Mixer: add class MixerListener

Use a listener interface instead of GlobalEvents.

src/output/Init.cxx

@@ -116,6 +116,7 @@ audio_output_load_mixer(EventLoop &event_loop, AudioOutput &ao,
 			const config_param &param,
 			const MixerPlugin *plugin,
 			Filter &filter_chain,
+			MixerListener &listener,
 			Error &error)
 {
 	Mixer *mixer;
@@ -129,10 +130,12 @@ audio_output_load_mixer(EventLoop &event_loop, AudioOutput &ao,
 		if (plugin == nullptr)
 			return nullptr;
 
-		return mixer_new(event_loop, *plugin, ao, param, error);
+		return mixer_new(event_loop, *plugin, ao, listener,
+				 param, error);
 
 	case MIXER_TYPE_SOFTWARE:
 		mixer = mixer_new(event_loop, software_mixer_plugin, ao,
+				  listener,
 				  config_param(),
 				  IgnoreError());
 		assert(mixer != nullptr);
@@ -212,6 +215,7 @@ AudioOutput::Configure(const config_param &param, Error &error)
 
 static bool
 audio_output_setup(EventLoop &event_loop, AudioOutput &ao,
+		   MixerListener &mixer_listener,
 		   const config_param &param,
 		   Error &error)
 {
@@ -244,7 +248,9 @@ audio_output_setup(EventLoop &event_loop, AudioOutput &ao,
 	Error mixer_error;
 	ao.mixer = audio_output_load_mixer(event_loop, ao, param,
 					   ao.plugin.mixer_plugin,
-					   *ao.filter, mixer_error);
+					   *ao.filter,
+					   mixer_listener,
+					   mixer_error);
 	if (ao.mixer == nullptr && mixer_error.IsDefined())
 		FormatError(mixer_error,
 			    "Failed to initialize hardware mixer for '%s'",
@@ -279,6 +285,7 @@ audio_output_setup(EventLoop &event_loop, AudioOutput &ao,
 
 AudioOutput *
 audio_output_new(EventLoop &event_loop, const config_param &param,
+		 MixerListener &mixer_listener,
 		 PlayerControl &pc,
 		 Error &error)
 {
@@ -317,7 +324,8 @@ audio_output_new(EventLoop &event_loop, const config_param &param,
 	if (ao == nullptr)
 		return nullptr;
 
-	if (!audio_output_setup(event_loop, *ao, param, error)) {
+	if (!audio_output_setup(event_loop, *ao, mixer_listener,
+				param, error)) {
 		ao_plugin_finish(ao);
 		return nullptr;
 	}

src/output/Internal.hxx

@@ -33,6 +33,8 @@ class Error;
 class Filter;
 class MusicPipe;
 class EventLoop;
+class Mixer;
+class MixerListener;
 struct music_chunk;
 struct config_param;
 struct PlayerControl;
@@ -79,7 +81,7 @@ struct AudioOutput {
 	 * May be nullptr if none is available, or if software volume is
 	 * configured.
 	 */
-	class Mixer *mixer;
+	Mixer *mixer;
 
 	/**
 	 * Will this output receive tags from the decoder?  The
@@ -424,6 +426,7 @@ extern struct notify audio_output_client_notify;
 
 AudioOutput *
 audio_output_new(EventLoop &event_loop, const config_param &param,
+		 MixerListener &mixer_listener,
 		 PlayerControl &pc,
 		 Error &error);
 

src/output/MultipleOutputs.cxx

@@ -35,8 +35,9 @@
 #include <assert.h>
 #include <string.h>
 
-MultipleOutputs::MultipleOutputs()
-	:buffer(nullptr), pipe(nullptr),
+MultipleOutputs::MultipleOutputs(MixerListener &_mixer_listener)
+	:mixer_listener(_mixer_listener),
+	 buffer(nullptr), pipe(nullptr),
 	 elapsed_time(-1)
 {
 }
@@ -50,10 +51,13 @@ MultipleOutputs::~MultipleOutputs()
 }
 
 static AudioOutput *
-LoadOutput(EventLoop &event_loop, PlayerControl &pc, const config_param &param)
+LoadOutput(EventLoop &event_loop, MixerListener &mixer_listener,
+	   PlayerControl &pc, const config_param &param)
 {
 	Error error;
-	AudioOutput *output = audio_output_new(event_loop, param, pc, error);
+	AudioOutput *output = audio_output_new(event_loop, param,
+					       mixer_listener,
+					       pc, error);
 	if (output == nullptr) {
 		if (param.line > 0)
 			FormatFatalError("line %i: %s",
@@ -72,7 +76,8 @@ MultipleOutputs::Configure(EventLoop &event_loop, PlayerControl &pc)
 	const config_param *param = nullptr;
 	while ((param = config_get_next_param(CONF_AUDIO_OUTPUT,
 					      param)) != nullptr) {
-		auto output = LoadOutput(event_loop, pc, *param);
+		auto output = LoadOutput(event_loop, mixer_listener,
+					 pc, *param);
 		if (FindByName(output->name) != nullptr)
 			FormatFatalError("output devices with identical "
 					 "names: %s", output->name);
@@ -83,7 +88,8 @@ MultipleOutputs::Configure(EventLoop &event_loop, PlayerControl &pc)
 	if (outputs.empty()) {
 		/* auto-detect device */
 		const config_param empty;
-		auto output = LoadOutput(event_loop, pc, empty);
+		auto output = LoadOutput(event_loop, mixer_listener,
+					 pc, empty);
 		outputs.push_back(output);
 	}
 }

src/output/MultipleOutputs.hxx

@@ -38,12 +38,15 @@ struct AudioFormat;
 class MusicBuffer;
 class MusicPipe;
 class EventLoop;
+class MixerListener;
 struct music_chunk;
 struct PlayerControl;
 struct AudioOutput;
 class Error;
 
 class MultipleOutputs {
+	MixerListener &mixer_listener;
+
 	std::vector<AudioOutput *> outputs;
 
 	AudioFormat input_audio_format;
@@ -70,7 +73,7 @@ public:
 	 * Load audio outputs from the configuration file and
 	 * initialize them.
 	 */
-	MultipleOutputs();
+	MultipleOutputs(MixerListener &_mixer_listener);
 	~MultipleOutputs();
 
 	void Configure(EventLoop &event_loop, PlayerControl &pc);