add an idle callback at FPS

gtk2_ardour/ardour_ui.cc

@@ -151,6 +151,7 @@ UIConfiguration *ARDOUR_UI::ui_config = 0;
 sigc::signal<void,bool> ARDOUR_UI::Blink;
 sigc::signal<void>      ARDOUR_UI::RapidScreenUpdate;
 sigc::signal<void>      ARDOUR_UI::SuperRapidScreenUpdate;
+sigc::signal<void>      ARDOUR_UI::FPSUpdate;
 sigc::signal<void, framepos_t, bool, framepos_t> ARDOUR_UI::Clock;
 sigc::signal<void>      ARDOUR_UI::CloseAllDialogs;
 
@@ -992,6 +993,7 @@ If you still wish to quit, please use the\n\n\
 		second_connection.disconnect ();
 		point_one_second_connection.disconnect ();
 		point_zero_something_second_connection.disconnect();
+		fps_connection.disconnect();
 	}
 
 	delete ARDOUR_UI::instance()->video_timeline;
@@ -1139,6 +1141,35 @@ ARDOUR_UI::every_point_zero_something_seconds ()
 	return TRUE;
 }
 
+gint
+ARDOUR_UI::every_fps ()
+{
+	FPSUpdate(); /* EMIT_SIGNAL */
+	return TRUE;
+}
+
+void
+ARDOUR_UI::set_fps_timeout_connection ()
+{
+	unsigned int interval = 40;
+	if (!_session) return;
+	if (_session->timecode_frames_per_second() != 0) {
+		/* ideally we'll use a select() to sleep and not accumulate
+		 * idle time to provide a regular periodic signal.
+		 * See linux_vst_gui_support.cc 'elapsed_time_ms'.
+		 * However, that'll require a dedicated thread and cross-thread
+		 * signals to the GUI Thread..
+		 */
+		interval = floor(500. /* update twice per FPS, since Glib::signal_timeout is very irregular */
+				* _session->frame_rate() / _session->nominal_frame_rate()
+				/ _session->timecode_frames_per_second()
+				);
+		interval = std::max(8u, interval); // at most 120Hz.
+	}
+	fps_connection.disconnect();
+	fps_connection = Glib::signal_timeout().connect (sigc::mem_fun(*this, &ARDOUR_UI::every_fps), interval);
+}
+
 void
 ARDOUR_UI::update_sample_rate (framecnt_t)
 {

gtk2_ardour/ardour_ui.h

@@ -190,6 +190,9 @@ class ARDOUR_UI : public Gtkmm2ext::UI, public ARDOUR::SessionHandlePtr
 	/** point_zero_something_seconds -- currently 25Hz ^= 40ms */
 	static sigc::signal<void>      SuperRapidScreenUpdate;
 
+	/** every_fps -- see set_fps_timeout_connection() 25Hz < x < 120Hz */
+	static sigc::signal<void>      FPSUpdate;
+
 	/** Emitted frequently with the audible frame, false, and the edit point as
 	 *  parameters respectively.
 	 *
@@ -548,10 +551,14 @@ class ARDOUR_UI : public Gtkmm2ext::UI, public ARDOUR::SessionHandlePtr
 	gint every_second ();
 	gint every_point_one_seconds ();
 	gint every_point_zero_something_seconds ();
+	gint every_fps ();
 
 	sigc::connection second_connection;
 	sigc::connection point_one_second_connection;
 	sigc::connection point_zero_something_second_connection;
+	sigc::connection fps_connection;
+
+	void set_fps_timeout_connection ();
 
 	void open_session ();
 	void open_recent_session ();

gtk2_ardour/ardour_ui_dialogs.cc

@@ -183,6 +183,7 @@ ARDOUR_UI::set_session (Session *s)
 	second_connection = Glib::signal_timeout().connect (sigc::mem_fun(*this, &ARDOUR_UI::every_second), 1000);
 	point_one_second_connection = Glib::signal_timeout().connect (sigc::mem_fun(*this, &ARDOUR_UI::every_point_one_seconds), 100);
 	point_zero_something_second_connection = Glib::signal_timeout().connect (sigc::mem_fun(*this, &ARDOUR_UI::every_point_zero_something_seconds), 40);
+	set_fps_timeout_connection();
 
 	update_format ();
 
@@ -274,6 +275,7 @@ ARDOUR_UI::unload_session (bool hide_stuff)
 	second_connection.disconnect ();
 	point_one_second_connection.disconnect ();
 	point_zero_something_second_connection.disconnect();
+	fps_connection.disconnect();
 
 	if (editor_meter) {
 		meter_box.remove(*editor_meter);

gtk2_ardour/ardour_ui_options.cc

@@ -367,6 +367,7 @@ ARDOUR_UI::parameter_changed (std::string p)
 	} else if (p == "sync-source") {
 
 		synchronize_sync_source_and_video_pullup ();
+		set_fps_timeout_connection ();
 
 	} else if (p == "show-track-meters") {
 		editor->toggle_meter_updating();
@@ -426,7 +427,11 @@ ARDOUR_UI::session_parameter_changed (std::string p)
 {
 	if (p == "native-file-data-format" || p == "native-file-header-format") {
 		update_format ();
+	} else if (p == "timecode-format") {
+		set_fps_timeout_connection ();
 	} else if (p == "video-pullup" || p == "timecode-format") {
+		set_fps_timeout_connection ();
+
 		synchronize_sync_source_and_video_pullup ();
 		reset_main_clocks ();
 		editor->queue_visual_videotimeline_update();