From 4f87506e5caf6ee069d0a7364a9497e0b200f48f Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Sun, 9 Apr 2023 14:34:22 -0600
Subject: [PATCH] do not sort lineset every time a coord is added; use RAII to
 create scope and sort at end

---
 gtk2_ardour/grid_lines.cc      | 10 +++++-----
 gtk2_ardour/midi_streamview.cc |  2 +-
 libs/canvas/canvas/line_set.h  |  9 +++++++++
 libs/canvas/line_set.cc        | 17 ++++++++++++++---
 4 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/gtk2_ardour/grid_lines.cc b/gtk2_ardour/grid_lines.cc
index 978c3c51df..6fed78ccb0 100644
--- a/gtk2_ardour/grid_lines.cc
+++ b/gtk2_ardour/grid_lines.cc
@@ -55,19 +55,19 @@ GridLines::hide ()
 void
 GridLines::draw (std::vector<Ruler::Mark> const & marks)
 {
-	lines.clear();
+	LineSet::ResetRAII lr (lines);
 
 	const uint32_t major_color = UIConfiguration::instance().color_mod("grid line major", "grid line");
 	const uint32_t minor_color = UIConfiguration::instance().color_mod("grid line minor", "grid line");
 	const uint32_t micro_color = UIConfiguration::instance().color_mod("grid line micro", "grid line");
 
-	for (vector<Ruler::Mark>::const_iterator m = marks.begin(); m != marks.end(); ++m) {
+	for (auto const & m : marks) {
 
-		samplepos_t s = m->position;
+		samplepos_t s = m.position;
 
-		if ((*m).style == ArdourCanvas::Ruler::Mark::Major) {
+		if (m.style == ArdourCanvas::Ruler::Mark::Major) {
 			lines.add_coord (PublicEditor::instance().sample_to_pixel_unrounded (s), 1.0, major_color);
-		} else if ((*m).style == ArdourCanvas::Ruler::Mark::Minor) {
+		} else if (m.style == ArdourCanvas::Ruler::Mark::Minor) {
 			lines.add_coord (PublicEditor::instance().sample_to_pixel_unrounded (s), 1.0, minor_color);
 		} else {
 			lines.add_coord (PublicEditor::instance().sample_to_pixel_unrounded (s), 1.0, micro_color);
diff --git a/gtk2_ardour/midi_streamview.cc b/gtk2_ardour/midi_streamview.cc
index d2e264a814..f0da7c0a81 100644
--- a/gtk2_ardour/midi_streamview.cc
+++ b/gtk2_ardour/midi_streamview.cc
@@ -339,7 +339,7 @@ MidiStreamView::draw_note_lines()
 	double prev_y = .5;
 	uint32_t color;
 
-	_note_lines->clear();
+	ArdourCanvas::LineSet::ResetRAII lr (*_note_lines);
 
 	if (child_height() < 140 || note_height() < 3) {
 		/* track is too small for note lines, or there are too many */
diff --git a/libs/canvas/canvas/line_set.h b/libs/canvas/canvas/line_set.h
index 6752f5ac3f..2f5b977b64 100644
--- a/libs/canvas/canvas/line_set.h
+++ b/libs/canvas/canvas/line_set.h
@@ -47,6 +47,15 @@ public:
 	void set_extent (Distance);
 	Distance extent() const { return _extent; }
 
+	void begin_add ();
+	void end_add ();
+
+	struct ResetRAII {
+		ResetRAII (LineSet& l) : lines (l) { lines.clear(); lines.begin_add(); }
+		~ResetRAII () { lines.end_add (); }
+		LineSet& lines;
+	};
+
 	void add_coord (Coord, Distance, Gtkmm2ext::Color);
 	void clear ();
 
diff --git a/libs/canvas/line_set.cc b/libs/canvas/line_set.cc
index bf2b130a6b..0fd1656485 100644
--- a/libs/canvas/line_set.cc
+++ b/libs/canvas/line_set.cc
@@ -131,12 +131,23 @@ LineSet::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const
 }
 
 void
-LineSet::add_coord (Coord y, Distance width, Gtkmm2ext::Color color)
+LineSet::add_coord (Coord pos, Distance width, Gtkmm2ext::Color color)
+{
+	_lines.push_back (Line (pos, width, color));
+}
+
+void
+LineSet::begin_add ()
 {
 	begin_change ();
+}
 
-	_lines.push_back (Line (y, width, color));
-	sort (_lines.begin(), _lines.end(), LineSorter());
+void
+LineSet::end_add ()
+{
+	if (!_lines.empty()) {
+		sort (_lines.begin(), _lines.end(), LineSorter());
+	}
 
 	set_bbox_dirty ();
 	end_change ();