tempo display: further simplifications to handling map changes

When a tempo map change originates from a drag, we know the required redraws have
already been done. Use a new bool member, ignore_map_change, to tell the Editor
to ignore the map change signal. For all other map changes, do the full reset.

gtk2_ardour/editor.cc

@@ -388,6 +388,7 @@ Editor::Editor ()
 	, lock_dialog (0)
 	  /* , last_event_time { 0, 0 } */ /* this initialization style requires C++11 */
 	, _dragging_playhead (false)
+	, ignore_map_change (false)
 	, _follow_playhead (true)
 	, _stationary_playhead (false)
 	, _maximised (false)

gtk2_ardour/editor.h

@@ -1729,6 +1729,8 @@ private:
 
 	Temporal::TempoMap::WritableSharedPtr begin_tempo_map_edit ();
 	void abort_tempo_map_edit ();
+	void commit_tempo_map_edit (Temporal::TempoMap::WritableSharedPtr&);
+	bool ignore_map_change;
 
 	enum MidTempoChanges {
 		TempoChanged = 0x1,
@@ -1875,7 +1877,6 @@ private:
 	void update_tempo_curves (double min_tempo, double max_tempo, samplecnt_t sr);
 
 	void tempo_map_changed ();
-	void tempo_map_model_update ();
 
 	void redisplay_grid (bool immediate_redraw);
 

gtk2_ardour/editor_drag.cc

@@ -3145,7 +3145,7 @@ MeterMarkerDrag::finished (GdkEvent* event, bool movement_occurred)
 	_editor->set_grid_to (_old_grid_type);
 	_editor->set_snap_mode (_old_snap_mode);
 
-	TempoMap::update (map);
+	_editor->commit_tempo_map_edit (map);
 	XMLNode &after = map->get_state();
 
 	_editor->session()->add_command (new Temporal::TempoCommand (_("move time signature"), before_state, &after));
@@ -3237,7 +3237,7 @@ TempoCurveDrag::finished (GdkEvent* event, bool movement_occurred)
 
 	/* push the current state of our writable map copy */
 
-	TempoMap::update (map);
+	_editor->commit_tempo_map_edit (map);
 	XMLNode &after = map->get_state();
 
 	_editor->session()->add_command (new Temporal::TempoCommand (_("change tempo"), _before_state, &after));
@@ -3346,7 +3346,7 @@ TempoMarkerDrag::finished (GdkEvent* event, bool movement_occurred)
 
 	/* push the current state of our writable map copy */
 
-	TempoMap::update (map);
+	_editor->commit_tempo_map_edit (map);
 	XMLNode &after = map->get_state();
 
 	_editor->session()->add_command (new Temporal::TempoCommand (_("move tempo"), _before_state, &after));
@@ -3518,7 +3518,7 @@ BBTRulerDrag::finished (GdkEvent* event, bool movement_occurred)
 		}
 	}
 
-	TempoMap::update (map);
+	_editor->commit_tempo_map_edit (map);
 
 	XMLNode &after = map->get_state();
 
@@ -3628,7 +3628,7 @@ TempoTwistDrag::finished (GdkEvent* event, bool movement_occurred)
 	_editor->session()->add_command (new Temporal::TempoCommand (_("twist tempo"), _before_state, &after));
 	_editor->commit_reversible_command ();
 
-	TempoMap::update (map);
+	_editor->commit_tempo_map_edit (map);
 }
 
 void
@@ -3734,7 +3734,7 @@ TempoEndDrag::finished (GdkEvent* event, bool movement_occurred)
 		return;
 	}
 
-	TempoMap::update (map);
+	_editor->commit_tempo_map_edit (map);
 
 	XMLNode &after = map->get_state();
 	_editor->session()->add_command (new Temporal::TempoCommand (_("move tempo end"), _before_state, &after));

gtk2_ardour/editor_tempodisplay.cc

@@ -36,6 +36,7 @@
 
 #include "pbd/error.h"
 #include "pbd/memento_command.h"
+#include "pbd/unwind.h"
 
 #include <gtkmm2ext/utils.h>
 #include <gtkmm2ext/gtk_ui.h>
@@ -327,6 +328,10 @@ Editor::update_tempo_curves (double min_tempo, double max_tempo, samplecnt_t sr)
 void
 Editor::tempo_map_changed ()
 {
+	if (ignore_map_change) {
+		return;
+	}
+
 	TempoMap::SharedPtr current_map = TempoMap::fetch ();
 
 	/* If the tempo map was changed by something other than the Editor, we
@@ -334,25 +339,9 @@ Editor::tempo_map_changed ()
 	 * with the new map.
 	 */
 
-	if (!tempo_marks.empty()) {
+	 reset_metric_marks ();
-		/* a little awkward using shared_ptr<T>::get() but better than every
+	 update_tempo_based_rulers ();
-		 * point in the map holding a shared_ptr ref to the map that owns it.
+	 maybe_draw_grid_lines ();
-		 */
-
-		if (&tempo_marks.front()->point().map() != current_map.get()) {
-			reassociate_metric_markers (current_map);
-		}
-	}
-
-	tempo_map_model_update ();
-}
-
-void
-Editor::tempo_map_model_update ()
-{
-	reset_metric_marks ();
-	update_tempo_based_rulers ();
-	maybe_draw_grid_lines ();
 }
 
 void
@@ -730,6 +719,13 @@ Editor::abort_tempo_map_edit ()
 	reassociate_metric_markers (tmap);
 }
 
+void
+Editor::commit_tempo_map_edit (TempoMap::WritableSharedPtr& new_map)
+{
+	PBD::Unwinder<bool> uw (ignore_map_change, true);
+	TempoMap::update (new_map);
+}
+
 void
 Editor::mid_tempo_change (MidTempoChanges what_changed)
 {