Add API to run automation only (emit Changed signal).

Note: MuteControl already implemented this,
This removes the special case of boolean_automation_run().

Likewise this removes special-cases for actually_set_value() during
automation playback.

libs/ardour/ardour/automation_control.h

@@ -104,6 +104,8 @@ public:
 		actually_set_value (val, PBD::Controllable::NoGroup);
 	}
 
+	virtual void automation_run (framepos_t start, pframes_t nframes);
+
 	double lower()   const { return _desc.lower; }
 	double upper()   const { return _desc.upper; }
 	double normal()  const { return _desc.normal; }

libs/ardour/ardour/slavable_automation_control.h

@@ -46,6 +46,8 @@ public:
 	bool slaved_to (boost::shared_ptr<AutomationControl>) const;
 	bool slaved () const;
 
+	virtual void automation_run (framepos_t start, pframes_t nframes);
+
 	double get_masters_value () const {
 		Glib::Threads::RWLock::ReaderLock lm (master_lock);
 		return get_masters_value_locked ();

libs/ardour/automation_control.cc

@@ -146,6 +146,27 @@ AutomationControl::grouped_controls () const
 	}
 }
 
+void
+AutomationControl::automation_run (framepos_t start, pframes_t nframes)
+{
+	if (!automation_playback ()) {
+		return;
+	}
+
+	assert (_list);
+	bool valid = false;
+	double val = _list->rt_safe_eval (start, valid);
+	if (!valid) {
+		return;
+	}
+	if (toggled ()) {
+		const double thresh = .5 * (_desc.upper - _desc.lower);
+		set_value_unchecked (val >= thresh ? _desc.upper : _desc.lower);
+	} else {
+		set_value_unchecked (val);
+	}
+}
+
 /** Set the value and do the right thing based on automation state
  *  (e.g. record if necessary, etc.)
  *  @param value `user' value
@@ -156,7 +177,6 @@ AutomationControl::actually_set_value (double value, PBD::Controllable::GroupCon
 	boost::shared_ptr<AutomationList> al = boost::dynamic_pointer_cast<AutomationList> (_list);
 	const framepos_t pos = _session.transport_frame();
 	bool to_list;
-	double old_value;
 
 	/* We cannot use ::get_value() here since that is virtual, and intended
 	   to return a scalar value that in some way reflects the state of the
@@ -173,36 +193,28 @@ AutomationControl::actually_set_value (double value, PBD::Controllable::GroupCon
 	   anything has changed) is the one derived from the automation event
 	   list.
 	*/
+	float old_value = Control::user_double();
 
-	if (!al) {
-		to_list = false;
-		old_value = Control::user_double();
+	if (al && al->automation_write ()) {
+		to_list = true;
 	} else {
-		if (al->automation_write ()) {
-			to_list = true;
-			old_value = Control::user_double ();
-		} else if (al->automation_playback()) {
-			to_list = false;
-			old_value = al->eval (pos);
-		} else {
-			to_list = false;
-			old_value = Control::user_double ();
-		}
+		to_list = false;
 	}
 
 	Control::set_double (value, pos, to_list);
 
-	if (old_value != value) {
-		//AutomationType at = (AutomationType) _parameter.type();
-		//std::cerr << "++++ Changed (" << enum_2_string (at) << ", " << enum_2_string (gcd) << ") = " << value
-		//<< " (was " << old_value << ") @ " << this << std::endl;
+	if (old_value != (float)value) {
+#if 0
+		AutomationType at = (AutomationType) _parameter.type();
+		std::cerr << "++++ Changed (" << enum_2_string (at) << ", " << enum_2_string (gcd) << ") = " << value
+		<< " (was " << old_value << ") @ " << this << std::endl;
+#endif
 
 		Changed (true, gcd);
 		if (!al || !al->automation_playback ()) {
 			_session.set_dirty ();
 		}
 	}
-
 }
 
 void

libs/ardour/slavable_automation_control.cc

@@ -290,11 +290,7 @@ SlavableAutomationControl::master_changed (bool /*from_self*/, GroupControlDispo
 {
 	boost::shared_ptr<AutomationControl> m = wm.lock ();
 	assert (m);
-	Glib::Threads::RWLock::ReaderLock lm (master_lock, Glib::Threads::TRY_LOCK);
-	if (!lm.locked ()) {
-		/* boolean_automation_run_locked () special case */
-		return;
-	}
+	Glib::Threads::RWLock::ReaderLock lm (master_lock);
 	bool send_signal = handle_master_change (m);
 	lm.release (); // update_boolean_masters_records() takes lock
 
@@ -521,6 +517,28 @@ SlavableAutomationControl::handle_master_change (boost::shared_ptr<AutomationCon
 	return true; // emit Changed
 }
 
+void
+SlavableAutomationControl::automation_run (framepos_t start, pframes_t nframes)
+{
+	if (!automation_playback ()) {
+		return;
+	}
+
+	assert (_list);
+	bool valid = false;
+	double val = _list->rt_safe_eval (start, valid);
+	if (!valid) {
+		return;
+	}
+	if (toggled ()) {
+		const double thresh = .5 * (_desc.upper - _desc.lower);
+		bool on = (val >= thresh) || (get_masters_value () >= thresh);
+		set_value_unchecked (on ? _desc.upper : _desc.lower);
+	} else {
+		set_value_unchecked (val * get_masters_value ());
+	}
+}
+
 bool
 SlavableAutomationControl::boolean_automation_run_locked (framepos_t start, pframes_t len)
 {
@@ -551,11 +569,6 @@ SlavableAutomationControl::boolean_automation_run_locked (framepos_t start, pfra
 		if (mr->second.yn() != yn) {
 			rv |= handle_master_change (ac);
 			mr->second.set_yn (yn);
-			/* notify the GUI, without recursion:
-			 * master_changed() above will ignore the change if the lock is held.
-			 */
-			ac->set_value_unchecked (yn ? 1. : 0.);
-			ac->Changed (false, Controllable::NoGroup); /* EMIT SIGNAL */
 		}
 	}
 	return rv;