code: function ( index ) {
  
              var shapeGroup = this.pointShapes[ index ];
  
              // 重绘当前点
              this._redraw( this.getPointByIndex( index ) );
  
              // 清空其他点的
              Utils.each( this.pointShapes, function ( shape, i ) {
  
                  if ( i !== index ) {
  
                      this._clearShapePoint( i );
  
                  }
  
              }, this );
  
              // 更新辅助点
              if ( index > 0 ) {
                  this._drawAssistPoint( index-1 );
              }
  
          }
docs: 选中给定索引的点，该操作会引起其他点的连锁反应