code: function updateBezier ( controller, point ) {
  
          var bezierPoint = new BezierPoint( point.x, point.y, true );
  
          //添加可绘制控制点
          controller.getPointGroup().addPoint( bezierPoint.clone() );
  
          //记录贝塞尔的控制点
          controller.addPoint( bezierPoint );
  
          //更新贝塞尔曲线的点
          controller.getBezier().setPoints( controller.getPoints() );
  
  
      }
docs: 画贝塞尔曲线