protected override void MouseUp(MapDocument document, MapViewport viewport, PerspectiveCamera camera, ViewportEvent e)
        {
            if (viewport != ActiveViewport)
            {
                return;
            }

            if (_mouseDown != CircleType.None && _mouseMovePoint != null)
            {
                e.Handled = true;
            }

            var transformation = GetTransformationMatrix(viewport);

            OnTransformed(transformation);
            _mouseDown      = CircleType.None;
            _mouseMovePoint = null;
            viewport.ReleaseInputLock(this);
        }