Add invisible Rectangle to initiates Tempo(grid) drags

gtk2_ardour/editor.cc

@@ -300,6 +300,7 @@ Editor::Editor ()
 	, _trackview_group (0)
 	, _drag_motion_group (0)
 	, _canvas_drop_zone (0)
+	, _canvas_grid_zone (0)
 	, no_ruler_shown_update (false)
 	,  ruler_grabbed_widget (0)
 	, ruler_dialog (0)

gtk2_ardour/editor.h

@@ -968,6 +968,9 @@ private:
 	ArdourCanvas::Rectangle* _canvas_drop_zone;
 	bool canvas_drop_zone_event (GdkEvent* event);
 
+	ArdourCanvas::Rectangle* _canvas_grid_zone;
+	bool canvas_grid_zone_event (GdkEvent* event);
+
 	Glib::RefPtr<Gtk::ToggleAction> ruler_minsec_action;
 	Glib::RefPtr<Gtk::ToggleAction> ruler_timecode_action;
 	Glib::RefPtr<Gtk::ToggleAction> ruler_samples_action;

gtk2_ardour/editor_canvas.cc

@@ -292,9 +292,16 @@ Editor::initialize_canvas ()
 	_canvas_drop_zone->set_outline (false);
 	_canvas_drop_zone->Event.connect (sigc::mem_fun (*this, &Editor::canvas_drop_zone_event));
 
-	/* these signals will initially be delivered to the canvas itself, but if they end up remaining unhandled, they are passed to Editor-level
+	_canvas_grid_zone = new ArdourCanvas::Rectangle (hv_scroll_group, ArdourCanvas::Rect (0.0, 0.0, ArdourCanvas::COORD_MAX, 0.0));
-	   handlers.
+	/* this thing is transparent */
-	*/
+	_canvas_grid_zone->set_fill (false);
+	_canvas_grid_zone->set_outline (false);
+	_canvas_grid_zone->Event.connect (sigc::mem_fun (*this, &Editor::canvas_grid_zone_event));
+	_canvas_grid_zone->set_ignore_events (true);
+
+	/* these signals will initially be delivered to the canvas itself, but if they end up remaining unhandled,
+	 * they are passed to Editor-level handlers.
+	 */
 
 	_track_canvas->signal_scroll_event().connect (sigc::bind (sigc::mem_fun (*this, &Editor::canvas_scroll_event), true));
 	_track_canvas->signal_motion_notify_event().connect (sigc::mem_fun (*this, &Editor::track_canvas_motion_notify_event));
@@ -350,6 +357,8 @@ Editor::track_canvas_viewport_size_allocated ()
 
 	_canvas_drop_zone->set_y1 (_canvas_drop_zone->y0() + (_visible_canvas_height - 20.0));
 
+	_canvas_grid_zone->set_y1 (_visible_canvas_height);
+
 	// SHOWTRACKS
 
 	if (height_changed) {
@@ -1508,6 +1517,7 @@ Editor::which_canvas_cursor(ItemType type) const
 	case VideoBarItem:
 	case TransportMarkerBarItem:
 	case DropZoneItem:
+	case GridZoneItem:
 	case SelectionMarkerItem:
 		cursor = _cursors->grabber;
 		break;

gtk2_ardour/editor_canvas_events.cc

@@ -1160,8 +1160,8 @@ Editor::canvas_drop_zone_event (GdkEvent* event)
 
 	case GDK_SCROLL:
 		/* convert coordinates back into window space so that
-		   we can just call canvas_scroll_event().
+		 * we can just call canvas_scroll_event().
-		*/
+		 */
 		winpos = _track_canvas->canvas_to_window (Duple (event->scroll.x, event->scroll.y));
 		scroll = event->scroll;
 		scroll.x = winpos.x;
@@ -1186,6 +1186,50 @@ Editor::canvas_drop_zone_event (GdkEvent* event)
 	return true;
 }
 
+bool
+Editor::canvas_grid_zone_event (GdkEvent* event)
+{
+	GdkEventScroll scroll;
+	ArdourCanvas::Duple winpos;
+
+	switch (event->type) {
+
+		case GDK_BUTTON_PRESS:
+			choose_mapping_drag (_canvas_grid_zone, event);
+			break;
+
+		case GDK_BUTTON_RELEASE:
+			return typed_event (_canvas_grid_zone, event, GridZoneItem);
+			break;
+
+		case GDK_SCROLL:
+			/* convert coordinates back into window space so that
+			 * we can just call canvas_scroll_event().
+			 */
+			winpos   = _track_canvas->canvas_to_window (Duple (event->scroll.x, event->scroll.y));
+			scroll   = event->scroll;
+			scroll.x = winpos.x;
+			scroll.y = winpos.y;
+			return canvas_scroll_event (&scroll, true);
+			break;
+
+		case GDK_ENTER_NOTIFY:
+			return typed_event (_canvas_grid_zone, event, GridZoneItem);
+
+		case GDK_LEAVE_NOTIFY:
+			return typed_event (_canvas_grid_zone, event, GridZoneItem);
+
+		case GDK_MOTION_NOTIFY:
+			return motion_handler (_canvas_grid_zone, event);
+			break;
+
+		default:
+			break;
+	}
+
+	return true;
+}
+
 bool
 Editor::track_canvas_drag_motion (Glib::RefPtr<Gdk::DragContext> const& context, int x, int y, guint time)
 {

gtk2_ardour/editor_items.h

@@ -69,6 +69,7 @@ enum ItemType {
 	SamplesRulerItem,
 	SelectionMarkerItem,
 	DropZoneItem,
+	GridZoneItem,
 	VelocityItem,
 	VelocityBaseItem,
 

gtk2_ardour/editor_mouse.cc

@@ -1759,6 +1759,7 @@ Editor::button_release_handler (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 				}
 				break;
 
+			case GridZoneItem:
 			default:
 				break;
 			}
@@ -1854,6 +1855,7 @@ Editor::button_release_handler (ArdourCanvas::Item* item, GdkEvent* event, ItemT
 			}
 			return true;
 
+		case GridZoneItem:
 		case MappingBarItem:
 			return true;
 
@@ -2020,6 +2022,8 @@ Editor::enter_handler (ArdourCanvas::Item* item, GdkEvent* event, ItemType item_
 	switch (item_type) {
 	case MappingBarItem:
 		break;
+	case GridZoneItem:
+		break;
 
 	case ControlPointItem:
 		if (mouse_mode == MouseDraw || mouse_mode == MouseObject || mouse_mode == MouseContent) {
@@ -2167,6 +2171,7 @@ Editor::leave_handler (ArdourCanvas::Item* item, GdkEvent*, ItemType item_type)
 
 	switch (item_type) {
 	case MappingBarItem:
+	case GridZoneItem:
 		break;
 
 	case ControlPointItem: