WS: crash bugfix related to missing strip panner

Surface made Ardour crash when a client connected
and some session track was not a VCA nor had a panner,
like MIDI strips.

libs/surfaces/websockets/dispatcher.cc

@@ -65,19 +65,16 @@ WebsocketsDispatcher::update_all_nodes (Client client)
 		
 		ValueVector strip_desc = ValueVector ();
 		strip_desc.push_back (strip.name ());
-		strip_desc.push_back (strip.is_vca ());
+		strip_desc.push_back (strip.has_pan ());
 		
 		update (client, Node::strip_description, strip_addr, strip_desc);
 		
 		update (client, Node::strip_gain, strip_id, strip.gain ());
 		update (client, Node::strip_mute, strip_id, strip.mute ());
 
-		// Pan and plugins not available in VCAs
+		if (strip.has_pan ()) {
-		if (strip.is_vca ()) {
-			continue;
-		}
-
 			update (client, Node::strip_pan, strip_id, strip.pan ());
+		}
 
 		for (ArdourMixerStrip::PluginMap::iterator it = strip.plugins ().begin (); it != strip.plugins ().end (); ++it) {
 			uint32_t plugin_id                     = it->first;

libs/surfaces/websockets/mixer.cc

@@ -121,11 +121,6 @@ ArdourMixerPlugin::param_value (boost::shared_ptr<ARDOUR::AutomationControl> con
 ArdourMixerStrip::ArdourMixerStrip (boost::shared_ptr<ARDOUR::Stripable> stripable, PBD::EventLoop* event_loop)
 	: _stripable (stripable)
 {
-	if (is_vca ()) {
-		/* no plugins to handle */
-		return;
-	}
-
 	boost::shared_ptr<Route> route = boost::dynamic_pointer_cast<Route> (_stripable);
 
 	if (!route) {
@@ -188,6 +183,12 @@ ArdourMixerStrip::set_gain (double db)
 	_stripable->gain_control ()->set_value (from_db (db), PBD::Controllable::NoGroup);
 }
 
+bool
+ArdourMixerStrip::has_pan () const
+{
+	return _stripable->pan_azimuth_control () != 0;
+}
+
 double
 ArdourMixerStrip::pan () const
 {
@@ -224,12 +225,6 @@ ArdourMixerStrip::set_mute (bool mute)
 	_stripable->mute_control ()->set_value (mute ? 1.0 : 0.0, PBD::Controllable::NoGroup);
 }
 
-bool
-ArdourMixerStrip::is_vca () const
-{
-	return _stripable->presentation_info ().flags () & ARDOUR::PresentationInfo::VCA;
-}
-
 float
 ArdourMixerStrip::meter_level_db () const
 {

libs/surfaces/websockets/mixer.h

@@ -83,14 +83,13 @@ public:
 	double gain () const;
 	void   set_gain (double);
 
+	bool   has_pan () const;
 	double pan () const;
 	void   set_pan (double);
 
 	bool mute () const;
 	void set_mute (bool);
 
-	bool is_vca () const;
-
 	std::string name () const;
 
 	float meter_level_db () const;

share/web_surfaces/builtin/mixer/js/main.js

@@ -88,8 +88,9 @@ import { createRootContainer, Container, Dialog, Label, Button, Toggle,
         plugins.classList.add('strip-plugins');
         plugins.appendTo(container);
 
-        if (strip.isVca || (strip.plugins.length == 0)) {
+        if (strip.plugins.length == 0) {
             plugins.classList.add('disabled');
+            plugins.element.style.visibility = 'hidden';
         } else {
             plugins.callback = () => openPlugins (strip);
         }
@@ -97,8 +98,10 @@ import { createRootContainer, Container, Dialog, Label, Button, Toggle,
         const pan = new PanKnob();
         pan.appendTo(container);
 
-        if (!strip.isVca) {
+        if (strip.hasPan) {
             pan.bindTo(strip, 'pan');
+        } else {
+            pan.element.style.visibility = 'hidden';
         }
 
         const mute = new Toggle();
@@ -123,12 +126,6 @@ import { createRootContainer, Container, Dialog, Label, Button, Toggle,
         label.text = strip.name;
         label.classList.add('strip-label');
         label.appendTo(container);
-
-        if (strip.isVca) {
-            // hide plugins and pan keeping layout
-            pan.element.style.visibility = 'hidden';
-            plugins.element.style.visibility = 'hidden';
-        }
     }
 
     function openPlugins (strip) {

share/web_surfaces/shared/components/strip.js

@@ -33,7 +33,7 @@ export default class Strip extends AddressableComponent {
 		super(parent, addr);
 		this._plugins = {};
 		this._name = desc[0];
-		this._isVca = desc[1];
+		this._hasPan = desc[1];
 		this._meter = 0;
 		this._gain = 0;
 		this._pan = 0;
@@ -48,8 +48,8 @@ export default class Strip extends AddressableComponent {
 		return this._name;
 	}
 
-	get isVca () {
+	get hasPan () {
-		return this._isVca;
+		return this._hasPan;
 	}
 
 	get meter () {