rename ParameterChanged signal in Plugin to ParameterChangedExternally to reflect its intent, and clean up the result.

The signal exists to notify listeners that something outside of the host's control (e.g. a plugin's own GUI for AU or VST)
has modified a plugin parameter. Previous code had strange feedback loops and ambiguous semantics.

Significant modification of LV2 GUI updating was required.

Still to be tested for feedback loop issues: AudioUnits

4 files changed, 31 insertions, 37 deletions

diff --git a/gtk2_ardour/lv2_plugin_ui.cc b/gtk2_ardour/lv2_plugin_ui.cc
index 141f437f4c..e2c446ef20 100644
--- a/gtk2_ardour/lv2_plugin_ui.cc
+++ b/gtk2_ardour/lv2_plugin_ui.cc
@@ -20,7 +20,9 @@
 #include "ardour/lv2_plugin.h"
 #include "ardour/session.h"
 #include "pbd/error.h"
+#include "pbd/stacktrace.h"
 
+#include "gui_thread.h"
 #include "lv2_plugin_ui.h"
 #include "timers.h"
 
@@ -53,6 +55,9 @@ LV2PluginUI::write_from_ui(void*       controller,
 		}
 
 		boost::shared_ptr<AutomationControl> ac = me->_controllables[port_index];
+		/* Cache our local copy of the last value received from the GUI */
+		me->_values[port_index] = *(const float*) buffer;
+		/* Now update the control itself */
 		if (ac) {
 			ac->set_value(*(const float*)buffer);
 		}
@@ -120,26 +125,18 @@ LV2PluginUI::on_external_ui_closed(void* controller)
 }
 
 void
-LV2PluginUI::parameter_changed(uint32_t port_index, float val)
+LV2PluginUI::control_changed (uint32_t port_index)
 {
-	PlugUIBase::parameter_changed(port_index, val);
-
-	if (val != _values[port_index]) {
-		parameter_update(port_index, val);
+	/* Must run in GUI thread because we modify _updates with no lock */
+	if (_lv2->get_parameter (port_index) != _values[port_index]) {
+		/* current plugin parameter does not match last value received
+		   from GUI, so queue an update to push it to the GUI during
+		   our regular timeout.
+		*/
+		_updates.insert (port_index);
 	}
 }
 
-void
-LV2PluginUI::parameter_update(uint32_t port_index, float val)
-{
-	if (!_inst) {
-		return;
-	}
-
-	suil_instance_port_event((SuilInstance*)_inst, port_index, 4, 0, &val);
-	_values[port_index] = val;
-}
-
 bool
 LV2PluginUI::start_updating(GdkEventAny*)
 {
@@ -183,13 +180,14 @@ LV2PluginUI::output_update()
 		}
 	}
 
-	/* FIXME only works with control output ports (which is all we support now anyway) */
-	uint32_t nports = _output_ports.size();
-	for (uint32_t i = 0; i < nports; ++i) {
-		uint32_t index = _output_ports[i];
-		parameter_changed(index, _lv2->get_parameter(index));
+	if (_inst) {
+		for (Updates::iterator i = _updates.begin(); i != _updates.end(); ++i) {
+			float val = _lv2->get_parameter (*i);
+			/* push current value to the GUI */
+			suil_instance_port_event ((SuilInstance*)_inst, (*i), 4, 0, &val);
+		}
+		_updates.clear ();
 	}
-
 }
 
 LV2PluginUI::LV2PluginUI(boost::shared_ptr<PluginInsert> pi,
@@ -358,12 +356,14 @@ LV2PluginUI::lv2ui_instantiate(const std::string& title)
 		bool     ok;
 		uint32_t port = _lv2->nth_parameter(i, ok);
 		if (ok) {
-			_values[port]        = _lv2->get_parameter(port);
 			_controllables[port] = boost::dynamic_pointer_cast<ARDOUR::AutomationControl> (
 				insert->control(Evoral::Parameter(PluginAutomation, 0, port)));
 
-			if (_lv2->parameter_is_control(port) && _lv2->parameter_is_input(port)) {
-				parameter_update(port, _values[port]);
+			/* FIXME only works with control output ports (which is all we support now anyway) */
+			if (_controllables[port] && _lv2->parameter_is_control(port) && _lv2->parameter_is_input(port)) {
+				_controllables[port]->Changed.connect (control_connections, invalidator (*this), boost::bind (&LV2PluginUI::control_changed, this, port), gui_context());
+				/* queue for first update ("push") to GUI */
+				_updates.insert (port);
 			}
 		}
 	}
@@ -401,9 +401,7 @@ LV2PluginUI::lv2ui_free()
 
 LV2PluginUI::~LV2PluginUI ()
 {
-	if (_values) {
-		delete[] _values;
-	}
+	delete [] _values;
 
 	_message_update_connection.disconnect();
 	_screen_update_connection.disconnect();
diff --git a/gtk2_ardour/lv2_plugin_ui.h b/gtk2_ardour/lv2_plugin_ui.h
index 6a8acf9cf5..25ab4b9e30 100644
--- a/gtk2_ardour/lv2_plugin_ui.h
+++ b/gtk2_ardour/lv2_plugin_ui.h
@@ -26,6 +26,7 @@
 
 #include <list>
 #include <map>
+#include <set>
 #include <vector>
 
 #include <gtkmm/widget.h>
@@ -64,7 +65,7 @@ class LV2PluginUI : public PlugUIBase, public Gtk::VBox
 
   private:
 
-	void parameter_changed (uint32_t, float);
+	void control_changed (uint32_t);
 
 	typedef boost::shared_ptr<ARDOUR::AutomationControl> ControllableRef;
 
@@ -85,6 +86,8 @@ class LV2PluginUI : public PlugUIBase, public Gtk::VBox
 	LV2_Feature                          _parent_feature;
 	Gtk::Window*                         _win_ptr;
 	void*                                _inst;
+	typedef std::set<uint32_t> Updates;
+	Updates                              _updates;
 
 	static void on_external_ui_closed(void* controller);
 
diff --git a/gtk2_ardour/plugin_ui.cc b/gtk2_ardour/plugin_ui.cc
index 37c01462b2..19dbee422f 100644
--- a/gtk2_ardour/plugin_ui.cc
+++ b/gtk2_ardour/plugin_ui.cc
@@ -484,7 +484,7 @@ PlugUIBase::PlugUIBase (boost::shared_ptr<PluginInsert> pi)
 	plugin->PresetAdded.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::preset_added_or_removed, this), gui_context ());
 	plugin->PresetRemoved.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::preset_added_or_removed, this), gui_context ());
 	plugin->PresetLoaded.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::update_preset, this), gui_context ());
-	plugin->ParameterChanged.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::parameter_changed, this, _1, _2), gui_context ());
+	plugin->PresetDirty.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::update_preset_modified, this), gui_context ());
 
 	insert->AutomationStateChanged.connect (*this, invalidator (*this), boost::bind (&PlugUIBase::automation_state_changed, this), gui_context());
 
@@ -814,12 +814,6 @@ PlugUIBase::update_preset_modified ()
 }
 
 void
-PlugUIBase::parameter_changed (uint32_t, float)
-{
-	update_preset_modified ();
-}
-
-void
 PlugUIBase::preset_added_or_removed ()
 {
 	/* Update both the list and the currently-displayed preset */
diff --git a/gtk2_ardour/plugin_ui.h b/gtk2_ardour/plugin_ui.h
index 41f4ef39f1..d2e5e21cca 100644
--- a/gtk2_ardour/plugin_ui.h
+++ b/gtk2_ardour/plugin_ui.h
@@ -170,7 +170,6 @@ class PlugUIBase : public virtual sigc::trackable, public PBD::ScopedConnectionL
 	void processor_active_changed (boost::weak_ptr<ARDOUR::Processor> p);
 	void plugin_going_away ();
 	void automation_state_changed ();
-	virtual void parameter_changed (uint32_t, float);
 	void preset_added_or_removed ();
 	void update_preset_modified ();