TimeAxisView event handling calls into Editor track DnD code

This is not currently functional, but does the hard part of GUI display
during the drag.

gtk2_ardour/ardour_ui.h

@@ -275,8 +275,6 @@ public:
 
 	void reset_focus (Gtk::Widget*);
 
-	static PublicEditor* _instance;
-
 	/** Emitted frequently with the audible sample, false, and the edit point as
 	 *  parameters respectively.
 	 *

gtk2_ardour/editor.cc

@@ -473,6 +473,7 @@ Editor::Editor ()
 	, quantize_dialog (0)
 	, _main_menu_disabler (0)
 	, domain_bounce_info (nullptr)
+	, track_drag (nullptr)
 {
 	/* we are a singleton */
 
@@ -4282,6 +4283,11 @@ Editor::override_visible_track_count ()
 bool
 Editor::edit_controls_button_event (GdkEventButton* ev)
 {
+	if (ev->type == GDK_BUTTON_RELEASE && track_dragging()) {
+		end_track_drag ();
+		return true;
+	}
+
 	if ((ev->type == GDK_2BUTTON_PRESS && ev->button == 1) || (ev->type == GDK_BUTTON_RELEASE && Keyboard::is_context_menu_event (ev))) {
 		ARDOUR_UI::instance()->add_route ();
 	} else if (ev->button == 1 && ev->type == GDK_BUTTON_PRESS) {
@@ -6170,6 +6176,67 @@ struct TrackViewStripableSorter
   }
 };
 
+static const int track_drag_spacer_height = 25;
+
+void
+Editor::maybe_place_drag_spacer ()
+{
+	/* Build a map of track<->visual order */
+
+	std::map<TimeAxisView*,int> visual_order;
+	int n = 0;
+
+	for (auto & tv : track_views) {
+		if (!tv->marked_for_display () || (tv == track_drag->track)) {
+			continue;
+		}
+		visual_order[tv] = n;
+		++n;
+	}
+
+	for (auto & tv : track_views) {
+
+		if (!tv->marked_for_display () || (tv == track_drag->track)) {
+			continue;
+		}
+
+		/* find the track the mouse pointer is within, and if
+		 * we're in the upper or lower half of it (depending on
+		 * drag direction, move the spacer.
+		 */
+
+		if (track_drag->current >= tv->y_position() && track_drag->current < (tv->y_position() + tv->effective_height())) {
+
+			if (track_drag->bump_track == tv) {
+				/* already bumped for this track */
+				break;
+			}
+
+			if (track_drag->direction < 0) {
+
+				/* dragging up */
+
+				if (track_drag->current < (tv->y_position() + (tv->effective_height() / 2))) {
+					/* in top half of this track, move spacer */
+					track_drag->spacer_order = visual_order[tv];
+					track_drag->bump_track = tv;
+				}
+
+			} else if (track_drag->direction > 0) {
+
+				/* dragging down */
+
+				if (track_drag->current > (tv->y_position() + (tv->effective_height() / 2))) {
+					track_drag->spacer_order = visual_order[tv] + 1;
+					track_drag->bump_track = tv;
+				}
+			}
+
+			break;
+		}
+	}
+}
+
 bool
 Editor::redisplay_track_views ()
 {
@@ -6186,24 +6253,56 @@ Editor::redisplay_track_views ()
 
 	track_views.sort (TrackViewStripableSorter ());
 
-	uint32_t position;
-	TrackViewList::const_iterator i;
+	if (track_drag && track_drag->spacer) {
+		maybe_place_drag_spacer ();
+	}
 
 	/* n will be the count of tracks plus children (updated by TimeAxisView::show_at),
 	 * so we will use that to know where to put things.
 	 */
-	int n;
-	for (n = 0, position = 0, i = track_views.begin(); i != track_views.end(); ++i) {
-		TimeAxisView *tv = (*i);
+	int n = 0;
+	uint32_t position = 0;
+
+	for (auto & tv : track_views) {
+
+		int xtra = 0;
 
 		if (tv->marked_for_display ()) {
-			position += tv->show_at (position, n, &edit_controls_vbox);
+
+			if (track_drag) {
+
+				if (tv == track_drag->track) {
+					tv->hide ();
+					continue;
+				}
+
+				if (tv->stripable()->presentation_info().order() > track_drag->spacer_order) {
+					xtra = track_drag_spacer_height;
+					++n;
+				}
+			}
+
+			position += tv->show_at (position + xtra, n, &edit_controls_vbox);
+
 		} else {
 			tv->hide ();
 		}
+
 		n++;
 	}
 
+	if (track_drag) {
+
+		if (!track_drag->spacer) {
+			track_drag->spacer = manage (new Gtk::EventBox);
+			track_drag->spacer->set_size_request (-1, track_drag_spacer_height);
+			track_drag->spacer->show ();
+			edit_controls_vbox.pack_start (*track_drag->spacer, false, false);
+		}
+
+		edit_controls_vbox.reorder_child (*track_drag->spacer, track_drag->spacer_order);
+	}
+
 	reset_controls_layout_height (position);
 	reset_controls_layout_width ();
 	_full_canvas_height = position;
@@ -7002,3 +7101,105 @@ Editor::default_time_domain () const
 	}
 	return BeatTime;
 }
+
+void
+Editor::start_track_drag (TimeAxisView& tav, int y, Gtk::Widget& w)
+{
+	/* Find the visual order of this track */
+	int nth = 0;
+
+	for (auto const & tv : track_views) {
+		if (!tv->marked_for_display()) {
+			continue;
+		}
+
+		if (tv == &tav) {
+			break;
+		}
+
+		++nth;
+	}
+
+	track_drag = new TrackDrag (dynamic_cast<RouteTimeAxisView*> (&tav));
+
+	/* Create a useful dragging cursor from the first track's name */
+
+	Pango::FontDescription fd (UIConfiguration::instance().get_LargerBoldFont());
+	Gtkmm2ext::Color c (UIConfiguration::instance().color ("midi meter color0"));
+	Gdk::Color color (Gtkmm2ext::gdk_color_from_rgb (c));
+	Glib::RefPtr<Gdk::Pixbuf> pixbuf = Gtkmm2ext::pixbuf_from_string (track_drag->track->route()->name(), fd, 0, 0, color);
+
+	track_drag->drag_cursor = gdk_cursor_new_from_pixbuf (gdk_display_get_default(), pixbuf->gobj(), 0, 0);
+	track_drag->predrag_cursor = gdk_window_get_cursor (edit_controls_vbox.get_window()->gobj());
+
+	gdk_window_set_cursor (edit_controls_vbox.get_toplevel()->get_window()->gobj(), track_drag->drag_cursor);
+
+
+	int xo, yo;
+	w.translate_coordinates (edit_controls_vbox, 0, y, xo, yo);
+
+	track_drag->have_predrag_cursor = true;
+	track_drag->bump_track = nullptr;
+	track_drag->spacer_order = nth;
+	track_drag->previous = yo;
+	track_drag->start = yo;
+}
+
+void
+Editor::mid_track_drag (GdkEventMotion* ev, Gtk::Widget& w)
+{
+	int xo, yo;
+	w.translate_coordinates (edit_controls_vbox, ev->x, ev->y, xo, yo);
+
+	track_drag->current = yo;
+
+	if (track_drag->current > track_drag->previous) {
+		if (track_drag->direction != 1) {
+			track_drag->bump_track = nullptr;
+			track_drag->direction = 1;
+		}
+	} else if (track_drag->current < track_drag->previous) {
+		if (track_drag->direction != -1) {
+			track_drag->bump_track = nullptr;
+			track_drag->direction = -1;
+		}
+	}
+
+	if (track_drag->current == track_drag->previous) {
+		return;
+	}
+
+	redisplay_track_views ();
+	track_drag->previous = yo;
+}
+
+void
+Editor::end_track_drag ()
+{
+	if (track_drag->have_predrag_cursor) {
+		gdk_window_set_cursor (edit_controls_vbox.get_window()->gobj(), track_drag->predrag_cursor);
+	}
+
+
+	if (track_drag->spacer) {
+		edit_controls_vbox.remove (*track_drag->spacer);
+	}
+
+	delete track_drag;
+	track_drag = nullptr;
+
+	redisplay_track_views ();
+}
+
+void
+Editor::get_layout_relative_coordinates (Gtk::Widget& src, int x, int y, int &xo, int &yo)
+{
+	gtk_widget_translate_coordinates (src.gobj(), GTK_WIDGET (controls_layout.gobj()),
+	                                  x, y, &xo, &yo);
+}
+
+bool
+Editor::track_dragging() const
+{
+	return (bool) track_drag;
+}

gtk2_ardour/editor.h

@@ -1409,6 +1409,12 @@ private:
 	void insert_patch_change (bool from_context);
 	void fork_selected_regions ();
 	void fork_regions_from_unselected ();
+	void start_track_drag (TimeAxisView&, int y, Gtk::Widget& w);
+	void mid_track_drag (GdkEventMotion*, Gtk::Widget& e);
+	void end_track_drag ();
+	void maybe_place_drag_spacer ();
+	void get_layout_relative_coordinates (Gtk::Widget&, int x, int y, int &xo, int &yo);
+	bool track_dragging() const;
 
 	void do_insert_time ();
 	void insert_time (Temporal::timepos_t const &, Temporal::timecnt_t const &, Editing::InsertTimeOption, bool, bool, bool, bool);
@@ -2593,6 +2599,37 @@ private:
 	friend class Drag;
 	friend class RegionCutDrag;
 	friend class RegionDrag;
+
+	struct TrackDrag {
+		RouteTimeAxisView* track;
+		Gtk::EventBox*     spacer;
+		GdkCursor*         drag_cursor;
+		GdkCursor*         predrag_cursor;
+		TimeAxisView*      bump_track;
+		int                spacer_order;
+		double             start;
+		double             current;
+		double             previous;
+		bool               have_predrag_cursor;
+		int                direction;
+
+		TrackDrag (RouteTimeAxisView* rtav)
+			: track (rtav)
+			, spacer (nullptr)
+			, drag_cursor (nullptr)
+			, predrag_cursor (nullptr)
+			, bump_track (nullptr)
+			, spacer_order (-1)
+			, start (-1.)
+			, current (0.)
+			, previous (0.)
+			, have_predrag_cursor (false)
+			, direction (0)
+		{}
+
+	};
+	TrackDrag* track_drag;
+
 	friend class RegionMoveDrag;
 	friend class TrimDrag;
 	friend class MappingTwistDrag;

gtk2_ardour/public_editor.h

@@ -588,6 +588,12 @@ public:
 
 	virtual void set_tempo_curve_range (double& max, double& min) const = 0;
 
+	virtual void start_track_drag (TimeAxisView&, int y, Gtk::Widget&) = 0;
+	virtual void mid_track_drag (GdkEventMotion*, Gtk::Widget&) = 0;
+	virtual void end_track_drag () = 0;
+	virtual void get_layout_relative_coordinates (Gtk::Widget&, int x, int y, int &xo, int &yo) = 0;
+	virtual bool track_dragging() const = 0;
+
 	/// Singleton instance, set up by Editor::Editor()
 
 	static PublicEditor* _instance;

gtk2_ardour/time_axis_view.cc

@@ -438,7 +438,13 @@ TimeAxisView::controls_ebox_button_press (GdkEventButton* event)
 	_ebox_release_can_act = true;
 
 	if (maybe_set_cursor (event->y) > 0) {
+
 		_resize_drag_start = event->y_root;
+
+	} else {
+		if (event->button == 1) {
+			_editor.start_track_drag (*this, event->y, controls_ebox);
+		}
 	}
 
 	return true;
@@ -453,6 +459,12 @@ TimeAxisView::idle_resize (int32_t h)
 bool
 TimeAxisView::controls_ebox_motion (GdkEventMotion* ev)
 {
+	if (_editor.track_dragging()) {
+		_editor.mid_track_drag (ev, controls_ebox);
+		gdk_event_request_motions (ev);
+		return true;
+	}
+
 	if (_resize_drag_start >= 0) {
 
 		/* (ab)use the DragManager to do autoscrolling - basically we
@@ -468,13 +480,15 @@ TimeAxisView::controls_ebox_motion (GdkEventMotion* ev)
 		_editor.add_to_idle_resize (this, delta);
 		_resize_drag_start = ev->y_root;
 		_did_resize = true;
+		gdk_event_request_motions (ev);
+		return true;
 	} else {
 		/* not dragging but ... */
 		maybe_set_cursor (ev->y);
 	}
 
-	gdk_event_request_motions(ev);
-	return true;
+	gdk_event_request_motions (ev);
+	return false;
 }
 
 bool
@@ -518,6 +532,10 @@ TimeAxisView::maybe_set_cursor (int y)
 bool
 TimeAxisView::controls_ebox_button_release (GdkEventButton* ev)
 {
+	if (_editor.track_dragging()) {
+		return false;
+	}
+
 	if (_resize_drag_start >= 0) {
 		if (_have_preresize_cursor) {
 			gdk_window_set_cursor (controls_ebox.get_window()->gobj(), _preresize_cursor);

libs/gtkmm2ext/utils.cc

@@ -194,10 +194,10 @@ Gtkmm2ext::pixbuf_from_string(const string& name, const Pango::FontDescription&
 		int width, height;
 		pixel_size (name, font, width, height);
 		if (clip_width <= 0) {
-			clip_width = width - clip_width;
+			clip_width = width - clip_width;    /* this is an addition because clip_width is negative */
 		}
 		if (clip_height <= 0) {
-			clip_height = height - clip_height;
+			clip_height = height - clip_height; /* this is an addition because clip_height is negative */
 		}
 	}