rework snap

snap now fills in a struct (MusicFrame) which contins a snapped frame
along with a music divisor.
this gives useful information wrt magnetic snap which may or may not
have rounded to an exact musical position.

region position may now be set musically (using quarter notes for now).

this patch fixes several problems in the current code:

	- dragging a list of music-locked regions now maintains correct
	  musical offsets within the list.

	- splitting regions using magnetic snap works correctly (#7192)

	- cut drag should now work correctly with magnetic snap.

	- musical length of split midi regions is no longer frame based.

1 files changed, 189 insertions, 196 deletions

diff --git a/gtk2_ardour/editor_drag.cc b/gtk2_ardour/editor_drag.cc
index 9e763ff264..de3be07c8d 100644
--- a/gtk2_ardour/editor_drag.cc
+++ b/gtk2_ardour/editor_drag.cc
@@ -237,7 +237,7 @@ Drag::Drag (Editor* e, ArdourCanvas::Item* i, bool trackview_only)
 	, _raw_grab_frame (0)
 	, _grab_frame (0)
 	, _last_pointer_frame (0)
-	, _snap_delta (0)
+	, _snap_delta (0, 0)
 	, _constraint_pressed (false)
 {
 
@@ -268,7 +268,7 @@ Drag::start_grab (GdkEvent* event, Gdk::Cursor *cursor)
 	_raw_grab_frame = _editor->canvas_event_sample (event, &_grab_x, &_grab_y);
 
 	setup_pointer_frame_offset ();
-	_grab_frame = adjusted_frame (_raw_grab_frame, event);
+	_grab_frame = adjusted_frame (_raw_grab_frame, event).frame;
 	_last_pointer_frame = _grab_frame;
 	_last_pointer_x = _grab_x;
 
@@ -324,13 +324,13 @@ Drag::end_grab (GdkEvent* event)
 	return _move_threshold_passed;
 }
 
-framepos_t
+MusicFrame
 Drag::adjusted_frame (framepos_t f, GdkEvent const * event, bool snap) const
 {
-	framepos_t pos = 0;
+	MusicFrame pos (f, 0);
 
 	if (f > _pointer_frame_offset) {
-		pos = f - _pointer_frame_offset;
+		pos.frame = f - _pointer_frame_offset;
 	}
 
 	if (snap) {
@@ -343,14 +343,14 @@ Drag::adjusted_frame (framepos_t f, GdkEvent const * event, bool snap) const
 framepos_t
 Drag::adjusted_current_frame (GdkEvent const * event, bool snap) const
 {
-	return adjusted_frame (_drags->current_pointer_frame (), event, snap);
+	return adjusted_frame (_drags->current_pointer_frame (), event, snap).frame;
 }
 
 frameoffset_t
 Drag::snap_delta (guint state) const
 {
 	if (ArdourKeyboard::indicates_snap_delta (state)) {
-		return _snap_delta;
+		return _snap_delta.frame;
 	}
 
 	return 0;
@@ -373,11 +373,11 @@ Drag::current_pointer_y () const
 }
 
 void
-Drag::setup_snap_delta (framepos_t pos)
+Drag::setup_snap_delta (MusicFrame pos)
 {
-	framepos_t temp = pos;
-	_editor->snap_to (temp, ARDOUR::RoundNearest, false, true);
-	_snap_delta = temp - pos;
+	MusicFrame snap (pos);
+	_editor->snap_to (snap, ARDOUR::RoundNearest, false, true);
+	_snap_delta = snap - pos;
 }
 
 bool
@@ -513,7 +513,7 @@ Drag::show_verbose_cursor_text (string const & text)
 }
 
 boost::shared_ptr<Region>
-Drag::add_midi_region (MidiTimeAxisView* view, bool commit, const int32_t sub_num)
+Drag::add_midi_region (MidiTimeAxisView* view, bool commit)
 {
 	if (_editor->session()) {
 		const TempoMap& map (_editor->session()->tempo_map());
@@ -522,7 +522,7 @@ Drag::add_midi_region (MidiTimeAxisView* view, bool commit, const int32_t sub_nu
 		   might be wrong.
 		*/
 		framecnt_t len = map.frame_at_beat (max (0.0, map.beat_at_frame (pos)) + 1.0) - pos;
-		return view->add_region (grab_frame(), len, commit, sub_num);
+		return view->add_region (grab_frame(), len, commit);
 	}
 
 	return boost::shared_ptr<Region>();
@@ -599,33 +599,11 @@ RegionDrag::find_time_axis_view (TimeAxisView* t) const
 	return i;
 }
 
-/** determines if @pos is the closest frame to an exact musical division when using SnapMagnetic.
- *  (SnapMagnetic may snap to an exact division or no division at all).
- *  this is a hotfix for musical region position/trim. we should really
- *  deliver musical divisors when snapping magnetically to avoid this.
-*/
-int32_t
-RegionDrag::current_music_divisor (framepos_t pos, int32_t button_state)
-{
-	int32_t divisions = _editor->get_grid_music_divisions (button_state);
-
-	if (_editor->snap_mode() == Editing::SnapMagnetic && !ArdourKeyboard::indicates_snap (button_state)) {
-		TempoMap& tmap (_editor->session()->tempo_map());
-		const framepos_t exact_qn_pos = tmap.frame_at_quarter_note (tmap.exact_qn_at_frame (pos, divisions));
-
-		if (pos != exact_qn_pos) {
-			/* magnetic has not snapped */
-			divisions = 0;
-		}
-	}
-
-	return divisions;
-}
-
 RegionMotionDrag::RegionMotionDrag (Editor* e, ArdourCanvas::Item* i, RegionView* p, list<RegionView*> const & v, bool b)
 	: RegionDrag (e, i, p, v)
 	, _brushing (b)
 	, _ignore_video_lock (false)
+	, _last_position (0, 0)
 	, _total_x_delta (0)
 	, _last_pointer_time_axis_view (0)
 	, _last_pointer_layer (0)
@@ -640,9 +618,9 @@ void
 RegionMotionDrag::start_grab (GdkEvent* event, Gdk::Cursor* cursor)
 {
 	Drag::start_grab (event, cursor);
-	setup_snap_delta (_last_frame_position);
+	setup_snap_delta (_last_position);
 
-	show_verbose_cursor_time (_last_frame_position);
+	show_verbose_cursor_time (_last_position.frame);
 
 	pair<TimeAxisView*, double> const tv = _editor->trackview_by_y_position (current_pointer_y ());
 	if (tv.first) {
@@ -662,14 +640,13 @@ RegionMotionDrag::start_grab (GdkEvent* event, Gdk::Cursor* cursor)
 }
 
 double
-RegionMotionDrag::compute_x_delta (GdkEvent const * event, framepos_t* pending_region_position)
+RegionMotionDrag::compute_x_delta (GdkEvent const * event, MusicFrame* pending_region_position)
 {
 	/* compute the amount of pointer motion in frames, and where
 	   the region would be if we moved it by that much.
 	*/
 	*pending_region_position = adjusted_frame (_drags->current_pointer_frame (), event, false);
 
-	framepos_t sync_frame;
 	framecnt_t sync_offset;
 	int32_t sync_dir;
 
@@ -677,34 +654,35 @@ RegionMotionDrag::compute_x_delta (GdkEvent const * event, framepos_t* pending_r
 
 	/* we don't handle a sync point that lies before zero.
 	 */
-	if (sync_dir >= 0 || (sync_dir < 0 && *pending_region_position >= sync_offset)) {
+	if (sync_dir >= 0 || (sync_dir < 0 && pending_region_position->frame >= sync_offset)) {
 
 		framecnt_t const sd = snap_delta (event->button.state);
-		sync_frame = *pending_region_position + (sync_dir * sync_offset) + sd;
-
-		_editor->snap_to_with_modifier (sync_frame, event);
-
-		*pending_region_position = _primary->region()->adjust_to_sync (sync_frame) - sd;
-
+		MusicFrame sync_snap (pending_region_position->frame + (sync_dir * sync_offset) + sd, 0);
+		_editor->snap_to_with_modifier (sync_snap, event);
+		if (sync_offset == 0 && sd == 0) {
+			*pending_region_position = sync_snap;
+		} else {
+			pending_region_position->set (_primary->region()->adjust_to_sync (sync_snap.frame) - sd, 0);
+		}
 	} else {
-		*pending_region_position = _last_frame_position;
+		*pending_region_position = _last_position;
 	}
 
-	if (*pending_region_position > max_framepos - _primary->region()->length()) {
-		*pending_region_position = _last_frame_position;
+	if (pending_region_position->frame > max_framepos - _primary->region()->length()) {
+		*pending_region_position = _last_position;
 	}
 
 	double dx = 0;
 
 	bool const x_move_allowed = !_x_constrained;
 
-	if ((*pending_region_position != _last_frame_position) && x_move_allowed) {
+	if ((pending_region_position->frame != _last_position.frame) && x_move_allowed) {
 
 		/* x movement since last time (in pixels) */
-		dx = (static_cast<double> (*pending_region_position) - _last_frame_position) / _editor->samples_per_pixel;
+		dx = (static_cast<double> (pending_region_position->frame) - _last_position.frame) / _editor->samples_per_pixel;
 
 		/* total x movement */
-		framecnt_t total_dx = *pending_region_position;
+		framecnt_t total_dx = pending_region_position->frame;
 		if (regions_came_from_canvas()) {
 			total_dx = total_dx - grab_frame ();
 		}
@@ -713,7 +691,7 @@ RegionMotionDrag::compute_x_delta (GdkEvent const * event, framepos_t* pending_r
 		for (list<DraggingView>::const_iterator i = _views.begin(); i != _views.end(); ++i) {
 			if ((i->view->region()->position() + total_dx) < 0) {
 				dx = 0;
-				*pending_region_position = _last_frame_position;
+				*pending_region_position = _last_position;
 				break;
 			}
 		}
@@ -954,9 +932,9 @@ RegionMotionDrag::motion (GdkEvent* event, bool first_move)
 	}
 
 	/* Work out the change in x */
-	framepos_t pending_region_position;
+	MusicFrame pending_region_position (0, 0);
 	double const x_delta = compute_x_delta (event, &pending_region_position);
-	_last_frame_position = pending_region_position;
+	_last_position = pending_region_position;
 
 	/* calculate hidden tracks in current y-axis delta */
 	int delta_skip = 0;
@@ -1159,7 +1137,7 @@ RegionMotionDrag::motion (GdkEvent* event, bool first_move)
 			i->layer += this_delta_layer;
 
 			if (_brushing) {
-				_editor->mouse_brush_insert_region (rv, pending_region_position);
+				_editor->mouse_brush_insert_region (rv, pending_region_position.frame);
 			} else {
 				Duple track_origin;
 
@@ -1206,7 +1184,7 @@ RegionMotionDrag::motion (GdkEvent* event, bool first_move)
 	_total_x_delta += x_delta;
 
 	if (x_delta != 0 && !_brushing) {
-		show_verbose_cursor_time (_last_frame_position);
+		show_verbose_cursor_time (_last_position.frame);
 	}
 
 	/* keep track of pointer movement */
@@ -1296,12 +1274,7 @@ RegionMoveDrag::motion (GdkEvent* event, bool first_move)
 			const boost::shared_ptr<const Region> original = rv->region();
 			boost::shared_ptr<Region> region_copy;
 
-			if (rv == _primary) {
-				region_copy = RegionFactory::create (original, true
-								     , current_music_divisor (original->position(), event->button.state));
-			} else {
-				region_copy = RegionFactory::create (original, true, 0);
-			}
+			region_copy = RegionFactory::create (original, true);
 
 			/* need to set this so that the drop zone code can work. This doesn't
 			   actually put the region into the playlist, but just sets a weak pointer
@@ -1399,16 +1372,15 @@ RegionMoveDrag::finished (GdkEvent* ev, bool movement_occurred)
 		i->view->get_canvas_group()->show ();
 	}
 
-	bool const changed_position = (_last_frame_position != _primary->region()->position());
+	bool const changed_position = (_last_position.frame != _primary->region()->position());
 	bool const changed_tracks = (_time_axis_views[_views.front().time_axis_view] != &_views.front().view->get_time_axis_view());
-	framecnt_t const drag_delta = _primary->region()->position() - _last_frame_position;
 
 	if (_copy) {
 
 		finished_copy (
 			changed_position,
 			changed_tracks,
-			drag_delta,
+			_last_position,
 			ev->button.state
 			);
 
@@ -1417,7 +1389,7 @@ RegionMoveDrag::finished (GdkEvent* ev, bool movement_occurred)
 		finished_no_copy (
 			changed_position,
 			changed_tracks,
-			drag_delta,
+			_last_position,
 			ev->button.state
 			);
 
@@ -1462,15 +1434,16 @@ RegionMoveDrag::create_destination_time_axis (boost::shared_ptr<Region> region,
 }
 
 void
-RegionMoveDrag::finished_copy (bool const changed_position, bool const /*changed_tracks*/, framecnt_t const drag_delta, int32_t const ev_state)
+RegionMoveDrag::finished_copy (bool const changed_position, bool const /*changed_tracks*/, MusicFrame last_position, int32_t const ev_state)
 {
 	RegionSelection new_views;
 	PlaylistSet modified_playlists;
 	RouteTimeAxisView* new_time_axis_view = 0;
+	framecnt_t const drag_delta = _primary->region()->position() - _last_position.frame;
 
-	int32_t divisor = current_music_divisor (_primary->region()->position() - drag_delta, ev_state);
 	TempoMap& tmap (_editor->session()->tempo_map());
-	double qn_delta = _primary->region()->quarter_note() - tmap.exact_qn_at_frame (_primary->region()->position() - drag_delta, divisor);
+	const double last_pos_qn = tmap.exact_qn_at_frame (last_position.frame, last_position.division);
+	const double qn_delta = _primary->region()->quarter_note() - last_pos_qn;
 
 	if (_brushing) {
 		/* all changes were made during motion event handlers */
@@ -1495,12 +1468,16 @@ RegionMoveDrag::finished_copy (bool const changed_position, bool const /*changed
 			continue;
 		}
 
-		framepos_t where;
+		MusicFrame where (0, 0);
+		double quarter_note;
 
 		if (changed_position && !_x_constrained) {
-			where = i->view->region()->position() - drag_delta;
+			where.set (i->view->region()->position() - drag_delta, 0);
+			quarter_note = i->view->region()->quarter_note() - qn_delta;
 		} else {
-			where = i->view->region()->position();
+			/* region has not moved - divisor will not affect musical pos */
+			where.set (i->view->region()->position(), 0);
+			quarter_note = i->view->region()->quarter_note();
 		}
 
 		if (i->time_axis_view < 0 || i->time_axis_view >= (int)_time_axis_views.size()) {
@@ -1528,17 +1505,16 @@ RegionMoveDrag::finished_copy (bool const changed_position, bool const /*changed
 
 		if (dest_rtv != 0) {
 			RegionView* new_view;
-			if (i->view == _primary) {
-				new_view = insert_region_into_playlist (i->view->region(), dest_rtv, i->layer, where,
-									modified_playlists, current_music_divisor (where, ev_state));
+			if (i->view == _primary && !_x_constrained) {
+				new_view = insert_region_into_playlist (i->view->region(), dest_rtv, i->layer, last_position, last_pos_qn,
+									modified_playlists, true);
 			} else {
 				if (i->view->region()->position_lock_style() == AudioTime) {
-					new_view = insert_region_into_playlist (i->view->region(), dest_rtv, i->layer, where,
-										modified_playlists, 0);
+					new_view = insert_region_into_playlist (i->view->region(), dest_rtv, i->layer, where, quarter_note,
+										modified_playlists);
 				} else {
-					where = tmap.frame_at_quarter_note (i->view->region()->quarter_note() - qn_delta);
-					new_view = insert_region_into_playlist (i->view->region(), dest_rtv, i->layer, where,
-										modified_playlists, 0);
+					new_view = insert_region_into_playlist (i->view->region(), dest_rtv, i->layer, where, quarter_note,
+										modified_playlists, true);
 				}
 			}
 
@@ -1575,7 +1551,7 @@ void
 RegionMoveDrag::finished_no_copy (
 	bool const changed_position,
 	bool const changed_tracks,
-	framecnt_t const drag_delta,
+	MusicFrame last_position,
 	int32_t const ev_state
 	)
 {
@@ -1584,13 +1560,14 @@ RegionMoveDrag::finished_no_copy (
 	PlaylistSet frozen_playlists;
 	set<RouteTimeAxisView*> views_to_update;
 	RouteTimeAxisView* new_time_axis_view = 0;
+	framecnt_t const drag_delta = _primary->region()->position() - _last_position.frame;
 
 	typedef map<boost::shared_ptr<Playlist>, RouteTimeAxisView*> PlaylistMapping;
 	PlaylistMapping playlist_mapping;
 
-	int32_t divisor = current_music_divisor (_primary->region()->position() - drag_delta, ev_state);
 	TempoMap& tmap (_editor->session()->tempo_map());
-	double qn_delta = _primary->region()->quarter_note() - tmap.exact_qn_at_frame (_primary->region()->position() - drag_delta, divisor);
+	const double last_pos_qn = tmap.exact_qn_at_frame (last_position.frame, last_position.division);
+	const double qn_delta = _primary->region()->quarter_note() - last_pos_qn;
 
 	std::set<boost::shared_ptr<const Region> > uniq;
 	for (list<DraggingView>::const_iterator i = _views.begin(); i != _views.end(); ) {
@@ -1640,12 +1617,15 @@ RegionMoveDrag::finished_no_copy (
 
 		views_to_update.insert (dest_rtv);
 
-		framepos_t where;
+		MusicFrame where (0, 0);
+		double quarter_note;
 
 		if (changed_position && !_x_constrained) {
-			where = rv->region()->position() - drag_delta;
+			where.set (rv->region()->position() - drag_delta, 0);
+			quarter_note = i->view->region()->quarter_note() - qn_delta;
 		} else {
-			where = rv->region()->position();
+			where.set (rv->region()->position(), 0);
+			quarter_note = i->view->region()->quarter_note();
 		}
 
 		if (changed_tracks) {
@@ -1654,21 +1634,20 @@ RegionMoveDrag::finished_no_copy (
 			RegionView* new_view;
 			if (rv == _primary) {
 				new_view = insert_region_into_playlist (
-					RegionFactory::create (rv->region (), true), dest_rtv, dest_layer, where,
-					modified_playlists, current_music_divisor (where, ev_state)
+					RegionFactory::create (rv->region (), true), dest_rtv, dest_layer, last_position, last_pos_qn,
+					modified_playlists, true
 					);
 			} else {
 				if (rv->region()->position_lock_style() == AudioTime) {
 
 					new_view = insert_region_into_playlist (
-						RegionFactory::create (rv->region (), true), dest_rtv, dest_layer, where,
-						modified_playlists, 0
+						RegionFactory::create (rv->region (), true), dest_rtv, dest_layer, where, quarter_note,
+						modified_playlists
 						);
 				} else {
-					where = tmap.frame_at_quarter_note (rv->region()->quarter_note() - qn_delta);
 					new_view = insert_region_into_playlist (
-						RegionFactory::create (rv->region (), true), dest_rtv, dest_layer, where,
-						modified_playlists, 0
+						RegionFactory::create (rv->region (), true), dest_rtv, dest_layer, where, quarter_note,
+						modified_playlists, true
 						);
 				}
 			}
@@ -1730,13 +1709,14 @@ RegionMoveDrag::finished_no_copy (
 				playlist->freeze ();
 			}
 			if (rv == _primary) {
-				rv->region()->set_position (where, current_music_divisor (where, ev_state));
+				rv->region()->set_position (where.frame, last_position.division);
 			} else {
 				if (rv->region()->position_lock_style() == AudioTime) {
-					rv->region()->set_position (where, 0);
+					/* move by frame offset */
+					rv->region()->set_position (where.frame, 0);
 				} else {
-					rv->region()->set_position (tmap.frame_at_quarter_note (rv->region()->quarter_note() - qn_delta), 0);
-
+					/* move by music offset */
+					rv->region()->set_position_music (rv->region()->quarter_note() - qn_delta);
 				}
 			}
 			_editor->session()->add_command (new StatefulDiffCommand (rv->region()));
@@ -1838,11 +1818,12 @@ RegionMoveDrag::remove_region_from_playlist (
 RegionView *
 RegionMoveDrag::insert_region_into_playlist (
 	boost::shared_ptr<Region> region,
-	RouteTimeAxisView* dest_rtv,
-	layer_t dest_layer,
-	framecnt_t where,
-	PlaylistSet& modified_playlists,
-	const int32_t sub_num
+	RouteTimeAxisView*        dest_rtv,
+	layer_t                   dest_layer,
+	MusicFrame                where,
+	double                    quarter_note,
+	PlaylistSet&              modified_playlists,
+	bool                      for_music
 	)
 {
 	boost::shared_ptr<Playlist> dest_playlist = dest_rtv->playlist ();
@@ -1859,7 +1840,11 @@ RegionMoveDrag::insert_region_into_playlist (
 	if (r.second) {
 		dest_playlist->clear_changes ();
 	}
-	dest_playlist->add_region (region, where, 1.0, false, sub_num);
+	if (for_music) {
+		dest_playlist->add_region (region, where.frame, 1.0, false, where.division, quarter_note, true);
+	} else {
+		dest_playlist->add_region (region, where.frame, 1.0, false, where.division);
+	}
 
 	if (dest_rtv->view()->layer_display() == Stacked || dest_rtv->view()->layer_display() == Expanded) {
 		dest_playlist->set_layer (region, dest_layer);
@@ -1954,13 +1939,13 @@ RegionMoveDrag::RegionMoveDrag (Editor* e, ArdourCanvas::Item* i, RegionView* p,
 		speed = rtv->track()->speed ();
 	}
 
-	_last_frame_position = static_cast<framepos_t> (_primary->region()->position() / speed);
+	_last_position = MusicFrame (static_cast<framepos_t> (_primary->region()->position() / speed), 0);
 }
 
 void
 RegionMoveDrag::setup_pointer_frame_offset ()
 {
-	_pointer_frame_offset = raw_grab_frame() - _last_frame_position;
+	_pointer_frame_offset = raw_grab_frame() - _last_position.frame;
 }
 
 RegionInsertDrag::RegionInsertDrag (Editor* e, boost::shared_ptr<Region> r, RouteTimeAxisView* v, framepos_t pos)
@@ -1977,7 +1962,7 @@ RegionInsertDrag::RegionInsertDrag (Editor* e, boost::shared_ptr<Region> r, Rout
 	_primary->set_position (pos, 0);
 	_views.push_back (DraggingView (_primary, this, v));
 
-	_last_frame_position = pos;
+	_last_position = MusicFrame (pos, 0);
 
 	_item = _primary->get_canvas_group ();
 }
@@ -1997,11 +1982,11 @@ RegionInsertDrag::finished (GdkEvent * event, bool)
 
 	_editor->begin_reversible_command (Operations::insert_region);
 	playlist->clear_changes ();
-	playlist->add_region (_primary->region (), _last_frame_position);
+	playlist->add_region (_primary->region (), _last_position.frame, _editor->get_grid_music_divisions (event->button.state));
 
 	// Mixbus doesn't seem to ripple when inserting regions from the list: should we? yes, probably
 	if (Config->get_edit_mode() == Ripple) {
-		playlist->ripple (_last_frame_position, _primary->region()->length(), _primary->region());
+		playlist->ripple (_last_position.frame, _primary->region()->length(), _primary->region());
 	}
 
 	_editor->session()->add_command (new StatefulDiffCommand (playlist));
@@ -2278,7 +2263,7 @@ RegionRippleDrag::motion (GdkEvent* event, bool first_move)
 
 	framepos_t where = adjusted_current_frame (event);
 	assert (where >= 0);
-	framepos_t after;
+	MusicFrame after (0, 0);
 	double delta = compute_x_delta (event, &after);
 
 	framecnt_t amount = _editor->pixel_to_sample (delta);
@@ -2328,7 +2313,7 @@ RegionRippleDrag::motion (GdkEvent* event, bool first_move)
 		prev_amount += amount;
 	}
 
-	_last_frame_position = after;
+	_last_position = after;
 }
 
 void
@@ -2409,7 +2394,7 @@ RegionCreateDrag::motion (GdkEvent* event, bool first_move)
 {
 	if (first_move) {
 		_editor->begin_reversible_command (_("create region"));
-		_region = add_midi_region (_view, false, _editor->get_grid_music_divisions (event->button.state));
+		_region = add_midi_region (_view, false);
 		_view->playlist()->freeze ();
 	} else {
 		if (_region) {
@@ -2435,7 +2420,7 @@ void
 RegionCreateDrag::finished (GdkEvent* event, bool movement_occurred)
 {
 	if (!movement_occurred) {
-		add_midi_region (_view, true, _editor->get_grid_music_divisions (event->button.state));
+		add_midi_region (_view, true);
 	} else {
 		_view->playlist()->thaw ();
 		_editor->commit_reversible_command();
@@ -2867,7 +2852,7 @@ TrimDrag::start_grab (GdkEvent* event, Gdk::Cursor*)
 	framecnt_t const region_length = (framecnt_t) (_primary->region()->length() / speed);
 
 	framepos_t const pf = adjusted_current_frame (event);
-	setup_snap_delta (region_start);
+	setup_snap_delta (MusicFrame (region_start, 0));
 
 	if (Keyboard::modifier_state_equals (event->button.state, ArdourKeyboard::trim_contents_modifier ())) {
 		/* Move the contents of the region around without changing the region bounds */
@@ -2930,8 +2915,8 @@ TrimDrag::motion (GdkEvent* event, bool first_move)
 	if (tv && tv->is_track()) {
 		speed = tv->track()->speed();
 	}
-	framecnt_t adj_frame = adjusted_frame (_drags->current_pointer_frame () + snap_delta (event->button.state), event, true);
-	framecnt_t dt = adj_frame - raw_grab_frame () + _pointer_frame_offset - snap_delta (event->button.state);
+	MusicFrame adj_frame = adjusted_frame (_drags->current_pointer_frame () + snap_delta (event->button.state), event, true);
+	framecnt_t dt = adj_frame.frame - raw_grab_frame () + _pointer_frame_offset - snap_delta (event->button.state);
 
 	if (first_move) {
 
@@ -3012,13 +2997,11 @@ TrimDrag::motion (GdkEvent* event, bool first_move)
 		}
 	}
 
-	int32_t divisions = current_music_divisor (adj_frame, event->button.state);
-
 	switch (_operation) {
 	case StartTrim:
 		for (list<DraggingView>::iterator i = _views.begin(); i != _views.end(); ++i) {
 			bool changed = i->view->trim_front (i->initial_position + dt, non_overlap_trim
-							    , divisions);
+							    , adj_frame.division);
 
 			if (changed && _preserve_fade_anchor) {
 				AudioRegionView* arv = dynamic_cast<AudioRegionView*> (i->view);
@@ -3037,7 +3020,7 @@ TrimDrag::motion (GdkEvent* event, bool first_move)
 
 	case EndTrim:
 		for (list<DraggingView>::iterator i = _views.begin(); i != _views.end(); ++i) {
-			bool changed = i->view->trim_end (i->initial_end + dt, non_overlap_trim, divisions);
+			bool changed = i->view->trim_end (i->initial_end + dt, non_overlap_trim, adj_frame.division);
 			if (changed && _preserve_fade_anchor) {
 				AudioRegionView* arv = dynamic_cast<AudioRegionView*> (i->view);
 				if (arv) {
@@ -3156,7 +3139,7 @@ TrimDrag::finished (GdkEvent* event, bool movement_occurred)
 
 	} else {
 		/* no mouse movement */
-		if (adjusted_current_frame (event) != adjusted_frame (_drags->current_pointer_frame(), event, false)) {
+		if (adjusted_current_frame (event) != adjusted_frame (_drags->current_pointer_frame(), event, false).frame) {
 			_editor->point_trim (event, adjusted_current_frame (event));
 		}
 	}
@@ -3648,14 +3631,14 @@ void
 CursorDrag::start_grab (GdkEvent* event, Gdk::Cursor* c)
 {
 	Drag::start_grab (event, c);
-	setup_snap_delta (_editor->playhead_cursor->current_frame ());
+	const framepos_t current_frame = _editor->playhead_cursor->current_frame();
+	setup_snap_delta (MusicFrame (current_frame, 0));
 
 	_grab_zoom = _editor->samples_per_pixel;
 
-	framepos_t where = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
+	MusicFrame where (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
 
 	_editor->snap_to_with_modifier (where, event);
-
 	_editor->_dragging_playhead = true;
 
 	Session* s = _editor->session ();
@@ -3690,16 +3673,18 @@ CursorDrag::start_grab (GdkEvent* event, Gdk::Cursor* c)
 		}
 	}
 
-	fake_locate (where - snap_delta (event->button.state));
+	fake_locate (where.frame - snap_delta (event->button.state));
 }
 
 void
 CursorDrag::motion (GdkEvent* event, bool)
 {
-	framepos_t where = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
+	MusicFrame where (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
+
 	_editor->snap_to_with_modifier (where, event);
-	if (where != last_pointer_frame()) {
-		fake_locate (where - snap_delta (event->button.state));
+
+	if (where.frame != last_pointer_frame()) {
+		fake_locate (where.frame - snap_delta (event->button.state));
 	}
 }
 
@@ -3734,7 +3719,7 @@ CursorDrag::aborted (bool)
 		_editor->_dragging_playhead = false;
 	}
 
-	_editor->playhead_cursor->set_position (adjusted_frame (grab_frame (), 0, false));
+	_editor->playhead_cursor->set_position (adjusted_frame (grab_frame (), 0, false).frame);
 }
 
 FadeInDrag::FadeInDrag (Editor* e, ArdourCanvas::Item* i, RegionView* p, list<RegionView*> const & v)
@@ -3750,7 +3735,8 @@ FadeInDrag::start_grab (GdkEvent* event, Gdk::Cursor* cursor)
 
 	AudioRegionView* arv = dynamic_cast<AudioRegionView*> (_primary);
 	boost::shared_ptr<AudioRegion> const r = arv->audio_region ();
-	setup_snap_delta (r->position ());
+	const int32_t division = _editor->get_grid_music_divisions (event->button.state);
+	setup_snap_delta (MusicFrame (r->position(), division));
 
 	show_verbose_cursor_duration (r->position(), r->position() + r->fade_in()->back()->when, 32);
 }
@@ -3768,18 +3754,19 @@ FadeInDrag::motion (GdkEvent* event, bool)
 {
 	framecnt_t fade_length;
 
-	framepos_t pos = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
+	MusicFrame pos (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
 	_editor->snap_to_with_modifier (pos, event);
-	pos -= snap_delta (event->button.state);
+
+	pos.frame -= snap_delta (event->button.state);
 
 	boost::shared_ptr<AudioRegion> region = boost::dynamic_pointer_cast<AudioRegion> (_primary->region ());
 
-	if (pos < (region->position() + 64)) {
+	if (pos.frame < (region->position() + 64)) {
 		fade_length = 64; // this should be a minimum defined somewhere
-	} else if (pos > region->position() + region->length() - region->fade_out()->back()->when) {
+	} else if (pos.frame > region->position() + region->length() - region->fade_out()->back()->when) {
 		fade_length = region->length() - region->fade_out()->back()->when - 1;
 	} else {
-		fade_length = pos - region->position();
+		fade_length = pos.frame - region->position();
 	}
 
 	for (list<DraggingView>::iterator i = _views.begin(); i != _views.end(); ++i) {
@@ -3804,18 +3791,19 @@ FadeInDrag::finished (GdkEvent* event, bool movement_occurred)
 	}
 
 	framecnt_t fade_length;
-	framepos_t pos = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
+	MusicFrame pos (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
+
 	_editor->snap_to_with_modifier (pos, event);
-	pos -= snap_delta (event->button.state);
+	pos.frame -= snap_delta (event->button.state);
 
 	boost::shared_ptr<AudioRegion> region = boost::dynamic_pointer_cast<AudioRegion> (_primary->region ());
 
-	if (pos < (region->position() + 64)) {
+	if (pos.frame < (region->position() + 64)) {
 		fade_length = 64; // this should be a minimum defined somewhere
-	} else if (pos >= region->position() + region->length() - region->fade_out()->back()->when) {
+	} else if (pos.frame >= region->position() + region->length() - region->fade_out()->back()->when) {
 		fade_length = region->length() - region->fade_out()->back()->when - 1;
 	} else {
-		fade_length = pos - region->position();
+		fade_length = pos.frame - region->position();
 	}
 
 	bool in_command = false;
@@ -3874,7 +3862,8 @@ FadeOutDrag::start_grab (GdkEvent* event, Gdk::Cursor* cursor)
 
 	AudioRegionView* arv = dynamic_cast<AudioRegionView*> (_primary);
 	boost::shared_ptr<AudioRegion> r = arv->audio_region ();
-	setup_snap_delta (r->last_frame ());
+	const int32_t division = _editor->get_grid_music_divisions (event->button.state);
+	setup_snap_delta (MusicFrame (r->last_frame(), division));
 
 	show_verbose_cursor_duration (r->last_frame() - r->fade_out()->back()->when, r->last_frame());
 }
@@ -3891,19 +3880,19 @@ void
 FadeOutDrag::motion (GdkEvent* event, bool)
 {
 	framecnt_t fade_length;
+	MusicFrame pos (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
 
-	framepos_t pos = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
 	_editor->snap_to_with_modifier (pos, event);
-	pos -= snap_delta (event->button.state);
+	pos.frame -= snap_delta (event->button.state);
 
 	boost::shared_ptr<AudioRegion> region = boost::dynamic_pointer_cast<AudioRegion> (_primary->region ());
 
-	if (pos > (region->last_frame() - 64)) {
+	if (pos.frame > (region->last_frame() - 64)) {
 		fade_length = 64; // this should really be a minimum fade defined somewhere
-	} else if (pos <= region->position() + region->fade_in()->back()->when) {
+	} else if (pos.frame <= region->position() + region->fade_in()->back()->when) {
 		fade_length = region->length() - region->fade_in()->back()->when - 1;
 	} else {
-		fade_length = region->last_frame() - pos;
+		fade_length = region->last_frame() - pos.frame;
 	}
 
 	for (list<DraggingView>::iterator i = _views.begin(); i != _views.end(); ++i) {
@@ -3928,19 +3917,19 @@ FadeOutDrag::finished (GdkEvent* event, bool movement_occurred)
 	}
 
 	framecnt_t fade_length;
+	MusicFrame pos (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
 
-	framepos_t pos = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
 	_editor->snap_to_with_modifier (pos, event);
-	pos -= snap_delta (event->button.state);
+	pos.frame -= snap_delta (event->button.state);
 
 	boost::shared_ptr<AudioRegion> region = boost::dynamic_pointer_cast<AudioRegion> (_primary->region ());
 
-	if (pos > (region->last_frame() - 64)) {
+	if (pos.frame > (region->last_frame() - 64)) {
 		fade_length = 64; // this should really be a minimum fade defined somewhere
-	} else if (pos <= region->position() + region->fade_in()->back()->when) {
+	} else if (pos.frame <= region->position() + region->fade_in()->back()->when) {
 		fade_length = region->length() - region->fade_in()->back()->when - 1;
 	} else {
-		fade_length = region->last_frame() - pos;
+		fade_length = region->last_frame() - pos.frame;
 	}
 
 	bool in_command = false;
@@ -4035,7 +4024,9 @@ MarkerDrag::start_grab (GdkEvent* event, Gdk::Cursor* cursor)
 	} else {
 		show_verbose_cursor_time (location->end());
 	}
-	setup_snap_delta (is_start ? location->start() : location->end());
+	const int32_t division = _editor->get_grid_music_divisions (event->button.state);
+	const framepos_t pos = is_start ? location->start() : location->end();
+	setup_snap_delta (MusicFrame (pos, division));
 
 	Selection::Operation op = ArdourKeyboard::selection_type (event->button.state);
 
@@ -4139,7 +4130,7 @@ MarkerDrag::motion (GdkEvent* event, bool)
 	Location *copy_location = 0;
 	framecnt_t const sd = snap_delta (event->button.state);
 
-	framecnt_t const newframe = adjusted_frame (_drags->current_pointer_frame () + sd, event, true) - sd;
+	framecnt_t const newframe = adjusted_frame (_drags->current_pointer_frame () + sd, event, true).frame - sd;
 	framepos_t next = newframe;
 
 	if (Keyboard::modifier_state_contains (event->button.state, ArdourKeyboard::push_points_modifier ())) {
@@ -4422,8 +4413,9 @@ ControlPointDrag::start_grab (GdkEvent* event, Gdk::Cursor* /*cursor*/)
 	_fixed_grab_x = _point->get_x() + _editor->sample_to_pixel_unrounded (_point->line().offset());
 	_fixed_grab_y = _point->get_y();
 
-	framepos_t pos = _editor->pixel_to_sample (_fixed_grab_x);
-	setup_snap_delta (pos);
+	const framepos_t pos = _editor->pixel_to_sample (_fixed_grab_x);
+	const int32_t division = _editor->get_grid_music_divisions (event->button.state);
+	setup_snap_delta (MusicFrame (pos, division));
 
 	float const fraction = 1 - (_point->get_y() / _point->line().height());
 	show_verbose_cursor_text (_point->line().get_verbose_cursor_string (fraction));
@@ -4476,13 +4468,14 @@ ControlPointDrag::motion (GdkEvent* event, bool first_motion)
 		cy = zero_gain_y;
 	}
 
-	framepos_t cx_frames = _editor->pixel_to_sample (cx) + snap_delta (event->button.state);
+	MusicFrame cx_mf (_editor->pixel_to_sample (cx) + snap_delta (event->button.state), 0);
+
 	if (!_x_constrained && need_snap) {
-		_editor->snap_to_with_modifier (cx_frames, event);
+		_editor->snap_to_with_modifier (cx_mf, event);
 	}
 
-	cx_frames -= snap_delta (event->button.state);
-	cx_frames = min (cx_frames, _point->line().maximum_time() + _point->line().offset());
+	cx_mf.frame -= snap_delta (event->button.state);
+	cx_mf.frame = min (cx_mf.frame, _point->line().maximum_time() + _point->line().offset());
 
 	float const fraction = 1.0 - (cy / _point->line().height());
 
@@ -4492,7 +4485,7 @@ ControlPointDrag::motion (GdkEvent* event, bool first_motion)
 		_point->line().start_drag_single (_point, _fixed_grab_x, initial_fraction);
 	}
 	pair<double, float> result;
-	result = _point->line().drag_motion (_editor->sample_to_pixel_unrounded (cx_frames), fraction, false, _pushing, _final_index);
+	result = _point->line().drag_motion (_editor->sample_to_pixel_unrounded (cx_mf.frame), fraction, false, _pushing, _final_index);
 
 	show_verbose_cursor_text (_point->line().get_verbose_cursor_string (result.second));
 }
@@ -4755,24 +4748,23 @@ RubberbandSelectDrag::motion (GdkEvent* event, bool)
 	framepos_t end;
 	double y1;
 	double y2;
-
 	framepos_t const pf = adjusted_current_frame (event, UIConfiguration::instance().get_rubberbanding_snaps_to_grid());
+	MusicFrame grab (grab_frame (), 0);
 
-	framepos_t grab = grab_frame ();
 	if (UIConfiguration::instance().get_rubberbanding_snaps_to_grid ()) {
 		_editor->snap_to_with_modifier (grab, event);
 	} else {
-		grab = raw_grab_frame ();
+		grab.frame = raw_grab_frame ();
 	}
 
 	/* base start and end on initial click position */
 
-	if (pf < grab) {
+	if (pf < grab.frame) {
 		start = pf;
-		end = grab;
+		end = grab.frame;
 	} else {
 		end = pf;
-		start = grab;
+		start = grab.frame;
 	}
 
 	if (current_pointer_y() < grab_y()) {
@@ -4882,7 +4874,7 @@ RubberbandSelectDrag::finished (GdkEvent* event, bool movement_occurred)
 			/* MIDI track */
 			if (_editor->selection->empty() && _editor->mouse_mode == MouseDraw) {
 				/* nothing selected */
-				add_midi_region (mtv, true, _editor->get_grid_music_divisions(event->button.state));
+				add_midi_region (mtv, true);
 				do_deselect = false;
 			}
 		}
@@ -4922,7 +4914,8 @@ TimeFXDrag::start_grab (GdkEvent* event, Gdk::Cursor* cursor)
 	_editor->get_selection().add (_primary);
 
 	framepos_t where = _primary->region()->position();
-	setup_snap_delta (where);
+	const int32_t division = _editor->get_grid_music_divisions (event->button.state);
+	setup_snap_delta (MusicFrame (where, division));
 
 	show_verbose_cursor_duration (where, adjusted_current_frame (event), 0);
 }
@@ -4932,19 +4925,19 @@ TimeFXDrag::motion (GdkEvent* event, bool)
 {
 	RegionView* rv = _primary;
 	StreamView* cv = rv->get_time_axis_view().view ();
-
 	pair<TimeAxisView*, double> const tv = _editor->trackview_by_y_position (grab_y());
 	int layer = tv.first->layer_display() == Overlaid ? 0 : tv.second;
 	int layers = tv.first->layer_display() == Overlaid ? 1 : cv->layers();
-	framepos_t pf = _editor->canvas_event_sample (event) + snap_delta (event->button.state);
+	MusicFrame pf (_editor->canvas_event_sample (event) + snap_delta (event->button.state), 0);
+
 	_editor->snap_to_with_modifier (pf, event);
-	pf -= snap_delta (event->button.state);
+	pf.frame -= snap_delta (event->button.state);
 
-	if (pf > rv->region()->position()) {
-		rv->get_time_axis_view().show_timestretch (rv->region()->position(), pf, layers, layer);
+	if (pf.frame > rv->region()->position()) {
+		rv->get_time_axis_view().show_timestretch (rv->region()->position(), pf.frame, layers, layer);
 	}
 
-	show_verbose_cursor_duration (_primary->region()->position(), pf, 0);
+	show_verbose_cursor_duration (_primary->region()->position(), pf.frame, 0);
 }
 
 void
@@ -5128,7 +5121,7 @@ SelectionDrag::motion (GdkEvent* event, bool first_move)
 	framepos_t end = 0;
 	framecnt_t length = 0;
 	framecnt_t distance = 0;
-
+	MusicFrame start_mf (0, 0);
 	framepos_t const pending_position = adjusted_current_frame (event);
 
 	if (_operation != CreateSelection && pending_position == last_pointer_frame()) {
@@ -5142,23 +5135,22 @@ SelectionDrag::motion (GdkEvent* event, bool first_move)
 	switch (_operation) {
 	case CreateSelection:
 	{
-		framepos_t grab = grab_frame ();
-
+		MusicFrame grab (grab_frame (), 0);
 		if (first_move) {
-			grab = adjusted_current_frame (event, false);
-			if (grab < pending_position) {
+			grab.frame = adjusted_current_frame (event, false);
+			if (grab.frame < pending_position) {
 				_editor->snap_to (grab, RoundDownMaybe);
 			}  else {
 				_editor->snap_to (grab, RoundUpMaybe);
 			}
 		}
 
-		if (pending_position < grab) {
+		if (pending_position < grab.frame) {
 			start = pending_position;
-			end = grab;
+			end = grab.frame;
 		} else {
 			end = pending_position;
-			start = grab;
+			start = grab.frame;
 		}
 
 		/* first drag: Either add to the selection
@@ -5269,9 +5261,11 @@ SelectionDrag::motion (GdkEvent* event, bool first_move)
 		length = end - start;
 		distance = pending_position - start;
 		start = pending_position;
-		_editor->snap_to (start);
 
-		end = start + length;
+		start_mf.frame = start;
+		_editor->snap_to (start_mf);
+
+		end = start_mf.frame + length;
 
 		break;
 
@@ -5466,15 +5460,15 @@ RangeMarkerBarDrag::motion (GdkEvent* event, bool first_move)
 	framepos_t const pf = adjusted_current_frame (event);
 
 	if (_operation == CreateSkipMarker || _operation == CreateRangeMarker || _operation == CreateTransportMarker || _operation == CreateCDMarker) {
-		framepos_t grab = grab_frame ();
+		MusicFrame grab (grab_frame (), 0);
 		_editor->snap_to (grab);
 
 		if (pf < grab_frame()) {
 			start = pf;
-			end = grab;
+			end = grab.frame;
 		} else {
 			end = pf;
-			start = grab;
+			start = grab.frame;
 		}
 
 		/* first drag: Either add to the selection
@@ -5653,7 +5647,7 @@ NoteDrag::start_grab (GdkEvent* event, Gdk::Cursor *)
 		_copy = false;
 	}
 
-	setup_snap_delta (_region->source_beats_to_absolute_frames (_primary->note()->time ()));
+	setup_snap_delta (MusicFrame (_region->source_beats_to_absolute_frames (_primary->note()->time ()), 0));
 
 	if (!(_was_selected = _primary->selected())) {
 
@@ -6616,10 +6610,10 @@ RegionCutDrag::start_grab (GdkEvent* event, Gdk::Cursor* c)
 void
 RegionCutDrag::motion (GdkEvent* event, bool)
 {
-	framepos_t pos = _drags->current_pointer_frame();
+	MusicFrame pos (_drags->current_pointer_frame(), 0);
 	_editor->snap_to_with_modifier (pos, event);
 
-	line->set_position (pos);
+	line->set_position (pos.frame);
 }
 
 void
@@ -6627,19 +6621,18 @@ RegionCutDrag::finished (GdkEvent* event, bool)
 {
 	_editor->get_track_canvas()->canvas()->re_enter();
 
-	framepos_t pos = _drags->current_pointer_frame();
-	_editor->snap_to_with_modifier (pos, event);
 
+	MusicFrame pos (_drags->current_pointer_frame(), 0);
+	_editor->snap_to_with_modifier (pos, event);
 	line->hide ();
 
-	RegionSelection rs = _editor->get_regions_from_selection_and_mouse (pos);
+	RegionSelection rs = _editor->get_regions_from_selection_and_mouse (pos.frame);
 
 	if (rs.empty()) {
 		return;
 	}
 
-	_editor->split_regions_at (pos, rs, _editor->get_grid_music_divisions (event->button.state),
-	                           false);
+	_editor->split_regions_at (pos, rs, false);
 }
 
 void