From 5456fd5717feb3133cc22aef80cc858d1cb0551b Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Sun, 26 Feb 2017 18:19:50 +0100
Subject: [PATCH] make Selection::set (TrackViewList*) more efficient and emit
 less PI::Change signals

---
 gtk2_ardour/selection.cc | 49 +++++++++++++---------------------------
 1 file changed, 16 insertions(+), 33 deletions(-)

diff --git a/gtk2_ardour/selection.cc b/gtk2_ardour/selection.cc
index 23abfa17c3..ab26bfd48a 100644
--- a/gtk2_ardour/selection.cc
+++ b/gtk2_ardour/selection.cc
@@ -830,46 +830,29 @@ Selection::set (const TrackViewList& track_list)
 {
 	clear_objects();  //enforce object/range exclusivity
 
-	PresentationInfo::ChangeSuspender cs;
-
-	if (!tracks.empty()) {
 
-		/* cannot use set<T>::operator== (set<T> const &) here, because
-		 * apparently the ordering used within 2 sets is not
-		 * necessarily the same.
-		 */
-
-		if (tracks.size() == track_list.size()) {
-			bool missing = false;
-
-			for (TrackViewList::const_iterator x = track_list.begin(); x != track_list.end(); ++x) {
-				if (dynamic_cast<VCATimeAxisView*> (*x)) {
-					continue;
-				}
-				if (find (tracks.begin(), tracks.end(), *x) == tracks.end()) {
-					missing = true;
-				}
-			}
+	TrackViewList to_be_added;
+	TrackViewList to_be_removed;
 
-			if (!missing) {
-				/* already same selection: nothing to do */
-				return;
-			}
+	for (TrackViewList::const_iterator x = tracks.begin(); x != tracks.end(); ++x) {
+		if (find (track_list.begin(), track_list.end(), *x) == track_list.end()) {
+			to_be_removed.push_back (*x);
 		}
+	}
 
-		/* argument is different from existing selection */
-
-		for (TrackViewList::iterator x = tracks.begin(); x != tracks.end(); ++x) {
-			if (dynamic_cast<VCATimeAxisView*> (*x)) {
-				continue;
-			}
-			(*x)->set_selected (false);
+	for (TrackViewList::const_iterator x = track_list.begin(); x != track_list.end(); ++x) {
+		if (dynamic_cast<VCATimeAxisView*> (*x)) {
+			continue;
+		}
+		if (find (tracks.begin(), tracks.end(), *x) == tracks.end()) {
+			to_be_added.push_back (*x);
 		}
-
-		tracks.clear ();
 	}
 
-	add (track_list);
+	PresentationInfo::ChangeSuspender cs;
+	remove (to_be_removed);
+	add (to_be_added);
+
 }
 
 void
-- 
2.30.2