mixer/null: new mixer plugin

1 files changed, 67 insertions, 0 deletions

diff --git a/src/mixer/plugins/NullMixerPlugin.cxx b/src/mixer/plugins/NullMixerPlugin.cxx
new file mode 100644
index 000000000..b8894d443
--- /dev/null
+++ b/src/mixer/plugins/NullMixerPlugin.cxx
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "mixer/MixerInternal.hxx"
+
+class NullMixer final : public Mixer {
+	/**
+	 * The current volume in percent (0..100).
+	 */
+	unsigned volume;
+
+public:
+	NullMixer(MixerListener &_listener)
+		:Mixer(null_mixer_plugin, _listener),
+		 volume(100)
+	{
+	}
+
+	/* virtual methods from class Mixer */
+	bool Open(gcc_unused Error &error) override {
+		return true;
+	}
+
+	void Close() override {
+	}
+
+	int GetVolume(gcc_unused Error &error) override {
+		return volume;
+	}
+
+	bool SetVolume(unsigned _volume, gcc_unused Error &error) override {
+		volume = _volume;
+		return true;
+	}
+};
+
+static Mixer *
+null_mixer_init(gcc_unused EventLoop &event_loop,
+		gcc_unused AudioOutput &ao,
+		MixerListener &listener,
+		gcc_unused const config_param &param,
+		gcc_unused Error &error)
+{
+	return new NullMixer(listener);
+}
+
+const MixerPlugin null_mixer_plugin = {
+	null_mixer_init,
+	true,
+};