fix design and implementation of (GUI) transport controllables to make them usable with MIDI CC control

The old code meant that their current value was always zero, and that they would do nothing unless
the new value exceeded 0.5

gtk2_ardour/ardour_ui_dialogs.cc

@@ -163,6 +163,14 @@ ARDOUR_UI::set_session (Session *s)
 	transport_masters_window->set_session (s);
 	rc_option_editor->set_session (s);
 
+	roll_controllable->set_session (s);
+	stop_controllable->set_session (s);
+	goto_start_controllable->set_session (s);
+	goto_end_controllable->set_session (s);
+	auto_loop_controllable->set_session (s);
+	play_selection_controllable->set_session (s);
+	rec_controllable->set_session (s);
+
 	/* allow wastebasket flush again */
 
 	Glib::RefPtr<Action> act = ActionManager::get_action (X_("Main"), X_("FlushWastebasket"));

gtk2_ardour/transport_control.cc

@@ -16,12 +16,15 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include "pbd/i18n.h"
+
+#include "ardour/location.h"
+#include "ardour/session.h"
+
 #include "actions.h"
 #include "ardour_ui.h"
 #include "transport_control.h"
 
-#include "pbd/i18n.h"
-
 using namespace Gtk;
 
 TransportControlProvider::TransportControlProvider ()
@@ -43,7 +46,7 @@ TransportControlProvider::TransportControllable::TransportControllable (std::str
 void
 TransportControlProvider::TransportControllable::set_value (double val, PBD::Controllable::GroupControlDisposition /*group_override*/)
 {
-	if (val < 0.5) {
+	if (val == 0.0) {
 		/* do nothing: these are radio-style actions */
 		return;
 	}
@@ -86,3 +89,40 @@ TransportControlProvider::TransportControllable::set_value (double val, PBD::Con
 		act->activate ();
 	}
 }
+
+double
+TransportControlProvider::TransportControllable::get_value () const
+{
+	if (!_session) {
+		return 0.0;
+	}
+
+	ARDOUR::Location* rloc;
+
+	switch (type) {
+	case Roll:
+		return (_session->transport_rolling() ? 1.0 : 0.0);
+	case Stop:
+		return (!_session->transport_rolling() ? 1.0 : 0.0);
+	case GotoStart:
+		if ((rloc = _session->locations()->session_range_location()) != 0) {
+			return (_session->transport_sample() == rloc->start() ? 1.0 : 0.0);
+		}
+		return 0.0;
+	case GotoEnd:
+		if ((rloc = _session->locations()->session_range_location()) != 0) {
+			return (_session->transport_sample() == rloc->end() ? 1.0 : 0.0);
+		}
+		return 0.0;
+	case AutoLoop:
+		return ((_session->get_play_loop() && _session->transport_rolling())? 1.0 : 0.0);
+	case PlaySelection:
+		return ((_session->transport_rolling() && _session->get_play_range()) ? 1.0 : 0.0);
+	case RecordEnable:
+		return (_session->actively_recording() ? 1.0 : 0.0);
+	default:
+		break;
+	}
+
+	return 0.0;
+}

gtk2_ardour/transport_control.h

@@ -22,6 +22,8 @@
 #include <gtkmm/widget.h>
 #include "pbd/controllable.h"
 
+#include "ardour/session_handle.h"
+
 /* This is an API implemenetd by AROUR_UI,
  * and made available to transport-control-UIs
  */
@@ -34,7 +36,7 @@ public:
 	/* show metronome preferences */
 	virtual bool click_button_clicked (GdkEventButton *) = 0;
 
-	struct TransportControllable : public PBD::Controllable {
+	struct TransportControllable : public PBD::Controllable, public ARDOUR::SessionHandlePtr {
 		enum ToggleType {
 			Roll = 0,
 			Stop,
@@ -47,7 +49,7 @@ public:
 
 		TransportControllable (std::string name, ToggleType);
 		void set_value (double, PBD::Controllable::GroupControlDisposition group_override);
-		double get_value (void) const { return 0; }
+		double get_value (void) const;
 
 		ToggleType type;
 	};