Better-define behaviour when relayering a playlist with a single zero-length region. Fixes #3144.

git-svn-id: svn://localhost/ardour2/branches/3.0@7238 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 14 insertions, 6 deletions

diff --git a/libs/ardour/playlist.cc b/libs/ardour/playlist.cc
index 2044a2f142..bab4e358f9 100644
--- a/libs/ardour/playlist.cc
+++ b/libs/ardour/playlist.cc
@@ -2432,14 +2432,22 @@ Playlist::relayer ()
 		/* reset the pending explicit relayer flag for every region, now that we're relayering */
 		(*i)->set_pending_explicit_relayer (false);
 
-		/* find the time divisions that this region covers */
-		int const start_division = floor ( ((*i)->position() - start) / division_size);
-		int end_division = floor ( ((*i)->position() + (*i)->length() - start) / division_size );
-		if (end_division == divisions) {
-			end_division--;
+		/* find the time divisions that this region covers; if there are no regions on the list,
+		   division_size will equal 0 and in this case we'll just say that
+		   start_division = end_division = 0.
+		*/
+		int start_division = 0;
+		int end_division = 0;
+
+		if (division_size > 0) {
+			start_division = floor ( ((*i)->position() - start) / division_size);
+			end_division = floor ( ((*i)->position() + (*i)->length() - start) / division_size );
+			if (end_division == divisions) {
+				end_division--;
+			}
 		}
 
-		assert (end_division < divisions);
+		assert (divisions == 0 || end_division < divisions);
 
 		/* find the lowest layer that this region can go on */
 		size_t j = layers.size();