code: function() {
              _updateOrigin();
              var geom = conn.getConnector().getGeometry();
              if (geom && geom.controlPoints) {
                  cp = geom.controlPoints;
                  cp1[0] = geom.controlPoints[0][0];
                  cp1[1] = geom.controlPoints[0][1];
                  cp2[0] = geom.controlPoints[1][0];
                  cp2[1] = geom.controlPoints[1][1];
              }
          }
docs: updates the current origin of the connector's SVG element (the location of its to left corner wrt the origin of the jsplumb instance's container). Then updates the offset of the source and target points from the origin of the SVG element. Finally, extracts the control point information from the connection, either as geometry (if previously edited or set) or from the computed control points.  The offset of the source and target points is of interest because control points are treated as being with respect to the source point.  When you drag a handle, you get an offset for it wrt the the jsplumb instance's container. You can then adjust this