show/hide VCA assign buttons depending on VCA existence

gtk2_ardour/mixer_ui.cc

@@ -1233,6 +1233,7 @@ Mixer_UI::redisplay_track_list ()
 {
 	TreeModel::Children rows = track_model->children();
 	TreeModel::Children::iterator i;
+	uint32_t n_masters = 0;
 
 	if (no_track_list_redisplay) {
 		return;
@@ -1247,6 +1248,7 @@ Mixer_UI::redisplay_track_list ()
 		if (vms) {
 			vca_packer.pack_start (*vms, false, false);
 			vms->show ();
+			n_masters++;
 			continue;
 		}
 
@@ -1296,6 +1298,14 @@ Mixer_UI::redisplay_track_list ()
 		}
 	}
 
+	/* update visibility of VCA assign buttons */
+
+	if (n_masters == 0) {
+		UIConfiguration::instance().set_mixer_strip_visibility (VisibilityGroup::remove_element (UIConfiguration::instance().get_mixer_strip_visibility(), X_("VCA")));
+	} else {
+		UIConfiguration::instance().set_mixer_strip_visibility (VisibilityGroup::add_element (UIConfiguration::instance().get_mixer_strip_visibility(), X_("VCA")));
+	}
+
 	_group_tabs->set_dirty ();
 }
 

gtk2_ardour/visibility_group.cc

@@ -21,7 +21,10 @@
 #include <gtkmm/menu.h>
 #include <gtkmm/menushell.h>
 #include <gtkmm/treeview.h>
+
+#include "pbd/strsplit.h"
 #include "pbd/xml++.h"
+
 #include "visibility_group.h"
 
 #include "i18n.h"
@@ -167,6 +170,52 @@ VisibilityGroup::set_state (string v)
 	update ();
 }
 
+string
+VisibilityGroup::remove_element (std::string const& from, std::string const& element)
+{
+	std::vector<string> s;
+	std::string ret;
+
+	split (from, s, ',');
+	for (std::vector<string>::const_iterator i = s.begin(); i != s.end(); ++i) {
+		if ((*i) == element) {
+			continue;
+		}
+		if (!ret.empty()) {
+			ret += ',';
+		}
+		ret += *i;
+	}
+
+	return ret;
+}
+
+string
+VisibilityGroup::add_element (std::string const& from, std::string const& element)
+{
+	std::vector<string> s;
+	std::string ret;
+	
+	split (from, s, ',');
+
+	for (std::vector<string>::const_iterator i = s.begin(); i != s.end(); ++i) {
+		if ((*i) == element) {
+			/* already present, just return the original */
+			return from;
+		}
+	}
+
+	ret = from;
+
+	if (!ret.empty()) {
+		ret += ',';
+	}
+
+	ret += element;
+
+	return ret;
+}
+
 string
 VisibilityGroup::get_state_name () const
 {

gtk2_ardour/visibility_group.h

@@ -56,6 +56,9 @@ public:
 
 	PBD::Signal0<void> VisibilityChanged;
 
+	static std::string remove_element (std::string const& from, std::string const& element);
+	static std::string add_element (std::string const& from, std::string const& element);
+
 private:
 
 	struct Member {