Add support for Latch Automation

libs/ardour/ardour/automation_list.h

@@ -89,10 +89,10 @@ public:
 	PBD::Signal1<void, AutoState> automation_state_changed;
 
 	bool automation_playback() const {
-		return (_state & Play) || ((_state & Touch) && !touching());
+		return (_state & Play) || ((_state & (Touch | Latch)) && !touching());
 	}
 	bool automation_write () const {
-		return ((_state & Write) || ((_state & Touch) && touching()));
+		return ((_state & Write) || ((_state & (Touch | Latch)) && touching()));
 	}
 
 	PBD::Signal0<void> StateChanged;
@@ -106,7 +106,7 @@ public:
 	void stop_touch (double when);
 	bool touching() const { return g_atomic_int_get (const_cast<gint*>(&_touching)); }
 	bool writing() const { return _state == Write; }
-	bool touch_enabled() const { return _state == Touch; }
+	bool touch_enabled() const { return _state & (Touch | Latch); }
 
 	XMLNode& get_state ();
 	int set_state (const XMLNode &, int version);

libs/ardour/ardour/pannable.h

@@ -58,19 +58,19 @@ class LIBARDOUR_API Pannable : public PBD::Stateful, public Automatable, public
 	PBD::Signal1<void, AutoState> automation_state_changed;
 
 	bool automation_playback() const {
-		return (_auto_state & Play) || ((_auto_state & Touch) && !touching());
+		return (_auto_state & Play) || ((_auto_state & (Touch | Latch)) && !touching());
 	}
 	bool automation_write () const {
-		return ((_auto_state & Write) || ((_auto_state & Touch) && touching()));
+		return ((_auto_state & Write) || ((_auto_state & (Touch | Latch)) && touching()));
 	}
 
 	std::string value_as_string (boost::shared_ptr<const AutomationControl>) const;
 
 	void start_touch (double when);
 	void stop_touch (double when);
-        bool touching() const { return g_atomic_int_get (const_cast<gint*>(&_touching)); }
+	bool touching() const { return g_atomic_int_get (const_cast<gint*>(&_touching)); }
 	bool writing() const { return _auto_state == Write; }
-	bool touch_enabled() const { return _auto_state == Touch; }
+	bool touch_enabled() const { return _auto_state & (Touch | Latch); }
 
 	XMLNode& get_state ();
 	XMLNode& state (bool full_state);

libs/ardour/ardour/types.h

@@ -163,10 +163,11 @@ namespace ARDOUR {
 	};
 
 	enum AutoState {
-		Off = 0x0,
+		Off   = 0x00,
-		Write = 0x1,
+		Write = 0x01,
-		Touch = 0x2,
+		Touch = 0x02,
-		Play = 0x4
+		Play  = 0x04,
+		Latch = 0x08
 	};
 
 	std::string auto_state_to_string (AutoState);

libs/ardour/automatable.cc

@@ -329,6 +329,8 @@ Automatable::protect_automation ()
 		case Write:
 			l->set_automation_state (Off);
 			break;
+		case Latch:
+			// no break
 		case Touch:
 			l->set_automation_state (Play);
 			break;
@@ -408,6 +410,7 @@ Automatable::non_realtime_transport_stop (framepos_t now, bool /*flush_processor
 		*/
 		const bool list_did_write = !l->in_new_write_pass ();
 
+		c->stop_touch (now);
 		l->stop_touch (now);
 
 		c->commit_transaction (list_did_write);

libs/ardour/automation_control.cc

@@ -253,7 +253,7 @@ AutomationControl::set_automation_state (AutoState as)
 
 		if (as == Write) {
 			AutomationWatch::instance().add_automation_watch (shared_from_this());
-		} else if (as == Touch) {
+		} else if (as & (Touch | Latch)) {
 			if (alist()->empty()) {
 				Control::set_double (val, _session.current_start_frame (), true);
 				Control::set_double (val, _session.current_end_frame (), true);
@@ -283,7 +283,7 @@ AutomationControl::start_touch (double when)
 		return;
 	}
 
-	if (alist()->automation_state() == Touch) {
+	if (alist()->automation_state() & (Touch | Latch)) {
 		/* subtle. aligns the user value with the playback and
 		 * use take actual value (incl masters).
 		 *
@@ -306,9 +306,13 @@ AutomationControl::stop_touch (double when)
 		return;
 	}
 
+	if (alist()->automation_state() == Latch && _session.transport_rolling ()) {
+		return;
+	}
+
 	set_touching (false);
 
-	if (alist()->automation_state() == Touch) {
+	if (alist()->automation_state() & (Touch | Latch)) {
 		alist()->stop_touch (when);
 		if (!_desc.toggled) {
 			AutomationWatch::instance().remove_automation_watch (shared_from_this());

libs/ardour/enums.cc

@@ -177,6 +177,7 @@ setup_enum_writer ()
 	REGISTER_ENUM (Write);
 	REGISTER_ENUM (Touch);
 	REGISTER_ENUM (Play);
+	REGISTER_ENUM (Latch);
 	REGISTER_BITS (_AutoState);
 
 	REGISTER_ENUM (CaptureTime);

libs/ardour/luabindings.cc

@@ -1704,6 +1704,7 @@ LuaBindings::common (lua_State* L)
 		.addConst ("Write", ARDOUR::AutoState(Write))
 		.addConst ("Touch", ARDOUR::AutoState(Touch))
 		.addConst ("Play", ARDOUR::AutoState(Play))
+		.addConst ("Latch", ARDOUR::AutoState(Latch))
 		.endNamespace ()
 
 		.beginNamespace ("AutomationType")

libs/ardour/panner_shell.cc

@@ -382,7 +382,7 @@ PannerShell::run (BufferSet& inbufs, BufferSet& outbufs, framepos_t start_frame,
 
 	// If we shouldn't play automation defer to distribute_no_automation
 
-	if (!(as & Play || ((as & Touch) && !_panner->touching()))) {
+	if (!((as & Play) || ((as & (Touch | Latch)) && !_panner->touching()))) {
 
 		distribute_no_automation (inbufs, outbufs, nframes, 1.0);
 

libs/ardour/utils.cc

@@ -561,6 +561,8 @@ ARDOUR::string_to_auto_state (std::string str)
 		return Write;
 	} else if (str == X_("Touch")) {
 		return Touch;
+	} else if (str == X_("Latch")) {
+		return Latch;
 	}
 
 	fatal << string_compose (_("programming error: %1 %2"), "illegal AutoState string: ", str) << endmsg;
@@ -585,6 +587,10 @@ ARDOUR::auto_state_to_string (AutoState as)
 		break;
 	case Touch:
 		return X_("Touch");
+		break;
+	case Latch:
+		return X_("Latch");
+		break;
 	}
 
 	fatal << string_compose (_("programming error: %1 %2"), "illegal AutoState type: ", as) << endmsg;