consolidate engine-dialog widget sensitivity logic.

Use a single function with the complete logic.

Since the callgraph is complex, there is internal state as well as GUI
state (different pages), do not rely on individual methods to get it
right.

A widget's sensitivity should only be controlled by one function.

gtk2_ardour/engine_dialog.cc

@@ -716,6 +716,81 @@ EngineControl::setup_midi_tab_for_backend ()
 	midi_vbox.show_all ();
 }
 
+void
+EngineControl::update_sensitivity ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	if (!backend) {
+		ok_button->set_sensitive (false);
+		apply_button->set_sensitive (false);
+		return;
+	}
+
+	bool valid = true;
+	size_t devices_available = 0;
+
+	if (backend->use_separate_input_and_output_devices ()) {
+		devices_available += get_popdown_string_count (input_device_combo);
+		devices_available += get_popdown_string_count (output_device_combo);
+	} else {
+		devices_available += get_popdown_string_count (device_combo);
+	}
+
+	if (devices_available == 0) {
+		valid = false;
+		input_latency.set_sensitive (false);
+		output_latency.set_sensitive (false);
+		input_channels.set_sensitive (false);
+		output_channels.set_sensitive (false);
+	} else {
+		input_latency.set_sensitive (true);
+		output_latency.set_sensitive (true);
+		input_channels.set_sensitive (true);
+		output_channels.set_sensitive (true);
+	}
+
+	if (get_popdown_string_count (buffer_size_combo) > 0) {
+		if (!ARDOUR::AudioEngine::instance()->running()) {
+			buffer_size_combo.set_sensitive (valid);
+		} else if (backend->can_change_sample_rate_when_running()) {
+			buffer_size_combo.set_sensitive (valid || !_have_control);
+		} else {
+#if 1
+			/* TODO
+			 * Currently there is no way to manually stop the
+			 * engine in order to re-configure it.
+			 * This needs to remain sensitive for now.
+			 */
+			buffer_size_combo.set_sensitive (true);
+#else
+			buffer_size_combo.set_sensitive (false);
+#endif
+		}
+	} else {
+		buffer_size_combo.set_sensitive (false);
+		valid = false;
+	}
+
+	if (get_popdown_string_count (sample_rate_combo) > 0) {
+		if (!ARDOUR::AudioEngine::instance()->running()) {
+			sample_rate_combo.set_sensitive (true);
+		} else {
+			sample_rate_combo.set_sensitive (false);
+		}
+	} else {
+		sample_rate_combo.set_sensitive (false);
+		valid = false;
+	}
+
+	if (valid || !_have_control) {
+		ok_button->set_sensitive (true);
+		apply_button->set_sensitive (true);
+	} else {
+		ok_button->set_sensitive (false);
+		apply_button->set_sensitive (false);
+	}
+}
+
 void
 EngineControl::setup_midi_tab_for_jack ()
 {
@@ -853,6 +928,12 @@ EngineControl::backend_changed ()
 
 	started_at_least_once = false;
 
+	/* changing the backend implies stopping the engine
+	 * ARDOUR::AudioEngine() may or may not emit this signal
+	 * depending on previous engine state
+	 */
+	engine_stopped (); // set "active/inactive"
+
 	if (!ignore_changes) {
 		maybe_display_saved_state ();
 	}
@@ -1070,40 +1151,12 @@ EngineControl::list_devices ()
 
 	if (devices_available) {
 		device_changed ();
-
-		input_latency.set_sensitive (true);
-		output_latency.set_sensitive (true);
-		input_channels.set_sensitive (true);
-		output_channels.set_sensitive (true);
-
-		ok_button->set_sensitive (true);
-		apply_button->set_sensitive (true);
-
 	} else {
 		device_combo.clear();
 		input_device_combo.clear();
 		output_device_combo.clear();
-		sample_rate_combo.set_sensitive (false);
-		buffer_size_combo.set_sensitive (false);
-		input_latency.set_sensitive (false);
-		output_latency.set_sensitive (false);
-		input_channels.set_sensitive (false);
-		output_channels.set_sensitive (false);
-		if (_have_control) {
-			ok_button->set_sensitive (false);
-			apply_button->set_sensitive (false);
-		} else {
-			ok_button->set_sensitive (true);
-			apply_button->set_sensitive (true);
-			if (backend->can_change_sample_rate_when_running() && sample_rate_combo.get_children().size() > 0) {
-				sample_rate_combo.set_sensitive (true);
-			}
-			if (backend->can_change_buffer_size_when_running() && buffer_size_combo.get_children().size() > 0) {
-				buffer_size_combo.set_sensitive (true);
-			}
-
-		}
 	}
+	update_sensitivity ();
 }
 
 void
@@ -1163,11 +1216,6 @@ EngineControl::set_samplerate_popdown_strings ()
 
 	if (_have_control) {
 		sr = get_sample_rates_for_all_devices ();
-		// currently possible if both devices are set to "None" and the backend
-		// returns no supported rates for both devices
-		if (sr.empty()) {
-			sr = get_default_sample_rates ();
-		}
 	} else {
 		sr = get_default_sample_rates ();
 	}
@@ -1179,10 +1227,9 @@ EngineControl::set_samplerate_popdown_strings ()
 		}
 	}
 
-	if (!s.empty()) {
+	set_popdown_strings (sample_rate_combo, s);
-		sample_rate_combo.set_sensitive (true);
-		set_popdown_strings (sample_rate_combo, s);
 
+	if (!s.empty()) {
 		if (desired.empty ()) {
 			float new_active_sr = backend->default_sample_rate ();
 
@@ -1195,9 +1242,8 @@ EngineControl::set_samplerate_popdown_strings ()
 			sample_rate_combo.set_active_text (desired);
 		}
 
-	} else {
-		sample_rate_combo.set_sensitive (false);
 	}
+	update_sensitivity ();
 }
 
 vector<uint32_t>
@@ -1240,15 +1286,9 @@ EngineControl::set_buffersize_popdown_strings ()
 	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
 	vector<uint32_t> bs;
 	vector<string> s;
-	string device_name;
 
 	if (_have_control) {
 		bs = get_buffer_sizes_for_all_devices ();
-		// currently possible if both devices are set to "None" and the backend
-		// returns no supported sizes for both devices
-		if (bs.empty()) {
-			bs = get_default_buffer_sizes ();
-		}
 	} else if (backend->can_change_buffer_size_when_running()) {
 		bs = get_default_buffer_sizes ();
 	}
@@ -1257,26 +1297,26 @@ EngineControl::set_buffersize_popdown_strings ()
 		s.push_back (bufsize_as_string (*x));
 	}
 
-	if (backend->use_separate_input_and_output_devices ()) {
+	set_popdown_strings (buffer_size_combo, s);
-		device_name = get_input_device_name ();
-	} else {
-		device_name = get_device_name ();
-	}
 
 	if (!s.empty()) {
-		buffer_size_combo.set_sensitive (true);
-		set_popdown_strings (buffer_size_combo, s);
 		buffer_size_combo.set_active_text (s.front());
 
 		uint32_t period = backend->buffer_size();
-		if (0 == period) {
+		if (0 == period && backend->use_separate_input_and_output_devices ()) {
-			period = backend->default_buffer_size(device_name);
+			period = backend->default_buffer_size (get_input_device_name ());
 		}
+		if (0 == period && backend->use_separate_input_and_output_devices ()) {
+			period = backend->default_buffer_size (get_output_device_name ());
+		}
+		if (0 == period && !backend->use_separate_input_and_output_devices ()) {
+			period = backend->default_buffer_size (get_device_name ());
+		}
+
 		set_active_text_if_present (buffer_size_combo, bufsize_as_string (period));
 		show_buffer_duration ();
-	} else {
-		buffer_size_combo.set_sensitive (false);
 	}
+	update_sensitivity ();
 }
 
 void
@@ -1327,8 +1367,8 @@ EngineControl::device_changed ()
 
 		set_samplerate_popdown_strings ();
 		set_buffersize_popdown_strings ();
-		/* XXX theoretically need to set min + max channel counts here
+
-		*/
+		/* TODO set min + max channel counts here */
 
 		manage_control_app_sensitivity ();
 	}
@@ -2395,9 +2435,8 @@ EngineControl::on_switch_page (GtkNotebookPage*, guint page_num)
 {
 	if (page_num == 0) {
 		cancel_button->set_sensitive (true);
-		ok_button->set_sensitive (true);
-		apply_button->set_sensitive (true);
 		_measure_midi.reset();
+		update_sensitivity ();
 	} else {
 		cancel_button->set_sensitive (false);
 		ok_button->set_sensitive (false);
@@ -2679,14 +2718,12 @@ EngineControl::engine_running ()
 	set_active_text_if_present (buffer_size_combo, bufsize_as_string (backend->buffer_size()));
 	sample_rate_combo.set_active_text (rate_as_string (backend->sample_rate()));
 
-	buffer_size_combo.set_sensitive (true);
-	sample_rate_combo.set_sensitive (true);
-
 	connect_disconnect_button.set_label (string_compose (_("Disconnect from %1"), backend->name()));
 	connect_disconnect_button.show();
 
 	started_at_least_once = true;
 	engine_status.set_markup(string_compose ("<span foreground=\"green\">%1</span>", _("Active")));
+	update_sensitivity();
 }
 
 void
@@ -2695,13 +2732,16 @@ EngineControl::engine_stopped ()
 	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
 	assert (backend);
 
-	buffer_size_combo.set_sensitive (false);
 	connect_disconnect_button.set_label (string_compose (_("Connect to %1"), backend->name()));
 	connect_disconnect_button.show();
 
-	sample_rate_combo.set_sensitive (true);
+	if (ARDOUR::Profile->get_mixbus()) {
-	buffer_size_combo.set_sensitive (true);
+		engine_status.set_markup("");
-	engine_status.set_markup(string_compose ("<span foreground=\"red\">%1</span>", _("Inactive")));
+	} else {
+		engine_status.set_markup(string_compose ("<span foreground=\"red\">%1</span>", _("Inactive")));
+	}
+
+	update_sensitivity();
 }
 
 void

gtk2_ardour/engine_dialog.h

@@ -292,6 +292,7 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
     void manage_control_app_sensitivity ();
     int push_state_to_backend (bool start);
     void post_push ();
+    void update_sensitivity ();
 
     /* latency measurement */
     void latency_button_clicked ();