tape-track diskstream fixes

Due to the change to use a 64bit timeline (int64 as opposed
to previously [unsigned] pframes_t) many cases special to tape-tracks
no longer work.
e.g. region->length() can returns -1, rather than INT64_MAX.
which breaks ‘overlap’ in Evoral::Coverage. which in turn
breaks tape track’s use of ::find_next_region().

This commits begins the slow process to move away from relying
on integer overflow to wrap negative numbers for tape tracks and
restores basic functionality.

Still various edge cases pertaining tape tracks remain. particularly
when changing the session start-time and moving destructive regions.

1 files changed, 43 insertions, 3 deletions

diff --git a/libs/ardour/audio_diskstream.cc b/libs/ardour/audio_diskstream.cc
index 2d4d02f830..7e673c99d1 100644
--- a/libs/ardour/audio_diskstream.cc
+++ b/libs/ardour/audio_diskstream.cc
@@ -74,6 +74,10 @@ AudioDiskstream::AudioDiskstream (Session &sess, const string &name, Diskstream:
 	in_set_state = true;
 	use_new_playlist ();
 	in_set_state = false;
+
+	if (flag & Destructive) {
+		use_destructive_playlist ();
+	}
 }
 
 AudioDiskstream::AudioDiskstream (Session& sess, const XMLNode& node)
@@ -331,10 +335,13 @@ AudioDiskstream::setup_destructive_playlist ()
 	PropertyList plist;
 	plist.add (Properties::name, _name.val());
 	plist.add (Properties::start, 0);
-	plist.add (Properties::length, max_framepos - (max_framepos - srcs.front()->natural_position()));
+	plist.add (Properties::length, max_framepos - srcs.front()->natural_position());
 
 	boost::shared_ptr<Region> region (RegionFactory::create (srcs, plist));
 	_playlist->add_region (region, srcs.front()->natural_position());
+
+	/* apply region properties and update write sources */
+	use_destructive_playlist();
 }
 
 void
@@ -346,7 +353,14 @@ AudioDiskstream::use_destructive_playlist ()
 	   with the (presumed single, full-extent) region.
 	*/
 
-	boost::shared_ptr<Region> rp = _playlist->find_next_region (_session.current_start_frame(), Start, 1);
+	boost::shared_ptr<Region> rp;
+	{
+		const RegionList& rl (_playlist->region_list().rlist());
+		if (rl.size() > 0) {
+			assert((rl.size() == 1));
+			rp = rl.front();
+		}
+	}
 
 	if (!rp) {
 		reset_write_sources (false, true);
@@ -2324,6 +2338,13 @@ AudioDiskstream::can_become_destructive (bool& requires_bounce) const
 		return false;
 	}
 
+	/* if no regions are present: easy */
+
+	if (_playlist->n_regions() == 0) {
+		requires_bounce = false;
+		return true;
+	}
+
 	/* is there only one region ? */
 
 	if (_playlist->n_regions() != 1) {
@@ -2331,7 +2352,14 @@ AudioDiskstream::can_become_destructive (bool& requires_bounce) const
 		return false;
 	}
 
-	boost::shared_ptr<Region> first = _playlist->find_next_region (_session.current_start_frame(), Start, 1);
+	boost::shared_ptr<Region> first;
+	{
+		const RegionList& rl (_playlist->region_list().rlist());
+		assert((rl.size() == 1));
+		first = rl.front();
+
+	}
+
 	if (!first) {
 		requires_bounce = false;
 		return true;
@@ -2340,12 +2368,24 @@ AudioDiskstream::can_become_destructive (bool& requires_bounce) const
 	/* do the source(s) for the region cover the session start position ? */
 
 	if (first->position() != _session.current_start_frame()) {
+		// what is the idea here?  why start() ??
 		if (first->start() > _session.current_start_frame()) {
 			requires_bounce = true;
 			return false;
 		}
 	}
 
+	/* currently RouteTimeAxisView::set_track_mode does not
+	 * implement bounce. Existing regions cannot be converted.
+	 *
+	 * so let's make sure this region is already set up
+	 * as tape-track (spanning the complete range)
+	 */
+	if (first->length() != max_framepos - first->position()) {
+		requires_bounce = true;
+		return false;
+	}
+
 	/* is the source used by only 1 playlist ? */
 
 	boost::shared_ptr<AudioRegion> afirst = boost::dynamic_pointer_cast<AudioRegion> (first);