Hack round a maybe delightful (for some values of delightful) and certainly evil confluence of small bugs causing no MIDI notes on record (#3820).

git-svn-id: svn://localhost/ardour2/branches/3.0@9064 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 14 insertions, 0 deletions

diff --git a/gtk2_ardour/midi_streamview.cc b/gtk2_ardour/midi_streamview.cc
index 723b522202..f3b418fc99 100644
--- a/gtk2_ardour/midi_streamview.cc
+++ b/gtk2_ardour/midi_streamview.cc
@@ -452,6 +452,20 @@ MidiStreamView::setup_rec_box ()
 				
 				plist.add (ARDOUR::Properties::start, start);
 				plist.add (ARDOUR::Properties::length, 1);
+				/* Just above we're setting this nascent region's length to 1.  I think this
+				   is so that the RegionView gets created with a non-zero width, as apparently
+				   creating a RegionView with a zero width causes it never to be displayed
+				   (there is a warning in TimeAxisViewItem::init about this).  However, we
+				   must also set length_beats to something non-zero, otherwise the frame length
+				   of 1 causes length_beats to be set to some small quantity << 1.  Then
+				   when the position is set up below, this length_beats is used to recompute
+				   length using Tempo::framepos_plus_bbt, which is slightly innacurate for small
+				   beats values (see comment in Tempo::framepos_plus_bbt) [mostly because
+				   it converts floating point beats to bars, beats and integer ticks].  The upshot
+				   of which being that length gets set back to 0, meaning no region view is ever
+				   seen, meaning no MIDI notes during record (#3820).
+				*/
+				plist.add (ARDOUR::Properties::length_beats, 1);
 				plist.add (ARDOUR::Properties::name, string());
 				plist.add (ARDOUR::Properties::layer, 0);