Add stacked lanes mode which displays regions on different layers at different positions in the view.

git-svn-id: svn://localhost/ardour2/trunk@1855 d708f5d6-7413-0410-9779-e7cbd77b26cf

21 files changed, 260 insertions, 149 deletions

diff --git a/gtk2_ardour/audio_region_view.cc b/gtk2_ardour/audio_region_view.cc
index 2e1c13b487..bc0e3671c3 100644
--- a/gtk2_ardour/audio_region_view.cc
+++ b/gtk2_ardour/audio_region_view.cc
@@ -157,20 +157,18 @@ AudioRegionView::init (Gdk::Color& basic_color, bool wfd)
 		fade_in_handle = new ArdourCanvas::SimpleRect (*group);
 		fade_in_handle->property_fill_color_rgba() = RGBA_TO_UINT(r,g,b,0);
 		fade_in_handle->property_outline_pixels() = 0;
-		fade_in_handle->property_y1() = 2.0;
-		fade_in_handle->property_y2() = 7.0;
 		
 		fade_in_handle->set_data ("regionview", this);
 		
 		fade_out_handle = new ArdourCanvas::SimpleRect (*group);
 		fade_out_handle->property_fill_color_rgba() = RGBA_TO_UINT(r,g,b,0);
 		fade_out_handle->property_outline_pixels() = 0;
-		fade_out_handle->property_y1() = 2.0;
-		fade_out_handle->property_y2() = 7.0;
 		
 		fade_out_handle->set_data ("regionview", this);
 	}
 
+	setup_fade_handle_positions ();
+
 	string foo = _region->name();
 	foo += ':';
 	foo += "gain";
@@ -185,7 +183,7 @@ AudioRegionView::init (Gdk::Color& basic_color, bool wfd)
 
 	gain_line->reset ();
 
-	set_height (trackview.height);
+	set_y_position_and_height (0, trackview.height);
 
 	region_muted ();
 	region_sync_changed ();
@@ -400,38 +398,41 @@ AudioRegionView::region_muted ()
 }
 
 void
-AudioRegionView::set_height (gdouble height)
+AudioRegionView::set_y_position_and_height (double y, double h)
 {
-	RegionView::set_height(height);
-	
-	uint32_t wcnt = waves.size();
+	RegionView::set_y_position_and_height(y, h - 2);
+
+	_y_position = y;
+	_height = h;
 
-	for (uint32_t n=0; n < wcnt; ++n) {
-		gdouble ht;
+	uint32_t const wcnt = waves.size();
+	for (uint32_t n = 0; n < wcnt; ++n) {
+		double ht;
 
-		if ((height) <= NAME_HIGHLIGHT_THRESH) {
-			ht = ((height-2*wcnt) / (double) wcnt);
+		if (h <= NAME_HIGHLIGHT_THRESH) {
+			ht = ((_height - 2 * wcnt) / (double) wcnt);
 		} else {
-			ht = (((height-2*wcnt) - NAME_HIGHLIGHT_SIZE) / (double) wcnt);
+			ht = (((_height - 2 * wcnt) - NAME_HIGHLIGHT_SIZE) / (double) wcnt);
 		}
 		
-		gdouble yoff = n * (ht+1);
+		double const yoff = n * (ht + 1);
 		
 		waves[n]->property_height() = ht;
-		waves[n]->property_y() = yoff + 2;
+		waves[n]->property_y() = _y_position + yoff + 2;
 	}
 
 	if (gain_line) {
-		if ((height/wcnt) < NAME_HIGHLIGHT_SIZE) {
+		if ((_height / wcnt) < NAME_HIGHLIGHT_SIZE) {
 			gain_line->hide ();
 		} else {
 			if (_flags & EnvelopeVisible) {
 				gain_line->show ();
 			}
 		}
-		gain_line->set_height ((uint32_t) rint (height - NAME_HIGHLIGHT_SIZE));
+		gain_line->set_y_position_and_height ((uint32_t) _y_position, (uint32_t) rint (_height - NAME_HIGHLIGHT_SIZE));
 	}
 
+	setup_fade_handle_positions ();
 	manage_zero_line ();
 	reset_fade_shapes ();
 	
@@ -441,6 +442,25 @@ AudioRegionView::set_height (gdouble height)
 }
 
 void
+AudioRegionView::setup_fade_handle_positions()
+{
+	/* position of fade handle offset from the top of the region view */
+	double const handle_pos = 2;
+	/* height of fade handles */
+	double const handle_height = 5;
+
+	if (fade_in_handle) {
+		fade_in_handle->property_y1() = _y_position + handle_pos;
+		fade_in_handle->property_y2() = _y_position + handle_pos + handle_height;
+	}
+	
+	if (fade_out_handle) {
+		fade_out_handle->property_y1() = _y_position + handle_pos;
+		fade_out_handle->property_y2() = _y_position + handle_pos + handle_height;
+	}
+}
+
+void
 AudioRegionView::manage_zero_line ()
 {
 	if (!zero_line) {
@@ -448,7 +468,7 @@ AudioRegionView::manage_zero_line ()
 	}
 
 	if (_height >= 100) {
-		gdouble wave_midpoint = (_height - NAME_HIGHLIGHT_SIZE) / 2.0;
+		double const wave_midpoint = _y_position + (_height - NAME_HIGHLIGHT_SIZE) / 2.0;
 		zero_line->property_y1() = wave_midpoint;
 		zero_line->property_y2() = wave_midpoint;
 		zero_line->show();
@@ -529,16 +549,16 @@ AudioRegionView::reset_fade_in_shape_width (nframes_t width)
 
 	for (pi = 0, pc = 0; pc < npoints; ++pc) {
 		(*points)[pi].set_x(1 + (pc * xdelta));
-		(*points)[pi++].set_y(2 + (h - (curve[pc] * h)));
+		(*points)[pi++].set_y(_y_position + 2 + (h - (curve[pc] * h)));
 	}
 	
 	/* fold back */
 
 	(*points)[pi].set_x(pwidth);
-	(*points)[pi++].set_y(2);
+	(*points)[pi++].set_y(_y_position + 2);
 
 	(*points)[pi].set_x(1);
-	(*points)[pi++].set_y(2);
+	(*points)[pi++].set_y(_y_position + 2);
 
 	/* connect the dots ... */
 
@@ -615,16 +635,16 @@ AudioRegionView::reset_fade_out_shape_width (nframes_t width)
 
 	for (pi = 0, pc = 0; pc < npoints; ++pc) {
 		(*points)[pi].set_x(_pixel_width - 1 - pwidth + (pc*xdelta));
-		(*points)[pi++].set_y(2 + (h - (curve[pc] * h)));
+		(*points)[pi++].set_y(_y_position + 2 + (h - (curve[pc] * h)));
 	}
 	
 	/* fold back */
 
 	(*points)[pi].set_x(_pixel_width);
-	(*points)[pi++].set_y(h);
+	(*points)[pi++].set_y(_y_position + h);
 
 	(*points)[pi].set_x(_pixel_width);
-	(*points)[pi++].set_y(2);
+	(*points)[pi++].set_y(_y_position + 2);
 
 	/* connect the dots ... */
 
@@ -912,7 +932,7 @@ AudioRegionView::add_gain_point_event (ArdourCanvas::Item *item, GdkEvent *ev)
 
 	/* compute vertical fractional position */
 
-	y = 1.0 - (y / (trackview.height - NAME_HIGHLIGHT_SIZE));
+	y = 1.0 - ((y - _y_position) / (_height - NAME_HIGHLIGHT_SIZE));
 	
 	/* map using gain line */
 
diff --git a/gtk2_ardour/audio_region_view.h b/gtk2_ardour/audio_region_view.h
index 233e1a7c9b..e581e01146 100644
--- a/gtk2_ardour/audio_region_view.h
+++ b/gtk2_ardour/audio_region_view.h
@@ -63,7 +63,7 @@ class AudioRegionView : public RegionView
 	
 	boost::shared_ptr<ARDOUR::AudioRegion> audio_region() const;
 	
-	void set_height (double);
+	void set_y_position_and_height (double, double);
 	void set_samples_per_unit (double);
 	
 	void set_amplitude_above_axis (gdouble spp);
@@ -132,6 +132,8 @@ class AudioRegionView : public RegionView
     AudioRegionGainLine * gain_line;
 
     double _amplitude_above_axis;
+    double _y_position;
+    double _height;
 
     uint32_t _flags;
     uint32_t fade_color;
@@ -165,6 +167,10 @@ class AudioRegionView : public RegionView
     void color_handler (ColorID, uint32_t);
 
     vector<GnomeCanvasWaveViewCache*> wave_caches;
+
+  private:
+
+    void setup_fade_handle_positions ();
 };
 
 #endif /* __gtk_ardour_audio_region_view_h__ */
diff --git a/gtk2_ardour/audio_streamview.cc b/gtk2_ardour/audio_streamview.cc
index db7b07dfb2..4ca3ad38b9 100644
--- a/gtk2_ardour/audio_streamview.cc
+++ b/gtk2_ardour/audio_streamview.cc
@@ -79,23 +79,6 @@ AudioStreamView::~AudioStreamView ()
 {
 }
 
-int
-AudioStreamView::set_height (gdouble h)
-{
-	/* limit the values to something sane-ish */
-	if (h < 10.0 || h > 1000.0) {
-		return -1;
-	}
-
-	StreamView::set_height(h);
-
-	for (CrossfadeViewList::iterator i = crossfade_views.begin(); i != crossfade_views.end(); ++i) {
-		(*i)->set_height (h);
-	}
-
-	return 0;
-}
-
 int 
 AudioStreamView::set_samples_per_unit (gdouble spp)
 {
@@ -263,11 +246,23 @@ AudioStreamView::undisplay_diskstream ()
 }
 
 void
-AudioStreamView::playlist_modified ()
+AudioStreamView::playlist_modified_weak (boost::weak_ptr<Diskstream> ds)
 {
-	ENSURE_GUI_THREAD (mem_fun (*this, &AudioStreamView::playlist_modified));
+	boost::shared_ptr<Diskstream> sp (ds.lock());
+	if (!sp) {
+		return;
+	}
 
-	StreamView::playlist_modified();
+	playlist_modified (sp);
+}
+
+void
+AudioStreamView::playlist_modified (boost::shared_ptr<Diskstream> ds)
+{
+	/* we do not allow shared_ptr<T> to be bound to slots */
+	ENSURE_GUI_THREAD (bind (mem_fun (*this, &AudioStreamView::playlist_modified_weak), ds));
+
+	StreamView::playlist_modified (ds);
 	
 	/* make sure xfades are on top and all the regionviews are stacked correctly. */
 
@@ -314,7 +309,7 @@ AudioStreamView::add_crossfade (boost::shared_ptr<Crossfade> crossfade)
 
 	for (list<CrossfadeView *>::iterator i = crossfade_views.begin(); i != crossfade_views.end(); ++i) {
 		if ((*i)->crossfade == crossfade) {
-			if (!crossfades_visible) {
+			if (!crossfades_visible || layer_display == Stacked) {
 				(*i)->hide();
 			} else {
 				(*i)->show ();
@@ -347,7 +342,7 @@ AudioStreamView::add_crossfade (boost::shared_ptr<Crossfade> crossfade)
 	crossfade->Invalidated.connect (mem_fun (*this, &AudioStreamView::remove_crossfade));
 	crossfade_views.push_back (cv);
 
-	if (!Config->get_xfades_visible() || !crossfades_visible) {
+	if (!Config->get_xfades_visible() || !crossfades_visible || layer_display == Stacked) {
 		cv->hide ();
 	}
 }
@@ -378,7 +373,7 @@ AudioStreamView::redisplay_diskstream ()
 
 	for (xi = crossfade_views.begin(); xi != crossfade_views.end(); ++xi) {
 		(*xi)->set_valid (false);
-		if ((*xi)->visible()) {
+		if ((*xi)->visible() && layer_display != Stacked) {
 			(*xi)->show ();
 		}
 	}
@@ -755,7 +750,7 @@ void
 AudioStreamView::reveal_xfades_involving (AudioRegionView& rv)
 {
 	for (list<CrossfadeView *>::iterator i = crossfade_views.begin(); i != crossfade_views.end(); ++i) {
-		if ((*i)->crossfade->involves (rv.audio_region()) && (*i)->visible()) {
+		if ((*i)->crossfade->involves (rv.audio_region()) && (*i)->visible() && layer_display != Stacked) {
 			(*i)->show ();
 		}
 	}
@@ -784,3 +779,17 @@ AudioStreamView::color_handler (ColorID id, uint32_t val)
 	}
 }
 
+void
+AudioStreamView::update_contents_y_position_and_height ()
+{
+	StreamView::update_contents_y_position_and_height ();
+	
+	for (CrossfadeViewList::iterator i = crossfade_views.begin(); i != crossfade_views.end(); ++i) {
+		if (layer_display == Overlaid) {
+			(*i)->show ();
+			(*i)->set_y_position_and_height (0, height);
+		} else {
+			(*i)->hide ();
+		}
+	}
+}
diff --git a/gtk2_ardour/audio_streamview.h b/gtk2_ardour/audio_streamview.h
index 9f3630c182..fc707e97e7 100644
--- a/gtk2_ardour/audio_streamview.h
+++ b/gtk2_ardour/audio_streamview.h
@@ -63,7 +63,6 @@ class AudioStreamView : public StreamView
 	void set_waveform_scale (WaveformScale);
 	WaveformScale get_waveform_scale () const { return _waveform_scale; }
 
-	int set_height (gdouble h);
 	int set_samples_per_unit (gdouble spp);
 
 	int     set_amplitude_above_axis (gdouble app);
@@ -90,7 +89,8 @@ class AudioStreamView : public StreamView
 
 	void undisplay_diskstream ();
 	void redisplay_diskstream ();
-	void playlist_modified ();
+	void playlist_modified_weak (boost::weak_ptr<ARDOUR::Diskstream>);
+	void playlist_modified (boost::shared_ptr<ARDOUR::Diskstream>);
 	void playlist_changed (boost::shared_ptr<ARDOUR::Diskstream>);
 
 	void add_crossfade (boost::shared_ptr<ARDOUR::Crossfade>);
@@ -98,6 +98,8 @@ class AudioStreamView : public StreamView
 	void remove_crossfade (boost::shared_ptr<ARDOUR::Crossfade>);
 
 	void color_handler (ColorID id, uint32_t val);
+
+	void update_contents_y_position_and_height ();
 	
 	double _amplitude_above_axis;
 	
diff --git a/gtk2_ardour/audio_time_axis.cc b/gtk2_ardour/audio_time_axis.cc
index 414329f145..d37b164ed1 100644
--- a/gtk2_ardour/audio_time_axis.cc
+++ b/gtk2_ardour/audio_time_axis.cc
@@ -287,6 +287,18 @@ AudioTimeAxisView::append_extra_display_menu_items ()
 	}
 
 	items.push_back (MenuElem (_("Waveform"), *waveform_menu));
+
+
+	Menu *layers_menu = manage(new Menu);
+	MenuList &layers_items = layers_menu->items();
+	layers_menu->set_name("ArdourContextMenu");
+
+	RadioMenuItem::Group layers_group;
+	
+	layers_items.push_back(RadioMenuElem (layers_group, _("Overlaid"), bind (mem_fun (*this, &AudioTimeAxisView::set_layer_display), Overlaid)));
+	layers_items.push_back(RadioMenuElem (layers_group, _("Stacked"), bind (mem_fun (*this, &AudioTimeAxisView::set_layer_display), Stacked)));
+
+	items.push_back (MenuElem (_("Layers"), *layers_menu));
 }
 
 void
@@ -663,3 +675,11 @@ AudioTimeAxisView::get_child_xml_node (const string & childname)
 	return RouteUI::get_child_xml_node (childname);
 }
 
+void
+AudioTimeAxisView::set_layer_display (LayerDisplay d)
+{
+	AudioStreamView* asv = audio_view ();
+	if (asv) {
+		asv->set_layer_display (d);
+	}
+}
diff --git a/gtk2_ardour/audio_time_axis.h b/gtk2_ardour/audio_time_axis.h
index d8c3f07cc1..ab5ef955c7 100644
--- a/gtk2_ardour/audio_time_axis.h
+++ b/gtk2_ardour/audio_time_axis.h
@@ -77,6 +77,7 @@ class AudioTimeAxisView : public RouteTimeAxisView
 	void hide_all_xfades ();
 	void hide_dependent_views (TimeAxisViewItem&);
 	void reveal_dependent_views (TimeAxisViewItem&);
+	void set_layer_display (LayerDisplay d);
 		
 	/* Overridden from parent to store display state */
 	guint32 show_at (double y, int& nth, Gtk::VBox *parent);
diff --git a/gtk2_ardour/automation_line.cc b/gtk2_ardour/automation_line.cc
index 67f91e1ed4..a729161911 100644
--- a/gtk2_ardour/automation_line.cc
+++ b/gtk2_ardour/automation_line.cc
@@ -232,6 +232,7 @@ AutomationLine::AutomationLine (const string & name, TimeAxisView& tv, ArdourCan
 	no_draw = false;
 	_visible = true;
 	terminal_points_can_slide = true;
+	_y_position = 0;
 	_height = 0;
 
 	group = new ArdourCanvas::Group (parent);
@@ -307,17 +308,27 @@ AutomationLine::control_point_box_size ()
 }
 
 void
-AutomationLine::set_height (guint32 h)
+AutomationLine::set_y_position_and_height (guint32 y, guint32 h)
 {
+	bool changed = false;
+	
+	if (y != _y_position) {
+		_y_position = y;
+		changed = true;
+	}
+		
 	if (h != _height) {
 		_height = h;
 
-		double bsz = control_point_box_size();
+		double const bsz = control_point_box_size();
 
 		for (vector<ControlPoint*>::iterator i = control_points.begin(); i != control_points.end(); ++i) {
 			(*i)->set_size (bsz);
 		}
+		changed = true;
+	}
 
+	if (changed) {
 		reset ();
 	}
 }
@@ -365,7 +376,7 @@ AutomationLine::modify_view_point (ControlPoint& cp, double x, double y, bool wi
 
 	y = max (0.0, y);
 	y = min (1.0, y);
-	y = _height - (y * _height);
+	y = _y_position + _height - (y * _height);
 
 	if (cp.can_slide) {
 
@@ -494,7 +505,7 @@ AutomationLine::model_representation (ControlPoint& cp, ModelRepresentation& mr)
 	*/
 	
 	mr.xval = (nframes_t) floor (cp.get_x());
-	mr.yval = 1.0 - (cp.get_y() / _height);
+	mr.yval = 1.0 - ( (cp.get_y() - _y_position) / _height);
 
         /* if xval has not changed, set it directly from the model to avoid rounding errors */
 
@@ -831,7 +842,7 @@ AutomationLine::point_drag (ControlPoint& cp, nframes_t x, float fraction, bool
 void
 AutomationLine::line_drag (uint32_t i1, uint32_t i2, float fraction, bool with_push) 
 {
-	double ydelta = fraction - last_drag_fraction;
+	double const ydelta = fraction - last_drag_fraction;
 
 	did_push = with_push;
 	
@@ -844,7 +855,7 @@ AutomationLine::line_drag (uint32_t i1, uint32_t i2, float fraction, bool with_p
 
 	for (uint32_t i = i1 ; i <= i2; i++) {
 		cp = nth (i);
-		modify_view_point (*cp, trackview.editor.unit_to_frame (cp->get_x()), ((_height - cp->get_y()) /_height) + ydelta, with_push);
+		modify_view_point (*cp, trackview.editor.unit_to_frame (cp->get_x()), ((_height - cp->get_y() + _y_position) /_height) + ydelta, with_push);
 	}
 
 	if (line_points.size() > 1) {
@@ -1041,8 +1052,8 @@ AutomationLine::get_selectables (nframes_t& start, nframes_t& end,
 
 	/* Curse X11 and its inverted coordinate system! */
 	
-	bot = (1.0 - topfrac) * _height;
-	top = (1.0 - botfrac) * _height;
+	bot = _y_position + (1.0 - topfrac) * _height;
+	top = _y_position + (1.0 - botfrac) * _height;
 	
 	nstart = max_frames;
 	nend = 0;
@@ -1108,8 +1119,8 @@ AutomationLine::set_selected_points (PointSelection& points)
 
 		/* Curse X11 and its inverted coordinate system! */
 
-		bot = (1.0 - (*r).high_fract) * _height;
-		top = (1.0 - (*r).low_fract) * _height;
+		bot = _y_position + (1.0 - (*r).high_fract) * _height;
+		top = _y_position + (1.0 - (*r).low_fract) * _height;
 
 		for (vector<ControlPoint*>::iterator i = control_points.begin(); i != control_points.end(); ++i) {
 			
@@ -1203,7 +1214,7 @@ AutomationLine::reset_callback (const AutomationList& events)
 		model_to_view_y (translated_y);
 
 		tmp_points.push_back (ALPoint (trackview.editor.frame_to_unit ((*ai)->when),
-					       _height - (translated_y * _height)));
+					       _y_position + _height - (translated_y * _height)));
 	}
 	
 	determine_visible_control_points (tmp_points);
diff --git a/gtk2_ardour/automation_line.h b/gtk2_ardour/automation_line.h
index 76afff5097..2637a0c554 100644
--- a/gtk2_ardour/automation_line.h
+++ b/gtk2_ardour/automation_line.h
@@ -127,13 +127,14 @@ class AutomationLine : public sigc::trackable, public PBD::StatefulThingWithGoin
 	string  name() const { return _name; }
 	bool    visible() const { return _visible; }
 	guint32 height() const { return _height; }
+	guint32 y_position() const { return _y_position; }
 
 	void         set_line_color (uint32_t);
 	uint32_t get_line_color() const { return _line_color; }
 
 	void    show ();
 	void    hide ();
-	void    set_height (guint32);
+	void    set_y_position_and_height (uint32_t, uint32_t);
 	void    set_verbose_cursor_uses_gain_mapping (bool yn);
 
 	TimeAxisView& trackview;
@@ -164,6 +165,7 @@ class AutomationLine : public sigc::trackable, public PBD::StatefulThingWithGoin
   protected:
 
 	string _name;
+	guint32 _y_position;
 	guint32 _height;
 	uint32_t _line_color;
 	ARDOUR::AutomationList& alist;
diff --git a/gtk2_ardour/automation_time_axis.cc b/gtk2_ardour/automation_time_axis.cc
index 12998ee7d6..45103ec7f1 100644
--- a/gtk2_ardour/automation_time_axis.cc
+++ b/gtk2_ardour/automation_time_axis.cc
@@ -313,7 +313,7 @@ AutomationTimeAxisView::set_height (TrackHeight ht)
 	base_rect->property_y2() = h;
 
 	for (vector<AutomationLine*>::iterator i = lines.begin(); i != lines.end(); ++i) {
-		(*i)->set_height (h);
+		(*i)->set_y_position_and_height (0, h);
 	}
 
 	for (list<GhostRegion*>::iterator i = ghosts.begin(); i != ghosts.end(); ++i) {
@@ -771,7 +771,7 @@ AutomationTimeAxisView::add_line (AutomationLine& line)
 	}
 
 	lines.push_back (&line);
-	line.set_height (height);
+	line.set_y_position_and_height (0, height);
 
 	if (get) {
 		/* pick up the current state */
diff --git a/gtk2_ardour/crossfade_view.cc b/gtk2_ardour/crossfade_view.cc
index ef43ee9873..261b2b3ca4 100644
--- a/gtk2_ardour/crossfade_view.cc
+++ b/gtk2_ardour/crossfade_view.cc
@@ -68,7 +68,7 @@ CrossfadeView::CrossfadeView (ArdourCanvas::Group *parent,
 	fade_out->property_fill_color_rgba() = color_map[cCrossfadeLine];
 	fade_out->property_width_pixels() = 1;
 	
-	set_height (get_time_axis_view().height);
+	set_y_position_and_height (0, get_time_axis_view().height);
 
 	/* no frame around the xfade or overlap rects */
 
@@ -105,13 +105,16 @@ CrossfadeView::reset_width_dependent_items (double pixel_width)
 }
 
 void
-CrossfadeView::set_height (double height)
+CrossfadeView::set_y_position_and_height (double y, double h)
 {
-	if (height == TimeAxisView::hSmaller ||
-	    height == TimeAxisView::hSmall)
-		TimeAxisViewItem::set_height (height - 3 );
-	else
-		TimeAxisViewItem::set_height (height - NAME_HIGHLIGHT_SIZE - 3 );
+	if (h == TimeAxisView::hSmaller || h == TimeAxisView::hSmall) {
+		TimeAxisViewItem::set_y_position_and_height (y, h - 3 );
+	} else {
+		TimeAxisViewItem::set_y_position_and_height (y, h - NAME_HIGHLIGHT_SIZE - 3 );
+	}
+
+	_y_position = y;
+	_height = h;
 
 	redraw_curves ();
 }
@@ -158,9 +161,8 @@ CrossfadeView::redraw_curves ()
 	 At "height - 3.0" the bottom of the crossfade touches the name highlight or the bottom of the track (if the
 	 track is either Small or Smaller.
 	 */
-	double tav_height = get_time_axis_view().height;
-	if (tav_height == TimeAxisView::hSmaller ||
-	    tav_height == TimeAxisView::hSmall) {
+	double const tav_height = get_time_axis_view().height;
+	if (tav_height == TimeAxisView::hSmaller || tav_height == TimeAxisView::hSmall) {
 		h = tav_height - 3.0;
 	} else {
 		h = tav_height - NAME_HIGHLIGHT_SIZE - 3.0;
@@ -190,7 +192,7 @@ CrossfadeView::redraw_curves ()
 	for (int i = 0, pci = 0; i < npoints; ++i) {
 		Art::Point &p = (*points)[pci++];
 		p.set_x(i);
-		p.set_y(2.0 + h - (h * vec[i]));
+		p.set_y(_y_position + 2.0 + h - (h * vec[i]));
 	}
 	fade_in->property_points() = *points;
 
@@ -198,7 +200,7 @@ CrossfadeView::redraw_curves ()
 	for (int i = 0, pci = 0; i < npoints; ++i) {
 		Art::Point &p = (*points)[pci++];
 		p.set_x(i);
-		p.set_y(2.0 + h - (h * vec[i]));
+		p.set_y(_y_position + 2.0 + h - (h * vec[i]));
 	}
 	fade_out->property_points() = *points;
 
diff --git a/gtk2_ardour/crossfade_view.h b/gtk2_ardour/crossfade_view.h
index 556d8c80c5..02f3cd0df2 100644
--- a/gtk2_ardour/crossfade_view.h
+++ b/gtk2_ardour/crossfade_view.h
@@ -46,7 +46,7 @@ struct CrossfadeView : public TimeAxisViewItem
     AudioRegionView& left_view;    // and these too
     AudioRegionView& right_view;
 
-    void set_height (double);
+    void set_y_position_and_height (double, double);
 
     bool valid() const { return _valid; }
     bool visible() const { return _visible; }
@@ -68,6 +68,8 @@ struct CrossfadeView : public TimeAxisViewItem
     bool _visible;
 
     double spu;
+    double _y_position;
+    double _height;
 
     ArdourCanvas::Item *overlap_rect;
     ArdourCanvas::Line *fade_in;
diff --git a/gtk2_ardour/editor_mouse.cc b/gtk2_ardour/editor_mouse.cc
index 4f06562fb0..5247b596b6 100644
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -1066,7 +1066,7 @@ Editor::enter_handler (ArdourCanvas::Item* item, GdkEvent* event, ItemType item_
 			at_x += 20.0;
 			at_y += 20.0;
 
-			fraction = 1.0 - (cp->get_y() / cp->line.height());
+			fraction = 1.0 - ((cp->get_y() - cp->line.y_position()) / cp->line.height());
 
 			set_verbose_canvas_cursor (cp->line.get_verbose_cursor_string (fraction), at_x, at_y);
 			show_verbose_canvas_cursor ();
@@ -2446,7 +2446,7 @@ void
 Editor::start_control_point_grab (ArdourCanvas::Item* item, GdkEvent* event)
 {
 	ControlPoint* control_point;
-	
+
 	if ((control_point = reinterpret_cast<ControlPoint *> (item->get_data ("control_point"))) == 0) {
 		fatal << _("programming error: control point canvas item has no control point object pointer!") << endmsg;
 		/*NOTREACHED*/
@@ -2461,7 +2461,7 @@ Editor::start_control_point_grab (ArdourCanvas::Item* item, GdkEvent* event)
 
 	control_point->line.start_drag (control_point, drag_info.grab_frame, 0);
 
-	float fraction = 1.0 - (control_point->get_y() / control_point->line.height());
+	float fraction = 1.0 - ((control_point->get_y() - control_point->line.y_position()) / control_point->line.height());
 	set_verbose_canvas_cursor (control_point->line.get_verbose_cursor_string (fraction), 
 				   drag_info.current_pointer_x + 20, drag_info.current_pointer_y + 20);
 
@@ -2490,7 +2490,7 @@ Editor::control_point_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent*
 
 	cx = max (0.0, cx);
 	cy = max (0.0, cy);
-	cy = min ((double) cp->line.height(), cy);
+	cy = min ((double) (cp->line.y_position() + cp->line.height()), cy);
 
 	//translate cx to frames
 	nframes_t cx_frames = unit_to_frame (cx);
@@ -2499,8 +2499,8 @@ Editor::control_point_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent*
 		snap_to (cx_frames);
 	}
 
-	float fraction = 1.0 - (cy / cp->line.height());
-	
+	float const fraction = 1.0 - ((cy - cp->line.y_position()) / cp->line.height());
+
 	bool push;
 
 	if (Keyboard::modifier_state_contains (event->button.state, Keyboard::Control)) {
@@ -2590,7 +2590,7 @@ Editor::start_line_grab (AutomationLine* line, GdkEvent* event)
 
 	start_grab (event, fader_cursor);
 
-	double fraction = 1.0 - (cy / line->height());
+	double const fraction = 1.0 - ((cy - line->y_position()) / line->height());
 
 	line->start_drag (0, drag_info.grab_frame, fraction);
 	
@@ -2608,8 +2608,7 @@ Editor::line_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent* event)
 
 	line->parent_group().w2i (cx, cy);
 	
-	double fraction;
-	fraction = 1.0 - (cy / line->height());
+	double const fraction = 1.0 - ((cy - line->y_position()) / line->height());
 
 	bool push;
 
@@ -3140,7 +3139,7 @@ Editor::region_drag_motion_callback (ArdourCanvas::Item* item, GdkEvent* event)
 		  
 						tvp2 = trackview_by_y_position (iy1 + y_delta);
 						temp_rtv = dynamic_cast<RouteTimeAxisView*>(tvp2);
-						rv->set_height (temp_rtv->height);
+						rv->set_y_position_and_height (0, temp_rtv->height);
 	
 						/*   if you un-comment the following, the region colours will follow the track colours whilst dragging,
 						     personally, i think this can confuse things, but never mind.
diff --git a/gtk2_ardour/enums.h b/gtk2_ardour/enums.h
index d345b30bf8..fcb675fd46 100644
--- a/gtk2_ardour/enums.h
+++ b/gtk2_ardour/enums.h
@@ -44,6 +44,11 @@ namespace Gnome {
 	}
 }
 
+enum LayerDisplay {
+	Overlaid,
+	Stacked
+};
+
 struct SelectionRect {
     Gnome::Canvas::SimpleRect *rect;
     Gnome::Canvas::SimpleRect *end_trim;
diff --git a/gtk2_ardour/marker_time_axis_view.cc b/gtk2_ardour/marker_time_axis_view.cc
index f33e0bbefc..34acf51fbf 100644
--- a/gtk2_ardour/marker_time_axis_view.cc
+++ b/gtk2_ardour/marker_time_axis_view.cc
@@ -115,16 +115,14 @@ MarkerTimeAxisView::~MarkerTimeAxisView()
 int
 MarkerTimeAxisView::set_height(gdouble h)
 {
-	if (h < 10.0 || h > 1000.0)
-	{
-		return -1 ;
+	if (h < 10.0 || h > 1000.0) {
+		return -1;
 	}
 	
 	canvas_rect->property_y2() = h;
 
-	for (MarkerViewList::iterator i = marker_view_list.begin(); i != marker_view_list.end(); ++i)
-	{
-		(*i)->set_height(h) ;
+	for (MarkerViewList::iterator i = marker_view_list.begin(); i != marker_view_list.end(); ++i) {
+		(*i)->set_y_position_and_height(0, h);
 	}
 
 	return 0;
diff --git a/gtk2_ardour/midi_region_view.cc b/gtk2_ardour/midi_region_view.cc
index c225295f13..cef1329ed5 100644
--- a/gtk2_ardour/midi_region_view.cc
+++ b/gtk2_ardour/midi_region_view.cc
@@ -75,7 +75,7 @@ MidiRegionView::init (Gdk::Color& basic_color, bool wfd)
 
 	reset_width_dependent_items ((double) _region->length() / samples_per_unit);
 
-	set_height (trackview.height);
+	set_y_position_and_height (0, trackview.height);
 
 	region_muted ();
 	region_resized (BoundsChanged);
diff --git a/gtk2_ardour/region_view.cc b/gtk2_ardour/region_view.cc
index 859e2edfb4..3923f7e79a 100644
--- a/gtk2_ardour/region_view.cc
+++ b/gtk2_ardour/region_view.cc
@@ -72,7 +72,6 @@ RegionView::RegionView (ArdourCanvas::Group* parent,
 	  , current_visible_sync_position(0.0)
 	  , valid(false)
 	  , _pixel_width(1.0)
-	  , _height(1.0)
 	  , in_destructor(false)
 	  , wait_for_data(false)
 {
@@ -88,7 +87,6 @@ RegionView::RegionView (const RegionView& other)
 	current_visible_sync_position = other.current_visible_sync_position;
 	valid = false;
 	_pixel_width = other._pixel_width;
-	_height = other._height;
 }
 
 RegionView::RegionView (ArdourCanvas::Group*         parent, 
@@ -104,7 +102,6 @@ RegionView::RegionView (ArdourCanvas::Group*         parent,
 	, current_visible_sync_position(0.0)
 	, valid(false)
 	, _pixel_width(1.0)
-	, _height(1.0)
 	, in_destructor(false)
 	, wait_for_data(false)
 {
@@ -115,7 +112,6 @@ RegionView::init (Gdk::Color& basic_color, bool wfd)
 {
 	valid         = true;
 	in_destructor = false;
-	_height       = 0;
 	wait_for_data = wfd;
 
 	compute_colors (basic_color);
@@ -141,7 +137,7 @@ RegionView::init (Gdk::Color& basic_color, bool wfd)
 
 	reset_width_dependent_items ((double) _region->length() / samples_per_unit);
 
-	set_height (trackview.height);
+	set_y_position_and_height (0, trackview.height);
 
 	_region->StateChanged.connect (mem_fun(*this, &RegionView::region_changed));
 
@@ -255,14 +251,6 @@ RegionView::reset_width_dependent_items (double pixel_width)
 }
 
 void
-RegionView::set_height (gdouble height)
-{
-	TimeAxisViewItem::set_height (height - 2);
-	
-	_height = height;
-}
-
-void
 RegionView::region_layered ()
 {
 	RouteTimeAxisView *rtv = dynamic_cast<RouteTimeAxisView*>(&get_time_axis_view());
diff --git a/gtk2_ardour/region_view.h b/gtk2_ardour/region_view.h
index 0f4d57ad04..d16d81e373 100644
--- a/gtk2_ardour/region_view.h
+++ b/gtk2_ardour/region_view.h
@@ -60,7 +60,6 @@ class RegionView : public TimeAxisViewItem
 
 	void set_valid (bool yn) { valid = yn; }
 	
-	virtual void set_height (double);
 	virtual void set_samples_per_unit (double);
 	virtual bool set_duration (nframes_t, void*);
 	
@@ -134,7 +133,6 @@ class RegionView : public TimeAxisViewItem
 
     bool     valid; ///< see StreamView::redisplay_diskstream() 
     double  _pixel_width;
-    double  _height;
     bool    in_destructor;
     
     bool             wait_for_data;
diff --git a/gtk2_ardour/streamview.cc b/gtk2_ardour/streamview.cc
index d6f2edeba9..2997661848 100644
--- a/gtk2_ardour/streamview.cc
+++ b/gtk2_ardour/streamview.cc
@@ -56,6 +56,7 @@ StreamView::StreamView (RouteTimeAxisView& tv)
 	, use_rec_regions(tv.editor.show_waveforms_recording())
 	, region_color(_trackview.color())
 	, stream_base_color(0xFFFFFFFF)
+	, layers(1)
 	, last_rec_data_frame(0)
 {
 	/* set_position() will position the group */
@@ -96,7 +97,6 @@ StreamView::attach ()
 
 int
 StreamView::set_position (gdouble x, gdouble y)
-
 {
 	canvas_group->property_x() = x;
 	canvas_group->property_y() = y;
@@ -104,10 +104,9 @@ StreamView::set_position (gdouble x, gdouble y)
 }
 
 int
-StreamView::set_height (gdouble h)
+StreamView::set_height (double h)
 {
 	/* limit the values to something sane-ish */
-
 	if (h < 10.0 || h > 1000.0) {
 		return -1;
 	}
@@ -116,17 +115,8 @@ StreamView::set_height (gdouble h)
 		return 0;
 	}
 
-	canvas_rect->property_y2() = h;
-
-	for (RegionViewList::iterator i = region_views.begin(); i != region_views.end(); ++i) {
-		(*i)->set_height (h);
-	}
-
-	for (vector<RecBoxInfo>::iterator i = rec_rects.begin(); i != rec_rects.end(); ++i) {
-		RecBoxInfo &recbox = (*i);
-		recbox.rectangle->property_y2() = h - 1.0;
-	}
-
+	height = h;
+	update_contents_y_position_and_height ();
 	return 0;
 }
 
@@ -162,6 +152,7 @@ void
 StreamView::add_region_view (boost::shared_ptr<Region> r)
 {
 	add_region_view_internal (r, true);
+	update_contents_y_position_and_height ();
 }
 
 void
@@ -203,9 +194,25 @@ StreamView::display_diskstream (boost::shared_ptr<Diskstream> ds)
 }
 
 void
-StreamView::playlist_modified ()
+StreamView::playlist_modified_weak (boost::weak_ptr<Diskstream> ds)
 {
-	ENSURE_GUI_THREAD (mem_fun (*this, &StreamView::playlist_modified));
+	boost::shared_ptr<Diskstream> sp (ds.lock());
+	if (!sp) {
+		return;
+	}
+
+	playlist_modified (sp);
+}
+
+void
+StreamView::playlist_modified (boost::shared_ptr<Diskstream> ds)
+{
+	/* we do not allow shared_ptr<T> to be bound to slots */
+	ENSURE_GUI_THREAD (bind (mem_fun (*this, &StreamView::playlist_modified_weak), ds));
+
+	/* update layers count and the y positions and heights of our regions */
+	layers = ds->playlist()->top_layer() + 1;
+	update_contents_y_position_and_height ();
 
 	redisplay_diskstream ();
 }
@@ -213,6 +220,7 @@ StreamView::playlist_modified ()
 void
 StreamView::playlist_changed (boost::shared_ptr<Diskstream> ds)
 {
+	/* XXX: binding to a shared_ptr, is this ok? */
 	ENSURE_GUI_THREAD (bind (mem_fun (*this, &StreamView::playlist_changed), ds));
 
 	/* disconnect from old playlist */
@@ -230,7 +238,11 @@ StreamView::playlist_changed (boost::shared_ptr<Diskstream> ds)
 
 	/* catch changes */
 
-	playlist_connections.push_back (ds->playlist()->Modified.connect (mem_fun (*this, &StreamView::playlist_modified)));
+	playlist_connections.push_back (ds->playlist()->Modified.connect (bind (mem_fun (*this, &StreamView::playlist_modified_weak), ds)));
+
+	/* update layers count and the y positions and heights of our regions */
+	layers = ds->playlist()->top_layer() + 1;
+	update_contents_y_position_and_height ();
 }
 
 void
@@ -390,3 +402,33 @@ StreamView::get_inverted_selectables (Selection& sel, list<Selectable*>& results
 	}
 }
 
+void
+StreamView::update_contents_y_position_and_height ()
+{
+	canvas_rect->property_y2() = height;
+
+	const double lh = height / layers;
+
+	for (RegionViewList::iterator i = region_views.begin(); i != region_views.end(); ++i) {
+		switch (layer_display) {
+		case Overlaid:
+			(*i)->set_y_position_and_height (0, height);
+			break;
+		case Stacked:
+			double const y = (*i)->region()->layer() * lh;
+			(*i)->set_y_position_and_height (y, lh);
+			break;
+		}
+	}
+
+	for (vector<RecBoxInfo>::iterator i = rec_rects.begin(); i != rec_rects.end(); ++i) {
+		i->rectangle->property_y2() = height - 1.0;
+	}
+}
+
+void
+StreamView::set_layer_display (LayerDisplay d)
+{
+	layer_display = d;
+	update_contents_y_position_and_height ();
+}
diff --git a/gtk2_ardour/streamview.h b/gtk2_ardour/streamview.h
index 39c04aea7f..365f2d4edf 100644
--- a/gtk2_ardour/streamview.h
+++ b/gtk2_ardour/streamview.h
@@ -68,11 +68,13 @@ public:
 	void set_zoom_all();
 
 	int set_position (gdouble x, gdouble y);
-	virtual int set_height (gdouble);
+	virtual int set_height (double);
 
 	virtual int set_samples_per_unit (gdouble spp);
 	gdouble     get_samples_per_unit () { return _samples_per_unit; }
 
+	void set_layer_display (LayerDisplay);
+
 	ArdourCanvas::Item* canvas_item() { return canvas_group; }
 
 	enum ColorTarget {
@@ -117,10 +119,12 @@ protected:
 	void         diskstream_changed ();
 	
 	virtual void playlist_changed (boost::shared_ptr<ARDOUR::Diskstream>);
-	virtual void playlist_modified ();
+	virtual void playlist_modified_weak (boost::weak_ptr<ARDOUR::Diskstream>);
+	virtual void playlist_modified (boost::shared_ptr<ARDOUR::Diskstream>);
 	
 	virtual void color_handler (ColorID, uint32_t) = 0;
 
+	virtual void update_contents_y_position_and_height ();
 
 	RouteTimeAxisView&        _trackview;
 	ArdourCanvas::Group*      canvas_group;
@@ -143,6 +147,10 @@ protected:
 
 	vector<sigc::connection> playlist_connections;
 	sigc::connection         playlist_change_connection;
+
+	int layers;
+	double height;
+	LayerDisplay layer_display;
 	
 	list<sigc::connection>                       rec_data_ready_connections;
 	jack_nframes_t                               last_rec_data_frame;
diff --git a/gtk2_ardour/time_axis_view_item.cc b/gtk2_ardour/time_axis_view_item.cc
index 7830e8f437..0e66ab2bae 100644
--- a/gtk2_ardour/time_axis_view_item.cc
+++ b/gtk2_ardour/time_axis_view_item.cc
@@ -567,15 +567,16 @@ TimeAxisViewItem::set_name_text(const ustring& new_name)
 }
 
 /**
- * Set the height of this item
+ * Set the y position and height of this item.
  *
+ * @param y the new y position
  * @param h the new height
  */		
 void
-TimeAxisViewItem::set_height (double height)
+TimeAxisViewItem::set_y_position_and_height (double y, double h)
 {
 	if (name_highlight) {
-		if (height < NAME_HIGHLIGHT_THRESH) {
+		if (h < NAME_HIGHLIGHT_THRESH) {
 			name_highlight->hide();
 			if (name_text) {
 				name_text->hide();
@@ -587,20 +588,20 @@ TimeAxisViewItem::set_height (double height)
 			}
 		}
 
-		if (height > NAME_HIGHLIGHT_SIZE) {
-			name_highlight->property_y1() = (double) height+1 - NAME_HIGHLIGHT_SIZE;
-			name_highlight->property_y2() = (double) height;
+		if (h > NAME_HIGHLIGHT_SIZE) {
+			name_highlight->property_y1() = (double) y + h + 1 - NAME_HIGHLIGHT_SIZE;
+			name_highlight->property_y2() = (double) y + h;
 		}
 		else {
 			/* it gets hidden now anyway */
-			name_highlight->property_y1() = (double) 1.0;
-			name_highlight->property_y2() = (double) height;
+			name_highlight->property_y1() = (double) y;
+			name_highlight->property_y2() = (double) y + h;
 		}
 	}
 
 	if (name_text) {
-		name_text->property_y() = height+1 - NAME_Y_OFFSET;
-		if (height < NAME_HIGHLIGHT_THRESH) {
+		name_text->property_y() = y + h + 1 - NAME_Y_OFFSET;
+		if (h < NAME_HIGHLIGHT_THRESH) {
 			name_text->property_fill_color_rgba() =  fill_color;
 		}
 		else {
@@ -609,10 +610,12 @@ TimeAxisViewItem::set_height (double height)
 	}
 
 	if (frame) {
-		frame->property_y2() = height+1;
+		frame->property_y1() = y;
+		frame->property_y2() = y + h + 1;
 	}
 
-	vestigial_frame->property_y2() = height+1;
+	vestigial_frame->property_y1() = y;
+	vestigial_frame->property_y2() = y + h + 1;
 }
 
 /**
diff --git a/gtk2_ardour/time_axis_view_item.h b/gtk2_ardour/time_axis_view_item.h
index aeeebe1c79..118a042920 100644
--- a/gtk2_ardour/time_axis_view_item.h
+++ b/gtk2_ardour/time_axis_view_item.h
@@ -201,12 +201,7 @@ class TimeAxisViewItem : public Selectable
      */
     void set_name_text(const Glib::ustring& new_name) ;
     
-    /**
-     * Set the height of this item
-     *
-     * @param h the new height
-     */
-    virtual void set_height(double h) ;
+  virtual void set_y_position_and_height(double y, double h);
     
     /**
      *