From ba4464dc3ccf8dbe2c1641b2a49f58e513804b25 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Fri, 29 Apr 2016 10:33:05 -0400
Subject: [PATCH] show/hide VCA assign buttons depending on VCA existence

---
 gtk2_ardour/mixer_ui.cc         | 10 +++++++
 gtk2_ardour/visibility_group.cc | 49 +++++++++++++++++++++++++++++++++
 gtk2_ardour/visibility_group.h  |  3 ++
 3 files changed, 62 insertions(+)

diff --git a/gtk2_ardour/mixer_ui.cc b/gtk2_ardour/mixer_ui.cc
index 97485d162e..4d0c2c3e7f 100644
--- a/gtk2_ardour/mixer_ui.cc
+++ b/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 ();
 }
 
diff --git a/gtk2_ardour/visibility_group.cc b/gtk2_ardour/visibility_group.cc
index 46a941d0fc..9a59e613eb 100644
--- a/gtk2_ardour/visibility_group.cc
+++ b/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
 {
diff --git a/gtk2_ardour/visibility_group.h b/gtk2_ardour/visibility_group.h
index 8ac2c1db5f..ce1adecdd4 100644
--- a/gtk2_ardour/visibility_group.h
+++ b/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 {