fix error in framepos_{plus,minus}_bbt() which miscounted beats while stepping through bars - stops dragged MIDI notes from ending up in the wrong place, and more

git-svn-id: svn://localhost/ardour2/branches/3.0@11159 d708f5d6-7413-0410-9779-e7cbd77b26cf

2 files changed, 31 insertions, 12 deletions

diff --git a/libs/ardour/beats_frames_converter.cc b/libs/ardour/beats_frames_converter.cc
index 03a581e276..215292f6c1 100644
--- a/libs/ardour/beats_frames_converter.cc
+++ b/libs/ardour/beats_frames_converter.cc
@@ -24,7 +24,7 @@
 
 namespace ARDOUR {
 
-/** Takes a duration in beats and considers it as a distance from the origin
+/** Takes a positive duration in beats and considers it as a distance from the origin
  *  supplied to the constructor.  Returns the equivalent number of frames,
  *  taking tempo changes into account.
  */
@@ -32,7 +32,6 @@ framecnt_t
 BeatsFramesConverter::to (double beats) const
 {
 	assert (beats >= 0);
-
 	return _tempo_map.framepos_plus_beats (_origin_b, beats) - _origin_b;
 }
 
diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index e8f894c1b4..5d02746210 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -1655,6 +1655,7 @@ TempoMap::framepos_minus_bbt (framepos_t pos, BBT_Time op)
 	Glib::RWLock::ReaderLock lm (map_lock);
 	BBTPointList::const_iterator i;
 	framecnt_t extra_frames = 0;
+	bool had_bars = (op.bars != 0);
 
 	/* start from the bar|beat right before (or at) pos */
 
@@ -1667,11 +1668,19 @@ TempoMap::framepos_minus_bbt (framepos_t pos, BBT_Time op)
 
 	while (i != _map->begin() && (op.bars || op.beats)) {
 		--i;
-		if ((*i).is_bar()) {
-			if (op.bars) {
-				op.bars--;
+
+		if (had_bars) {
+			if ((*i).is_bar()) {
+				if (op.bars) {
+					op.bars--;
+				}
 			}
-		} else {
+		}
+
+		if ((had_bars && op.bars == 0) || !had_bars) {
+			/* finished counting bars, or none to count, 
+			   so decrement beat count
+			*/
 			if (op.beats) {
 				op.beats--;
 			}
@@ -1703,23 +1712,34 @@ TempoMap::framepos_plus_bbt (framepos_t pos, BBT_Time op)
 	int additional_minutes = 1;
 	BBTPointList::const_iterator i;
 	framecnt_t backup_frames = 0;
-
+	bool had_bars = (op.bars != 0);
+		
 	while (true) {
 
 		i = bbt_before_or_at (pos);
-		
+
 		op = op_copy;
 
 		/* we know that (*i).frame is before or equal to pos */
 		backup_frames = pos - (*i).frame;
 
 		while (i != _map->end() && (op.bars || op.beats)) {
+
 			++i;
-			if ((*i).is_bar()) {
-				if (op.bars) {
-					op.bars--;
+
+			if (had_bars) {
+				if ((*i).is_bar()) {
+					if (op.bars) {
+						op.bars--;
+					}
 				}
-			} else {
+			}
+			
+			if ((had_bars && op.bars == 0) || !had_bars) {
+				/* finished counting bars, or none to count, 
+				   so decrement beat count
+				*/
+
 				if (op.beats) {
 					op.beats--;
 				}