working track drag-n-drop, re-picked from a 2nd implementation on a branch

gtk2_ardour/editor.cc

@@ -6184,6 +6184,54 @@ struct TrackViewStripableSorter
   }
 };
 
+static const int track_drag_spacer_height = 25;
+
+void
+Editor::maybe_move_tracks ()
+{
+	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->bump_track = tv;
+					move_selected_tracks (true);
+				}
+
+			} else if (track_drag->direction > 0) {
+
+				/* dragging down */
+
+				if (track_drag->current > (tv->y_position() + (tv->effective_height() / 2))) {
+					track_drag->bump_track = tv;
+					move_selected_tracks (false);
+				}
+			}
+
+			break;
+		}
+	}
+}
+
 bool
 Editor::redisplay_track_views ()
 {
@@ -6200,21 +6248,24 @@ Editor::redisplay_track_views ()
 
 	track_views.sort (TrackViewStripableSorter ());
 
-	uint32_t position;
-	TrackViewList::const_iterator i;
+	if (track_drag) { //  && track_drag->spacer) {
+		maybe_move_tracks ();
+	}
 
 	/* 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) {
 
 		if (tv->marked_for_display ()) {
 			position += tv->show_at (position, n, &edit_controls_vbox);
 		} else {
 			tv->hide ();
 		}
+
 		n++;
 	}
 
@@ -7016,3 +7067,74 @@ Editor::default_time_domain () const
 	}
 	return BeatTime;
 }
+
+void
+Editor::start_track_drag (TimeAxisView& tav, int y, Gtk::Widget& w)
+{
+	track_drag = new TrackDrag (dynamic_cast<RouteTimeAxisView*> (&tav));
+
+	track_drag->drag_cursor = _cursors->move->gobj();
+	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->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);
+
+	if (track_drag->first_move) {
+		if (!track_drag->track->selected()) {
+			set_selected_track (*track_drag->track, Selection::Set, false);
+		}
+		track_drag->first_move = false;
+	}
+
+	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_toplevel()->get_window()->gobj(), track_drag->predrag_cursor);
+	}
+
+	delete track_drag;
+	track_drag = nullptr;
+}
+
+bool
+Editor::track_dragging() const
+{
+	return (bool) track_drag;
+}

gtk2_ardour/editor.h

@@ -1416,8 +1416,7 @@ private:
 	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);
+	void maybe_move_tracks ();
 	bool track_dragging() const;
 
 	void do_insert_time ();
@@ -2607,29 +2606,27 @@ private:
 
 	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;
+		bool               first_move;
 
 		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)
+			, first_move (true)
 		{}
 
 	};

gtk2_ardour/public_editor.h

@@ -591,7 +591,6 @@ public:
 	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()

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
@@ -519,28 +533,28 @@ bool
 TimeAxisView::controls_ebox_button_release (GdkEventButton* ev)
 {
 	if (_editor.track_dragging()) {
-		return false;
+		_editor.end_track_drag ();
+	} else {
+		if (_resize_drag_start >= 0) {
+			if (_have_preresize_cursor) {
+				gdk_window_set_cursor (controls_ebox.get_window()->gobj(), _preresize_cursor);
+				_preresize_cursor = 0;
+				_have_preresize_cursor = false;
+			}
+			_editor.stop_canvas_autoscroll ();
+			_resize_drag_start = -1;
+			if (_did_resize) {
+				_did_resize = false;
+				// don't change selection
+				return true;
+			}
 	}
 
-	if (_resize_drag_start >= 0) {
-		if (_have_preresize_cursor) {
-			gdk_window_set_cursor (controls_ebox.get_window()->gobj(), _preresize_cursor);
-			_preresize_cursor = 0;
-			_have_preresize_cursor = false;
-		}
-		_editor.stop_canvas_autoscroll ();
-		_resize_drag_start = -1;
-		if (_did_resize) {
-			_did_resize = false;
-			// don't change selection
+		if (!_ebox_release_can_act) {
 			return true;
 		}
 	}
 
-	if (!_ebox_release_can_act) {
-		return true;
-	}
-
 	switch (ev->button) {
 	case 1:
 		if (selectable()) {