add JACK backend support for MIDI option discovery

libs/backends/jack/jack_audiobackend.cc

@@ -490,6 +490,8 @@ JACKAudioBackend::setup_jack_startup_command ()
 	options.realtime = true;
 	options.ports_max = 2048;
 	
+	ARDOUR::set_midi_option (options, _target_midi_option);
+
 	/* this must always be true for any server instance we start ourselves
 	 */
 
@@ -1110,3 +1112,16 @@ JACKAudioBackend::launch_control_app ()
 	args.push_back (appname);
 	Glib::spawn_async ("", args, Glib::SPAWN_SEARCH_PATH);
 }
+
+vector<string>
+JACKAudioBackend::enumerate_midi_options () const
+{
+	return ARDOUR::enumerate_midi_options ();
+}
+
+int
+JACKAudioBackend::set_midi_option (const string& opt)
+{
+	_target_midi_option = opt;
+	return 0;
+}

libs/backends/jack/jack_audiobackend.h

@@ -149,6 +149,9 @@ class JACKAudioBackend : public AudioBackend {
     
     /* MIDI */
 
+    std::vector<std::string> enumerate_midi_options () const;
+    int set_midi_option (const std::string&);
+
     int      midi_event_get (pframes_t& timestamp, size_t& size, uint8_t** buf, void* port_buffer, uint32_t event_index);
     int      midi_event_put (void* port_buffer, pframes_t timestamp, const uint8_t* buffer, size_t size);
     uint32_t get_midi_event_count (void* port_buffer);
@@ -237,6 +240,7 @@ class JACKAudioBackend : public AudioBackend {
     uint32_t     _target_systemic_output_latency;
     uint32_t     _current_sample_rate;
     uint32_t     _current_buffer_size;
+    std::string  _target_midi_option;
 
     typedef std::set<std::string> DeviceList;
     typedef std::map<std::string,DeviceList> DriverDeviceMap;

libs/backends/jack/jack_utils.cc

@@ -92,6 +92,8 @@ namespace {
 	const char * const default_device_name = X_("Default");
 }
 
+static ARDOUR::MidiOptions midi_options;
+
 std::string
 get_none_string ()
 {
@@ -846,6 +848,9 @@ ARDOUR::get_jack_command_line_string (JackCommandLineOptions& options, string& c
 		if (options.soft_mode) {
 			args.push_back ("-s");
 		}
+	}
+
+	if (options.driver == alsa_driver_name || options.driver == coreaudio_driver_name) {
 
 		if (!options.midi_driver.empty() && options.midi_driver != get_none_string ()) {
 			args.push_back ("-X");
@@ -900,3 +905,52 @@ ARDOUR::write_jack_config_file (const std::string& config_file_path, const strin
 	jackdrc.close ();
 	return true;
 }
+
+vector<string>
+ARDOUR::enumerate_midi_options () 
+{
+	if (midi_options.empty()) {
+#ifdef HAVE_ALSA
+		midi_options.push_back (make_pair (_("ALSA raw devices"), alsaraw_midi_driver_name));
+		midi_options.push_back (make_pair (_("ALSA sequencer"), alsaseq_midi_driver_name));
+#endif
+#ifdef HAVE_PORTAUDIO
+		/* Windows folks: what name makes sense here? Are there other
+		   choices as well ?
+		*/
+		midi_options.push_back (make_pair (_("Multimedia Extension"), winmme_midi_driver_name));
+#endif
+#ifdef __APPLE__
+		midi_options.push_back (make_pair (_("CoreMIDI"), coremidi_midi_driver_name));
+#endif
+	}
+
+	vector<string> v;
+
+	v.push_back (get_none_string());
+
+	for (MidiOptions::const_iterator i = midi_options.begin(); i != midi_options.end(); ++i) {
+		v.push_back (i->first);
+	}
+
+	return v;
+}
+
+int
+ARDOUR::set_midi_option (ARDOUR::JackCommandLineOptions& options, const string& opt)
+{
+	if (opt.empty() || opt == get_none_string()) {
+		options.midi_driver = "";
+		return 0;
+	}
+
+	for (MidiOptions::const_iterator i = midi_options.begin(); i != midi_options.end(); ++i) {
+		if (i->first == opt) {
+			options.midi_driver = i->second;
+			return 0;
+		}
+	}
+
+	return -1;
+}
+

libs/backends/jack/jack_utils.h

@@ -180,6 +180,8 @@ namespace ARDOUR {
 	 */
 	bool get_jack_default_server_path (std::string& server_path);
 
+	typedef std::vector<std::pair<std::string,std::string> > MidiOptions;
+
 	/**
 	 * @return The name of the jack server config file
 	 */
@@ -228,6 +230,9 @@ namespace ARDOUR {
 		std::string      midi_driver;
 	};
 
+	std::vector<std::string> enumerate_midi_options ();
+	int set_midi_option (ARDOUR::JackCommandLineOptions&, const std::string& opt);
+
 	/**
 	 * @return true if able to build a valid command line based on options
 	 */