+ if (!session) {
+ return;
+ }
+
+ ENSURE_GUI_THREAD(bind (mem_fun (*this, &Editor::tempo_map_changed), ignored));
+
+ redisplay_tempo (false); // redraw rulers and measures
+ session->tempo_map().apply_with_metrics (*this, &Editor::draw_metric_marks); // redraw metric markers
+}
+
+/**
+ * This code was originally in tempo_map_changed, but this is called every time the canvas scrolls horizontally.
+ * That's why this is moved in here. The new tempo_map_changed is called when the ARDOUR::TempoMap actually changed.
+ */
+void
+Editor::redisplay_tempo (bool immediate_redraw)
+{
+ if (!session) {
+ return;
+ }
+
+ BBT_Time previous_beat, next_beat; // the beats previous to the leftmost frame and after the rightmost frame
+
+ session->bbt_time(leftmost_frame, previous_beat);
+ session->bbt_time(leftmost_frame + current_page_frames(), next_beat);
+
+ if (previous_beat.beats > 1) {
+ previous_beat.beats -= 1;
+ } else if (previous_beat.bars > 1) {
+ previous_beat.bars--;
+ previous_beat.beats += 1;
+ }
+ previous_beat.ticks = 0;
+
+ if (session->tempo_map().meter_at(leftmost_frame + current_page_frames()).beats_per_bar () > next_beat.beats + 1) {
+ next_beat.beats += 1;
+ } else {
+ next_beat.bars += 1;
+ next_beat.beats = 1;
+ }
+ next_beat.ticks = 0;