From 12e82351936efd066ff063b7f59dd869314e3e27 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sat, 5 Feb 2022 00:06:19 +0100
Subject: [PATCH] Add API to query set of used MIDI channels in a SMF

---
 libs/evoral/SMF.cc       | 5 +++--
 libs/evoral/evoral/SMF.h | 3 +++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/libs/evoral/SMF.cc b/libs/evoral/SMF.cc
index 2509970cb9..0120815b7f 100644
--- a/libs/evoral/SMF.cc
+++ b/libs/evoral/SMF.cc
@@ -126,6 +126,7 @@ SMF::open(const std::string& path, int track)
 	Glib::Threads::Mutex::Lock lm (_smf_lock);
 
 	_num_channels = 0;
+	_used_channels.clear ();
 
 	assert(track >= 1);
 	if (_smf) {
@@ -185,10 +186,10 @@ SMF::open(const std::string& path, int track)
 				uint8_t type = buf[0] & 0xf0;
 				uint8_t chan = buf[0] & 0x0f;
 				if (type >= 0x80 && type <= 0xE0) {
-					used.insert(chan);
+					_used_channels.insert(chan);
 				}
 			}
-			_num_channels += used.size();
+			_num_channels += _used_channels.size();
 			free (buf);
 		}
 
diff --git a/libs/evoral/evoral/SMF.h b/libs/evoral/evoral/SMF.h
index 641a00f736..975ce15707 100644
--- a/libs/evoral/evoral/SMF.h
+++ b/libs/evoral/evoral/SMF.h
@@ -88,6 +88,8 @@ public:
 
 	int smf_format () const;
 	int num_channels () const { return _num_channels; }
+	std::set<uint8_t> const& used_channels () const { return _used_channels; }
+
 	void track_names (std::vector<std::string>&) const;
 	void instrument_names (std::vector<std::string>&) const;
 
@@ -136,6 +138,7 @@ public:
 	mutable Glib::Threads::Mutex _smf_lock;
 
 	int _num_channels;
+	std::set<uint8_t> _used_channels;
 
 	mutable Markers _markers;
 };