Refactor scrolling track canvas in Editor class into two utility methods

gtk2_ardour/editor.h

@@ -374,6 +374,9 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 	bool scroll_up_one_track (bool skip_child_views = false);
 	bool scroll_down_one_track (bool skip_child_views = false);
 
+	void scroll_left_step ();
+	void scroll_right_step ();
+
 	void prepare_for_cleanup ();
 	void finish_cleanup ();
 

gtk2_ardour/editor_canvas_events.cc

@@ -64,7 +64,6 @@ using Gtkmm2ext::Keyboard;
 bool
 Editor::track_canvas_scroll (GdkEventScroll* ev)
 {
-	framepos_t xdelta;
 	int direction = ev->direction;
 
 	/* this event arrives without transformation by the canvas, so we have
@@ -134,21 +133,13 @@ Editor::track_canvas_scroll (GdkEventScroll* ev)
 		break;
 
 	case GDK_SCROLL_LEFT:
-		xdelta = (current_page_samples() / 8);
-		if (leftmost_frame > xdelta) {
-			reset_x_origin (leftmost_frame - xdelta);
-		} else {
-			reset_x_origin (0);
-		}
+		scroll_left_step ();
+		return true;
 		break;
 
 	case GDK_SCROLL_RIGHT:
-		xdelta = (current_page_samples() / 8);
-		if (max_framepos - xdelta > leftmost_frame) {
-			reset_x_origin (leftmost_frame + xdelta);
-		} else {
-			reset_x_origin (max_framepos - current_page_samples());
-		}
+		scroll_right_step ();
+		return true;
 		break;
 
 	default:

gtk2_ardour/editor_ops.cc

@@ -1589,6 +1589,31 @@ Editor::scroll_up_one_track (bool skip_child_views)
 	return false;
 }
 
+void
+Editor::scroll_left_step ()
+{
+	framepos_t xdelta = (current_page_samples() / 8);
+
+	if (leftmost_frame > xdelta) {
+		reset_x_origin (leftmost_frame - xdelta);
+	} else {
+		reset_x_origin (0);
+	}
+}
+
+
+void
+Editor::scroll_right_step ()
+{
+	framepos_t xdelta = (current_page_samples() / 8);
+
+	if (max_framepos - xdelta > leftmost_frame) {
+		reset_x_origin (leftmost_frame + xdelta);
+	} else {
+		reset_x_origin (max_framepos - current_page_samples());
+	}
+}
+
 /* ZOOM */
 
 void