From e62f1093ea8851289278aba36470811b7a282cef Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Fri, 9 Sep 2022 17:30:32 +0200
Subject: [PATCH] Add playlist APIs to find audible regions

This traverses the layered region stack at a given time,
taking both mute and transparency into account.
---
 libs/ardour/ardour/playlist.h |  2 ++
 libs/ardour/playlist.cc       | 60 +++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/libs/ardour/ardour/playlist.h b/libs/ardour/ardour/playlist.h
index a71d921025..59d86b6e80 100644
--- a/libs/ardour/ardour/playlist.h
+++ b/libs/ardour/ardour/playlist.h
@@ -225,6 +225,7 @@ public:
 	boost::shared_ptr<RegionList> regions_touched (timepos_t const & start, timepos_t const & end);
 	boost::shared_ptr<RegionList> regions_with_start_within (Temporal::TimeRange);
 	boost::shared_ptr<RegionList> regions_with_end_within (Temporal::TimeRange);
+	boost::shared_ptr<RegionList> audible_regions_at (timepos_t const &);
 	uint32_t                   region_use_count (boost::shared_ptr<Region>) const;
 	boost::shared_ptr<Region>  find_region (const PBD::ID&) const;
 	boost::shared_ptr<Region>  top_region_at (timepos_t const &);
@@ -233,6 +234,7 @@ public:
 	timepos_t                  find_next_region_boundary (timepos_t const &, int dir);
 	bool                       region_is_shuffle_constrained (boost::shared_ptr<Region>);
 	bool                       has_region_at (timepos_t const &) const;
+	bool                       region_is_audible_at (boost::shared_ptr<Region>, timepos_t const&);
 
 	timepos_t                  find_prev_region_start (timepos_t const & sample);
 
diff --git a/libs/ardour/playlist.cc b/libs/ardour/playlist.cc
index f5052cffd0..dff0ffa5db 100644
--- a/libs/ardour/playlist.cc
+++ b/libs/ardour/playlist.cc
@@ -1838,6 +1838,66 @@ Playlist::top_unmuted_region_at (timepos_t const & pos)
 	return region;
 }
 
+boost::shared_ptr<RegionList>
+Playlist::audible_regions_at (timepos_t const& pos)
+{
+	boost::shared_ptr<RegionList> rv (new RegionList);
+	boost::shared_ptr<RegionList> rlist;
+	{
+		RegionReadLock rlock (this);
+		rlist = find_regions_at (pos);
+	}
+
+	if (!rlist->size ()) {
+		return rv;
+	}
+
+	RegionSortByLayer cmp;
+	rlist->sort (cmp);
+
+	for (auto i = rlist->rbegin (); i != rlist->rend (); ++i) {
+		if ((*i)->muted ()) {
+			continue;
+		}
+		rv->push_back (*i);
+		if ((*i)->opaque ()) {
+			break;
+		}
+	}
+
+	return rv;
+}
+
+bool
+Playlist::region_is_audible_at (boost::shared_ptr<Region> r, timepos_t const& pos)
+{
+	boost::shared_ptr<RegionList> rlist;
+	{
+		RegionReadLock rlock (this);
+		rlist = find_regions_at (pos);
+	}
+
+	if (!rlist->size ()) {
+		return false;
+	}
+
+	RegionSortByLayer cmp;
+	rlist->sort (cmp);
+
+	for (auto i = rlist->rbegin (); i != rlist->rend (); ++i) {
+		if ((*i)->muted ()) {
+			continue;
+		}
+		if (r == *i) {
+			return true;
+		}
+		if ((*i)->opaque ()) {
+			break;
+		}
+	}
+	return false;
+}
+
 boost::shared_ptr<RegionList>
 Playlist::find_regions_at (timepos_t const & pos)
 {