From 0b7db6ebbb5dc297d9feeac3fac687c93651e6e4 Mon Sep 17 00:00:00 2001
From: nick_m <mainsbridge@gmail.com>
Date: Wed, 9 Nov 2016 00:37:52 +1100
Subject: [PATCH] add empoMap::quarter_notes_between_frames().

	- in an ideal world, this wouldn't be here at all,
	  but is required to support framewalk_to_qn().
	  if Beats are at tick resolution, the frame-induced
	  temporal rounding is acceptable.
---
 libs/ardour/ardour/tempo.h |  2 ++
 libs/ardour/tempo.cc       | 70 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/libs/ardour/ardour/tempo.h b/libs/ardour/ardour/tempo.h
index e820a1cbdc..a35e1b4fba 100644
--- a/libs/ardour/ardour/tempo.h
+++ b/libs/ardour/ardour/tempo.h
@@ -458,6 +458,7 @@ class LIBARDOUR_API TempoMap : public PBD::StatefulDestructible
 	framepos_t frame_at_quarter_note (const double quarter_note) const;
 
 	framecnt_t frames_between_quarter_notes (const double start, const double end) const;
+	double     quarter_notes_between_frames (const framecnt_t start, const framecnt_t end) const;
 
 	double quarter_note_at_beat (const double beat);
 	double beat_at_quarter_note (const double beat);
@@ -515,6 +516,7 @@ private:
 	double beat_at_quarter_note_locked (const Metrics& metrics, const double beat) const;
 
 	double minutes_between_quarter_notes_locked (const Metrics& metrics, const double start_qn, const double end_qn) const;
+	double quarter_notes_between_frames_locked (const Metrics& metrics, const framecnt_t  start, const framecnt_t end) const;
 
 	const TempoSection& tempo_section_at_minute_locked (const Metrics& metrics, double minute) const;
 	const TempoSection& tempo_section_at_beat_locked (const Metrics& metrics, const double& beat) const;
diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 0279007a21..8ae25fe24d 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -334,6 +334,26 @@ TempoSection::minute_at_pulse (const double& p) const
 	return _time_at_pulse (p - pulse()) + minute();
 }
 
+double
+TempoSection::pulse_at_frame (const framepos_t& f) const
+{
+	if (_type == Constant || _c_func == 0.0) {
+		return (minute_at_frame (f - frame()) * pulses_per_minute()) + pulse();
+	}
+
+	return _pulse_at_time (minute_at_frame (f - frame())) + pulse();
+}
+
+framepos_t
+TempoSection::frame_at_pulse (const double& p) const
+{
+	if (_type == Constant || _c_func == 0.0) {
+		return frame_at_minute (((p - pulse()) / pulses_per_minute()) + minute());
+	}
+
+	return frame_at_minute (_time_at_pulse (p - pulse()) + minute());
+}
+
 /*
 Ramp Overview
 
@@ -2392,6 +2412,54 @@ TempoMap::minutes_between_quarter_notes_locked (const Metrics& metrics, const do
 	return minute_at_pulse_locked (metrics, end / 4.0) - minute_at_pulse_locked (metrics, start / 4.0);
 }
 
+double
+TempoMap::quarter_notes_between_frames (const framecnt_t start, const framecnt_t end) const
+{
+	Glib::Threads::RWLock::ReaderLock lm (lock);
+
+	return quarter_notes_between_frames_locked (_metrics, start, end);
+}
+
+double
+TempoMap::quarter_notes_between_frames_locked (const Metrics& metrics, const framecnt_t start, const framecnt_t end) const
+{
+	const TempoSection* prev_t = 0;
+
+	for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
+		TempoSection* t;
+
+		if ((*i)->is_tempo()) {
+			t = static_cast<TempoSection*> (*i);
+			if (!t->active()) {
+				continue;
+			}
+			if (prev_t && t->frame() > start) {
+				break;
+			}
+			prev_t = t;
+		}
+	}
+	const double start_qn = prev_t->pulse_at_frame (start);
+
+	for (Metrics::const_iterator i = metrics.begin(); i != metrics.end(); ++i) {
+		TempoSection* t;
+
+		if ((*i)->is_tempo()) {
+			t = static_cast<TempoSection*> (*i);
+			if (!t->active()) {
+				continue;
+			}
+			if (prev_t && t->frame() > end) {
+				break;
+			}
+			prev_t = t;
+		}
+	}
+	const double end_qn = prev_t->pulse_at_frame (end);
+
+	return (end_qn - start_qn) * 4.0;
+}
+
 bool
 TempoMap::check_solved (const Metrics& metrics) const
 {
@@ -4329,7 +4397,7 @@ TempoMap::framewalk_to_qn (framepos_t pos, framecnt_t distance) const
 {
 	Glib::Threads::RWLock::ReaderLock lm (lock);
 
-	return Evoral::Beats (quarter_note_at_minute_locked (_metrics, minute_at_frame (pos + distance)) - quarter_note_at_minute_locked (_metrics, minute_at_frame (pos)));
+	return Evoral::Beats (quarter_notes_between_frames_locked (_metrics, pos, pos + distance));
 }
 
 struct bbtcmp {