Make the trim knob on busses show only if there is audio

The trim knob has been designed to operate only on audio channels. If
the bus has none, hide the knob that would otherwise have no effect at
all.

Factor the trim control show/hide code out of MixerStrip::set_route(),
and also call that code in response to I/O changes in the route.

1 files changed, 16 insertions, 8 deletions

diff --git a/gtk2_ardour/mixer_strip.cc b/gtk2_ardour/mixer_strip.cc
index b5ae269c7f..1e8717d327 100644
--- a/gtk2_ardour/mixer_strip.cc
+++ b/gtk2_ardour/mixer_strip.cc
@@ -458,6 +458,20 @@ MixerStrip::name() const
 }
 
 void
+MixerStrip::update_trim_control ()
+{
+	if (route()->trim() && route()->trim()->active() &&
+	    route()->n_inputs().n_audio() > 0) {
+		trim_control.show ();
+		trim_control.set_controllable (route()->trim()->gain_control());
+	} else {
+		trim_control.hide ();
+		boost::shared_ptr<Controllable> none;
+		trim_control.set_controllable (none);
+	}
+}
+
+void
 MixerStrip::set_route (boost::shared_ptr<Route> rt)
 {
 	//the rec/monitor stuff only shows up for tracks.
@@ -563,14 +577,7 @@ MixerStrip::set_route (boost::shared_ptr<Route> rt)
 		monitor_disk_button->hide ();
 	}
 
-	if (route()->trim() && route()->trim()->active()) {
-		trim_control.show ();
-		trim_control.set_controllable (route()->trim()->gain_control());
-	} else {
-		trim_control.hide ();
-		boost::shared_ptr<Controllable> none;
-		trim_control.set_controllable (none);
-	}
+	update_trim_control();
 
 	if (is_midi_track()) {
 		if (midi_input_enable_button == 0) {
@@ -1509,6 +1516,7 @@ void
 MixerStrip::io_changed_proxy ()
 {
 	Glib::signal_idle().connect_once (sigc::mem_fun (*this, &MixerStrip::update_panner_choices));
+	Glib::signal_idle().connect_once (sigc::mem_fun (*this, &MixerStrip::update_trim_control));
 }
 
 void