Auditioner: retain instrument plugin

This allows the Trigger Clip Picker to keep the
Plugin GUI available, and retain any custom settings.

libs/ardour/ardour/auditioner.h

@@ -89,7 +89,7 @@ public:
 
 	int export_stuff (BufferSet&, samplepos_t, samplecnt_t, boost::shared_ptr<Processor>, bool, bool, bool, MidiNoteTracker&) { return -1; }
 
-	void set_audition_synth_info(PluginInfoPtr in) { audition_synth_info = in; }
+	void set_audition_synth_info(PluginInfoPtr in);
 
 	samplecnt_t output_latency () const { return 0; }
 
@@ -104,6 +104,7 @@ private:
 	Glib::Threads::Mutex lock;
 	timecnt_t length;
 	sampleoffset_t _seek_sample;
+	bool _reload_synth;
 	bool _seeking;
 	bool _seek_complete;
 	bool via_monitor;
@@ -115,7 +116,7 @@ private:
 	PluginInfoPtr lookup_fallback_synth_plugin_info (std::string const&) const;
 	void drop_ports ();
 	void lookup_fallback_synth ();
-	void load_synth(bool);
+	bool load_synth();
 	void unload_synth (bool);
 	static void*_drop_ports (void*);
 	void actually_drop_ports ();

libs/ardour/auditioner.cc

@@ -53,6 +53,7 @@ Auditioner::Auditioner (Session& s)
 	, current_sample (0)
 	, length (0)
 	, _seek_sample (-1)
+	, _reload_synth (false)
 	, _seeking (false)
 	, _seek_complete (false)
 	, via_monitor (false)
@@ -126,23 +127,47 @@ Auditioner::lookup_fallback_synth ()
 	set_audition_synth_info(nfo);
 }
 
-void
-Auditioner::load_synth (bool need_lock)
+bool
+Auditioner::load_synth ()
 {
-	unload_synth(need_lock);
-
 	if (!audition_synth_info) {
 		lookup_fallback_synth ();
 	}
 
 	if (!audition_synth_info) {
-		return;
+		unload_synth (true);
+		return false;
 	}
 
+	if (asynth && !_reload_synth) {
+		asynth->deactivate ();
+		asynth->activate ();
+		_queue_panic = true;
+		return true;
+	}
+
+	unload_synth (true);
+
 	boost::shared_ptr<Plugin> p = audition_synth_info->load (_session);
 	if (p) {
 		asynth = boost::shared_ptr<Processor> (new PluginInsert (_session, time_domain(), p));
 	}
+
+	if (asynth) {
+		ProcessorStreams ps;
+		if (add_processor (asynth, PreFader, &ps, true)) {
+			error << _("Failed to load synth for MIDI-Audition.") << endmsg;
+		}
+
+		Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
+		if (configure_processors (&ps)) {
+			error << _("Cannot setup auditioner processing flow.") << endmsg;
+			unload_synth (true);
+			return false;
+		}
+		_reload_synth = false;
+	}
+	return true;
 }
 
 void
@@ -320,8 +345,8 @@ Auditioner::audition_region (boost::shared_ptr<Region> region)
 		_disk_reader->audio_playlist()->drop_regions ();
 		_disk_reader->audio_playlist()->add_region (the_region, timepos_t (Temporal::AudioTime), 1);
 
-		ProcessorStreams ps;
 		{
+			ProcessorStreams ps;
 			Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
 
 			if (configure_processors (&ps)) {
@@ -347,26 +372,8 @@ Auditioner::audition_region (boost::shared_ptr<Region> region)
 		_disk_reader->midi_playlist()->add_region (midi_region, _import_position, 1);
 		_disk_reader->reset_tracker();
 
-		ProcessorStreams ps;
-
-		load_synth (true);
-
-		if (asynth) {
-			int rv = add_processor (asynth, PreFader, &ps, true);
-			if (rv) {
-				error << _("Failed to load synth for MIDI-Audition.") << endmsg;
-			}
-		}
-
-		{
-			Glib::Threads::Mutex::Lock lm (AudioEngine::instance()->process_lock ());
-
-			if (configure_processors (&ps)) {
-				error << string_compose (_("Cannot setup auditioner processing flow for %1 channels"),
-				                         region->sources().size()) << endmsg;
-				unload_synth (true);
-				return;
-			}
+		if (!load_synth ()) {
+			return;
 		}
 
 	} else {
@@ -421,6 +428,16 @@ Auditioner::audition_region (boost::shared_ptr<Region> region)
 	g_atomic_int_set (&_auditioning, 1);
 }
 
+void
+Auditioner::set_audition_synth_info(PluginInfoPtr in)
+{
+	if (audition_synth_info == in) {
+		return;
+	}
+	audition_synth_info = in;
+	_reload_synth = true;
+}
+
 int
 Auditioner::play_audition (samplecnt_t nframes)
 {
@@ -430,7 +447,9 @@ Auditioner::play_audition (samplecnt_t nframes)
 
 	if (g_atomic_int_get (&_auditioning) == 0) {
 		silence (nframes);
-		unload_synth (false);
+		if (_reload_synth) {
+			unload_synth (false);
+		}
 		return 0;
 	}
 
@@ -489,7 +508,9 @@ Auditioner::play_audition (samplecnt_t nframes)
 
 	if (current_sample >= (length + _import_position).samples()) {
 		_session.cancel_audition ();
-		unload_synth (false);
+		if (_reload_synth) {
+			unload_synth (false);
+		}
 		return 0;
 	} else {
 		return need_butler ? 1 : 0;