+	// Register the PA Control Model
 	qmlRegisterType<PaControlModel>("PaControlModel", 1, 0, "PaControlModel");
 
 	QQmlApplicationEngine engine;
 	engine.load(QUrl(QStringLiteral("qrc:/Mixer.qml")));
 
+	// Find the instantiated model QObject and connect the signals/slots
+	QList<QObject *> mobjs = engine.rootObjects();
+	PaControlModel *pacm = mobjs.first()->findChild<PaControlModel *>("pacm");
+	QObject::connect(client, SIGNAL(controlAdded(int, QString, int, int, const char *, int)),
+			 pacm, SLOT(addOneControl(int, QString, int, int, const char *, int)));
+	QObject::connect(pacm, SIGNAL(volumeChanged(uint32_t, uint32_t, uint32_t, uint32_t)),
+			client, SLOT(setVolume(uint32_t, uint32_t, uint32_t, uint32_t)));
+
+	// Initalize PA client
+	client->init();
+
 	return app.exec();
 }
diff --git a/app/pac.c b/app/pac.c
deleted file mode 100644
index 83b4604..0000000
--- a/app/pac.c
+++ /dev/null
@@ -1,225 +0,0 @@
-/*
- * Copyright (C) 2016 Konsulko Group
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <signal.h>
-#include <errno.h>
-#include <unistd.h>
-#include <limits.h>
-#include <assert.h>
-
-#include <pulse/pulseaudio.h>
-#include <sys/queue.h>
-
-#include "pacontrolmodel.h"
-#include "pac.h"
-
-/* FIXME: move these into a pac context */
-static pa_threaded_mainloop* m;
-TAILQ_HEAD(pac_cstateq, pac_cstate);
-static struct pac_cstateq cstateq;
-
-static void add_one_cstate(int type, int index, const pa_cvolume *cvolume)
-{
-	struct pac_cstate *cstate;
-	int i;
-
-	cstate = pa_xnew(struct pac_cstate, 1);
-	cstate->type = type;
-	cstate->index = index;
-	cstate->cvolume.channels = cvolume->channels;
-	for (i = 0; i < cvolume->channels; i++)
-		cstate->cvolume.values[i] = cvolume->values[i];
-
-	TAILQ_INSERT_TAIL(&cstateq, cstate, tailq);
-}
-
-static void get_source_list_cb(pa_context *c,
-		const pa_source_info *i,
-		int eol,
-		void *data)
-{
-	int chan;
-
-	if (eol < 0) {
-		fprintf(stderr, "get source list: %s\n",
-				pa_strerror(pa_context_errno(c)));
-
-		pa_threaded_mainloop_stop(m);
-		return;
-	}
-
-	if (!eol) {
-		assert(i);
-		add_one_cstate(C_SOURCE, i->index, &i->volume);
-		for (chan = 0; chan < i->channel_map.channels; chan++) {
-			add_one_control(data, i->index, i->description,
-					C_SOURCE, chan,
-					channel_position_string[i->channel_map.map[chan]],
-					i->volume.values[chan]);
-		}
-	}
-}
-
-static void get_sink_list_cb(pa_context *c,
-		const pa_sink_info *i,
-		int eol,
-		void *data)
-{
-	int chan;
-
-	if(eol < 0) {
-		fprintf(stderr, "get sink list: %s\n",
-				pa_strerror(pa_context_errno(c)));
-
-		pa_threaded_mainloop_stop(m);
-		return;
-	}
-
-	if(!eol) {
-		assert(i);
-		add_one_cstate(C_SINK, i->index, &i->volume);
-		for (chan = 0; chan < i->channel_map.channels; chan++) {
-			add_one_control(data, i->index, i->description,
-					C_SINK, chan,
-					channel_position_string[i->channel_map.map[chan]],
-					i->volume.values[chan]);
-		}
-	}
-}
-
-static void context_state_cb(pa_context *c, void *data) {
-	pa_operation *o;
-
-	assert(c);
-	switch (pa_context_get_state(c)) {
-		case PA_CONTEXT_CONNECTING:
-		case PA_CONTEXT_AUTHORIZING:
-		case PA_CONTEXT_SETTING_NAME:
-			break;
-		case PA_CONTEXT_READY:
-			/* Fetch the controls of interest */
-			if (!(o = pa_context_get_source_info_list(c, get_source_list_cb, data))) {
-				fprintf(stderr, "get source info list: %s\n",
-					pa_strerror(pa_context_errno(c)));
-				return;
-			}
-			pa_operation_unref(o);
-			if (!(o = pa_context_get_sink_info_list(c, get_sink_list_cb, data))) {
-				fprintf(stderr, "get sink info list: %s\n",
-					pa_strerror(pa_context_errno(c)));
-				return;
-			}
-			break;
-		case PA_CONTEXT_TERMINATED:
-			pa_threaded_mainloop_stop(m);
-			break;
-		case PA_CONTEXT_FAILED:
-		default:
-			fprintf(stderr, "PA connection failed: %s\n",
-					pa_strerror(pa_context_errno(c)));
-			pa_threaded_mainloop_stop(m);
-	}
-}
-
-static void pac_set_source_volume_cb(pa_context *c, int success, void *userdata __attribute__((unused))) {
-	assert(c);
-	if (!success)
-		fprintf(stderr, "Set source volume: %s\n",
-				pa_strerror(pa_context_errno(c)));
-}
-
-static void pac_set_sink_volume_cb(pa_context *c, int success, void *userdata __attribute__((unused))) {
-	assert(c);
-	if (!success)
-		fprintf(stderr, "Set source volume: %s\n",
-				pa_strerror(pa_context_errno(c)));
-}
-
-void pac_set_volume(pa_context *c, uint32_t type, uint32_t idx, uint32_t channel, uint32_t volume)
-{
-	pa_operation *o;
-	struct pac_cstate *cstate;
-
-	TAILQ_FOREACH(cstate, &cstateq, tailq)
-		if (cstate->index == idx)
-			break;
-	cstate->cvolume.values[channel] = volume;
-
-	if (type == C_SOURCE) {
-		if (!(o = pa_context_set_source_volume_by_index(c, idx, &cstate->cvolume, pac_set_source_volume_cb, NULL))) {
-			fprintf(stderr, "set source #%d channel #%d volume: %s\n",
-				idx, channel, pa_strerror(pa_context_errno(c)));
-			return;
-		}
-		pa_operation_unref(o);
-	} else if (type == C_SINK) {
-		if (!(o = pa_context_set_sink_volume_by_index(c, idx, &cstate->cvolume, pac_set_sink_volume_cb, NULL))) {
-			fprintf(stderr, "set sink #%d channel #%d volume: %s\n",
-				idx, channel, pa_strerror(pa_context_errno(c)));
-			return;
-		}
-		pa_operation_unref(o);
-	}
-}
-
-pa_context *pac_init(void *this, const char *name) {
-	pa_context *c;
-	pa_mainloop_api *mapi;
-	char *server = NULL;
-	char *client = pa_xstrdup(name);
-
-	TAILQ_INIT(&cstateq);
-
-	if (!(m = pa_threaded_mainloop_new())) {
-		fprintf(stderr, "pa_mainloop_new() failed.\n");
-		return NULL;
-	}
-
-	pa_threaded_mainloop_set_name(m, "pa_mainloop");
-	mapi = pa_threaded_mainloop_get_api(m);
-
-	if (!(c = pa_context_new(mapi, client))) {
-		fprintf(stderr, "pa_context_new() failed.\n");
-		goto exit;
-	}
-
-	pa_context_set_state_callback(c, context_state_cb, this);
-	if (pa_context_connect(c, server, 0, NULL) < 0) {
-		fprintf(stderr, "pa_context_connect(): %s", pa_strerror(pa_context_errno(c)));
-		goto exit;
-	}
-
-	if (pa_threaded_mainloop_start(m) < 0) {
-		fprintf(stderr, "pa_mainloop_run() failed.\n");
-		goto exit;
-	}
-
-	return c;
-
-exit:
-	if (c)
-		pa_context_unref(c);
-
-	if (m)
-		pa_threaded_mainloop_free(m);
-
-	pa_xfree(client);
-
-	return NULL;
-}
diff --git a/app/pac.h b/app/pac.h
deleted file mode 100644
index ef0209d..0000000
--- a/app/pac.h
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Copyright (C) 2016 Konsulko Group
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <pulse/pulseaudio.h>
-#include <sys/queue.h>
-
-#ifdef __cplusplus
-extern "C" void pac_set_volume(pa_context *, uint32_t, uint32_t, uint32_t, uint32_t);
-extern "C" pa_context *pac_init(void *, const char *);
-#else
-static char * channel_position_string[] =
-{
-	"Mono",
-	"Front Left",
-	"Front Right",
-	"Center",
-	"Rear Center",
-	"Rear Left",
-	"Rear Right",
-	"LFE",
-	"Left Center",
-	"Right Center",
-	"Side Left",
-	"Side Right",
-};
-
-enum control_type
-{
-	C_SOURCE,
-	C_SINK
-};
-
-struct pac_cstate
-{
-	TAILQ_ENTRY(pac_cstate) tailq;
-	int type;
-	uint32_t index;
-	pa_cvolume cvolume;
-};
-
-#endif
diff --git a/app/paclient.cpp b/app/paclient.cpp
new file mode 100644
index 0000000..78567ce
--- /dev/null
+++ b/app/paclient.cpp
@@ -0,0 +1,228 @@
+/*
+ * Copyright (C) 2016,2017 Konsulko Group
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "paclient.h"
+
+#include <QtCore/QDebug>
+
+PaClient::PaClient()
+	: m_init(false), m_ml(nullptr), m_mlapi(nullptr), m_ctx(nullptr)
+{
+}
+
+PaClient::~PaClient()
+{
+	if (m_init)
+		close();
+}
+
+void PaClient::close()
+{
+	if (!m_init) return;
+	pa_threaded_mainloop_stop(m_ml);
+	pa_threaded_mainloop_free(m_ml);
+	m_init = false;
+}
+
+static void set_sink_volume_cb(pa_context *c, int success, void *data __attribute__((unused)))
+{
+	if (!success)
+		qWarning() << "PaClient: set sink volume: " <<
+			pa_strerror(pa_context_errno(c));
+}
+
+static void set_source_volume_cb(pa_context *c, int success, void *data __attribute__((unused)))
+{
+	if (!success)
+		qWarning() << "PaClient: set source volume: " <<
+			pa_strerror(pa_context_errno(c));
+}
+
+void PaClient::setVolume(uint32_t type, uint32_t index, uint32_t channel, uint32_t volume)
+{
+	pa_operation *o;
+	pa_context *c = context();
+	CState *cstate = NULL;
+
+	foreach (cstate, m_cstatelist)
+		if ((cstate->index == index) && (cstate->type == type))
+			break;
+
+	cstate->cvolume.values[channel] = volume;
+
+	if (type == C_SINK) {
+		if (!(o = pa_context_set_sink_volume_by_index(c, index, &cstate->cvolume, set_sink_volume_cb, NULL))) {
+			qWarning() << "PaClient: set sink #" << index <<
+				" channel #" << channel <<
+				" volume: " << pa_strerror(pa_context_errno(c));
+			return;
+		}
+		pa_operation_unref(o);
+	} else if (type == C_SOURCE) {
+		if (!(o = pa_context_set_source_volume_by_index(c, index, &cstate->cvolume, set_source_volume_cb, NULL))) {
+			qWarning() << "PaClient: set source #" << index <<
+				" channel #" << channel <<
+				" volume: " << pa_strerror(pa_context_errno(c));
+			return;
+		}
+		pa_operation_unref(o);
+	}
+}
+
+void get_source_list_cb(pa_context *c,
+		const pa_source_info *i,
+		int eol,
+		void *data)
+{
+	int chan;
+
+	PaClient *self = reinterpret_cast<PaClient*>(data);
+
+	if (eol < 0) {
+		qWarning() << "PaClient: get source list: " <<
+			pa_strerror(pa_context_errno(c));
+
+		self->close();
+		return;
+	}
+
+	if (!eol) {
+		self->addOneControlState(C_SOURCE, i->index, &i->volume);
+		for (chan = 0; chan < i->channel_map.channels; chan++) {
+			emit self->controlAdded(i->index, QString(i->description), C_SOURCE, chan,
+						channel_position_string[i->channel_map.map[chan]],
+						i->volume.values[chan]);
+		}
+	}
+}
+
+void get_sink_list_cb(pa_context *c,
+		const pa_sink_info *i,
+		int eol,
+		void *data)
+{
+	int chan;
+	PaClient *self = reinterpret_cast<PaClient*>(data);
+
+	if(eol < 0) {
+		qWarning() << "PaClient: get sink list: " <<
+			pa_strerror(pa_context_errno(c));
+		self->close();
+		return;
+	}
+
+	if(!eol) {
+		self->addOneControlState(C_SINK, i->index, &i->volume);
+		for (chan = 0; chan < i->channel_map.channels; chan++) {
+			emit self->controlAdded(i->index, QString(i->description), C_SINK, chan,
+						 channel_position_string[i->channel_map.map[chan]],
+						 i->volume.values[chan]);
+		}
+	}
+}
+
+void context_state_cb(pa_context *c, void *data)
+{
+	pa_operation *o;
+	PaClient *self = reinterpret_cast<PaClient*>(data);
+
+	switch (pa_context_get_state(c)) {
+		case PA_CONTEXT_CONNECTING:
+		case PA_CONTEXT_AUTHORIZING:
+		case PA_CONTEXT_SETTING_NAME:
+			break;
+		case PA_CONTEXT_READY:
+			// Fetch the controls of interest
+			if (!(o = pa_context_get_source_info_list(c, get_source_list_cb, data))) {
+				qWarning() << "PaClient: get source info list: " <<
+					pa_strerror(pa_context_errno(c));
+				return;
+			}
+			pa_operation_unref(o);
+			if (!(o = pa_context_get_sink_info_list(c, &get_sink_list_cb, data))) {
+				qWarning() << "PaClient: get sink info list: " <<
+					pa_strerror(pa_context_errno(c));
+				return;
+			}
+			break;
+		case PA_CONTEXT_TERMINATED:
+			self->close();
+			break;
+
+		case PA_CONTEXT_FAILED:
+		default:
+			qCritical() << "PaClient: connection failed: " <<
+				pa_strerror(pa_context_errno(c));
+			self->close();
+			break;
+	}
+}
+
+void PaClient::init()
+{
+	m_ml = pa_threaded_mainloop_new();
+	if (!m_ml) {
+		qCritical("PaClient: failed to create mainloop");
+		return;
+	}
+
+	pa_threaded_mainloop_set_name(m_ml, "PaClient mainloop");
+
+	m_mlapi = pa_threaded_mainloop_get_api(m_ml);
+
+	lock();
+
+	m_ctx = pa_context_new(m_mlapi, "Mixer");
+	if (!m_ctx) {
+		qCritical("PaClient: failed to create context");
+		pa_threaded_mainloop_free(m_ml);
+		return;
+	}
+	pa_context_set_state_callback(m_ctx, context_state_cb, this);
+
+	if (pa_context_connect(m_ctx, 0, (pa_context_flags_t)0, 0) < 0) {
+		qCritical("PaClient: failed to connect");
+		pa_context_unref(m_ctx);
+		pa_threaded_mainloop_free(m_ml);
+		return;
+	}
+
+	if (pa_threaded_mainloop_start(m_ml) != 0) {
+		qCritical("PaClient: failed to start mainloop");
+		pa_context_unref(m_ctx);
+		pa_threaded_mainloop_free(m_ml);
+		return;
+	}
+
+	unlock();
+
+	m_init = true;
+}
+
+void PaClient::addOneControlState(int type, int index, const pa_cvolume *cvolume)
+{
+	int i;
+	CState *cstate;
+
+	cstate = new CState;
+	cstate->type = type;
+	cstate->index = index;
+	cstate->cvolume.channels = cvolume->channels;
+	for (i = 0; i < cvolume->channels; i++)
+		cstate->cvolume.values[i] = cvolume->values[i];
+
+	m_cstatelist.append(cstate);
+}
diff --git a/app/paclient.h b/app/paclient.h
new file mode 100644
index 0000000..1367e81
--- /dev/null
+++ b/app/paclient.h
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2016,2017 Konsulko Group
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <pulse/pulseaudio.h>
+
+#include <QtCore/QObject>
+
+const char * const channel_position_string[] =
+{
+	"Mono",
+	"Front Left",
+	"Front Right",
+	"Center",
+	"Rear Center",
+	"Rear Left",
+	"Rear Right",
+	"LFE",
+	"Left Center",
+	"Right Center",
+	"Side Left",
+	"Side Right",
+};
+
+enum control_type
+{
+	C_SOURCE,
+	C_SINK
+};
+
+typedef struct
+{
+	uint32_t type;
+	uint32_t index;
+	pa_cvolume cvolume;
+} CState;
+
+class PaClient : public QObject
+{
+	Q_OBJECT
+	public:
+		PaClient();
+		~PaClient();
+
+		void init();
+		void close();
+
+ 		inline pa_context *context() const
+		{
+			return m_ctx;
+		}
+
+		inline void lock()
+		{
+			pa_threaded_mainloop_lock(m_ml);
+		}
+
+		inline void unlock()
+		{
+			pa_threaded_mainloop_unlock(m_ml);
+		}
+
+		void addOneControlState(int type, int index, const pa_cvolume *cvolume);
+
+	public slots:
+		void setVolume(uint32_t type, uint32_t index, uint32_t channel, uint32_t volume);
+
+	signals:
+		void controlAdded(int cindex, QString desc, int type, int channel, const char *cdesc, int volume);
+
+	private:
+		bool m_init;
+		pa_threaded_mainloop *m_ml;
+		pa_mainloop_api *m_mlapi;
+		pa_context *m_ctx;
+		QList<CState *> m_cstatelist;
+};
diff --git a/app/pacontrolmodel.cpp b/app/pacontrolmodel.cpp
index 520233b..bca72c5 100644
--- a/app/pacontrolmodel.cpp
+++ b/app/pacontrolmodel.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016 Konsulko Group
+ * Copyright (C) 2016,2017 Konsulko Group
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +15,6 @@
  */
 
 #include "pacontrolmodel.h"
-#include "pac.h"
 
 PaControl::PaControl(const quint32 &cindex, const QString &desc, const quint32 &type, const quint32 &channel, const QString &cdesc, const quint32 &volume)
 	: m_cindex(cindex), m_desc(desc), m_type(type), m_channel(channel), m_cdesc(cdesc), m_volume(volume)
@@ -79,18 +78,17 @@ void PaControl::setCDesc(const QVariant &cdesc)
 	m_cdesc = cdesc.toString();
 }
 
-void PaControl::setVolume(pa_context *pa_ctx, const QVariant &volume)
+void PaControl::setVolume(PaControlModel *pacm, const QVariant &volume)
 {
 	if (volume != m_volume) {
 		m_volume = volume.toUInt();
-		pac_set_volume(pa_ctx, type(), cindex(), channel(), m_volume);
+		emit pacm->volumeChanged(type(), cindex(), channel(), m_volume);
 	}
 }
 
 PaControlModel::PaControlModel(QObject *parent)
 	: QAbstractListModel(parent)
 {
-	pa_ctx = pac_init(this, "Mixer");
 }
 
 void PaControlModel::addControl(const PaControl &control)
@@ -100,11 +98,9 @@ void PaControlModel::addControl(const PaControl &control)
 	endInsertRows();
 }
 
-void add_one_control(void *ctx, int cindex, const char *desc, int type, int channel, const char *cdesc, int volume)
+void PaControlModel::addOneControl(int cindex, QString desc, int type, int channel, const char *cdesc, int volume)
 {
-	// Get the PaControlModel object from the opaque pointer context
-	PaControlModel *pacm = static_cast<PaControlModel*>(ctx);
-	pacm->addControl(PaControl(cindex, desc, type, channel, cdesc, volume));
+	addControl(PaControl(cindex, desc, type, channel, cdesc, volume));
 }
 
 int PaControlModel::rowCount(const QModelIndex & parent) const {
@@ -127,7 +123,7 @@ bool PaControlModel::setData(const QModelIndex &index, const QVariant &value, in
 	else if (role == CDescRole)
 		control.setCDesc(value);
 	else if (role == VolumeRole)
-		control.setVolume(pa_ctx, value);
+		control.setVolume(this, value);
 	emit dataChanged(index, index);
 	return true;
 }
diff --git a/app/pacontrolmodel.h b/app/pacontrolmodel.h
index aa34a79..475f7ce 100644
--- a/app/pacontrolmodel.h
+++ b/app/pacontrolmodel.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016 Konsulko Group
+ * Copyright (C) 2016,2017 Konsulko Group
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,13 +16,8 @@
 
 #include <pulse/pulseaudio.h>
 
-#ifndef __cplusplus
-extern void add_one_control(void *ctx, int, const char *, int, int, const char *, int);
-#else
-extern "C" void add_one_control(void *ctx, int, const char *, int, int, const char *, int);
-
-#include <QAbstractListModel>
-#include <QStringList>
+#include <QtCore/QAbstractListModel>
+#include <QtCore/QList>
 
 class PaControlModel;
 
@@ -42,7 +37,7 @@ class PaControl
 		void setType(const QVariant&);
 		void setChannel(const QVariant&);
 		void setCDesc(const QVariant&);
-		void setVolume(pa_context *, const QVariant&);
+		void setVolume(PaControlModel *, const QVariant&);
 
 	private:
 		quint32 m_cindex;
@@ -78,10 +73,15 @@ class PaControlModel : public QAbstractListModel
 
 		Qt::ItemFlags flags(const QModelIndex &index) const;
 
+	public slots:
+		void addOneControl(int cindex, QString desc, int type, int channel, const char *cdesc, int volume);
+
+	signals:
+		void volumeChanged(uint32_t type, uint32_t index, uint32_t channel, uint32_t volume);
+
 	protected:
 		QHash<int, QByteArray> roleNames() const;
 	private:
 		QList<PaControl> m_controls;
 		pa_context *pa_ctx;
 };
-#endif // __cplusplus